Fish kill
Encyclopedia
The term fish kill, known also as fish die-off and (in Britain) as fish mortality
, is a localized die-off of fish
populations which may also be associated with more generalised mortality of aquatic life. The most common cause is reduced oxygen in the water, which in turn may be due to factors such as drought
, algae bloom, overpopulation
, or a sustained increase in water temperature. Infectious diseases and parasites
can also lead to fish kill. Toxicity
is a real but far less common cause of fish kill.
stress and are usually investigated as a matter of urgency by environmental agencies to determine the cause of the kill. Many fish species have a relatively low tolerance of variations in environmental conditions and their death is often a potent indicator of problems in their environment that may be affecting other animals and plants and may have a direct impact on other uses of the water such as for drinking water
production. Pollution events may affect fish species and fish age classes
in different ways. If it is a cold-related fish kill, juvenile fish and/or species that are not cold-tolerant may be selectively affected. If toxicity
is the cause, species are more generally affected and the event may include amphibians and shellfish as well. A reduction in dissolved oxygen may affect larger specimens more than smaller fish as these may be able to access oxygen richer water at the surface, at least for a short time.
Fish kills may result from a variety of causes. Of known causes, fish kills are most frequently caused by pollution from agricultural runoff or biotoxins. ecological hypoxia
(oxygen depletion)is one of the most common natural causes of fish kills. The hypoxic event may be brought on by factors such as algae blooms, drought
s, high temperatures and thermal pollution
. Fish kills may also occur due to the presence of disease
, agricultural and sewage
runoff
, oil
or hazardous waste
spills, sea-quake
s, inappropriate re-stocking of fish, poaching
with chemicals, underwater explosion
s, and other catastrophic events that upset a normally stable aquatic population. Because of the difficulty and lack of standard protocol to investigate fish kills, many fish kill cases are designated as having an 'unknown' cause.
. The amount of oxygen that can be dissolved in water depends on the atmospheric pressure
, the water temperature and whether the water is salty. For example, at 20°C (68°F) and one atmosphere of pressure, a maximum of 8 mg/l of oxygen can dissolve in sea water (35 mg/l salinity
) while a maximum of 9 mg/l of oxygen can dissolve in fresh water. The amount of oxygen that can be dissolved in the water decreases by about 1 mg/l for each 10°C increase in water temperature above 20°C.
Many cold water fish that have evolved to live in clean cold waters become stressed when oxygen concentrations fall below 8 mg/l whilst warm water fish generally need at least 5 ppm (5 mg/l) of dissolved oxygen. Fish can endure short periods of reduced oxygen. Depleted oxygen levels are the most common cause of fish kills. Oxygen levels normally fluctuate even over the course of a day and are affected by weather, temperature, the amount of sunlight available, and the amount of living and dead plant and animal matter in the water. In temperate zones oxygen levels in eutrophic rivers in summertime can exhibit very large diurnal
fluctuations with many hours of oxygen supersaturation
during daylight followed by oxygen depletion at night. Associated with these photosynthetic rhythms there is a matching pH
rhythm as bicarbonate ion is metabolised by plant cells. This can lead to pH stress even when oxygen levels are high.
Additional dissolved organic loads are the most common cause of oxygen depletion and such organic loads may come from sewage
, farm
waste, tip leachate
and many other sources
For example, since 2004 fish kills have been observed in the Shenandoah River
basin in the spring, from the time water temperatures are in the 50s (°F) until they reach the mid-70s. So far, investigators suspect certain bacteria
, along with environmental and contaminant factors that may cause immune suppression.
In fish farming
, where populations are optimized for the available resources, parasites or disease
can spread quickly. In channel catfish
aquaculture ponds, for example, the “hamburger gill disease” is caused by a protozoan called Aurantiactinomyxon and can kill all the fish in an affected pond. In addition to altered behaviour, affected fish have swollen gills that are mottled and have the appearance of ground hamburger meat.
Some early warning signs of fish suffering from disease or parasite infections include:
, surface runoff
, chemical spills, hazardous waste
spills can all potentially lead to water toxicity
and fish kill. Some algae species also produce toxins. In Florida, these include Aphanizomenon
, Anabaena
and Microcystis. Some notable fish kills in Louisiana in the 1950s were due to a specific pesticide
called endrin
.
Natural instances of toxic conditions can occur, especially in poorly buffer
ed water. Aluminium
compound can cause complete fish kills, sometimes associated with autumn turn-over of lakes leading to complex chemical interactions between pH, calcium
ions and complex polymeric
salts of Aluminium
Human-induced fish kills are unusual, but occasionally a spilled substance causes direct toxicity or a shift in water temperature or pH that can lead to fish kill. For example, in 1997 a phosphate
plant in Mulberry
, Florida, accidentally dumped 60 million gallons of acidic process water into Skinned Sapling Creek, reducing the pH from about 8 to less than 4 along for about 36 miles and resulting in the death of about 1.3 million fish.
It is often difficult or impossible to determine whether a potential toxin is the direct cause of a fish kill. For example, hundreds of thousands of fish died after an accidental spill of bourbon whiskey
into the Kentucky River
near Lawrenceburg. However, officials could not determine whether the fish kill was due to the bourbon directly or to oxygen depletion that resulted when aquatic microbes rapidly began to consume and digest the liquor.
Cyanide
is a particular toxic compound that has been used to poach fish. In cyanide poisoning the gills turn a distinctive cherry red. Chlorine
introduced as alkaline hypochlorite solution is also extremely toxic leaving pale mucilaginous gills and an over-production of mucilage across the whole body. Lime
produces similar symptoms but is also often associated with milk eyes.
An algae bloom is the appearance of a large amount of algae
or scum
floating on the surface of a body of water. Algae blooms are a natural occurrence in nutrient-rich lakes and rivers, though sometimes increased nutrient levels leading to algae blooms are due to fertilizer or animal waste runoff. A few species of algae produce toxin
s, but most fish kills due to algae bloom are a result of decreased oxygen levels. When the algae die, decomposition
uses oxygen in the water that would be available to fish. A fish kill in a lake in Estonia in 2002 was attributed to a combination of algae bloom and high temperatures. When people manage algae blooms in fish pond
s, it is recommended that treatments be staggered to avoid too much algae dying at once, which may result in a large drop in oxygen content.
Some diseases result in mass die offs. One of the more bizarre and recently discovered diseases produces huge fish kills in shallow marine waters. It is caused by the ambush predator
dinoflagellate
Pfiesteria piscicida
. When large numbers of fish, like shoaling
forage fish
, are in confined situations such as shallow bays, the excretions from the fish encourage this dinoflagellate, which is not normally toxic, to produce free-swimming zoospore
s. If the fish remain in the area, continuing to provide nourishment, then the zoospores start secreting a neurotoxin
. This toxin results in the fish developing bleeding lesions, and their skin flakes off in the water. The dinoflagellates then eat the blood and flakes of tissue while the affected fish die. Fish kills by this dinoflagellate are common, and they may also have been responsible for kills in the past which were thought to have had other causes. Kills like these can be viewed as natural mechanisms for regulating the population of exceptionally abundant fish. The rate at which the kills occur increases as organically polluted land runoff increases.
Red tide
is the name commonly given to an algal bloom of Karenia brevis
, a microscopic marine dinoflagellate which is common in Gulf of Mexico
waters. In high concentrations it discolours the water which often appears reddish-brown in colour. It produces a toxin which paralyses the central nervous system of fish so they cannot breathe. Dead fish wash up on beaches around Texas and Florida. Humans can also become seriously ill from eating oysters and other shellfish contaminated with the red tide toxin.
The term "red tide" is also commonly used to describe harmful algal blooms on the northern east coast of the United States, particularly in the Gulf of Maine
. This type of bloom is caused by another species of dinoflagellate
known as Alexandrium fundyense
.
These blooms are natural phenomenon, but the exact cause or combination of factors that result in red tides outbreak not fully understood.
ing biological material in general to a body of water leads to oxygen depletion as microorganism
s use up available oxygen in the process of breaking down organic matter
. For example, a 10-mile-long fish kill in September, 2010, in the Sangamon River
in Illinois was traced to discharge of animal waste into the river from a large dairy
operation. The illegal discharge resulted in a complete kill of fish, frogs, mussel
s and mudpuppies
.
Some species of fish exhibit mass simultaneous mortality as part of their natural life cycle.
Fish kill due to spawning fatalities can occur when fish are exhausted from spawning activities
such as courtship, nest building, and the release of eggs or milt
(sperm). Fish are generally weaker after spawning and are less resilient than usual to smaller changes in the environment. Examples include the Atlantic salmon
and the Sockeye salmon
where many of the females routinely die immediately after spawning.
was attributed to low oxygen as a result of high temperatures.
A massive (hundreds of thousands) fish kill at the mouth of the Mississippi River
in Louisiana, September, 2010, was attributed to a combination of high temperatures and low tide. Such kills are known to happen in this region in late summer and early fall, but this one was unusually large.
A short period of hot weather can increase temperatures in the surface layer of water, as the warmer water tends to stay near the surface and be further heated by the air. In this case, the top warmer layer may have more oxygen than the lower, cooler layers because it has constant access to atmospheric oxygen. If a heavy wind or cold rain then occurs (usually during the autumn but sometimes in summer), the layers can mix
. If the volume of low oxygen water is much greater than the volume in the warm surface layer, this mixing can reduce oxygen levels throughout the water column and lead to fish kill.
Fish kills can also result from a dramatic or prolonged drop in air (and thus, water) temperature. This kind of fish kill is selective - usually the dead fish are species that cannot tolerate cold. This has been observed in cases where a fish native to a more tropical region has been introduced to cooler waters, such as the introduction of the tilapia
to bodies of water in Florida. Native to Africa’s Nile River, the tilapia stop feeding when water temperatures drop below 60°F and die when it reaches 45°F. Thus, tilapia that have survived and successfully reproduced in Florida are occasionally killed by a winter cold front.
In January, 2011, a selective fish kill affecting an estimated 2 million juvenile spot fish
was attributed to a combination of cold stress and overpopulation after a particularly large spawn.
Underwater explosion
s can lead to fish kill, and fish with swim bladders are more susceptible. Sometimes underwater explosions are used on purpose to induce fish kills, a generally illegal practice known as blast fishing
. Underwater explosions may be accidental or planned, such as for construction, seismic testing, mining or blast testing of structures under water. In many places, an assessment of potential effects of underwater explosions on marine life must be completed and preventive measures taken before blasting.
A drought
can lead to lower water volumes so that even if the water contains a high level of dissolved oxygen, the reduced volume may not be enough for the fish population. Droughts often occur in conjunction with high temperatures so that the oxygen carrying capacity
of the water may also be reduced. Low river flows also reduce the available dilution for permitted discharges of treated sewage or industrial waste
. The reduced dilution increases the organic demand for oxygen further reducing the oxygen concentration available to fish
Overstocking of fish (or an unusually large spawn
) can also result in inland fish kills. Fish kill due to insufficient oxygen is really a matter of too much demand and too little supply for whatever reason(s). Recommended stocking densities
are available from many sources for bodies of water ranging from a home aquarium
or backyard pond to commercial aquaculture
facilities.
Some very large fish kills may never be estimated because of these factors. The discharge of red aluminium sludge
from a reservoir in Hungary
into the Marcai River is acknowledged as causing environmental devastation, The loss of adult fish also can have long term impacts on the success of the fishery as the following year's spawning
stock may have been lost and recovery of the pre-kill population may take years to recover. The loss of food supplies or recreational income may be very significant to the local economy.
Many countries in the developed world have specific provisions in place to encourage the public to report fish kills so that a proper investigation can take place. Investigation of the cause of a kill requires a multi-disciplinary approach including on-site environmental measurements, investigation of inputs, review of meteorology and past history, toxicology, fish autopsy, invertebrate analysis and a robust knowledge of the area and its problems.
Fish mortality
Fish mortality is a term widely used in fisheries science that denotes the loss of fish from a stock through death. The term is also commonly used in British English as a synonym for fish kill. Fish mortality can be divided into two types:...
, is a localized die-off of fish
Fish
Fish are a paraphyletic group of organisms that consist of all gill-bearing aquatic vertebrate animals that lack limbs with digits. Included in this definition are the living hagfish, lampreys, and cartilaginous and bony fish, as well as various extinct related groups...
populations which may also be associated with more generalised mortality of aquatic life. The most common cause is reduced oxygen in the water, which in turn may be due to factors such as drought
Drought
A drought is an extended period of months or years when a region notes a deficiency in its water supply. Generally, this occurs when a region receives consistently below average precipitation. It can have a substantial impact on the ecosystem and agriculture of the affected region...
, algae bloom, overpopulation
Overpopulation
Overpopulation is a condition where an organism's numbers exceed the carrying capacity of its habitat. The term often refers to the relationship between the human population and its environment, the Earth...
, or a sustained increase in water temperature. Infectious diseases and parasites
Fish diseases and parasites
Like humans and other animals, fish suffer from diseases and parasites. Fish defences against disease are specific and non-specific. Non-specific defences include skin and scales, as well as the mucus layer secreted by the epidermis that traps microorganisms and inhibits their growth...
can also lead to fish kill. Toxicity
Toxicity
Toxicity is the degree to which a substance can damage a living or non-living organisms. Toxicity can refer to the effect on a whole organism, such as an animal, bacterium, or plant, as well as the effect on a substructure of the organism, such as a cell or an organ , such as the liver...
is a real but far less common cause of fish kill.
Indicators of environmental stress
Fish kills are often the first visible signs of environmentalEnvironmental quality
Environmental quality is a set of properties and characteristics of the environment, either generalized or local, as they impinge on human beings and other organisms...
stress and are usually investigated as a matter of urgency by environmental agencies to determine the cause of the kill. Many fish species have a relatively low tolerance of variations in environmental conditions and their death is often a potent indicator of problems in their environment that may be affecting other animals and plants and may have a direct impact on other uses of the water such as for drinking water
Drinking water
Drinking water or potable water is water pure enough to be consumed or used with low risk of immediate or long term harm. In most developed countries, the water supplied to households, commerce and industry is all of drinking water standard, even though only a very small proportion is actually...
production. Pollution events may affect fish species and fish age classes
Age class structure
Age class structure in fisheries and wildlife management is a part of population assessment. Age can be determined by counting growth rings in fish scales, otoliths, cross-sections of fin spines for species with thick spines such as triggerfish, or teeth for a few species. Each method has its...
in different ways. If it is a cold-related fish kill, juvenile fish and/or species that are not cold-tolerant may be selectively affected. If toxicity
Toxicity
Toxicity is the degree to which a substance can damage a living or non-living organisms. Toxicity can refer to the effect on a whole organism, such as an animal, bacterium, or plant, as well as the effect on a substructure of the organism, such as a cell or an organ , such as the liver...
is the cause, species are more generally affected and the event may include amphibians and shellfish as well. A reduction in dissolved oxygen may affect larger specimens more than smaller fish as these may be able to access oxygen richer water at the surface, at least for a short time.
Causes
Hypoxia (environmental)
Hypoxia, or oxygen depletion, is a phenomenon that occurs in aquatic environments as dissolved oxygen becomes reduced in concentration to a point where it becomes detrimental to aquatic organisms living in the system...
(oxygen depletion)is one of the most common natural causes of fish kills. The hypoxic event may be brought on by factors such as algae blooms, drought
Drought
A drought is an extended period of months or years when a region notes a deficiency in its water supply. Generally, this occurs when a region receives consistently below average precipitation. It can have a substantial impact on the ecosystem and agriculture of the affected region...
s, high temperatures and thermal pollution
Thermal pollution
Thermal pollution is the degradation of water quality by any process that changes ambient water temperature.A common cause of thermal pollution is the use of water as a coolant by power plants and industrial manufacturers...
. Fish kills may also occur due to the presence of disease
Disease
A disease is an abnormal condition affecting the body of an organism. It is often construed to be a medical condition associated with specific symptoms and signs. It may be caused by external factors, such as infectious disease, or it may be caused by internal dysfunctions, such as autoimmune...
, agricultural and sewage
Sewage
Sewage is water-carried waste, in solution or suspension, that is intended to be removed from a community. Also known as wastewater, it is more than 99% water and is characterized by volume or rate of flow, physical condition, chemical constituents and the bacteriological organisms that it contains...
runoff
Surface runoff
Surface runoff is the water flow that occurs when soil is infiltrated to full capacity and excess water from rain, meltwater, or other sources flows over the land. This is a major component of the water cycle. Runoff that occurs on surfaces before reaching a channel is also called a nonpoint source...
, oil
Oil
An oil is any substance that is liquid at ambient temperatures and does not mix with water but may mix with other oils and organic solvents. This general definition includes vegetable oils, volatile essential oils, petrochemical oils, and synthetic oils....
or hazardous waste
Hazardous waste
A hazardous waste is waste that poses substantial or potential threats to public health or the environment. According to the U.S. environmental laws hazardous wastes fall into two major categories: characteristic wastes and listed wastes.Characteristic hazardous wastes are materials that are known...
spills, sea-quake
Earthquake
An earthquake is the result of a sudden release of energy in the Earth's crust that creates seismic waves. The seismicity, seismism or seismic activity of an area refers to the frequency, type and size of earthquakes experienced over a period of time...
s, inappropriate re-stocking of fish, poaching
Poaching
Poaching is the illegal taking of wild plants or animals contrary to local and international conservation and wildlife management laws. Violations of hunting laws and regulations are normally punishable by law and, collectively, such violations are known as poaching.It may be illegal and in...
with chemicals, underwater explosion
Explosion
An explosion is a rapid increase in volume and release of energy in an extreme manner, usually with the generation of high temperatures and the release of gases. An explosion creates a shock wave. If the shock wave is a supersonic detonation, then the source of the blast is called a "high explosive"...
s, and other catastrophic events that upset a normally stable aquatic population. Because of the difficulty and lack of standard protocol to investigate fish kills, many fish kill cases are designated as having an 'unknown' cause.
Oxygen depletion
Oxygen enters the water through diffusionDiffusion
Molecular diffusion, often called simply diffusion, is the thermal motion of all particles at temperatures above absolute zero. The rate of this movement is a function of temperature, viscosity of the fluid and the size of the particles...
. The amount of oxygen that can be dissolved in water depends on the atmospheric pressure
Atmospheric pressure
Atmospheric pressure is the force per unit area exerted into a surface by the weight of air above that surface in the atmosphere of Earth . In most circumstances atmospheric pressure is closely approximated by the hydrostatic pressure caused by the weight of air above the measurement point...
, the water temperature and whether the water is salty. For example, at 20°C (68°F) and one atmosphere of pressure, a maximum of 8 mg/l of oxygen can dissolve in sea water (35 mg/l salinity
Salinity
Salinity is the saltiness or dissolved salt content of a body of water. It is a general term used to describe the levels of different salts such as sodium chloride, magnesium and calcium sulfates, and bicarbonates...
) while a maximum of 9 mg/l of oxygen can dissolve in fresh water. The amount of oxygen that can be dissolved in the water decreases by about 1 mg/l for each 10°C increase in water temperature above 20°C.
Many cold water fish that have evolved to live in clean cold waters become stressed when oxygen concentrations fall below 8 mg/l whilst warm water fish generally need at least 5 ppm (5 mg/l) of dissolved oxygen. Fish can endure short periods of reduced oxygen. Depleted oxygen levels are the most common cause of fish kills. Oxygen levels normally fluctuate even over the course of a day and are affected by weather, temperature, the amount of sunlight available, and the amount of living and dead plant and animal matter in the water. In temperate zones oxygen levels in eutrophic rivers in summertime can exhibit very large diurnal
Diurnal cycle
A diurnal cycle is any pattern that recurs every 24 hours as a result of one full rotation of the Earth.In climatology, the diurnal cycle is one of the most basic forms of climate patterns. The most familiar such pattern is the diurnal temperature variation...
fluctuations with many hours of oxygen supersaturation
Supersaturation
The term supersaturation refers to a solution that contains more of the dissolved material than could be dissolved by the solvent under normal circumstances...
during daylight followed by oxygen depletion at night. Associated with these photosynthetic rhythms there is a matching pH
PH
In chemistry, pH is a measure of the acidity or basicity of an aqueous solution. Pure water is said to be neutral, with a pH close to 7.0 at . Solutions with a pH less than 7 are said to be acidic and solutions with a pH greater than 7 are basic or alkaline...
rhythm as bicarbonate ion is metabolised by plant cells. This can lead to pH stress even when oxygen levels are high.
Additional dissolved organic loads are the most common cause of oxygen depletion and such organic loads may come from sewage
Sewage
Sewage is water-carried waste, in solution or suspension, that is intended to be removed from a community. Also known as wastewater, it is more than 99% water and is characterized by volume or rate of flow, physical condition, chemical constituents and the bacteriological organisms that it contains...
, farm
Farm
A farm is an area of land, or, for aquaculture, lake, river or sea, including various structures, devoted primarily to the practice of producing and managing food , fibres and, increasingly, fuel. It is the basic production facility in food production. Farms may be owned and operated by a single...
waste, tip leachate
Leachate
Leachate is any liquid that, in passing through matter, extracts solutes, suspended solids or any other component of the material through which it has passed....
and many other sources
Diseases and parasites
Fish are subject to various viruses, bacteria and fungi in addition to parasites such as protozoans, flukes and worms, or crustaceans. These are naturally occurring in many bodies of water, and fish that are stressed for other reasons, such as spawning or suboptimal water quality, are more susceptible. Signs of disease include sores, missing scales or lack of slime, strange growths or visible parasites, and abnormal behaviour – lazy, erratic, gasping at the water surface or floating head, tail or belly up.For example, since 2004 fish kills have been observed in the Shenandoah River
Shenandoah River
The Shenandoah River is a tributary of the Potomac River, long with two forks approximately long each, in the U.S. states of Virginia and West Virginia...
basin in the spring, from the time water temperatures are in the 50s (°F) until they reach the mid-70s. So far, investigators suspect certain bacteria
Bacteria
Bacteria are a large domain of prokaryotic microorganisms. Typically a few micrometres in length, bacteria have a wide range of shapes, ranging from spheres to rods and spirals...
, along with environmental and contaminant factors that may cause immune suppression.
In fish farming
Fish farming
Fish farming is the principal form of aquaculture, while other methods may fall under mariculture. Fish farming involves raising fish commercially in tanks or enclosures, usually for food. A facility that releases young fish into the wild for recreational fishing or to supplement a species'...
, where populations are optimized for the available resources, parasites or disease
Disease
A disease is an abnormal condition affecting the body of an organism. It is often construed to be a medical condition associated with specific symptoms and signs. It may be caused by external factors, such as infectious disease, or it may be caused by internal dysfunctions, such as autoimmune...
can spread quickly. In channel catfish
Channel catfish
Channel catfish, Ictalurus punctatus, is North America's most numerous catfish species. It is the official fish of Missouri, Iowa, Nebraska, Kansas, and Tennessee, and is informally referred to as a "channel cat". In the United States they are the most fished catfish species with approximately 8...
aquaculture ponds, for example, the “hamburger gill disease” is caused by a protozoan called Aurantiactinomyxon and can kill all the fish in an affected pond. In addition to altered behaviour, affected fish have swollen gills that are mottled and have the appearance of ground hamburger meat.
Some early warning signs of fish suffering from disease or parasite infections include:
- Discolouration, open sores, reddening of the skin, bleeding, black or white spots on the skin
- Abnormal shape, swollen areas, abnormal lumps, or popeyes
- Abnormal distribution of the fish such as crowding at the surface, inlet, or pond edges (though crowding at the surface during specific times of day, such as early morning, is more likely a sign of low oxygen)
- Abnormal activity such as flashing, twisting, whirling, convulsions, loss of buoyancy
- Listlessness, weakness, sluggishness, lack of activity
- Loss of appetite or refusal to feed
Toxins
Agricultural runoff, sewageSewage
Sewage is water-carried waste, in solution or suspension, that is intended to be removed from a community. Also known as wastewater, it is more than 99% water and is characterized by volume or rate of flow, physical condition, chemical constituents and the bacteriological organisms that it contains...
, surface runoff
Surface runoff
Surface runoff is the water flow that occurs when soil is infiltrated to full capacity and excess water from rain, meltwater, or other sources flows over the land. This is a major component of the water cycle. Runoff that occurs on surfaces before reaching a channel is also called a nonpoint source...
, chemical spills, hazardous waste
Hazardous waste
A hazardous waste is waste that poses substantial or potential threats to public health or the environment. According to the U.S. environmental laws hazardous wastes fall into two major categories: characteristic wastes and listed wastes.Characteristic hazardous wastes are materials that are known...
spills can all potentially lead to water toxicity
Toxicity
Toxicity is the degree to which a substance can damage a living or non-living organisms. Toxicity can refer to the effect on a whole organism, such as an animal, bacterium, or plant, as well as the effect on a substructure of the organism, such as a cell or an organ , such as the liver...
and fish kill. Some algae species also produce toxins. In Florida, these include Aphanizomenon
Aphanizomenon
Aphanizomenon is an important genus of cyanobacteria that inhabits freshwater lakes and can cause choking blooms. Studies on the species Aphanizomenon flos-aquae have shown that it can regulate buoyancy through light-induced changes in turgor pressure...
, Anabaena
Anabaena
Anabaena is a genus of filamentous cyanobacteria that exists as plankton. It is known for its nitrogen fixing abilities, and they form symbiotic relationships with certain plants, such as the mosquito fern. They are one of four genera of cyanobacteria that produce neurotoxins, which are harmful to...
and Microcystis. Some notable fish kills in Louisiana in the 1950s were due to a specific pesticide
Pesticide
Pesticides are substances or mixture of substances intended for preventing, destroying, repelling or mitigating any pest.A pesticide may be a chemical unicycle, biological agent , antimicrobial, disinfectant or device used against any pest...
called endrin
Endrin
Endrin is an organochloride that was primarily used as an insecticide. It is a colourless odorless solid, although commercial samples are often off-white. It is also a rodenticide. This compound became infamous as persistent organic pollutant and for this reason is banned in many...
.
Natural instances of toxic conditions can occur, especially in poorly buffer
Buffer solution
A buffer solution is an aqueous solution consisting of a mixture of a weak acid and its conjugate base or a weak base and its conjugate acid. It has the property that the pH of the solution changes very little when a small amount of strong acid or base is added to it. Buffer solutions are used as a...
ed water. Aluminium
Aluminium
Aluminium or aluminum is a silvery white member of the boron group of chemical elements. It has the symbol Al, and its atomic number is 13. It is not soluble in water under normal circumstances....
compound can cause complete fish kills, sometimes associated with autumn turn-over of lakes leading to complex chemical interactions between pH, calcium
Calcium
Calcium is the chemical element with the symbol Ca and atomic number 20. It has an atomic mass of 40.078 amu. Calcium is a soft gray alkaline earth metal, and is the fifth-most-abundant element by mass in the Earth's crust...
ions and complex polymeric
Polymer
A polymer is a large molecule composed of repeating structural units. These subunits are typically connected by covalent chemical bonds...
salts of Aluminium
Human-induced fish kills are unusual, but occasionally a spilled substance causes direct toxicity or a shift in water temperature or pH that can lead to fish kill. For example, in 1997 a phosphate
Phosphate
A phosphate, an inorganic chemical, is a salt of phosphoric acid. In organic chemistry, a phosphate, or organophosphate, is an ester of phosphoric acid. Organic phosphates are important in biochemistry and biogeochemistry or ecology. Inorganic phosphates are mined to obtain phosphorus for use in...
plant in Mulberry
Mulberry
Morus is a genus of flowering plants in the family Moraceae. The 10–16 species of deciduous trees it contains are commonly known as Mulberries....
, Florida, accidentally dumped 60 million gallons of acidic process water into Skinned Sapling Creek, reducing the pH from about 8 to less than 4 along for about 36 miles and resulting in the death of about 1.3 million fish.
It is often difficult or impossible to determine whether a potential toxin is the direct cause of a fish kill. For example, hundreds of thousands of fish died after an accidental spill of bourbon whiskey
Bourbon whiskey
Bourbon is a type of American whiskey – a barrel-aged distilled spirit made primarily from corn. The name of the spirit derives from its historical association with an area known as Old Bourbon, around what is now Bourbon County, Kentucky . It has been produced since the 18th century...
into the Kentucky River
Kentucky River
The Kentucky River is a tributary of the Ohio River, long, in the U.S. state of Kentucky. The river and its tributaries drain much of the central region of the state, with its upper course passing through the coal-mining regions of the Cumberland Mountains, and its lower course passing through the...
near Lawrenceburg. However, officials could not determine whether the fish kill was due to the bourbon directly or to oxygen depletion that resulted when aquatic microbes rapidly began to consume and digest the liquor.
Cyanide
Cyanide
A cyanide is a chemical compound that contains the cyano group, -C≡N, which consists of a carbon atom triple-bonded to a nitrogen atom. Cyanides most commonly refer to salts of the anion CN−. Most cyanides are highly toxic....
is a particular toxic compound that has been used to poach fish. In cyanide poisoning the gills turn a distinctive cherry red. Chlorine
Chlorine
Chlorine is the chemical element with atomic number 17 and symbol Cl. It is the second lightest halogen, found in the periodic table in group 17. The element forms diatomic molecules under standard conditions, called dichlorine...
introduced as alkaline hypochlorite solution is also extremely toxic leaving pale mucilaginous gills and an over-production of mucilage across the whole body. Lime
Calcium oxide
Calcium oxide , commonly known as quicklime or burnt lime, is a widely used chemical compound. It is a white, caustic, alkaline crystalline solid at room temperature....
produces similar symptoms but is also often associated with milk eyes.
Algae blooms and red tides
An algae bloom is the appearance of a large amount of algae
Algae
Algae are a large and diverse group of simple, typically autotrophic organisms, ranging from unicellular to multicellular forms, such as the giant kelps that grow to 65 meters in length. They are photosynthetic like plants, and "simple" because their tissues are not organized into the many...
or scum
Scum
Scum may refer to:* A layer of impurities that accumulates at the surface of a liquid * A greenish water vegetation , usually found floating on the surface of ponds...
floating on the surface of a body of water. Algae blooms are a natural occurrence in nutrient-rich lakes and rivers, though sometimes increased nutrient levels leading to algae blooms are due to fertilizer or animal waste runoff. A few species of algae produce toxin
Toxin
A toxin is a poisonous substance produced within living cells or organisms; man-made substances created by artificial processes are thus excluded...
s, but most fish kills due to algae bloom are a result of decreased oxygen levels. When the algae die, decomposition
Decomposition
Decomposition is the process by which organic material is broken down into simpler forms of matter. The process is essential for recycling the finite matter that occupies physical space in the biome. Bodies of living organisms begin to decompose shortly after death...
uses oxygen in the water that would be available to fish. A fish kill in a lake in Estonia in 2002 was attributed to a combination of algae bloom and high temperatures. When people manage algae blooms in fish pond
Fish pond
A fish pond, or fishpond, is a controlled pond, artificial lake, or reservoir that is stocked with fish and is used in aquaculture for fish farming, or is used for recreational fishing or for ornamental purposes...
s, it is recommended that treatments be staggered to avoid too much algae dying at once, which may result in a large drop in oxygen content.
Some diseases result in mass die offs. One of the more bizarre and recently discovered diseases produces huge fish kills in shallow marine waters. It is caused by the ambush predator
Ambush predator
Ambush predators or sit-and-wait predators are carnivorous animals that capture prey by stealth or cunning, not by speed or necessarily by strength. These organisms usually hide motionless and wait for prey to come within striking distance. They are often camouflaged, and may be solitary...
dinoflagellate
Dinoflagellate
The dinoflagellates are a large group of flagellate protists. Most are marine plankton, but they are common in fresh water habitats as well. Their populations are distributed depending on temperature, salinity, or depth...
Pfiesteria piscicida
Pfiesteria piscicida
Pfiesteria piscicida is a dinoflagellate species of the genus Pfiesteria that some researchers claim is responsible for many harmful algal blooms in the 1980s and 1990s on the coast of North Carolina and Maryland...
. When large numbers of fish, like shoaling
Shoaling and schooling
In biology, any group of fish that stay together for social reasons are said to be shoaling , and if, in addition, the group is swimming in the same direction in a coordinated manner, they are said to be schooling . In common usage, the terms are sometimes used rather loosely...
forage fish
Forage fish
Forage fish, also called prey fish or bait fish, are small fish which are preyed on by larger predators for food. Predators include other larger fish, seabirds and marine mammals. Typical ocean forage fish feed near the base of the food chain on plankton, often by filter feeding...
, are in confined situations such as shallow bays, the excretions from the fish encourage this dinoflagellate, which is not normally toxic, to produce free-swimming zoospore
Zoospore
A zoospore is a motile asexual spore that uses a flagellum for locomotion. Also called a swarm spore, these spores are created by some algae, bacteria and fungi to propagate themselves.-Flagella:...
s. If the fish remain in the area, continuing to provide nourishment, then the zoospores start secreting a neurotoxin
Neurotoxin
A neurotoxin is a toxin that acts specifically on nerve cells , usually by interacting with membrane proteins such as ion channels. Some sources are more general, and define the effect of neurotoxins as occurring at nerve tissue...
. This toxin results in the fish developing bleeding lesions, and their skin flakes off in the water. The dinoflagellates then eat the blood and flakes of tissue while the affected fish die. Fish kills by this dinoflagellate are common, and they may also have been responsible for kills in the past which were thought to have had other causes. Kills like these can be viewed as natural mechanisms for regulating the population of exceptionally abundant fish. The rate at which the kills occur increases as organically polluted land runoff increases.
Red tide
Red tide
Red tide is a common name for a phenomenon also known as an algal bloom , an event in which estuarine, marine, or fresh water algae accumulate rapidly in the water column and results in discoloration of the surface water. It is usually found in coastal areas...
is the name commonly given to an algal bloom of Karenia brevis
Karenia brevis
Karenia brevis is a marine dinoflagellate common in Gulf of Mexico waters, and is the organism responsible for Florida red tide, as well as red tide in Texas.-Description:K...
, a microscopic marine dinoflagellate which is common in Gulf of Mexico
Gulf of Mexico
The Gulf of Mexico is a partially landlocked ocean basin largely surrounded by the North American continent and the island of Cuba. It is bounded on the northeast, north and northwest by the Gulf Coast of the United States, on the southwest and south by Mexico, and on the southeast by Cuba. In...
waters. In high concentrations it discolours the water which often appears reddish-brown in colour. It produces a toxin which paralyses the central nervous system of fish so they cannot breathe. Dead fish wash up on beaches around Texas and Florida. Humans can also become seriously ill from eating oysters and other shellfish contaminated with the red tide toxin.
The term "red tide" is also commonly used to describe harmful algal blooms on the northern east coast of the United States, particularly in the Gulf of Maine
Gulf of Maine
The Gulf of Maine is a large gulf of the Atlantic Ocean on the east coast of North America.It is delineated by Cape Cod at the eastern tip of Massachusetts in the southwest and Cape Sable at the southern tip of Nova Scotia in the northeast. It includes the entire coastlines of the U.S...
. This type of bloom is caused by another species of dinoflagellate
Dinoflagellate
The dinoflagellates are a large group of flagellate protists. Most are marine plankton, but they are common in fresh water habitats as well. Their populations are distributed depending on temperature, salinity, or depth...
known as Alexandrium fundyense
Alexandrium fundyense
Alexandrium fundyense is a dinoflagellate. It produces toxins that induce paralytic shellfish poisoning , and is a common cause of red tide.-References:...
.
These blooms are natural phenomenon, but the exact cause or combination of factors that result in red tides outbreak not fully understood.
Biological decay
Just as an algae bloom can lead to oxygen depletion, introduction of a large amount of decayDecay
-Science and technlogy:* Bit decay, in computing* Software decay, in computing* Distance decay, in geography* Exponential decay, the decrease of a value in proportion to its value* Decay time , in electronics...
ing biological material in general to a body of water leads to oxygen depletion as microorganism
Microorganism
A microorganism or microbe is a microscopic organism that comprises either a single cell , cell clusters, or no cell at all...
s use up available oxygen in the process of breaking down organic matter
Organic matter
Organic matter is matter that has come from a once-living organism; is capable of decay, or the product of decay; or is composed of organic compounds...
. For example, a 10-mile-long fish kill in September, 2010, in the Sangamon River
Sangamon River
The Sangamon River is a principal tributary of the Illinois River, approximately long, in central Illinois in the United States. It drains a mostly rural agricultural area between Peoria and Springfield...
in Illinois was traced to discharge of animal waste into the river from a large dairy
Dairy
A dairy is a business enterprise established for the harvesting of animal milk—mostly from cows or goats, but also from buffalo, sheep, horses or camels —for human consumption. A dairy is typically located on a dedicated dairy farm or section of a multi-purpose farm that is concerned...
operation. The illegal discharge resulted in a complete kill of fish, frogs, mussel
Mussel
The common name mussel is used for members of several families of clams or bivalvia mollusca, from saltwater and freshwater habitats. These groups have in common a shell whose outline is elongated and asymmetrical compared with other edible clams, which are often more or less rounded or oval.The...
s and mudpuppies
Mudpuppy
Mudpuppies or waterdogs are aquatic salamanders of the family Proteidae. Their name originates from the misconception that they make a dog-like barking sound. The range of the genus Necturus runs from southern central Canada, through the midwestern United States, east to North Carolina and south to...
.
Spawning fatalities
Fish kill due to spawning fatalities can occur when fish are exhausted from spawning activities
Spawn (biology)
Spawn refers to the eggs and sperm released or deposited, usually into water, by aquatic animals. As a verb, spawn refers to the process of releasing the eggs and sperm, also called spawning...
such as courtship, nest building, and the release of eggs or milt
Milt
Milt is the seminal fluid of fish, mollusks, and certain other water-dwelling animals who reproduce by spraying this fluid, which contains the sperm, onto roe .-Milt as food:...
(sperm). Fish are generally weaker after spawning and are less resilient than usual to smaller changes in the environment. Examples include the Atlantic salmon
Atlantic salmon
The Atlantic salmon is a species of fish in the family Salmonidae, which is found in the northern Atlantic Ocean and in rivers that flow into the north Atlantic and the north Pacific....
and the Sockeye salmon
Sockeye salmon
Sockeye salmon , also called red salmon or blueback salmon in the USA, is an anadromous species of salmon found in the Northern Pacific Ocean and rivers discharging into it...
where many of the females routinely die immediately after spawning.
Water temperature
A fish kill can occur with rapid fluctuations in temperature or sustained high temperatures. Generally, cooler water has the potential to hold more oxygen, so a period of sustained high temperatures can lead to decreased dissolved oxygen in a body of water. An August, 2010, fish kill in Delaware BayDelaware Bay
Delaware Bay is a major estuary outlet of the Delaware River on the Northeast seaboard of the United States whose fresh water mixes for many miles with the waters of the Atlantic Ocean. It is in area. The bay is bordered by the State of New Jersey and the State of Delaware...
was attributed to low oxygen as a result of high temperatures.
A massive (hundreds of thousands) fish kill at the mouth of the Mississippi River
Mississippi River
The Mississippi River is the largest river system in North America. Flowing entirely in the United States, this river rises in western Minnesota and meanders slowly southwards for to the Mississippi River Delta at the Gulf of Mexico. With its many tributaries, the Mississippi's watershed drains...
in Louisiana, September, 2010, was attributed to a combination of high temperatures and low tide. Such kills are known to happen in this region in late summer and early fall, but this one was unusually large.
A short period of hot weather can increase temperatures in the surface layer of water, as the warmer water tends to stay near the surface and be further heated by the air. In this case, the top warmer layer may have more oxygen than the lower, cooler layers because it has constant access to atmospheric oxygen. If a heavy wind or cold rain then occurs (usually during the autumn but sometimes in summer), the layers can mix
Stratification (water)
Water stratification occurs when water masses with different properties - salinity , oxygenation , density , temperature - form layers that act as barriers to water mixing...
. If the volume of low oxygen water is much greater than the volume in the warm surface layer, this mixing can reduce oxygen levels throughout the water column and lead to fish kill.
Fish kills can also result from a dramatic or prolonged drop in air (and thus, water) temperature. This kind of fish kill is selective - usually the dead fish are species that cannot tolerate cold. This has been observed in cases where a fish native to a more tropical region has been introduced to cooler waters, such as the introduction of the tilapia
Tilapia
Tilapia , is the common name for nearly a hundred species of cichlid fish from the tilapiine cichlid tribe. Tilapia inhabit a variety of fresh water habitats, including shallow streams, ponds, rivers and lakes. Historically, they have been of major importance in artisan fishing in Africa and the...
to bodies of water in Florida. Native to Africa’s Nile River, the tilapia stop feeding when water temperatures drop below 60°F and die when it reaches 45°F. Thus, tilapia that have survived and successfully reproduced in Florida are occasionally killed by a winter cold front.
In January, 2011, a selective fish kill affecting an estimated 2 million juvenile spot fish
Spot croaker
The spot croaker or spot is a small saltwater fish. The species inhabits estuary and coastal waters along the eastern coast of United States, Gulf of Mexico, and the Caribbean....
was attributed to a combination of cold stress and overpopulation after a particularly large spawn.
Underwater explosions
Underwater explosion
An underwater explosion, also known as an UNDEX, is an explosion beneath the surface of water. The type of explosion may be chemical or nuclear...
s can lead to fish kill, and fish with swim bladders are more susceptible. Sometimes underwater explosions are used on purpose to induce fish kills, a generally illegal practice known as blast fishing
Blast fishing
Blast fishing or dynamite fishing is the practice of using explosives to stun or kill schools of fish for easy collection. This often illegal practice can be extremely destructive to the surrounding ecosystem, as the explosion often destroys the underlying habitat that supports the fish...
. Underwater explosions may be accidental or planned, such as for construction, seismic testing, mining or blast testing of structures under water. In many places, an assessment of potential effects of underwater explosions on marine life must be completed and preventive measures taken before blasting.
Droughts and overstocking
Droughts and overstocking can also result in inland fish kills.A drought
Drought
A drought is an extended period of months or years when a region notes a deficiency in its water supply. Generally, this occurs when a region receives consistently below average precipitation. It can have a substantial impact on the ecosystem and agriculture of the affected region...
can lead to lower water volumes so that even if the water contains a high level of dissolved oxygen, the reduced volume may not be enough for the fish population. Droughts often occur in conjunction with high temperatures so that the oxygen carrying capacity
Carrying capacity
The carrying capacity of a biological species in an environment is the maximum population size of the species that the environment can sustain indefinitely, given the food, habitat, water and other necessities available in the environment...
of the water may also be reduced. Low river flows also reduce the available dilution for permitted discharges of treated sewage or industrial waste
Industrial wastewater treatment
Industrial wastewater treatment covers the mechanisms and processes used to treat waters that have been contaminated in some way by anthropogenic industrial or commercial activities prior to its release into the environment or its re-use....
. The reduced dilution increases the organic demand for oxygen further reducing the oxygen concentration available to fish
Overstocking of fish (or an unusually large spawn
Spawn (biology)
Spawn refers to the eggs and sperm released or deposited, usually into water, by aquatic animals. As a verb, spawn refers to the process of releasing the eggs and sperm, also called spawning...
) can also result in inland fish kills. Fish kill due to insufficient oxygen is really a matter of too much demand and too little supply for whatever reason(s). Recommended stocking densities
Fish stock
Fish stocks are subpopulations of a particular species of fish, for which intrinsic parameters are the only significant factors in determining population dynamics, while extrinsic factors are considered to be insignificant.-The stock concept:All species have geographic limits to their...
are available from many sources for bodies of water ranging from a home aquarium
Aquarium
An aquarium is a vivarium consisting of at least one transparent side in which water-dwelling plants or animals are kept. Fishkeepers use aquaria to keep fish, invertebrates, amphibians, marine mammals, turtles, and aquatic plants...
or backyard pond to commercial aquaculture
Aquaculture
Aquaculture, also known as aquafarming, is the farming of aquatic organisms such as fish, crustaceans, molluscs and aquatic plants. Aquaculture involves cultivating freshwater and saltwater populations under controlled conditions, and can be contrasted with commercial fishing, which is the...
facilities.
Estimation
Estimating the magnitude of a kill presents a number of problems.- Polluted waters are often very turbidTurbidityTurbidity is the cloudiness or haziness of a fluid caused by individual particles that are generally invisible to the naked eye, similar to smoke in air. The measurement of turbidity is a key test of water quality....
or have low transparency making it difficult or impossible to see fish that have sunk - Rivers and streams can move fish downstream out of the investigation area.
- Small fish and fry can decompose or become buried in sediments very quickly and are lost from the count.
- Predators and scavengerScavengerScavenging is both a carnivorous and herbivorous feeding behavior in which individual scavengers search out dead animal and dead plant biomass on which to feed. The eating of carrion from the same species is referred to as cannibalism. Scavengers play an important role in the ecosystem by...
s remove and eat fish. - Stressed fish may swim up tributaries and die there
- Many kills are reported only when dead fish resurface due to decompositional gas formation, often several hours after the kill has occurred.
Some very large fish kills may never be estimated because of these factors. The discharge of red aluminium sludge
Sludge
Sludge refers to the residual, semi-solid material left from industrial wastewater, or sewage treatment processes. It can also refer to the settled suspension obtained from conventional drinking water treatment, and numerous other industrial processes...
from a reservoir in Hungary
Hungary
Hungary , officially the Republic of Hungary , is a landlocked country in Central Europe. It is situated in the Carpathian Basin and is bordered by Slovakia to the north, Ukraine and Romania to the east, Serbia and Croatia to the south, Slovenia to the southwest and Austria to the west. The...
into the Marcai River is acknowledged as causing environmental devastation, The loss of adult fish also can have long term impacts on the success of the fishery as the following year's spawning
Spawn (biology)
Spawn refers to the eggs and sperm released or deposited, usually into water, by aquatic animals. As a verb, spawn refers to the process of releasing the eggs and sperm, also called spawning...
stock may have been lost and recovery of the pre-kill population may take years to recover. The loss of food supplies or recreational income may be very significant to the local economy.
Prevention and investigation
Fish kills are difficult to predict. Even when conditions that contribute to fish kill are known to exist, prevention is hard because often conditions cannot be improved and fish cannot be safely removed in time. In small ponds, mechanical aeration and/or removal of decaying matter (such as fallen leaves or dead algae) may be reasonable and effective preventive measures.Many countries in the developed world have specific provisions in place to encourage the public to report fish kills so that a proper investigation can take place. Investigation of the cause of a kill requires a multi-disciplinary approach including on-site environmental measurements, investigation of inputs, review of meteorology and past history, toxicology, fish autopsy, invertebrate analysis and a robust knowledge of the area and its problems.
Notable events
The counts given below are all estimates. They tend to be underestimates, and may omit, for example, small fish, those removed by scavengers and those that settle to the bottom.| Event/Location | Date | Count | Species | Remarks |
|---|---|---|---|---|
| Gulf of Mexico Gulf of Mexico The Gulf of Mexico is a partially landlocked ocean basin largely surrounded by the North American continent and the island of Cuba. It is bounded on the northeast, north and northwest by the Gulf Coast of the United States, on the southwest and south by Mexico, and on the southeast by Cuba. In... (Corpus Christi Corpus Christi, Texas Corpus Christi is a coastal city in the South Texas region of the U.S. state of Texas. The county seat of Nueces County, it also extends into Aransas, Kleberg, and San Patricio counties. The MSA population in 2008 was 416,376. The population was 305,215 at the 2010 census making it the... ) |
1935 | Caused by red tide Red tide Red tide is a common name for a phenomenon also known as an algal bloom , an event in which estuarine, marine, or fresh water algae accumulate rapidly in the water column and results in discoloration of the surface water. It is usually found in coastal areas... . Also caused coughing, sneezing and watery red eyes in humans. |
||
| River Aeron River Aeron The River Aeron is a small river in Ceredigion, Wales, that flows into Cardigan Bay at Aberaeron. It is also referred to on some older maps as the River Ayron.- Source :... |
1974 | salmon Salmon Salmon is the common name for several species of fish in the family Salmonidae. Several other fish in the same family are called trout; the difference is often said to be that salmon migrate and trout are resident, but this distinction does not strictly hold true... , trout Trout Trout is the name for a number of species of freshwater and saltwater fish belonging to the Salmoninae subfamily of the family Salmonidae. Salmon belong to the same family as trout. Most salmon species spend almost all their lives in salt water... |
Discharge of creamery Creamery In a dairy, the creamery is the location of cream processing. Cream is separated from whole milk; pasteurization is done to the skimmed milk and cream separately. Whole milk for sale has had some cream returned to the skimmed milk.... waste through poorly maintained sewer. Successful prosecution followed. |
|
| River Neath River Neath River Neath is a river in south Wales running south west from its source in the Brecon Beacons National Park to its mouth at Baglan Bay below Briton Ferry on the east side of Swansea Bay.Several minor rivers rise on the southern slopes of Fforest Fawr... |
1976 | salmon Salmon Salmon is the common name for several species of fish in the family Salmonidae. Several other fish in the same family are called trout; the difference is often said to be that salmon migrate and trout are resident, but this distinction does not strictly hold true... , trout Trout Trout is the name for a number of species of freshwater and saltwater fish belonging to the Salmoninae subfamily of the family Salmonidae. Salmon belong to the same family as trout. Most salmon species spend almost all their lives in salt water... |
Extreme drought left fish stranded in stagnant pools into which sewers drained. | |
| River Ogmore River Ogmore The River Ogmore is a river in South Wales popular with anglers. It runs generally from north to south from the Ogmore Vale and Pentre, past Bridgend and Ogmore... |
1979 | salmon Salmon Salmon is the common name for several species of fish in the family Salmonidae. Several other fish in the same family are called trout; the difference is often said to be that salmon migrate and trout are resident, but this distinction does not strictly hold true... , trout Trout Trout is the name for a number of species of freshwater and saltwater fish belonging to the Salmoninae subfamily of the family Salmonidae. Salmon belong to the same family as trout. Most salmon species spend almost all their lives in salt water... |
Spillage of Kymene from a paper mill Paper mill A paper mill is a factory devoted to making paper from vegetable fibres such as wood pulp, old rags and other ingredients using a Fourdrinier machine or other type of paper machine.- History :... on the River Llynfi River Llynfi The River Llynfi, otherwise referred to as the Llynfi River or Afon Llynfi in Welsh , is one of three main tributaries of the River Ogmore or Afon Ogwr.... a tributary of the Ogmore. Successful prosecution followed and substantial compensation. |
|
| Gulf of Mexico Gulf of Mexico The Gulf of Mexico is a partially landlocked ocean basin largely surrounded by the North American continent and the island of Cuba. It is bounded on the northeast, north and northwest by the Gulf Coast of the United States, on the southwest and south by Mexico, and on the southeast by Cuba. In... |
1986 | Gulf menhaden Gulf menhaden The Gulf menhaden is a small marine filter feeding fish belonging to the family Clupeidae. The range of Gulf menhaden encompasses the entirety of the Gulf of Mexico nearshore waters, with the exception of the extreme eastern Yucatan and western Cuba... , striped mullet, various other species |
Caused by red tide Red tide Red tide is a common name for a phenomenon also known as an algal bloom , an event in which estuarine, marine, or fresh water algae accumulate rapidly in the water column and results in discoloration of the surface water. It is usually found in coastal areas... . |
|
| Rhine River | 1986 01 | Caused by spill from Swiss chemical warehouse | ||
| Texas Texas Texas is the second largest U.S. state by both area and population, and the largest state by area in the contiguous United States.The name, based on the Caddo word "Tejas" meaning "friends" or "allies", was applied by the Spanish to the Caddo themselves and to the region of their settlement in... coast |
1997–1998 | Caused by a bloom of Karenia brevis Karenia brevis Karenia brevis is a marine dinoflagellate common in Gulf of Mexico waters, and is the organism responsible for Florida red tide, as well as red tide in Texas.-Description:K... |
||
| White River White River (Indiana) The White River is a two-forked river that flows through central and southern Indiana and is the main tributary to the Wabash River. Via the west fork, considered to be the main stem of the river by the U.S. Board on Geographic Names, the White River is long.-West Fork:The West Fork, long, is... ; West Fork, Indiana West Fork, Indiana West Fork is an unincorporated town in Union Township, Crawford County, Indiana.... |
1999 | Caused by an automotive parts maker in Anderson, Indiana Anderson, Indiana Anderson is a city in and the county seat of Madison County, Indiana, United States. It is the principal city of the Anderson, Indiana Metropolitan Statistical Area which encompasses Madison county. Anderson is the headquarters of the Church of God and home of Anderson University, which is... , which had discharged 10,000 gallons of the chemical HMP 2000 into the river. |
||
| River Dee (United Kingdom) | 2002 07 | salmon Salmon Salmon is the common name for several species of fish in the family Salmonidae. Several other fish in the same family are called trout; the difference is often said to be that salmon migrate and trout are resident, but this distinction does not strictly hold true... , trout Trout Trout is the name for a number of species of freshwater and saltwater fish belonging to the Salmoninae subfamily of the family Salmonidae. Salmon belong to the same family as trout. Most salmon species spend almost all their lives in salt water... , roach Roach -Animals:* Cockroaches* Roach , including** Certain members of family Cyprinidae** the genus Rutilus*** Common Roach ** the California Roach of the monotypic genus Hesperoleucus-Other:... , perch Perch Perch is a common name for fish of the genus Perca, freshwater gamefish belonging to the family Percidae. The perch, of which there are three species in different geographical areas, lend their name to a large order of vertebrates: the Perciformes, from the Greek perke meaning spotted, and the... |
Unconfirmed link to release of whey Whey Whey or Milk Serum is the liquid remaining after milk has been curdled and strained. It is a by-product of the manufacture of cheese or casein and has several commercial uses. Sweet whey is manufactured during the making of rennet types of hard cheese like cheddar or Swiss cheese... into river |
|
| Klamath River 2002 Klamath River fish kill The 2002 Klamath River fish kill occurred on the Klamath River in California in September 2002. Over 70,000 adult chinook salmon were killed when returning to the river to spawn, making it the largest salmon kill in the history of the American west. The kill resulted from water diversions to... |
2002 09 | salmon Salmon Salmon is the common name for several species of fish in the family Salmonidae. Several other fish in the same family are called trout; the difference is often said to be that salmon migrate and trout are resident, but this distinction does not strictly hold true... |
Low flow of water due to drought and water diversions for agriculture led to heated and shallow water, increasing vulnerability to a gill disease. | |
| Neuse River Neuse River The Neuse River is a river rising in the Piedmont of North Carolina and emptying into Pamlico Sound below New Bern. Its total length is approximately , making it the longest river entirely contained in North Carolina. The Trent River joins it at New Bern. Its drainage basin, measuring in area,... , North Carolina North Carolina North Carolina is a state located in the southeastern United States. The state borders South Carolina and Georgia to the south, Tennessee to the west and Virginia to the north. North Carolina contains 100 counties. Its capital is Raleigh, and its largest city is Charlotte... |
2004 09 | menhaden Menhaden Menhaden, also known as mossbunker, bunker and pogy, are forage fish of the genera Brevoortia and Ethmidium, two genera of marine fish in the family Clupeidae.-Description:... |
"Natural upwelling" of an acknowledged polluted river. Hydrogen sulfide smell reported | |
| Taal Lake Taal Lake Taal Lake is a freshwater lake in the province of Batangas, on the island of Luzon, Philippines. The lake is situated within a caldera formed by very large eruptions between 500,000 and 100,000 years ago. It is the country's third largest lake... , Luzon Luzon Luzon is the largest island in the Philippines. It is located in the northernmost region of the archipelago, and is also the name for one of the three primary island groups in the country centered on the Island of Luzon... , Philippines Philippines The Philippines , officially known as the Republic of the Philippines , is a country in Southeast Asia in the western Pacific Ocean. To its north across the Luzon Strait lies Taiwan. West across the South China Sea sits Vietnam... |
2008 01 05 | tilapia Tilapia Tilapia , is the common name for nearly a hundred species of cichlid fish from the tilapiine cichlid tribe. Tilapia inhabit a variety of fresh water habitats, including shallow streams, ponds, rivers and lakes. Historically, they have been of major importance in artisan fishing in Africa and the... |
May be linked to volcanic activity and large fish farms | |
| Liuxihe River Liuxihe River The Liuxihe River or simply Liuxi is a tributary of the Pearl River in China with its basin situated northeast of Guangzhou in Guangdong Province. It lies between the Beijiang River and Dongjiang River and is interrupted by the Liuxihe Dam.... Guangzhou Guangzhou Guangzhou , known historically as Canton or Kwangchow, is the capital and largest city of the Guangdong province in the People's Republic of China. Located in southern China on the Pearl River, about north-northwest of Hong Kong, Guangzhou is a key national transportation hub and trading port... People's Republic of China People's Republic of China China , officially the People's Republic of China , is the most populous country in the world, with over 1.3 billion citizens. Located in East Asia, the country covers approximately 9.6 million square kilometres... |
2008 09 09 | carp Carp Carp are various species of oily freshwater fish of the family Cyprinidae, a very large group of fish native to Europe and Asia. The cypriniformes are traditionally grouped with the Characiformes, Siluriformes and Gymnotiformes to create the superorder Ostariophysi, since these groups have certain... |
Unknown | |
| Beaches at Thanet Thanet Thanet is a local government district of Kent, England which was formed under the Local Government Act 1972, and came into being on 1 April 1974... , Kent Kent Kent is a county in southeast England, and is one of the home counties. It borders East Sussex, Surrey and Greater London and has a defined boundary with Essex in the middle of the Thames Estuary. The ceremonial county boundaries of Kent include the shire county of Kent and the unitary borough of... , England |
2010 01 | velvet crab Velvet crab The velvet crab , Necora puber, is a species of crab. It is the largest swimming crab found in British coastal waters, with a carapace width of up to , and the only species in the genus Necora. The body is coated with short hairs, giving the animal a velvety texture, hence the common name... |
20000 + dead crabs - along with dead starfish, lobsters, sponges and anemones. Probably killed by hypothermia Hypothermia Hypothermia is a condition in which core temperature drops below the required temperature for normal metabolism and body functions which is defined as . Body temperature is usually maintained near a constant level of through biologic homeostasis or thermoregulation... . |
|
| Ting River Fujian Fujian ' , formerly romanised as Fukien or Huguing or Foukien, is a province on the southeast coast of mainland China. Fujian is bordered by Zhejiang to the north, Jiangxi to the west, and Guangdong to the south. Taiwan lies to the east, across the Taiwan Strait... People's Republic of China People's Republic of China China , officially the People's Republic of China , is the most populous country in the world, with over 1.3 billion citizens. Located in East Asia, the country covers approximately 9.6 million square kilometres... |
2010 07 | Enough to feed 70,000 people a year | Part of the Zijin mining disaster | |
| Mississippi River Mississippi River The Mississippi River is the largest river system in North America. Flowing entirely in the United States, this river rises in western Minnesota and meanders slowly southwards for to the Mississippi River Delta at the Gulf of Mexico. With its many tributaries, the Mississippi's watershed drains... ; Plaquemines Parish, Louisiana Plaquemines Parish, Louisiana Plaquemines Parish is the parish with the most combined land and water area in the U.S. state of Louisiana. The parish seat is Pointe à la Hache... |
2010 09 | redfish Redfish Redfish is a common name for several species of fish. It is most commonly applied to members of the deep-sea genus Sebastes, or the reef dwelling snappers, Lutjanus. It is also applied to the slimeheads or roughies , and the alfonsinos .... , trout Trout Trout is the name for a number of species of freshwater and saltwater fish belonging to the Salmoninae subfamily of the family Salmonidae. Salmon belong to the same family as trout. Most salmon species spend almost all their lives in salt water... , flounder Flounder The flounder is an ocean-dwelling flatfish species that is found in coastal lagoons and estuaries of the Northern Atlantic and Pacific Oceans.-Taxonomy:There are a number of geographical and taxonomical species to which flounder belong.*Western Atlantic... |
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| Arkansas River Arkansas River The Arkansas River is a major tributary of the Mississippi River. The Arkansas generally flows to the east and southeast as it traverses the U.S. states of Colorado, Kansas, Oklahoma, and Arkansas. The river's initial basin starts in the Western United States in Colorado, specifically the Arkansas... ; Ozark, Arkansas Ozark, Arkansas Ozark is a city in Franklin County, Arkansas, United States, and one of the two county seats of Franklin County. It is part of the Fort Smith, Arkansas-Oklahoma Metropolitan Statistical Area. The population was 3,525 at the 2000 census, making Ozark the ninth largest municipality in the metro area... |
2010 12 | freshwater drum Freshwater Drum -Introduction:The freshwater drum, Aplodinotus grunniens, is a fish endemic to North and Central America. It is the only species in the genus Aplodinotus. The Freshwater drum is a member of the family Sciaenidae, and is the only member of the species that inhabits freshwater for its entire life... |
Coincided with death of 5,000 Red-winged Blackbird Red-winged Blackbird The Red-winged Blackbird is a passerine bird of the family Icteridae found in most of North and much of Central America. It breeds from Alaska and Newfoundland south to Florida, the Gulf of Mexico, Mexico, and Guatemala, with isolated populations in western El Salvador, northwestern Honduras, and... s that fell from the sky. |
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| Chesapeake Bay Chesapeake Bay The Chesapeake Bay is the largest estuary in the United States. It lies off the Atlantic Ocean, surrounded by Maryland and Virginia. The Chesapeake Bay's drainage basin covers in the District of Columbia and parts of six states: New York, Pennsylvania, Delaware, Maryland, Virginia, and West... |
2011 01 | spot croaker Spot croaker The spot croaker or spot is a small saltwater fish. The species inhabits estuary and coastal waters along the eastern coast of United States, Gulf of Mexico, and the Caribbean.... s |
Included some juvenile croakers. Cold water stress was believed to be the cause. | |
| Jiaxing Jiaxing Jiaxing is a prefecture-level city in northern Zhejiang province of Eastern China. Lying on the Grand Canal of China, Jiaxing borders Hangzhou to the southwest, Huzhou to the west, Shanghai to the northeast, and the province of Jiangsu to the north.... Xiuzhou District Xiuzhou District Xiuzhou District is a district in Jiaxing, Zhejiang, China. It is located between Shanghai and Hangzhou. There is 90KM to Shanghai in the northeast, 80KM to Hangzhou in the southwest and 70KM to Suzhou in the north. It is an important urban district of Jiaxing city... People's Republic of China People's Republic of China China , officially the People's Republic of China , is the most populous country in the world, with over 1.3 billion citizens. Located in East Asia, the country covers approximately 9.6 million square kilometres... |
2011 01 06 | bream, carp Carp Carp are various species of oily freshwater fish of the family Cyprinidae, a very large group of fish native to Europe and Asia. The cypriniformes are traditionally grouped with the Characiformes, Siluriformes and Gymnotiformes to create the superorder Ostariophysi, since these groups have certain... , murrel, silver carp Silver carp The silver carp is a species of freshwater cyprinid fish, a variety of Asian carp native to north and northeast Asia. It is cultivated in China.... , grass carp Grass carp The grass carp is a herbivorous, freshwater fish species of family Cyprinidae, and the only species of the genus Ctenopharyngodon. It is cultivated in China for food, but was introduced in Europe and the United States for aquatic weed control... |
Fish caught and transported to market held in large fish tanks fed with river water. Very rapid die-off and loss exceeded 100 tonnes. Only fish caught from a river under China National Highway 320 China National Highway 320 China National Highway 320 runs southwest from Shanghai towards Zhejiang Province, Jiangxi Province, Hunan Province, Guizhou Province, and ends in Ruili, Yunnan, which is on China-Burma border. It is 3,695 kilometres in length. In 2010, the Kali section of this highway was hampered due to cold... east died. |
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| Redondo Beach, California Redondo Beach, California Redondo Beach is one of the three Beach Cities located in Los Angeles County, California, United States. The population was 66,748 at the 2010 census, up from 63,261 at the 2000 census. The city is located in the South Bay region of the greater Los Angeles area.Redondo Beach was originally part of... |
2011 03 | anchovies, mackerel Mackerel Mackerel is a common name applied to a number of different species of fish, mostly, but not exclusively, from the family Scombridae. They may be found in all tropical and temperate seas. Most live offshore in the oceanic environment but a few, like the Spanish mackerel , enter bays and can be... , sardines and other small fish |
Caused by oxygen deprivation | |
| Taal Lake Taal Lake Taal Lake is a freshwater lake in the province of Batangas, on the island of Luzon, Philippines. The lake is situated within a caldera formed by very large eruptions between 500,000 and 100,000 years ago. It is the country's third largest lake... , Batangas, Philippines |
2011 05 29 | Tilapia Tilapia Tilapia , is the common name for nearly a hundred species of cichlid fish from the tilapiine cichlid tribe. Tilapia inhabit a variety of fresh water habitats, including shallow streams, ponds, rivers and lakes. Historically, they have been of major importance in artisan fishing in Africa and the... , milkfish Milkfish The milkfish is the sole living species in the family Chanidae. - Description and biology :... |
Caused by oxygen deprivation and large fish farms | |
| Lingayen Gulf Lingayen Gulf The Lingayen Gulf is an extension of the South China Sea on Luzon in the Philippines stretching . It is framed by the provinces of Pangasinan and La Union and sits between the Zambales Mountains and the Cordillera Central... , Anda, Pangasinan, Philippines |
2011 05 30 | Milkfish Milkfish The milkfish is the sole living species in the family Chanidae. - Description and biology :... |
Oxygen depletion and change of water climate |
See also
- Aquatic biomonitoring
- Bird killBird killBird kill is a localized event resulting in the death of large numbers of birds at the same time.-Scientific explanations:According to scientists, massive die offs of animals are not unusual in nature and happen for a variety of reasons including bad weather, disease outbreaks and poisonings, with...
- RoadkillRoadkillRoadkill is an animal or animals that have been struck and killed by motor vehicles. In the United States of America, removal and disposal of animals struck by motor vehicles is usually the responsibility of the state's state trooper association or department of transportation.-History:During the...
- Aflockalypse
- ParamoebiasisParamoebiasisParamoeba Parasite is a parasite that attacks the nervous system of lobsters. Lately, lobsters that have been pulled up in Western LIS have been dead with the parasite. Also, it caused almost all the deaths of the lobsters in 1999....
External links
- Herring, and Scott (2002) Fish Kill in the Gulf of Oman: A space-based diagnosis NASANASAThe National Aeronautics and Space Administration is the agency of the United States government that is responsible for the nation's civilian space program and for aeronautics and aerospace research...
: Earth Observatory, featured article. - La, V. and S.J. Cooke (2011). Advancing the Science and Practice of Fish Kill Investigations Reviews in Fisheries Science 19(1): 21-33.
- Oxygen Depletion in Ponds, University of Georgia Cooperative Extension Service, Publication L233, 1993
- Fish Kills - Their Causes and Prevention, Virginia Tech, Virginia Cooperative Extension Publication 420-252, 2009
- Fish Kills in Coastal Georgia Ponds and Lagoons, Georgia Department of Natural Resources
- "The Fish Kill Mystery" - Erica F. Kosal, North Carolina Wesleyan College (2003)
- Maryland DNR page on Pfiesteria (sometimes toxic dinoflagellate)
- Fish kill hotline in Florida to report observed fish kills