A spawning bed is an underwater solid surface on which 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...

 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...

 to reproduce themselves.

In fishery management, a spawning bed is an artificial bed constructed by wildlife professionals in order to improve the ability of desired game fish to reproduce. Increasing the spawning ability of a fish population may reduce pressure on a fishery and improve the productivity of supplemental stocking from fish hatcheries

Fish hatchery

A fish hatchery is a "place for artificial breeding, hatching and rearing through the early life stages of animals, finfish and shellfish in particular". Hatcheries produce larval and juvenile fish primarily to support the aquaculture industry where they are transferred to on-growing systems...

.

In the inland waters of North America, a typical spawning bed will consist of a series of concrete boxes filled with aggregate

Construction Aggregate

Construction aggregate, or simply "aggregate", is a broad category of coarse particulate material used in construction, including sand, gravel, crushed stone, slag, recycled concrete and geosynthetic aggregates. Aggregates are the most mined material in the world...

 gravel. The concept is credited to the Kentucky Department of Fish and Wildlife

Kentucky Department of Fish and Wildlife

The Kentucky Department of Fish and Wildlife Resources, an agency of the Kentucky Tourism, Arts and Heritage Cabinet, is responsible for the conservation of fish and wildlife resources and for boating projects in the state. A commissioner appointed by the Fish and Wildlife Commission heads the...

.

In a typical example of spawning beds in action, the Illinois Department of Natural Resources

Illinois Department of Natural Resources

The Illinois Department of Natural Resources is a cabinet-level department of the state government of Illinois. It is headquartered in the state capital of Springfield...

 has installed approximately 50 largemouth bass

Largemouth bass

The largemouth bass is a species of black bass in the sunfish family native to North America . It is also known as widemouth bass, bigmouth, black bass, bucketmouth, Potter's fish, Florida bass, Florida largemouth, green bass, green trout, linesides, Oswego bass, southern largemouth...

 spawning beds in Crab Orchard Lake

Crab Orchard Lake

Crab Orchard Lake is a 6,965-acre reservoir in Williamson County, Illinois. It is the centerpiece of the Crab Orchard National Wildlife Refuge...

 in southern Illinois.

In some cases, especially in salt water, an artificial structure may significantly alter underwater morphology

Geomorphology

Geomorphology is the scientific study of landforms and the processes that shape them...

 and create an artificial reef

Artificial reef

An artificial reef is a human-made underwater structure, typically built to promote marine life in areas with a generally featureless bottom, control erosion, block ship passage, or improve surfing....

. Some vessels have been deliberately sunken, especially in salt water, in order to provide a destination for diver

Underwater diving

Underwater diving is the practice of going underwater, either with breathing apparatus or by breath-holding .Recreational diving is a popular activity...

s. In some of these cases the artificial reef also serves a supplemental purpose as a spawning bed.