Hydrographic containment

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Hydrographic containment is a concept in fisheries oceanography that refers to the way a fish population utilizes different tides and currents at different times to remain in a certain region. [1] This concept was developed based on Harden Jones' triangle of migration. [2] This refers to the idea that fish migrate from their spawning grounds to their nursery ground. Then from the nursery grounds, they join the adult population of fish at the feeding ground. Finally, the fish returns to the spawning grounds to spawn. [2]

Fisheries science The academic discipline of managing and understanding fisheries

Fisheries science is the academic discipline of managing and understanding fisheries. It is a multidisciplinary science, which draws on the disciplines of limnology, oceanography, freshwater biology, marine biology, meteorology, conservation, ecology, population dynamics, economics and management to attempt to provide an integrated picture of fisheries. In some cases new disciplines have emerged, as in the case of bioeconomics and fisheries law.

Ocean current Directional mass flow of oceanic water generated by external or internal forces

An ocean current is a continuous, directed movement of sea water generated by a number of forces acting upon the water, including wind, the Coriolis effect, breaking waves, cabbeling, and temperature and salinity differences. Depth contours, shoreline configurations, and interactions with other currents influence a current's direction and strength. Ocean currents are primarily horizontal water movements.

The process of hydrographic containment typically works in this way: Fish migrate from their feeding grounds to their spawning grounds using selective tidal transport or a current/counter-current system to move against a stream of water. The fish population then releases their larvae into the same current and the larvae drift to their nursery grounds in shallower waters while the spent adults are carried back in the stream they arrived in. After a certain period of time, the juvenile fish migrate from the nursery grounds to the feeding grounds. [2] These two migrations, the mature adults back to the spawning grounds and the immature fish from the nursery grounds to the feeding grounds, make up the identity of the fish stock. [3] Different stocks of fish carry out this migration pattern differently to minimize the loss of larvae and juveniles to waters unsuitable for survival and make sure that the juveniles arrive at an optimal nursery habitat. [1]

This process has been well documented in plaice of the North Sea. The North Sea plaice gather over a modest region in the southwest corner of the North Sea to spawn, some fish traveling vast distances to arrive at this location. The almost certain reason the plaice choose this region for spawning is because the drift of the larvae from the English Channel will bring them from their spawning grounds in the southwest corner to the entry of the Dutch Wadden Sea, an optimal juvenile rearing habitat, right as the plaice reach their juvenile life phase. [2]

Plaice common name for a group of flatfish

Plaice is a common name for a group of flatfish that comprises four species: the European, American, Alaskan and scale-eye plaice.

North Sea marginal sea of the Atlantic Ocean

The North Sea is a marginal sea of the Atlantic Ocean located between the United Kingdom, Denmark, Norway, Sweden, Germany, the Netherlands, Belgium and France. An epeiric sea on the European continental shelf, it connects to the ocean through the English Channel in the south and the Norwegian Sea in the north. It is more than 970 kilometres (600 mi) long and 580 kilometres (360 mi) wide, with an area of 570,000 square kilometres (220,000 sq mi).

English Channel Arm of the Atlantic Ocean that separates southern England from northern France

The English Channel, also called simply the Channel, is the body of water that separates Southern England from northern France and links the southern part of the North Sea to the Atlantic Ocean. It is the busiest shipping area in the world.

See also

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This is a glossary of terms used in fisheries, fisheries management and fisheries science.

Spawn (biology) process of aquatic animals releasing sperm and eggs into water

Spawn is the eggs and sperm released or deposited into water by aquatic animals. As a verb, to spawn refers to the process of releasing the eggs and sperm, and the act of both sexes is called spawning. Most aquatic animals, except for aquatic mammals and reptiles, reproduce through the process of spawning.

Forage fish small fish which are preyed on by larger predators for food

Forage fish, also called prey fish or bait fish, are small pelagic 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. They include particularly fishes of the family Clupeidae, but also other small fish, including halfbeaks, silversides, smelt such as capelin, and the goldband fusiliers pictured on the right.

European pilchard species of fish

The European pilchard is a species of ray-finned fish in the monotypic genus Sardina. The young of the species are among the many fish that are sometimes called sardines. This common species is found in the northeast Atlantic, the Mediterranean, and the Black Sea at depths of 10–100 m (33–328 ft). It reaches up to 27.5 cm (10.8 in) in length and mostly feeds on planktonic crustaceans. This schooling species is a batch spawner where each female lays 50,000–60,000 eggs.

Ichthyoplankton The eggs and larvae of fish that drift in the water column

Ichthyoplankton are the eggs and larvae of fish. They are mostly found in the sunlit zone of the water column, less than 200 metres deep, which is sometimes called the epipelagic or photic zone. Ichthyoplankton are planktonic, meaning they cannot swim effectively under their own power, but must drift with the ocean currents. Fish eggs cannot swim at all, and are unambiguously planktonic. Early stage larvae swim poorly, but later stage larvae swim better and cease to be planktonic as they grow into juveniles. Fish larvae are part of the zooplankton that eat smaller plankton, while fish eggs carry their own food supply. Both eggs and larvae are themselves eaten by larger animals.

Juvenile fish young salmon

Juvenile fish go through various stages between birth and adulthood. They start as eggs which hatch into larvae. The larvae are not able to feed themselves, and carry a yolk-sac which provides their nutrition. Before the yolk-sac completely disappears, the tiny fish must become capable of feeding themselves. When they have developed to the point where they are capable of feeding themselves, the fish are called fry. When, in addition, they have developed scales and working fins, the transition to a juvenile fish is complete and it is called a fingerling. Fingerlings are typically about the size of fingers. The juvenile stage lasts until the fish is fully grown, sexually mature and interacting with other adult fish.

References

  1. 1 2 Miller, Charles B. Biological oceanography. John Wiley & Sons, 2009.
  2. 1 2 3 4 Cushing, D. H. "Hydrographic containment of a spawning group of plaice in the Southern Bight of the North Sea." Marine Ecology Progress Series (1990): 287-297.
  3. Cushing, David H. Population production and regulation in the sea: a fisheries perspective. Cambridge University Press, 1995. Cushing, David H. Population production and regulation in the sea: a fisheries perspective. Cambridge University Press, 1995.