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 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.
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 is a common name for a group of flatfish that comprises four species: the European, American, Alaskan and scale-eye plaice.
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).
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.
The Atlantic cod is a benthopelagic fish of the family Gadidae, widely consumed by humans. It is also commercially known as cod or codling. Dry cod may be prepared as unsalted stockfish, as cured salt cod or clipfish.
Many types of fish migrate on a regular basis, on time scales ranging from daily to annually or longer, and over distances ranging from a few metres to thousands of kilometres. Fish usually migrate to feed or to reproduce, but in other cases the reasons are unclear.
The Kuroshio (黒潮), also known as the Black or Japan Current or the Black Stream, is a north-flowing ocean current on the west side of the North Pacific Ocean. It is similar to the Gulf Stream in the North Atlantic and is part of the North Pacific ocean gyre. Like the Gulf stream, it is a strong western boundary current.
A marine reserve is a type of marine protected area that has legal protection against fishing or development. As of 2007 less than 1% of the world's oceans had been set aside in marine reserves. Benefits include increases in the diversity, density, biomass, body size and reproductive potential of fishery and other species within their boundaries.
The sauger is a freshwater perciform fish of the family Percidae which resembles its close relative the walleye. They are members of the largest vertebrate order, Perciformes. They are the most migratory percid species in North America. Saugers obtain two dorsal fins, the first is spiny and the posterior dorsal fin is a soft-rayed fin. Their paired fins are in the thoracic position and their caudal fin is truncated which means squared off at the corners, a characteristic of the family Percidae. Another physical characteristic of Saugers are their ctenoid scales which is common in advanced fishes. Saugers have a fusiform body structure, and as a result saugers are well adapted predatory fishes and are capable of swimming into fast currents with minimal drag on their bodies. They may be distinguished from walleyes by the distinctly spotted dorsal fin, by the lack of a white splotch on the caudal fin, by the rough skin over their gill, and by their generally more brassy color, or darker color in some regions. The average sauger in an angler's creel is 300 to 400 g in weight.
The European plaice is a commercially important flatfish.
Pelagic fish live in the pelagic zone of ocean or lake waters – being neither close to the bottom nor near the shore – in contrast with demersal fish, which do live on or near the bottom, and reef fish, which are associated with coral reefs.
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, shellfish, and crustaceans, primarily to support the aquaculture industry where they are transferred to on-growing systems, such as fish farms, to reach harvest size. Some species that are commonly raised in hatcheries include Pacific oysters, shrimp, Indian prawns, salmon, tilapia and scallops. The value of global aquaculture production is estimated to be US$98.4 billion in 2008 with China significantly dominating the market; however, the value of aquaculture hatchery and nursery production has yet to be estimated. Additional hatchery production for small-scale domestic uses, which is particularly prevalent in South-East Asia or for conservation programmes, has also yet to be quantified.
Hippoglossus stenolepis, the Pacific halibut, is a species of righteye flounder. This very large species of flatfish is native to the North Pacific and is fished by commercial fisheries, sport fishers, and subsistence fishers.
The yellowbelly flounder is a flatfish of the genus Rhombosolea, found around New Zealand. A different species from the genus Rhombosolea is found in Australia and also goes by the name yellow-belly flounder. The Māori people have commonly fished for R.leporina, and many other species of flatfish, throughout New Zealand's coastal waters for hundreds of years. The Māori name for this species is 'patiki totara'.
The New Zealand longfin eel is a species of freshwater eel that is endemic to New Zealand. It is the largest freshwater eel in New Zealand and the only endemic species – the other eels found in New Zealand are the native shortfin eel, also found in Australia, and the naturally introduced Australian longfin eel. Longfin eels are long-lived, migrating to the Pacific Ocean near Tonga to breed at the end of their lives. They are good climbers as juveniles and so are found in streams and lakes a long way inland. An important traditional food source for Māori, longfin eels are threatened and declining but still commercially fished.
Spotted galaxias is a largish, primarily-freshwater galaxias species found in southern Australia. Spotted galaxias are perhaps the most beautiful of the Australian galaxias species. They are a somewhat tubular, deep-bodied fish, with a dusky brownish-red colouration overlain with dark, haloed spots, dramatic black edges to dorsal, anal and pelvic fins, and a dark diagonal stripe through the eye.
The narrow-barred Spanish mackerel is a mackerel of the Scombridae family found in a wide-ranging area centering in Southeast Asia, but as far west as the east coast of Africa and from the Middle East and along the northern coastal areas of the Indian Ocean, and as far east as the South West Pacific Ocean.
Acipenser oxyrinchus is a species of sturgeon.
This is a glossary of terms used in fisheries, fisheries management and fisheries science.
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, 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.
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 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 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.