Fish stocks are subpopulations of a particular species of fish, for which intrinsic parameters (growth, recruitment, mortality and fishing mortality) are traditionally regarded as the significant factors determining the stock's population dynamics, while extrinsic factors (immigration and emigration) are traditionally ignored.
All species have geographic limits to their distribution, which are determined by their tolerance to environmental conditions, and their ability to compete successfully with other species. In marine environments this may be less evident than on land because there are fewer topographical boundaries, however, discontinuities still exist, produced for example by mesoscale and sub-mesoscale circulations that minimize long-distance dispersal of fish larvae.
For fish, it is rare for an individual to reproduce randomly with all other individuals of that species within its biological range. There is a tendency to form a structured series of discrete populations which have a degree of reproductive isolation from each other in space, in time, or in both. This isolation is reflected in the development between sub-populations of genetic differences, morphological variations and exposure to different chemical regimes and parasitic species. Sub-populations also respond to fishing in such a way that fishing on one population appears to have no effect on the population dynamics of a neighbouring population.
The currently accepted definition of a stock in fisheries science, is that of Begg et al. (1999), “…[a “stock”] describes characteristics of semi-discrete groups of fish with some definable attributes which are of interest to fishery managers.”
Stock identification is a field of fisheries science which aims to identify these subpopulations, based on a number of techniques.This concept is applied in sustainable development goal 14 where target 14.4 is measured a fish stock sustainability indicator 14.4.1. [1]
The United Nations defines straddling stocks as "stocks of fish such as pollock, which migrate between, or occur in both, the economic exclusion zones (EEZ) of one or more states and the high seas". [2] Sovereign responsibility must be worked out in collaboration with neighbouring coastal states and fishing entities. Usually this is done through the medium of an intergovernmental regional organisation set up for the purpose of coordinating the management of that stock.
Straddling stocks are usually pelagic, rather than demersal. Demersal species move less than pelagic species, since they tend to relate to bottom topography. Pelagic species are more mobile, their movements influenced by ocean temperatures and the availability of zooplankton as food. Example pelagic fish are capelin, herring, whiting, mackerel and redfish, There are, however, a few demersal species that are straddling, such as the Greenland halibut migrates in feeding/spawning migrations to Greenland in the west and to the Faeroes in the east. [3]
Straddling stock can be compared with transboundary stock. Straddling stock range both within an EEZ as well as in the high seas. Transboundary stock range in the EEZs of at least two countries. A stock can be both transboundary and straddling. [4]
In fisheries science and ecology, stock assessment is an important tool in fisheries management.
In particular, to ensure continued, healthy, fish stocks, measurements of the Spawning Stock Biomass (the stock population capable of reproducing) allows sensible conservation strategies to be developed and maintained through the application of sustainable fishing quotas. [5]
The World Wildlife Fund and the Zoological Society of London jointly issued their "Living Blue Planet Report" on 16 September 2015 which states that there was a dramatic fall of 74% in world-wide stocks of the important scombridae fish such as mackerel, tuna and bonitos between 1970 and 2010, and the global overall "population sizes of mammals, birds, reptiles, amphibians and fish fell by half on average in just 40 years." [6] It is hoped that global efforts like the United Nations Sustainable Development Goal 14 meets its targets aimed at reversing these trends. [7]
The stocks for individual marine species can "boom and bust" in linked and compensatory ways. For example, in billfish longline fisheries, the Atlantic catch of blue marlin declined in the 1960s. This was accompanied by an increase in sailfish catch. The sailfish catch then declined from the end of the 1970s to the end of the 1980s, compensated by an increase in swordfish catch. As a result, the overall billfish catch remained fairly stable. At Georges Bank, a decline in cod during the 1960s was accompanied by a rise in flatfish, and more recently, with the collapse of the predatory Atlantic cod, lobster catches in Maine have boomed. [8]
Mackerel is a common name applied to a number of different species of pelagic fish, mostly from the family Scombridae. They are found in both temperate and tropical seas, mostly living along the coast or offshore in the oceanic environment.
Overfishing is the removal of a species of fish from a body of water at a rate greater than that the species can replenish its population naturally, resulting in the species becoming increasingly underpopulated in that area. Overfishing can occur in water bodies of any sizes, such as ponds, wetlands, rivers, lakes or oceans, and can result in resource depletion, reduced biological growth rates and low biomass levels. Sustained overfishing can lead to critical depensation, where the fish population is no longer able to sustain itself. Some forms of overfishing, such as the overfishing of sharks, has led to the upset of entire marine ecosystems. Types of overfishing include growth overfishing, recruitment overfishing, and ecosystem overfishing.
The Atlantic horse mackerel, also known as the European horse mackerel or common scad, is a species of jack mackerel in the family Carangidae, which includes the jacks, pompanos and trevallies. It is found in the eastern Atlantic Ocean off Europe and Africa and into the south-eastern Indian Ocean. It is an important species in commercial fisheries and is listed as a Vulnerable species on The IUCN Red List of Threatened Species.
The billfish are a group of saltwater predatory fish characterised by prominent pointed bills (rostra), and by their large size; some are longer than 4 m (13 ft). Extant billfish include sailfish and marlin, which make up the family Istiophoridae; and swordfish, sole member of the family Xiphiidae. They are often apex predators which feed on a wide variety of smaller fish, crustaceans and cephalopods. These two families are sometimes classified as belonging to the order Istiophoriformes, a group which originated around 71 million years ago in the Late Cretaceous, with the two families diverging around 15 million years ago in the Late Miocene. However, they are also classified as being closely related to the mackerels and tuna within the suborder Scombroidei of the order Perciformes. However, the 5th edition of the Fishes of the World does recognise the Istiophoriformes as a valid order, albeit including the Sphyraenidae, the barracudas.
The fishing industry in Scotland comprises a significant proportion of the United Kingdom fishing industry. A recent inquiry by the Royal Society of Edinburgh found fishing to be of much greater social, economic and cultural importance to Scotland than it is relative to the rest of the UK. Scotland has just 8.4 per cent of the UK population but lands at its ports over 60 per cent of the total catch in the UK.
A factory ship, also known as a fish processing vessel, is a large ocean-going vessel with extensive on-board facilities for processing and freezing caught fish or whales. Modern factory ships are automated and enlarged versions of the earlier whalers, and their use for fishing has grown dramatically. Some factory ships are equipped to serve as a mother ship.
The South East Atlantic Fisheries Organisation (SEAFO) is an organization that maintains controls over fishing and fishing related acts in the Southeastern Atlantic Ocean.
This is a glossary of terms used in fisheries, fisheries management and fisheries science.
As with other countries, the 200 nautical miles (370 km) exclusive economic zone (EEZ) off the coast of the United States gives its fishing industry special fishing rights. It covers 11.4 million square kilometres, which is the second largest zone in the world, exceeding the land area of the United States.
The fishing industry in the Maldives is the island's second main industry. According to national tradition in the words of former President Maumoon Abdul Gayoom, "Fishing is the lifeblood of our nation, it is inborn. From the soil on which we live, to the sea around us, it remains an integral part of our existence. Fishing, and our country and its people, [are] one and shall remain inseparable forever." The Maldives has an abundance of aquatic life and species of fish. Common are tuna, groupers, dolphin fish, barracuda, rainbow runner, trevally and squirrelfish and many more. Aside from being of essential importance to the economy, fishing is also a popular recreational activity in the Maldives, not only among locals but by tourists. The islands have numerous fishing resorts which cater for these activities.
Stock assessments provide fisheries managers with the information that is used in the regulation of a fish stock. Biological and fisheries data are collected in a stock assessment.
The false scad, also known as the spotfin scad, ten-finned horse mackerel and yellow horse mackerel, is a species of medium-sized marine fish classified in the jack family Carangidae. The false scad is distributed throughout the tropical and temperate waters of the eastern Atlantic Ocean from Namibia in the south to Spain and throughout most of the Mediterranean in the north. The species has an atypical body form compared to other species of Caranx, and can be distinguished from these on its elongate 'scad-like' body shape alone. Distinguishing the species from members of Decapterus and Trachurus is more difficult, requiring detailed anatomical analysis. The false scad is known to grow to a length of 60 cm and a weight of 1 kg. The species lives both pelagically and demersally in continental shelf waters, ranging from depths of 15 to 200 m. It is a predatory fish, taking small fishes, crustaceans including euphausiids and shrimps, and cephalopods as its main prey, with significant dietary shifts as it ages. The false scad reaches sexual maturity at 2 years of age, with spawning occurring between April and July in shallow inshore waters, where the juveniles remain. The species is of major importance to fisheries throughout its range, but particularly from Morocco to Senegal, with annual catches ranging from 500 to 19000 t. The species is caught using trawls, seine nets and gill nets and sold fresh, frozen or salted.
Fishery and fishing industry plays a significant part in the national economy of Pakistan. With a coastline of about 1,120 km, Pakistan has enough fishery resources that remain to be developed. Most of the population of the coastal areas of Sindh and Balochistan depends on fisheries for livelihood. It is also a major source of export earning.
The Mediterranean horse mackerel, also known as the Black Sea horse mackerel, horse mackerel, Mediterranean scad, common scad, or simply scad, is a species of mackerel in the family Carangidae found in the eastern Atlantic from Bay of Biscay to Mauritania, including the Mediterranean Sea. It is a benthopelagic, subtropical, marine fish that can reach up to 60 cm (24 in) in length. In the countries near the Mediterranean and Black Seas, it makes up a significant portion of fish catch, 54% of fish caught in the latter. Despite overfishing in the 1980s, catch numbers have leveled out and it is listed as least concern by the International Union for Conservation of Nature.
The Chilean jack mackerel, sometimes called the Inca scad or Peruvian jack mackerel, is a species of jack mackerel in the genus Trachurus of the family Carangidae. Since the 1970s, it has become one of the world's more important commercial fish species. High volumes have been harvested, but the fishery may now be in danger of collapsing.
The Cape horse mackerel is a mackerel-like species in the family Carangidae. It is a pelagic species of the south eastern Atlantic Ocean which is a target of fisheries, mainly as bycatch.
Fishing is important to the national economy of Vanuatu. It is the main source of income for many in the islands and Vanuatu's biggest export. According to 2009 figures, approximately 77% of households in Vanuatu are involved in fishing activity. According to 2005 figures, Vanuatu caught 151,080 fish in that year, with frozen fish accounted for half of Vanuatu's commodity exports.
The fishing industry in Denmark operates around the coastline, from western Jutland to Bornholm. While the overall contribution of the fisheries sector to the country's economy is only about 0.5 percent, Denmark is ranked fifth in the world in exports of fish and fish products. Approximately 20,000 Danish people are employed in fishing, aquaculture, and related industries.
Of the twelve species of billfish, there are six species of Billfish in the Indian Ocean.
The Arabian scad is a species of jack mackerel from the family Carangidae which is found in the Western Indian Ocean.
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