Saltwater fish

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Saltwater fish, also called marine fish or sea fish, are fish that live in seawater. Saltwater fish can swim and live alone or in a large group called a school. [1]

Contents

Saltwater fish are very commonly kept in aquariums for entertainment. Many saltwater fish are also caught to be eaten, [2] [3] or grown in aquaculture. However, many fish species have been overfished and are otherwise threatened by marine pollution or ecological changes caused by climate change.

Diet

Fishes that live in the ocean can be carnivores, herbivores, or omnivores. [4] Herbivores in the ocean eat things such as algae and flowering seagrasses. Many herbivores' diets consist of primarily algae. Most saltwater fish will eat both macroalgae and microalgae. Many fish eat red, green, brown, and blue algae, but some fish prefer other types. Most saltwater fish that are carnivores will never eat algae under any circumstances. Carnivores' diets consist of shrimp, plankton, or tiny crustaceans. [4]

Captivity

Saltwater fish tanks are popular among businesses and households. Saltwater-fish-tanks-saltwater-aquarium.jpg
Saltwater fish tanks are popular among businesses and households.

Saltwater aquariums are a multi-million dollar industry in the United States. About 10 million marine fish are imported into the United States each year for aquarium use. The United States imports more saltwater fish than any other country in the world. There are approximately 2,000 different species of saltwater fish that are imported and used in captivity. [3] In many circumstances, fish used for marine trade are collected using harmful tactics such as cyanide. One way that people are trying to protect the coral reefs is by breeding marine fish in captivity. Captive-bred fish are known to be healthier and likely to live longer. Captive-bred fish are less susceptible to disease because they have not been exposed to the wild and they have not been damaged during the shipment process. Fish that are bred in captivity are already accustomed to aquarium habitats and food. [2]

Habitats

There are many different components that make up a marine life habitat. Some of them are the temperature of the water, the quality, and quantity of water (flow and depth). Other components that can also contribute to the habitat of saltwater fish are pH level, salt level, and alkalinity level. Levels of nitrates and phosphates are also relevant, particularly when considering conditions for fish in captivity. There are other physical features that contribute to a habitat which are physical materials like rocks, reefs, and sand or the vegetation like the amount of algae, water plants, and saltmarsh. Specific fish live in specific habitats based on what they eat or what cycle of life they are currently at, another thing is the amount of salt that is in the water at that specific location. Some ocean habitats are not technically in the ocean and these are called estuaries, areas when oceans and rivers meet creating a mixture of salt water and freshwater making a different habitat for different types of fish and creatures to live in. [5] [6] The ocean is home to organisms as large as whales and as small as microscopic marine organisms such as phytoplankton. However, the vast majority of ocean life that humans are exposed to is simple saltwater fish. Saltwater fish can live in the deepest depths of the ocean where no sunlight can penetrate, but they can also live on the surface of the water. [1]

Threats

Marine fish face many anthropogenic threats. Common human-induced threats include overfishing, pollution, habitat loss and destruction, climate change and invasive species. The aforementioned threats all come with a multitude of negative direct and indirect affects to marine ecosystems. With the human population growing at an exponential rate, these threats are likely to continue to be prevalent in marine ecosystems.

Commercial fishing boats bring in massive amounts of fish on a regular basis. Pictured above is a fisherman trawl harvesting cod. Trawlers overfishing cod.jpg
Commercial fishing boats bring in massive amounts of fish on a regular basis. Pictured above is a fisherman trawl harvesting cod.

Overfishing

Overfishing is defined as the mass removal of fish from a body of water that results in halting the ability for breeding populations to replenish what has been removed. Fish is one of the most popular foods in the world and consumption has continued to rise with the growing human population and will continue to do so. The value of the global seafood market has seen a 15% increase from 2016 to 2020 and is projected to increase even more by 2023. [7] Although it provides many people with a source of food, the global seafood market is a major threat to the biodiversity of fishes. Bycatch is a direct effect of overfishing and is defined as the unwanted capture of different marine organisms during industrial fishing. This results in many different species of fish dying after they are captured and discarded. Data on bycatch is often unclear and not well recorded but it is estimated that the U.S. alone discards 17–22% of their catch annually. [8] The Mesopredator release hypothesis is one of the indirect effects of overfishing that is also often referred to as "fishing down the food web". This phenomenon means as fisheries deplete large apex predatory species, mid-sized predatory species increase in abundance and assume the role as top predators on the food web. [9] This impacts the food web in marine environments and disrupts the balance of the ecosystem and is likely to cause trophic cascades.

Species affected by overfishing

Profitable fish stocks like the bluefin tuna are decreasing in numbers because of high demand. According to the IUCN Red List, the Pacific bluefin tuna, Atlantic bluefin tuna, and southern bluefin tuna are classified as vulnerable, endangered and critically endangered [10] all due to over-exploitation.

According to the IUCN Red List, the oceanic whitetip shark is considered critically endangered because of its value in the seafood market. Their rapidly declining population is due to people overfishing them for their fins. They are a popular species of shark used in shark fin soup because of the size of their fins. All sharks are used for shark fin soup, however, certain species of sharks are preferred over others because of the large size of their fins.

The great white shark is listed as vulnerable on the IUCN Red List because its fins are commonly used in shark fin soup and has led to people over harvesting them for their fins. This shark belongs to the class Chondrichthyes that includes all sharks, skates and rays. The great white shark is one of the many examples of shark species threatened by human consumption because of the shark fin soup, large population declines of this class has been noted since the early 2000s due to the high demand for their fins, gill rakers and liver oil. [11]

The Atlantic cod was historically abundant in the waters off the coast of New England. Due to its low fat content and dense white flesh, this fish is a popular choice among humans. Now considered vulnerable, [12] its populations have both decreased in abundance and their distribution has shifted from northern to southern areas due to overfishing. [13]

Cage aquaculture

Photo of cage aquaculture located in Australia CSIRO ScienceImage 2686 Salmon Cages.jpg
Photo of cage aquaculture located in Australia

Aquaculture is defined as the farming of aquatic organisms in controlled environments for the purpose of providing food and resources for humans. Aquaculture can take place in both marine and freshwater environments, however, because this is the saltwater fish page this entry will only cover the effects of aquaculture on marine fishes. The rising global demand for fish has contributed to the increase in aquaculture. Due to the decline of many wild fish stocks, aquaculture is the fastest growing food production system that contributes about 50% of the worlds fish supply. [14] There is a lot of debate on whether or not aquaculture is an environmentally sustainable practice, yet the socioeconomic benefits that humans receive is tough to argue against. That being said there are significant negative effects that aquaculture, especially cage aquaculture, has on the surrounding environment.

Cage aquaculture involves rearing aquatic organisms in natural water sources while enclosed in a mesh/net cage that allows water from the surrounding environment to freely flow in and out. Cage aquaculture in marine environments has been particularly controversial because of the effects it has on the surrounding ecosystem thus, affecting wild marine fish populations. The main impacts of cage aquaculture are reduced water quality from fish sewage, high potential of genetic pollution of wild stocks due to escapees from aquaculture cages [15] and the possibility of introducing an invasive species if the fish being reared are non-native . Fish sewage is the combination of fish feed, fecal material and antibiotics that is accumulated on the seafloor and in the water column from fish that are being farmed. It is not only harmful to wild fish stocks but it also poses a threat to marine plant life which is often a food source for wild fish stocks. Fish sewage is harmful because it pollutes the surrounding ecosystem and can cause problems like eutrophication, transmission of parasites and diseases to wild populations [16] and developmental abnormalities on surrounding wild fish. [17] Genetic pollution of wild fish populations is a common risk that cage aquaculture faces. For example, there are many scientific papers that have examined the effects of Atlantic Salmon escaping from their enclosures and interacting with wild populations. Farmed salmon have lower fitness (low survival rates and reproductive success) than a wild salmon would due to differences in artificial and natural selection. [18] Artificial selection that chooses phenotypic traits that are desired for human consumption will alter the genetics of wild stocks if farmed fish interact and breed with wild populations. This would result in the reduction of fitness related traits that wild stocks possess which is a serious threat to these populations.

Categorization of saltwater fish by habitats

Related Research Articles

Aquaculture, also known as aquafarming, is the controlled cultivation ("farming") of aquatic organisms such as fish, crustaceans, mollusks, algae and other organisms of value such as aquatic plants. Aquaculture involves cultivating freshwater, brackish water, and saltwater populations under controlled or semi-natural conditions and can be contrasted with commercial fishing, which is the harvesting of wild fish. Aquaculture is also a practice used for restoring and rehabilitating marine and freshwater ecosystems. Mariculture, commonly known as marine farming, is aquaculture in seawater habitats and lagoons, as opposed to freshwater aquaculture. Pisciculture is a type of aquaculture that consists of fish farming to obtain fish products as food.

<span class="mw-page-title-main">Mariculture</span> Cultivation of marine organisms in saltwater environments

Mariculture, sometimes called marine farming or marine aquaculture, is a branch of aquaculture involving the cultivation of marine organisms for food and other animal products, in seawater. Subsets of it include, fish farms built on littoral waters, or in artificial tanks, ponds or raceways which are filled with seawater. An example of the latter is the farming of plankton and seaweed, shellfish like shrimp or oysters, and marine finfish, in saltwater ponds. Non-food products produced by mariculture include: fish meal, nutrient agar, jewellery, and cosmetics.

<span class="mw-page-title-main">Tuna</span> Tribe of fishes

A tuna is a saltwater fish that belongs to the tribe Thunnini, a subgrouping of the Scombridae (mackerel) family. The Thunnini comprise 17 species across five genera, the sizes of which vary greatly, ranging from the bullet tuna up to the Atlantic bluefin tuna, which averages 2 m (6.6 ft) and is believed to live up to 50 years.

<span class="mw-page-title-main">Fishery</span> Raising or harvesting fish

Fishery can mean either the enterprise of raising or harvesting fish and other aquatic life or, more commonly, the site where such enterprise takes place. Commercial fisheries include wild fisheries and fish farms, both in freshwater waterbodies and the oceans. About 500 million people worldwide are economically dependent on fisheries. 171 million tonnes of fish were produced in 2016, but overfishing is an increasing problem, causing declines in some populations.

<span class="mw-page-title-main">Yellow tang</span> Species of fish

The yellow tang, also known as the lemon sailfin, yellow sailfin tang or somber surgeonfish, is a species of marine ray-finned fish belonging to the family Acanthuridae which includes the surgeonfishes, unicornfishes and tangs. It is one of the most popular marine aquarium fish. It is bright yellow in color, and it lives in reefs. The yellow tang spawn around a full moon. The yellow tang eats algae. The yellow tang has a white barb, located just before the tail fin, to protect itself.

<span class="mw-page-title-main">Overfishing</span> Removal of a species of fish from water at a rate that the species cannot replenish

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.

<span class="mw-page-title-main">Sustainable fishery</span> Sustainable fishing for the long term fishing

A conventional idea of a sustainable fishery is that it is one that is harvested at a sustainable rate, where the fish population does not decline over time because of fishing practices. Sustainability in fisheries combines theoretical disciplines, such as the population dynamics of fisheries, with practical strategies, such as avoiding overfishing through techniques such as individual fishing quotas, curtailing destructive and illegal fishing practices by lobbying for appropriate law and policy, setting up protected areas, restoring collapsed fisheries, incorporating all externalities involved in harvesting marine ecosystems into fishery economics, educating stakeholders and the wider public, and developing independent certification programs.

<span class="mw-page-title-main">Fishing industry</span> Economic branch

The fishing industry includes any industry or activity that takes, cultures, processes, preserves, stores, transports, markets or sells fish or fish products. It is defined by the Food and Agriculture Organization as including recreational, subsistence and commercial fishing, as well as the related harvesting, processing, and marketing sectors. The commercial activity is aimed at the delivery of fish and other seafood products for human consumption or as input factors in other industrial processes. The livelihood of over 500 million people in developing countries depends directly or indirectly on fisheries and aquaculture.

<span class="mw-page-title-main">Atlantic bluefin tuna</span> Species of fish

The Atlantic bluefin tuna is a species of tuna in the family Scombridae. It is variously known as the northern bluefin tuna, giant bluefin tuna, and formerly as the tunny.

<span class="mw-page-title-main">Tropical fish</span> Fish found in aquatic tropical environments

Tropical fish are fish found in aquatic tropical environments around the world. Fishkeepers often keep tropical fish in freshwater and saltwater aquariums. The term "tropical fish" is not a taxonomic group, but rather is a general term for fish found in such environments, particularly those kept in aquariums.

<span class="mw-page-title-main">Seafood Watch</span> Consumer advisory list

Seafood Watch is a sustainable seafood advisory list, and has influenced similar programs around the world. It is best known for developing science-based seafood recommendations that consumers, chefs, and business professionals use to inform their seafood purchasing decisions.

<span class="mw-page-title-main">Bluefin trevally</span> Species of fish

The bluefin trevally, also known as the bluefin jack, bluefin kingfish, bluefinned crevalle, blue ulua, omilu, and spotted trevally, is a species of large, widely distributed marine fish classified in the jack family, Carangidae. The bluefin trevally is distributed throughout the tropical waters of the Indian and Pacific Oceans, ranging from Eastern Africa in the west to Central America in the east, including Japan in the north and Australia in the south. The species grows to a maximum known length of 117 centimetres (46 in) and a weight of 43.5 kilograms (96 lb), however is rare above 80 centimetres (31 in). Bluefin trevally are easily recognised by their electric blue fins, tapered snout and numerous blue and black spots on their sides. Juveniles lack these obvious colours, and must be identified by more detailed anatomical features such as fin ray and scute counts. The bluefin trevally inhabits both inshore environments such as bays, lagoons and shallow reefs, as well as deeper offshore reefs, atolls and bomboras. Juveniles prefer shallower, protected waters, even entering estuaries for short periods in some locations.

<span class="mw-page-title-main">Environmental impact of fishing</span>

The environmental impact of fishing includes issues such as the availability of fish, overfishing, fisheries, and fisheries management; as well as the impact of industrial fishing on other elements of the environment, such as bycatch. These issues are part of marine conservation, and are addressed in fisheries science programs. According to a 2019 FAO report, global production of fish, crustaceans, molluscs and other aquatic animals has continued to grow and reached 172.6 million tonnes in 2017, with an increase of 4.1 percent compared with 2016. There is a growing gap between the supply of fish and demand, due in part to world population growth.

Sustainable seafood is seafood that is caught or farmed in ways that consider the long-term vitality of harvested species and the well-being of the oceans, as well as the livelihoods of fisheries-dependent communities. It was first promoted through the sustainable seafood movement which began in the 1990s. This operation highlights overfishing and environmentally destructive fishing methods. Through a number of initiatives, the movement has increased awareness and raised concerns over the way our seafood is obtained.

<span class="mw-page-title-main">Wild fisheries</span> Area containing fish that are harvested commercially

A wild fishery is a natural body of water with a sizeable free-ranging fish or other aquatic animal population that can be harvested for its commercial value. Wild fisheries can be marine (saltwater) or lacustrine/riverine (freshwater), and rely heavily on the carrying capacity of the local aquatic ecosystem.

<span class="mw-page-title-main">Friend of the Sea</span> Sustainable seafood organization

Friend of the Sea is a project of the World Sustainability Organization for the certification and promotion of seafood from sustainable fisheries and sustainable aquaculture. It is the only certification scheme which, with the same logo, certifies both wild and farmed seafood.

<span class="mw-page-title-main">Fishing industry in the United States</span>

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.

<span class="mw-page-title-main">Aquaculture in Canada</span>

Aquaculture is the farming of fish, shellfish or aquatic plants in either fresh or saltwater, or both. The farmed animals or plants are cared for under a controlled environment to ensure optimum growth, success and profit. When they have reached an appropriate size, they are harvested, processed, and shipped to markets to be sold. Aquaculture is practiced all over the world and is extremely popular in countries such as China, where population is high and fish is a staple part of their everyday diet.

The following outline is provided as an overview of and topical guide to fisheries:

The following outline is provided as an overview of and topical guide to fish:

References

  1. 1 2 Chesley, Paul (2017-01-05). "Ocean Habitats and Information". National Geographic. Archived from the original on 2020-05-15. Retrieved 2018-10-21.
  2. 1 2 Bale, Rachael (2016-05-03). "Breeding Aquarium Fish Can Help Save Reefs". National Geographic. Archived from the original on 2018-10-26. Retrieved 2018-10-21.
  3. 1 2 Actman, Jani (March 29, 2018). "See How Fish Get From Coral Reefs to Your Aquarium Tank". National Geographic. Archived from the original on August 26, 2013. Retrieved January 28, 2021.
  4. 1 2 Hauter, Stan. "What Saltwater Fish Eat in the Wild". The Spruce Pets. Archived from the original on 2020-05-03. Retrieved 2018-10-21.
  5. ↑ "Facts About Saltwater Fish". Gone Outdoors | Your Adventure Awaits. Archived from the original on 2018-06-27. Retrieved 2018-05-03.
  6. ↑ "Ocean Habitat". Archived from the original on 2018-10-26. Retrieved 2018-05-03.
  7. ↑ "Seafood industry". Statista. Archived from the original on 2017-06-25. Retrieved 2020-04-28.
  8. ↑ "Oceana". Oceana. Archived from the original on 2020-05-14. Retrieved 2020-04-28.
  9. ↑ "Fishing Down through the Food Web | American Fisheries Society". fisheries.org. Archived from the original on 2018-04-04. Retrieved 2020-04-29.
  10. ↑ "The IUCN Red List of Threatened Species". IUCN Red List of Threatened Species. Archived from the original on 2020-03-04. Retrieved 2020-04-28.
  11. ↑ Davidson, Lindsay N. K.; Krawchuk, Meg A.; Dulvy, Nicholas K. (2016). "Why have global shark and ray landings declined: improved management or overfishing?". Fish and Fisheries. 17 (2): 438–458. CiteSeerX   10.1.1.706.43 . doi:10.1111/faf.12119. ISSN   1467-2979.
  12. ↑ "IUCN Red List of Threatened Species: Atlantic Cod". IUCN Red List of Threatened Species. 1996-08-01. Archived from the original on 2020-03-04. Retrieved 2020-04-29.
  13. ↑ Fletcher, Garth. "Distribution shifts and overfishing the northern cod (<i>Gadus morhua</i>): a view from the ocean". Canadian Journal of Fisheries and Aquatic Sciences. Archived from the original on 2021-01-28. Retrieved 2020-04-29.
  14. ↑ "Aquaculture". Food and Agriculture Organization of the United Nations. Archived from the original on 2019-11-16. Retrieved 2020-04-29.
  15. ↑ Mazur, Nicole A.; Curtis, Allan L. (2008-12-01). "Understanding community perceptions of aquaculture: lessons from Australia". Aquaculture International. 16 (6): 601–621. doi: 10.1007/s10499-008-9171-0 . ISSN   1573-143X.
  16. ↑ "Ocean Pollution and Diseases from Aquaculture or Fish Farming from the Seafood Watch Program of the Monterey Bay Aquarium". www.seafoodwatch.org. Archived from the original on 2020-05-18. Retrieved 2020-04-29.
  17. ↑ "Fish". Beyond Pesticides. Archived from the original on 2020-05-11. Retrieved 2020-04-29.
  18. ↑ Weber, Peter (February 1995). "Facing limits in oceanic fisheries". Natural Resources Forum. 19 (1): 39–46. doi:10.1111/j.1477-8947.1995.tb00591.x. ISSN   0165-0203.
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