Sea Cucumber (Holothuroidea)
Tawana Morris
"Without sound conservation and management measures, fisheries will quickly become depleted and a basic component of global food security will be lost."
- Sigmar Gabriel |
Sea cucumber or sea slug, different cultures have found many different ways to name this underwater sea creature. There are several hundred species of the sea cucumber. None of them are safe from the threat of extinction due to overfishing. Laws should be put in place to protect these colorful underwater sea creatures. Several species of sea cucumber have already been fished into extinction. There are growing concerns regarding biodiversity conservation of these benthic sea creatures. Environmental protection has been made an important part of trying to keep the sea cucumber from going into extinction.
The sea cucumber has been fished for at least 350 years. This sea creature started as a delicacy in countries such as Japan, China, and Korea. Currently, there are other ways the sea cucumber has been used. One way it has been used is for medicinal purposes. It has been said that the sea cucumber can treat high blood pressure. It also is well-known for its ability to reduce arthritis pain, for HIV therapy, and in treatments of asthma, and ulcerative colitis.[9] Another purposeful way the sea cucumber has been used is for food. They are used in a variety of dishes. Thought to have the same properties of tofu, as far as taste, sea cucumbers are thought to be tasteless. They are, however, thought to have the ability to soak up the flavors of foods and seasonings it is cooked with. They are used in soups, stir-fries, and certain braised dishes. [10]
The sea cucumber has been fished for at least 350 years. This sea creature started as a delicacy in countries such as Japan, China, and Korea. Currently, there are other ways the sea cucumber has been used. One way it has been used is for medicinal purposes. It has been said that the sea cucumber can treat high blood pressure. It also is well-known for its ability to reduce arthritis pain, for HIV therapy, and in treatments of asthma, and ulcerative colitis.[9] Another purposeful way the sea cucumber has been used is for food. They are used in a variety of dishes. Thought to have the same properties of tofu, as far as taste, sea cucumbers are thought to be tasteless. They are, however, thought to have the ability to soak up the flavors of foods and seasonings it is cooked with. They are used in soups, stir-fries, and certain braised dishes. [10]
The sea cucumber belongs to the phylum Echinodermata. They live on the bottom of the ocean in what’s called the benthic zone. Some even live partially buried in under the ocean floor. Sea cucumbers come in an array of colors from orange, to black, olive green, brown, purple, and blue. They have bumpy, leathery skin which is embedded with bony particles. Some even have tiny tube feet that stretch the length of their bodies. There are over 1,250 known species of sea cucumbers. The life span of a sea cucumber is 5 to 10 years if in the wild. Sea cucumbers range in length and can grow from about one inch to about six feet.1
These sea creatures eat mainly plankton and decaying organic matter that can be found in the sea. They are scavengers and considered omnivores. They also sift through the bottom sediments using their tentacles. Some sea cucumbers position themselves in currents and catch food that flows by with their open tentacle. Sea cucumbers feed on tiny particles like algae, minute aquatic animals, or waste materials, which they gather in with 8 to 30 tube feet that look like tentacles surrounding their mouths. The animals break down these particles into even smaller pieces, which become fodder for bacteria, and thus recycle them back into the ocean ecosystem.[1]
Eggs and young larvae of the sea cucumber are threatened by fish and other marine animals. Marine predators for the sea cucumber consist of fish and crabs. Another threat to the sea cucumber is humans. They are eaten by humans, especially in Asia where some species of sea cucumbers are farmed and eaten as delicacies. When the sea cucumber is threatened, it discharges sticky threads to cover and entangle the predator. Some species of sea cucumber violently contract their bodies and cast out a large part of their internal organs out of their anus. The internal organs contain a toxin that is deadly to fish and other marine animals (but not to humans). The organs regenerate quickly. It normally takes about six weeks. Sea cucumbers breed sexually and asexually. Sexual reproduction is more typical. Eggs and sperm are released into the water and fertilization occurs when they meet. In order for the sea cucumber population to grow successfully, there must be many sea cucumbers in the area where reproduction is taking place. Reproduction happens from June to August. The fertilized eggs develop into larvae which may spend 70 days as plankton suspended in the water before settling on the bottom and changing into miniature, juvenile sea cucumbers. Juveniles are very secretive and hide among sea weed, under stones, and in crevices. Growth is thought to be slow, requiring at least four to five years for adult size of 0.5 kg to be reached. In September, after the spawning season, they become dormant and their internal organs shrink and atrophy. During the ensuing fall and winter months, they can lose up to 25% of their body weight. During the spring the cucumbers begin feeding again, and recover their body weight during the spring and summer.[6]
These sea creatures eat mainly plankton and decaying organic matter that can be found in the sea. They are scavengers and considered omnivores. They also sift through the bottom sediments using their tentacles. Some sea cucumbers position themselves in currents and catch food that flows by with their open tentacle. Sea cucumbers feed on tiny particles like algae, minute aquatic animals, or waste materials, which they gather in with 8 to 30 tube feet that look like tentacles surrounding their mouths. The animals break down these particles into even smaller pieces, which become fodder for bacteria, and thus recycle them back into the ocean ecosystem.[1]
Eggs and young larvae of the sea cucumber are threatened by fish and other marine animals. Marine predators for the sea cucumber consist of fish and crabs. Another threat to the sea cucumber is humans. They are eaten by humans, especially in Asia where some species of sea cucumbers are farmed and eaten as delicacies. When the sea cucumber is threatened, it discharges sticky threads to cover and entangle the predator. Some species of sea cucumber violently contract their bodies and cast out a large part of their internal organs out of their anus. The internal organs contain a toxin that is deadly to fish and other marine animals (but not to humans). The organs regenerate quickly. It normally takes about six weeks. Sea cucumbers breed sexually and asexually. Sexual reproduction is more typical. Eggs and sperm are released into the water and fertilization occurs when they meet. In order for the sea cucumber population to grow successfully, there must be many sea cucumbers in the area where reproduction is taking place. Reproduction happens from June to August. The fertilized eggs develop into larvae which may spend 70 days as plankton suspended in the water before settling on the bottom and changing into miniature, juvenile sea cucumbers. Juveniles are very secretive and hide among sea weed, under stones, and in crevices. Growth is thought to be slow, requiring at least four to five years for adult size of 0.5 kg to be reached. In September, after the spawning season, they become dormant and their internal organs shrink and atrophy. During the ensuing fall and winter months, they can lose up to 25% of their body weight. During the spring the cucumbers begin feeding again, and recover their body weight during the spring and summer.[6]
Economically, sea cucumbers are important in two main ways. First, some species produce toxins that are of interest to pharmaceutical firms seeking to learn their medical value. Some compounds isolated to date exhibit antimicrobial activity or act as anti-inflammatory agents and anticoagulants. Second, as a gourmet food item in the orient, they form the basis of a multimillion-dollar industry that processes the body wall for sale as bêche-de-mer or trepang. However, the high value of some species, the ease with which such shallow-water forms can be collected and their top-heavy age structures all contribute to over-exploitation and collapse of the fisheries in some regions. Fishermen in the Pacific islands use the toxins, some of which act as respiratory inhibitors, to entice fish and octopus from crevices so that they may be more easily speared. Furthermore, the sticky Cuvierian tubules are placed over bleeding wounds as a bandage.[4] Sea cucumbers (Holothuridae and Stichopodidae) have been harvested commercially for at least 1,000 years. The world fisheries for sea cucumbers, however, are not well documented and in general are poorly managed.
Depending upon the species exploited, there are two processing procedures for the sea cucumber product. Some species are eaten raw, while most commercial species are processed into a dry product called bêche-de-mer or trepang. This dry product called bêche-de-mer is exported to a central market such as Hong Kong and then re-exported to the consumers.[2] Sea cucumbers have been harvested in parts of the western Pacific for hundreds of years, and more recently the fisheries have expanded worldwide. At least 60 species are fished from more than 40 countries and most of the harvests are processed then exported to Asian markets. Fishermen and processors prefer to harvest sea cucumbers during the period when the sea cucumber’s internal organs are atrophied, because they get a higher recovery weight from the animals, processing is easier, and the meat and skin are of a higher quality. Therefore the fishery tends to be opened in the fall and winter when weather conditions are often poor.
"Boats used in fisheries range in size from 22-foot skiffs to 40-foot salmon boats converted to diving. The median vessel size may lie between 30 and 38 feet. The typical operation has three to four persons, which includes two divers and a tender. Scuba gear is used to put the sea cucumbers into bags, where they are left behind on the sea bottom but later recovered. They are slit and eviscerated on the surface."[6] By the early nineties almost all sea cucumbers were landed “split” rather than round. Reported fisheries statistics generally converted to split weight in 1992 to recognize this change in the fishery practices (Muse). Because of its high nutritional value, it is considered an important seafood. In addition, more recently medical research has discovered that sea cucumbers are rich in acidic amylose, suggesting that they could possess medicinal properties. From 1971 up to 1990, entry to the fishery was not limited. Anyone with a “C” license and “fisher’s registration cards” for everyone on board could fish for sea cucumbers. A “C” license is a license for someone who obtains their fish by hook and line.
Later a “Z-D” license was issued for sea cucumbers in 1983, but still not limited. A “Z-D” license stands for “Sea Cucumbers by Dive”.[3] In 1991, the DFO finally shortened the fishery season for sea cucumbers and limited the number of “Z-D” licenses that would be issued due to the high demand of sea cucumber and the amount they were selling for in the markets.
Depending upon the species exploited, there are two processing procedures for the sea cucumber product. Some species are eaten raw, while most commercial species are processed into a dry product called bêche-de-mer or trepang. This dry product called bêche-de-mer is exported to a central market such as Hong Kong and then re-exported to the consumers.[2] Sea cucumbers have been harvested in parts of the western Pacific for hundreds of years, and more recently the fisheries have expanded worldwide. At least 60 species are fished from more than 40 countries and most of the harvests are processed then exported to Asian markets. Fishermen and processors prefer to harvest sea cucumbers during the period when the sea cucumber’s internal organs are atrophied, because they get a higher recovery weight from the animals, processing is easier, and the meat and skin are of a higher quality. Therefore the fishery tends to be opened in the fall and winter when weather conditions are often poor.
"Boats used in fisheries range in size from 22-foot skiffs to 40-foot salmon boats converted to diving. The median vessel size may lie between 30 and 38 feet. The typical operation has three to four persons, which includes two divers and a tender. Scuba gear is used to put the sea cucumbers into bags, where they are left behind on the sea bottom but later recovered. They are slit and eviscerated on the surface."[6] By the early nineties almost all sea cucumbers were landed “split” rather than round. Reported fisheries statistics generally converted to split weight in 1992 to recognize this change in the fishery practices (Muse). Because of its high nutritional value, it is considered an important seafood. In addition, more recently medical research has discovered that sea cucumbers are rich in acidic amylose, suggesting that they could possess medicinal properties. From 1971 up to 1990, entry to the fishery was not limited. Anyone with a “C” license and “fisher’s registration cards” for everyone on board could fish for sea cucumbers. A “C” license is a license for someone who obtains their fish by hook and line.
Later a “Z-D” license was issued for sea cucumbers in 1983, but still not limited. A “Z-D” license stands for “Sea Cucumbers by Dive”.[3] In 1991, the DFO finally shortened the fishery season for sea cucumbers and limited the number of “Z-D” licenses that would be issued due to the high demand of sea cucumber and the amount they were selling for in the markets.
Sea cucumbers have inspired thousands of haiku in Japan, where they are called namako (海鼠), written with characters that can be translated "sea mice" and in English translations, the haiku usually calls them "sea slugs". Over the years, there has been a big increase in the fisheries for the sea cucumber. This benthic creature’s popularity as a delicacy and for medicinal purposes will only continue to increase the demand for it. As for the current status of the sea cucumber, the numbers are declining. Even with the evidence of some species of sea cucumbers going extinct, the fisheries’ demands for the sea cucumber are still high. The declining exports are being attributed to unsustainable fishing done in various areas around the world, naturally low abundances of many commercial species in remote Pacific islands and atolls, and new technology enabled them to harvest far more efficiently.
In order to meet the increasing demand, research and development of sea cucumber seed production, farming and enhancement has become a priority since the 1980s. As early as the 1950s, artificially produced seeds of sea cucumber were tested.2 Currently, 35 different species of sea cucumber are thought to be harvested. On average, 13 species of sea cucumber are harvested per country. “According to a report by the National Oceanic and Atmospheric Administration (NOAA) (undated), tropical and sub-tropical species that are heavily exploited globally (including Asia) and whose populations are seriously depleted include: Holothuria fuscogilva, H. whitmaei, H. scabra and T. ananas, and species that are heavily fished
in certain countries including those in Asia are: A. echinites, H. scabra versicolor, A. lecanora, A. miliaris, A. mauritiana, S. herrmanni, S. horrens and S. chloronotus. Species that may be under potential fishing threats are B. argus and H. fuscopunctata. The temperate species of sea cucumbers, including A. japonicus has also been reported to be depleted in Democratic Peoples’s Republic of Korea and Russian Federation."[2]
People have gone to drastic measures to ensure they keep this fishery around by farming, but they produce lackluster products in farming sea cucumbers themselves. These sea cucumbers only turn out to be about a couple of kilograms heavy and are not very long. They are not very marketable at all. With the depleting wild resources, some farmers have been trying to rear small sandfish collected from the wild to larger sizes in pond (Pitt and Duy, 2004). In Phu Quoc Island, a sharp decrease in sea cucumber stock during the last five years was reported; H. scabra and S. herrmanni, once listed as highly abundant are believed to be approaching local extinction. Currently, dried sea cucumber will sell for US$ 22.00/kg.
The forecast for the sea cucumber does not look bright. If people continue to ignore laws and fish for these echinoderms as they please, they will be fished into extinction. The laws that we currently have must remain as such, such as having the license in order to fish for the sea cucumber. Less exporting of the sea cucumber may also help save all of the species of cucumber that are not extinct yet. Also limiting the season and the amount of the catch will allow for a better outcome for this sea creature. If there was a time limit for time at sea, that may also help keep sea cucumbers safe from extinction. But at the current rate of demand for this creature, it does not stand a chance of survival.
Trade and market scouts are always searching for new species, and since the fishing infrastructure and know-how already exist in Galapagos, there is always the chance of new species being harvested, both legally and illegally. “Fished populations should be monitored regularly so as to provide basic information on recovery rates and resilience. As sea cucumbers are an important part of the food web, ecosystem monitoring should be encouraged in order to understand the possible changes caused by their removal.”[2] It is even recommended to place a ban on the fisheries all together to allow for the fisheries to recover. This may not be a bad idea; the only problem is knowing how long is long enough for recovery.
It is also recommended that there be research placed on the unfished populations of sea cucumbers. Knowing how history repeats itself, one can see that people tend to fish fisheries into extinction. Consequently, when a fishery goes extinct, people move on to the next available, profitable resource. This speaks volumes. If the fished species of sea cucumbers, both wild and aquacultured are fished into extinction, the unfished populations of sea cucumber will then start to look marketable to the corporate world. We can help this sea creature not become extinct by enforcing the laws currently put in place. There is still a lot of illegal fishing for sea cucumbers worldwide. Another solution to help the population of sea cucumbers prosper would be to recognize the pricing that's placed on this seafood item. The more expensive an item, the harder it is to find. This is a general rule of thumb which rings true in many cases.
Trade and market scouts are always searching for new species, and since the fishing infrastructure and know-how already exist in Galapagos, there is always the chance of new species being harvested, both legally and illegally. “Fished populations should be monitored regularly so as to provide basic information on recovery rates and resilience. As sea cucumbers are an important part of the food web, ecosystem monitoring should be encouraged in order to understand the possible changes caused by their removal.”[2] It is even recommended to place a ban on the fisheries all together to allow for the fisheries to recover. This may not be a bad idea; the only problem is knowing how long is long enough for recovery.
It is also recommended that there be research placed on the unfished populations of sea cucumbers. Knowing how history repeats itself, one can see that people tend to fish fisheries into extinction. Consequently, when a fishery goes extinct, people move on to the next available, profitable resource. This speaks volumes. If the fished species of sea cucumbers, both wild and aquacultured are fished into extinction, the unfished populations of sea cucumber will then start to look marketable to the corporate world. We can help this sea creature not become extinct by enforcing the laws currently put in place. There is still a lot of illegal fishing for sea cucumbers worldwide. Another solution to help the population of sea cucumbers prosper would be to recognize the pricing that's placed on this seafood item. The more expensive an item, the harder it is to find. This is a general rule of thumb which rings true in many cases.
1. National Georgraphic
http://animals.nationalgeographic.com/animals/invertebrates/sea-cucumber
2. Conand, Chantal. Advances in sea cucumber aquaculture and management. Fisheries and Aquaculture Department.
2004. 439pgs.
http://www.fao.org/docrep/007/y5501e/y5501e00.htm#Contents
3. Fisheries and Oceans - Canada
http://www.pac.dfo-mpo.gc.ca/fm-gp/licence-permis/lpc-eng.htm
4. Hui, KaWai. Sea Cucumber-Holothuria pardalis.
http://bioweb.uwlax.edu/bio203/s2008/hui_ka/04Life_Cycle.html
5. Tree of Life Web Project.
http://tolweb.org/Holothuroidea/19240
6. Management of the British Columbia Sea Cucumber.
http://www.cfec.state.ak.us/RESEARCH/divefish/SEACUKES.PDF
7. Sea Cucumber
http://www.asnailsodyssey.com/LEARNABOUT/CUCUMBER/cucuMeta.php
8. Brainy Quote.
http://www.brainyquote.com/quotes/quotes/s/sigmargabr459397.html
9. Institute for Traditional Medicine - Subhuti Dharmananda, Ph.D., Director.
http://www.itmonline.org/arts/seacucumber.htm
10. About.com - Parkinson, Rhonda.
http://chinesefood.about.com/od/shopingredients/p/seacucumber.htm
http://animals.nationalgeographic.com/animals/invertebrates/sea-cucumber
2. Conand, Chantal. Advances in sea cucumber aquaculture and management. Fisheries and Aquaculture Department.
2004. 439pgs.
http://www.fao.org/docrep/007/y5501e/y5501e00.htm#Contents
3. Fisheries and Oceans - Canada
http://www.pac.dfo-mpo.gc.ca/fm-gp/licence-permis/lpc-eng.htm
4. Hui, KaWai. Sea Cucumber-Holothuria pardalis.
http://bioweb.uwlax.edu/bio203/s2008/hui_ka/04Life_Cycle.html
5. Tree of Life Web Project.
http://tolweb.org/Holothuroidea/19240
6. Management of the British Columbia Sea Cucumber.
http://www.cfec.state.ak.us/RESEARCH/divefish/SEACUKES.PDF
7. Sea Cucumber
http://www.asnailsodyssey.com/LEARNABOUT/CUCUMBER/cucuMeta.php
8. Brainy Quote.
http://www.brainyquote.com/quotes/quotes/s/sigmargabr459397.html
9. Institute for Traditional Medicine - Subhuti Dharmananda, Ph.D., Director.
http://www.itmonline.org/arts/seacucumber.htm
10. About.com - Parkinson, Rhonda.
http://chinesefood.about.com/od/shopingredients/p/seacucumber.htm