Seahorses: Characteristics and Conservation
June 4, 2000
Tropical Marine Ecology
"Seahorses and tiny mermaids living admidst gardens of flowing seaweeds and pretty seashells are common in children's fantasies (Moore 1)." But unlike mermaids, seahorses are a real type of fish (Moore 1). "The head of a chess piece, the tail of a monkey, a rigid body that seems carved from wood, and a father who becomes pregnant" (Packer 22). Seahorses have many unique characteristics that make them intriguing to humans. This intrigue has led to the use of seahorses, which could be potentially detrimental to the survival of the species. It is important to understand the characteristics that make seahorses so unique; however, it is probably more important to understand the pressures that are effecting seahorses and what can be done to help alleviate these problems.
To begin, it is important to understand the basics of seahorses. Seahorses are a type of bony fish, which classifies them in the animal kingdom, phylum Chordata, and class, Osteichthyes. Seahorses are part of the family Syngnathidae, which also includes pipefish and sea dragons (Boschung 530 and Moore 1). This family of fish has small, atypical bodies that are encased in bony rings (Boschung 530). All seahorses belong to the genus Hippocampus. The genus name is based on Greek in which it means "bent horse" (Animal Bytes 1). They have a small, toothless mouth at the end of their tubular snout (Boschung 530). Seahorses range in size from 2.5-35 cm. (Seahorse Park 2). They are more commonly between 10-15 cm. in length (Moore 1).
Most of the species have pectoral and dorsal fins, but they all lack pelvic fins (Boschung 530). They do not have any spines in their fins and if they have an anal fin it is very small (Boschung 530). Seahorses do move with the help of these fins; however, due to the small size and their body shape they are not really very agile (Moore 1). They swim upright propelled by a waving dorsal fin that can beat 20-35 times per second (Macquitty 25 and Packer 22). To avoid being eaten they rely on camouflage and their prehensile (grasping) tail (Moore 1). Their tail curls around seaweed to anchor the seahorse in place ( Macquitty 17). Seahorses do not like to be in the open (Macquitty 17). If the seahorse does wish to rise, it can uncurl its tail (Macquitty 17). Seahorses also have the ability to change color (Seahorse Park 2). It is even stronger than the well-known chameleon (Seahorse Park 2). This happens for camouflage as well as for expressing emotions and reacting to other seahorses (Seahorse Park 2). Seahorses can develop actual skin filaments to help them camouflage (Seahorse Park 2). Hippocampus hippocampus can grow skin filaments that look like seaweed and H. bargibanti grows filaments to look like coral (Seahorse Park 2).
Seahorses' main food source is shrimp and other crustaceans, worms, and other invertebrates (Seahorse Park 2 and Moore 1). Their food is ambushed as it swims past (Moore 1). When the prey is within range, they suck it through their bony snout (Frequently 4). They swallow their prey whole because they have no teeth (Frequently 4). Seahorses also lack stomachs, so they must consume large amounts of food to compensate for their inefficient digestive system (Frequently 4).
The reproductive patterns of seahorses are very unusual. A very unique feature of the family Syngnathidae is the presence of a brooding pouch in males called the marsupium (Boschung 530). A pair of seahorses usually goes through courtship rituals for several days before mating (Moore 1). These rituals include color changes, synchronized swimming and other ritualistic behavior (Moore 1). After courtship, the female inserts her ovidepositor into the males pouch and deposits eggs (Moore 1). The female seahorse can lay about 200 eggs (Seahorse Park 2). The eggs are fertilized by the male and incorporated in the lining of the pouch to create a pseudo-placenta (Moore 1). The developing embryos are nurtured, oxygenated and maintained for as long as 6 weeks entirely by the male (Moore 1). The male is truly pregnant (Moore 1). During the male's pregnancy they dance before sunrise each day with the same female(Sea Horses on Path 1). Males even experience birth pains (Moore 1). When giving birth, the male bends forward and backward as the pouch opens for the baby to pass out (Packer 22). This continues as the babies are born in batches of five or so (Packer 22). The father is very tired at the end of the session which can last as long as 2 days (Packer 22). When the babies are born, all parental care ceases and they must fend for themselves (Moore 1). Seahorses mate for life (Sea Horses on Path 1). The same female will return to mate again once the male has given birth (Moore 1).
Most seahorses are found near shore (Boschung 530). Worldwide, seahorses are found in most coastal areas, which have sea grass beds, mangroves, coral reefs and estuaries (TED Case 2 and Frequently 3). Worldwide, there are estimated to be approximately 35 species (TED Case 2). The most populated areas for seahorses are southern Australia and Tasmania, China, and the Philippines (TED Case 2).
One species of Seahorses found in North America is the Lined Seahorse (Hippocampus erectus) (Boschung 530). It can grow up to 13 cm. (5 inches) in size (Boschung 530). Its head is perpendicular to its vertical body (Boschung 530). Its coloration changes with its background including light brown, dusky, gray, blackish, brick-red, unmarked, or various mottled (Boschung 530). It has a fan-shaped dorsal fin and no caudal fin (Boschung 530). It is usually found associated with vegetation such as eelgrass and sargassum ranging from Nova Scotia to Argentina and Bermuda to the Gulf of Mexico (Boschung 530). The Dwarf Seahorse (H. zosterae) is related to the Lined Seahorse and is found in a similar habitat in the Gulf of Mexico and Caribbean (Boschung 530). However, the Dwarf Seahorse grows to 7.5 cm (3 inches) and has a green to blackish body (Boschung 530).
Once the uniqueness of the seahorse is understood, it is easier to discuss the concerns related to conservation of the species. It is known that approximately 20 million live and dead seahorses were legally traded in 1993 (TED Case 1, Seahorse Park 2). Many more were smuggled across the Taiwan Strait (TED Case 1). Great Britain has taken the lead in trying to evaluate if the seahorse can withstand this amount of trade (TED Case 1).
A study conducted by Amanda Vincent has brought seahorse trade to international attention (TED Case 1). Amanda Vincent from Magill University is the founder of a conservation project called Project Seahorse; she is the leader of the charge to conserve seahorses (Radio National 1). She began studying seahorses in 1986 (TED Case 1). She studied the unique mating and reproduction of seahorses and the difficulty in trying to raise seahorses on her own (TED Case 2). She also discovered the large number of seahorses traded (TED Case 2). Seahorses are mostly used for medicine and aphrodisiacs in Asia (TED Case 2). They are also used for aquariums, curios, and food all around the world including the United States (TED Case 2). The illegal trade in Taiwan may be even more devastating (TED Case 2). Seahorses are shipped in such large numbers that it makes it impossible to make an educated guess at the quantity illegally traded (TED Case 2). The Philippines and China probably have the most invested in the seahorse trade (TED Case 2). Amanda Vincent found the following flashing on a news board in 1990: "Seahorses are the most valuable fisheries export of the Philippines" (TED Case 2).
Specific countries contribute to the concerns for conservation of the species. It is estimated that in China roughly 20 tons of seahorses or 6 million animals were consumed in 1992 (TED Case 2). They are the largest consumer of seahorses (TED Case 3). It is believed by some that more than 95% of seahorses are used in traditional Chinese medicine (Roach 2). They have been used for centuries as an ingredient for medicines, aphrodisiacs, and a dinner delicacy (TED Case 3). The Chinese believe that seahorses can cure asthma, arteriosclerosis, broken bones, goiter, impotence, phlegm, psoriasis, and general health (TED Case 8). The reason why seahorses are considered so unique in medicinal use is due to the fact that the male becomes pregnant (Roach 2). In Australia and the surrounding nations, seahorses are used for the tourist industry (TED Case 4). They are used to make souvenir items such as key chains (TED Case 4). In Hong Kong chemist's shops, 1 dried kilogram of seahorses is worth $1,200 (TED Case 6). In the United States both live and dried seahorses are imported mostly from the Philippines for aquarium use and for China towns (TED Case 4). In 1987, 200,000 seahorses were imported to the United States from the Philippines (TED Case 6). In Perth, a live aquarium fish may sell for $20. Other countries that import seahorses include: Taiwan, Singapore, Japan, Malaysia, and South Korea (TED Case 7).
Amanda Vincent feels that if trade remains at current levels it will be a threat to the survival of seahorses (TED Case 2). She has reported from her travels that less animals are being caught and the size animal being utilized is decreasing (TED Case 2). Seahorse fishermen reported a 15-50% decline in the seahorses in the last 5 years and a 70% decline over the past 10 years (Sea Horses on Path 1). The loss of their habitat is another threat to seahorses (TED Case 2). Aquarium species collectors and exporters are blasting coral reefs and destroying mangroves and sea grass meadows (TED Case 2). Pollution and the development of marinas have also contributed to the pressures on the survival of seahorses (Moore 2). The loss of the seahorse from its habitat could also have an effect on the balanced ecosystem (TED Case 3). As with most animals, there is a typical food web that exists related to the seahorse. The main food source of seahorses is shrimp (TED Case 3). Even though seahorses have the ability to change color and camouflage, they are often eaten by penguins and crabs (TED Case 3). The other natural enemy of seahorses is the weather (TED Case 3). A storm can cast seahorses adrift and they often die of exhaustion (TED Case 3).
Because of all the pressures that exist, efforts have been made to try and remedy the problems. During the 1990's there has been the initiation of studies into the seahorse trade (TED Case 3). In 1992 at the Rio Earth Summit, a key convention was proposed and then ratified in Great Britain in 1994 (TED Case 3). 5.6 million United Kingdom pounds were provided by the Rio Summit Convention for research and conservation of threatened seahorse species (TED Case 6). The Biodiversity Convention is a framework for international action to protect the species, habitats, and ecosystems (TED Case 3). Most of the nations agreed that there should be studies conducted on the seahorse population; however, there is not much agreement as to what if any limitation should be put on seahorses (TED Case 5). Naturally the nations that benefit from the trade of seahorses have an interest in keeping unrestricted trade (TED Case 5). These nations would probably include: China, the Philippines, Australia, Hong Kong, Tasmania, and Singapore (TED Case 5). Other exporters of seahorses include: Belize, Brazil, Indonesia, Kuwait, Malaysia, Mexico, Pakistan, Tanzania, Thailand, United Arab Emeritus, United States, and Vietnam (TED Case 6-7).
Through this convention the Darwin Initiative for the Survival of the Species is funding a study of the possible commercial breeding of seahorses for Chinese medicine (TED Case 3). The goal of the study is to determine if seahorses can withstand the current exploitation (TED Case 3). There is an official trade ban on produce from China to Taiwan; however, the illegal trade still flourishes and seahorses are a common commodity (TED Case 3). Individual fishing boats carry illegal cargo to the island, as well as, local businessmen doing business through party nations like Hong Kong (TED Case 3). In all other nations, seahorse trade is legal (TED Case 5).
Another convention that addressed conservation was held in 1998. Marine biologists and aquaria experts from around the world met at Shedd Aquarium in Chicago, Illinois to work out ways to coordinate their research on the care and management of seahorses (Roach 2). Their hopes were to conserve the genus before any of the species become endangered (Roach 2). This conference helped encourage the research community to return home to their various countries and spread the word about seahorse conservation (Roach 3).
It seems that the simple solution would be to stop the consumption of seahorses; however, one needs to consider the effects from such actions. If seahorse trade was to decline significantly, it would effect both the consuming and producing nations (TED Case 7). However, it is probable that another similar fish could be substituted for aquarium and tourist use (TED Case 8). It is also possible that countries could find other income sources. The most difficult to deal with would be the medicinal use in China (TED Case 8). These practices go back 2000 years and it would be hard to persuade the idea of a substitute (TED Case 8 and Sea Horses on Path 2). Plus, without scientific knowledge about what makes seahorse derived medicines effective, it makes it very difficult to develop a synthetic version or a substitute (Roach 2). Amanda Vincent feels that instead of trying to convince the Asians not to use fish for medicine, a better approach is to get them to help conserve the species (Sea Horses on Path 2).
One solution that has been proposed by Amanda Vincent is a joint venture between Project Seahorse and the Shedd Aquarium in the coastal village of Handumon in the Philippines (Roach 2). The villagers make handicrafts that are sold at Shedd aquarium (Roach 2). This income is used to replace the income that would have been obtained from the harvest of seahorses (Roach 2). "We take the approach that discussion is better than conflict, " said Vincent (Roach 2). The village now has several protected areas and seahorse reserves (Roach 2). Project Seahorse has a program in the Philippines and Vietnam to educate fishermen how to conserve seahorses (Sea Horses on Path 2). The fishermen use special mesh underwater cages to hold the pregnant males (Sea Horses on Path 2). The mesh is large enough so the babies can swim away when born (Sea Horses on Path 2). Another possible solution is the development of small, family based seahorse farms (Roach 2). Vincent is skeptical of this, however, due to the lack of knowledge on seahorse husbandry (Roach 2). There are also hopes that education of the public can help improve conservation of seahorses (Roach 3). For example, a display titled "Seahorse Symphony" was at Shedd Aquarium that was meant to educate the public about seahorses and their conservation needs (Roach 3). Over a million people visited this display (Roach 3).
Another threat to seahorses is the popularity with aquarists who don't know how to care for the seahorses (Roach 2). It is very difficult to provide seahorses in an aquarium the fresh, live food and environmental conditions that they need (Seahorse Park 2). It seems to be almost impossible to keep seahorses alive for more than 1 year in captivity (Seahorse Park 2). They can die in a matter of months (Roach 2). Many seahorses contract bacterial, fungal, and parasitic ailments (Seahorse Park 2). Veterinary studies have only just begun, so there is not a lot of information to help treat these problems (Seahorse Park 2). It is a sad fact that most seahorses that are sold for aquarium use are being sent to death (Moore 2). "It is the rare aquarist who has the knowledge to keep sea horses," said Jeff Boehm, head of research and veterinary services at Shedd aquarium (Roach 3). Vincent is telling Americans to stop buying live seahorses for their home aquariums unless they have extensive experience working with saltwater fish (Sea Horses on Path 2). She feels this could help improve the current situation. Various biologists are also working to improve breeding techniques by studying various seahorses to decrease the dependence on wild stocks (Hayden 1).
Seahorses are fascinating animals. They have characteristics that are highly unusual, especially for fish. They have no scales. They are monogamous. They have an unusual horse-like, upright structure. They can change colors. The male is pregnant and goes through labor. All of this has created an aura of mystery and intrigue that has led to pressures on this animal's survival. The Chinese believe that they can cure all sorts of ailments from asthma to impotence. This has led to a large trade industry. It has allowed people to rely on catching these fish as a source of income. Some eat the animal as a delicacy. Still others, including the United States, find this intriguing animal desirable to have in an aquarium, despite the low survival rates in captivity. Conservation has become a concern based on the decrease in populations of seahorses. Amanda Vincent has led most efforts based on her research and possible solutions. Many countries have met and tried to help contribute to finding solutions. The main goal is to prevent seahorses from being added to the list of endangered species.
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