- Culturing the oceanic seahorse, Hippocampus kuda.
Job, SD*; Do, HH; Meeuwig, JJ; Hall, HJ
Aquaculture [Aquaculture]. Vol. 214, no. 1-4, pp. 333-341. 15 Nov 2002.
Seahorse aquaculture has received widespread attention due to concerns over declines in wild seahorse populations, and in recognition of their high economic value and marketability. Seahorse aquaculture has great potential to integrate both conservation and sustainable development goals by providing an alternative livelihood option for fishers in source countries who, in the absence of alternatives to fishing, continue to exploit declining seahorse populations. To date, few culturing protocols have been established for tropical species exploited in Indo-Pacific source countries. We here present data on culturing Hippocampus kuda, one of the more heavily exploited species in both traditional medicines and marine aquarium trades. We also present results of an experiment testing the effects of three locally available Artemia enrichments on H. kuda survivorship, sex ratios, and growth to market size (14 weeks of age). Our results indicate that H. kuda grows rapidly from birth to 14 weeks, at a rate of 0.9-1.53 mm day super(-1). Survivorship to market size varied among Artemia enrichments and was highest (73%) when seahorses were fed Artemia enriched with an emulsion derived from Acetes sp., a locally available planktonic crustacean, and lowest (40%) when seahorses were fed Artemia enriched with an emulsion derived from local fish. Growth, however, did not vary among enrichments. Sex ratios were not significantly different from the expected ratio of 1:1 nor did enrichment affect sex ratio. The seahorses were only marginally sexually dimorphic at market size (males 3 mm>females in standard length). The rapid growth rate and high survival of H. kuda on readily available local Artemia enrichments is promising for the development of seahorse aquaculture in source countries.
- Biology of a seahorse species, Hippocampus comes in the central Philippines.
Perante, NC; Pajaro, MG; Meeuwig, JJ; Vincent, AC*
Journal of Fish Biology [J. Fish Biol.]. Vol. 60, no. 4, pp. 821-837. Apr 2002.
Based on 16 months of field observations on tagged seahorses Hippocampus comes in the Philippines, adults were found to be nocturnal, to maintain small home ranges, and to live mostly among corals. Prolonged pair associations suggested that H. comes, like many other seahorse species, were probably monogamous, a conclusion consistent with their low density and sparse distribution. Site and mate fidelity suggest that H. comes populations may fare poorly under current high levels of exploitation. Copyright 2002 The Fisheries Society of the British Isles. Published by Elsevier Science Ltd. All rights reserved.
- The ingestion, growth and ecological conversion efficiency of Hippocampus kuda under the intensive rearing conditions.
Lu, Junyi; Li, Bingji; Sun, Yanyan; Yang, Dawei; Huang, Kun
Journal of fisheries of China/Shuichan Xuebao. Shanghai [J. Fish. China/Shuichan Xuebao]. Vol. 26, no. 1, pp. 61-66. 2002.
Hippocampus kuda Bleeker is an official oceanic fish in Chinese traditional medicine. Because of the great contradiction between supply and need, the natural resources of Hippocampus kuda Bleeker have declined sharply. The food consumption, growth and ecological conversion efficiency of H. kuda were studied in the Commercial Rearing Base Guangdong Richvast, the South China Sea, Guangdong Province. The Elliott-Persson model and Eggers model were used to determine its feeding periodicity, to quantify its food consumption quantity, consumption rate, evacuation rate and food as well as energy conversion efficiency. The results indicated that seahorse (the range of body length 88.5-141.3 mm, body weight 5.75-13.27 g wet) fed in daytime with two peaks in 12:00 and 18:00 and were not fed in nighttime (the density is 200 ind times m super(-3), DO is beyond 5.5 mg times L super(-1), BOD is below 3mg times L super(-1), pH is 7.5-8.2, transparency is 50-85 cm, salinity is 15.2-26.5). The mean daily food consumption of H. Kuda was 16.6342 plus or minus 0.7820 g times (100 g) super(-1) per day. The food consumption rate was 1177.25 cal times ind super(-1) per day and evacuation rate was 0.1444g times (100g) super(-1) times h super(-1). Its food and energy conversion efficiency was 20.04% and 31.42% respectively. The mean growth speed of its body length and daily growth rate was 1.1766mm per day and 1.2% respectively. The mean body weight growth speed of H. kuda and daily body weight growth rate were 0.1820 g per day and 2.27% respectively. The food consumption of seahorse correlated with environmental water temperature significantly.
- The plight of Indian sea horses: need for conservation and management.
Sreepada, RA; Desai, UM; Naik, S
Current Science [Curr. Sci.]. Vol. 82, no. 4, pp. 377-378. 2002.
The increasing demand for seahorses in Asian traditional medicines, tonic food aphrodisiacs, as aquarium fishes, souvenirs and curios are concomitant with a decline in capture fisheries and destruction of habitats. The exploitation of seahorses along the Indian coast in the last decade has been alarming. Conservation and management are currently limited by the absence of data on the abundance and distribution of seahorses species in the region. This paper highlights the plight of Indian seahorses and the proactive initiatives taken by the National Institute of Oceanography (NIO), Goa, India for their conservation and management. Seahorses could serve as a popular flagship species for engendering support for general concerns in marine conservation and sustainable management.
- Husbandry of pot-bellied seahorses H. abdominalis.
Today's Aquarist [Today's Aquar.]. Vol. 7, no. 5, pp. 5-7,13. 2002.
The commercial farming of seahorses comes in response to market demand and the unsustainable level of harvesting wild stock. The ocean can no longer sustain continuing wild harvests of most any species to supply the world's needs. Aquaculture is the most efficient way of meeting the demands while having minimal impact on the environment. Based in Port Lincoln, South Australian Seahorse Marine Services is one operation totally committed to captive breeding seahorses for aquarists to enjoy without impacting on the wild stock. Every year more and more species are being farmed or captive breed. Only 10 years ago wild harvest was the only supplier of marine and freshwater creatures. The concept of farming seahorses for trade has met with resistance from conservation groups that believe that public outrage will diminish the wild harvest and slow the demand for these unique fish. This is not the case. Many strategies need to be implemented to protect these species and one way is by controlled wild stock harvesting and the development of farming seahorses as a sustainable alternative. There are currently 20,000,000 seahorses taken annually from the wild throughout the world. The current world markets are supplied from wild harvests. Peoples of the world are becoming more educated in the plight of the seahorse and their diminishing world wide numbers, the demand none the less is increasing, we believe a captive breeding program, and educating the world to purchase "Captive Bred Seahorses" to be a sustainable alternative.
- The effect of social context and reproductive status on the metabolic rates of dwarf seahorses (Hippocampus zosterae).
Comparative Biochemistry and Physiology, A [Comp. Biochem. Physiol., A]. Vol. 129, no. 2-3, pp. 541-555. Jun 2001.
Although we are beginning to understand the conditions in which monogamy is favored over a more promiscuous lifestyle, little is known about the proximate effects of monogamous pair bonding, and subsequent reproduction, on general metabolism. I determined the effects of these factors on the metabolic rates of dwarf seahorses (Hippocampus zosterae), recognized for their monogamous lifestyle and unique male care of offspring, in a sealed brood pouch where embryos develop until birth. Resting routine oxygen consumption rates were measured in newly-paired and reproductive adults using a continuous flow respirometer, and then compared to metabolic rates of sexually-isolated fish. Sex differences were observed in the relationship between log sub(10)mass and log sub(10)oxygen consumption, with pair-bonded females exhibiting a significantly higher slope than either pair-bonded males, or sexually-isolated fish. Mass-specific metabolic rates in sexually-isolated fish were 15% higher than in pair-bonded fish, indicating that social conditions can strongly influence metabolic rate. Specific metabolic rates only differed by gender during male pregnancy, when male metabolic rate increased from 10 to 52% over pre-gravid levels. A male's developing brood only explained 4-31% of this increase, suggesting that increased metabolic demands on fathers accounts for most of the increase in metabolic rate during gestation. This study suggests that pair bonding can strongly affect the general metabolism of organisms, with potential differences between males and females that increase with age.
- Factors affecting successful culture of the seahorse Hippocampus abdominalis Leeson, 1827.
Marine Ornamentals 2001: Collection, Culture & Conservation Program and Abstracts. 85 p. 2001.
In Australia and New Zealand there is interest in the commercial culture of the temperate seahorse Hippocampus abdominalis for supply to the ornamental aquarium and traditional medicinal trades, and there are now several commercial ventures culturing this species. NIWA has been conducting research into successful culture techniques for H. abdominalis since 1997 with public dissemination of the knowledge gained. Using standard hatchery techniques, H. abdominalis can be successfully reared through multiple captive generations with high survival rates (e.g. 80+% survival to sexual maturity) and good growth (e.g. 11cm+ in length within 1 year). Using enriched Artemia as a food, survival in the most vulnerable stages, 0-2 months of age, is dramatically improved by blacking off glass aquaria from the top to the waterline (i.e. from 18% survival at 2 months of age in normal aquaria to 80+% at 2 months of age in blacked-off aquaria). In newborn juveniles, feeding strike rates are greater in clear culture vessels compared to black or white culture vessels, but at 1 month of age this effect reduces and juveniles can feed better in non-clear culture vessels.
- Rearing the coral seahorse, Hippocampus barbouri, on inert prey.
Marine Ornamentals 2001: Collection, Culture & Conservation Program and Abstracts. 75 p. 2001.
Of all the seahorse species, the Coral seahorse, Hippocampus barbouri, is one of the easiest to keep in aquaria, primarily because adults readily accept dead prey and have voracious appetites. In addition, they are unusual amongst seahorses as they regularly use hard corals and other solid substrates as attachment sites, and are reported to be less prone to cnidarian stings than other species. This makes them suitable for display in reef tanks. Coral seahorses give birth to relatively large young that attach themselves to substrate soon after birth. Juveniles will readily feed on Artemia nauplii and when these nauplii are suitably enriched, survival of juveniles is sufficiently high to enable viable commercial production. However, hatching and preparation of Artemia nauplii is very time consuming, and enrichment media are invariably expensive. Cultured algae can be used for enrichment, although this too is very time consuming. Development of an inert diet for rearing juvenile seahorses may result in considerable savings in time and may also be more cost effective. This study compares the growth and survival of newborn Coral seahorses on diets of enriched Artemia nauplii and copepods collected from intensive culture and stored frozen. Artemia nauplii were enriched with Algamac 2000 and the microalga Tetraselmis suecica, while copepods were collected from a 5,000 1 culture that had been fed the microalga Isochrysis galbana for a prolonged period. Three separate batches of seahorse juveniles were separated into two groups that were fed the treatment diets. Length and wet weight of four seahorses from each experimental unit were recorded weekly for four weeks. Growth and survival data, along with the fatty acid profiles of each diet, are presented.
- The role of public aquaria in the conservation and sustainability of the marine ornamentals trade.
Hall, H; Warmolts, D
Marine Ornamentals 2001: Collection, Culture & Conservation Program and Abstracts. 18 p. 2001.
Worldwide, public aquaria and zoos enjoy immense popularity with a collective annual attendance estimated in excess of 600 million visitors, representing approximately 10% of the world's population. These organizations are experienced in using this popularity to educate and influence their visitors, local communities and other target groups about wildlife conservation concepts and issues. Increasingly, the direct and indirect participation of public aquaria in field conservation programs has become an integral component of institutional missions. Over the past ten years, specialized taxonomic advisory groups have been formed in European, North American and, most recently, Australian zoos and aquaria to establish a collective approach towards the conservation of marine resources. Programs have been developed that target flagship marine species, such as sharks and seahorses, but also threatened habitats, such as coral reefs. The remit of these initiatives encompasses advancing husbandry techniques and biological knowledge to taking an active role in field conservation efforts, such as Project Seahorse. Public aquaria recognize that they are one, highly visible component of the aquarium trade. As such, they have a responsibility to encourage and support the sustainable use of marine ornamental species and associated conservation of habitats. Current initiatives range from individual institutional projects towards sustainable trade, to global programs such as the Marine Aquarium Council's certification scheme.
- Studies on the captive culture of the Knysna seashore, Hippocampus capensis.
Lockyear, JF; Hecht, T; Kaiser, H
10th Southern African Marine Science Symposium (SAMSS 2000): Land, Sea and People in the New Millennium -- Abstracts. p. 1. 2000.
This presentation is based on the captive breeding programme for the Knysna seahorse, Hippocampus capensis. The different experiments can be divided into three broad categories: Breeding, rearing and nutritional studies. (1) Breeding studies: Experiments were designed to determine the effects of photoperiod and temperature manipulation on the reproductive activity of the Knysna seahorse. Seahorse pairs were kept at three constant photoperiod regimes 20L: 4D and 12L: 12D each at three temperatures 22 degree C, 25 degree C and 28 degree C for a period of four months. The number of broods and the total number of young produced from the different treatment groups was not dependent on the temperature or photoperiod regimes (P greater than or equal to 0.05). A further breeding experiment was initiated to determine the effects of light intensity on reproductive success of the Knysna seahorse. Seahorse pairs were placed under low, medium and high (9.1 X 10 super(14), 5.45 X 10 super(15) and 9.83 X 10 super(15) quanta.sec super(-1).cm super(-2)) light intensities for a period of four months. The seahorse pairs exposed to the medium light intensity produced more broods (x super(2)=6.14, k=2, P greater than or equal to 0.05) than those pairs maintained under the low and high light intensities. (2) Rearing studies: Two pilot scale experiments were conducted to determine the appropriate Artemia feeding densities for newly born seahorses in relation to seahorse stocking density. The appropriate feeding densities were then used for experiments, which tested the effects of tank background colour, light spectra and light intensities on growth and survival of the juveniles over a five-week period. Tank background colour and the different light spectra tested did not influence growth or survival of the young (P greater than or equal to 0.05), while those seahorses exposed to the medium light intensity displayed the highest mean lengths and weights (P=0.0001). (3) Nutritional studies: Highly unsaturated fatty acids (HUFA), such as eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA), have been found to be important components in the diets of marine larvae. More recently, the ratio between EPA and DHA has been found to influence the survival, growth and fitness of marine larvae. The DHA/EPA ratio of 0.6 was found to have a profound effect on reproductive output, increasing the number of young produced from the broodstock during the study. The young were however smaller in size compared to the young produced from the broodstock fed the remaining diets. These studies were extended to determine the effects of DHA/EPA ratios on the growth and survival of juvenile seahorses reared for four months. DHA and/or EPA were important for survival of the juvenile seahorses (P<0.05).
- Preliminary observations on breeding and rearing the seahorse Hippocampus abdominalis (Teleostei: Syngnathidae) in captivity.
New Zealand Journal of Marine and Freshwater Research [N. Z. J. Mar. Freshwat. Res.]. Vol. 34, no. 3, pp. 475-485. Sep 2000.
A small-scale preliminary investigation into the breeding and rearing of the seahorse Hippocampus abdominalis Leeson, 1827 in New Zealand was conducted using 12 wild broodstock. These broodstock were maintained in a hatchery for breeding and the breeding behaviours exhibited by these were observed and described. Over a period of 6 months a total of 12 broods of juveniles were produced. These were then raised on a diet consisting mainly of enriched Artemia for a period of 1 year. After this period juveniles had reached a mean plus or minus 1 SE total length of 110.73 plus or minus 0.13 mm, mean plus or minus 1 SE wet weight of 3.07 plus or minus 0.23 g, and were reproductively mature. The mean plus or minus 1 SE survival per brood after 1 year was 10.57 plus or minus 3.49%.
- Differences in potential reproductive rates of male and female seahorses related to courtship roles.
Masonjones, HD; Lewis, SM
Animal Behaviour [Anim. Behav.]. Vol. 59, no. 1, pp. 11-20. Jan 2000.
Dwarf seahorses, Hippocampus zosterae (Syngnathidae), are distinguished by extreme morphological specialization for paternal care, the formation of monogamous pair bonds and mating repeatedly over the course of a breeding season. To determine the potential reproductive rates of male and female dwarf seahorses, we measured (1) the maximum number of offspring produced per breeding cycle when sexually receptive mates were unlimited, and (2) the relative time each sex was unavailable for mating ('time out'). We paired sexually isolated males and females with sexually receptive partners and observed them from the day of introduction through to copulation, to determine the length of time it takes each sex to prepare to mate. We conducted additional experiments to determine the length of gestation, which when added to the time needed to prepare to mate and copulate gives an estimate of total reproductive cycle duration, T. We estimated potential reproductive rate by dividing the mean number of offspring produced per breeding cycle by the duration of the breeding cycle (T). We estimated reproductive 'time out' by identifying the period of time males and females were physiologically capable of mating ('time in', S) and subtracting time S from time T. When provided with sexually receptive partners, females took 2 days longer than males to complete courtship and copulation, but neither males nor females remated during gestation. Therefore, males could potentially produce 17% more offspring than females over the course of one breeding season. Females had reproductive 'times out' 1.2 times longer than did males, as they were only capable of mating during the 4 h directly preceding copulation. Thus, H. zosterae males have higher potential reproductive rates and shorter reproductive 'times out' compared with H. zosterae females. These results and previous work indicating that seahorses display traditional courtship roles support the prediction that the sex having the higher potential reproductive rate, or equivalently, the shorter 'time out', will compete more intensely for access to the opposite sex. Copyright 2000 The Association for the Study of Animal Behaviour
- Farmed seahorses: a boon to the aquarium trade.
INFOFISH International. Kuala Lumpur [INFOFISH Int.]. no. 3, pp. 48-50. 2000.
Seahorses have generally been considered as difficult to breed and rear in captivity. Recently, a small group of researchers in Australia have carried out the rearing of large-bellied seahorses (Hippocampus abdominalis) on an industrial scale. Seahorse Pty Ltd has established the first large-scale farm in the world for producing seahorses, through the use of new technology, careful selection of the species, and the bringing together of a team of experts. The company is focussing on supplying the aquarium industry and it is hoped that the availability of such quality farm-reared seahorses will reduce demand for wild-caught specimens, thereby adding to moves to conserve these beautiful creatures.
- Searching for dragons: the enigma of southern waters.
Wildlife Australia. Brisbane [Wildl. Aust.]. Vol. 36, no. 1, pp. 12-15. 1999.
Australia's southern coastal waters are home to some of the world's unique and mysterious fishes, the seadragons, which are members of the Sygnathidae family which includes seahorses and pipefishes. Although there are more than 200 species in the Sygnathidae family, the common or weedy seadragon (Phyllopteryx taeniolatus) and the leafy seadragon (Phycodurus eques) are the only known species of seadragon and both are endemic to Australian waters. Like so many Australian non-commercial fish species, little is known about seadragons and this is of concern to researchers and conservationists. Seadragons may be threatened by legal over-collection in some areas and there may be an illegal trade in the animal, but the extent of this is unknown.
- Leafy sea dragons.
Scientific American [Sci. Am.]. Vol. 279, no. 6, p. 85. Dec 1998.
The leafy sea dragon (Phycodurus eques) and its more common cousin, the weedy sea dragon (Phyllopteryx taeniolatus), are the only sea dragons in the world. Along with sea horses and pipefish, they are members of the family Syngnathidae, fish characterized by a hard external skeleton arranged as a series of rings around the animal's body and by a long tubular snout with no teeth. Sea dragons are distinctive in that frondlike appendages branch out from their armor-plated bodies. As befits their names, the leafy sea dragons' appendages are broader and flatter than the more stringy ones of the weedy dragons. Both creatures are endemic to the southern Australian coastline. The waters off the islands of the Archipelago of the Recherche where we are diving are a favorite haunt for sea dragons. These huge, sparsely vegetated granite islands are a refuge for an amazing array of exotic animals, some of them found nowhere else in the world.
- Pipefishes of the Syngnathid genus Dunckerocampus (Sygnathiformes: Syngnathidae), with a description of a new species from the Indian ocean.
Aqua - Journal of Ichthyology & Aquatic Biology [Aqua J. Ichthyol. Aquat. Biol.]. Vol. 3, no. 2, pp. 81-84. Sep 1998.
Dunckerocampus Whitley, 1933, is recognised as valid pipefish genus, rather than a sub-genus of Doryrhamphus Kaup, 1856, as treated by Dawson, 1985. A new species, D. boylei, with a distinctive broadly-banded pattern is described from the Indian Ocean, bringing the total number of species in the genus to six. Notes and underwater photographs of species occurring sympatric with D. boylei are provided.
- NZ seashore project looks to sea cages.
Fish Farming International [Fish Farm. Int.]. Vol. 25, no. 7, p. 21. Jul 1998.
Two New Zealand scientists working on the culture of seahorse (Hippocampus abdominalis) are looking to expand their project with special emphasis on sea cage farming of this highly lucrative species. Michelle McLean and Chris Woods of New Zealand's National Institute of Water and Atmosphere Research (NIWA), began their research in answer to the heavy fishing effort on these creatures which has dramatically affected their wild populations.
- Preliminary success in closing the life cycle of exploited seahorse species, Hippocampus spp., in captivity.
Wilson, MJ; Vincent, ACJ
Aquarium Sciences and Conservation [Aquarium Sci. Conserv.]. Vol. 2, no. 4, pp. 179-196. 1998.
The trade in seahorses for aquarium fishes is contributing to the depletion of many wild populations of these animals. Many seahorses are sold to replace those that have died in captivity as a result of husbandry problems. It can be particularly difficult to rear the young seahorses, because of their need for varied live food and their vulnerability to disease. We here report a pilot study on rearing broods from males of three species (H. fuscus, H. barbouri, and H. kuda) that had mated in the wild and gave birth in captivity. The new-born seahorses were fed an initial diet of enriched Artemia until 7 days, after which copepods were added to the diet. From 5 weeks, frozen mysids were gradually phased in to replace both other food items. Scrupulous hygiene was maintained. We achieved 100% survival of the partial broods we reared for all three species and achieved life cycle closure in two of these during the experimental period. Of the three species, H. kuda grew to be largest and longest, and H. barbouri grew least. However, H. kuda were the slowest to mature and reproduce while H. fuscus (intermediate in growth) were the fastest. Techniques used in this work should be more generally applicable, both for aquarium husbandry and for small-scale aquaculture to help provide alternative incomes for small-scale fishers who are otherwise dependent on catching wild seahorses.
- Breeding seahorses - facts and fallacies.
Western Fisheries (Western Australia) [West. Fish.]. pp. 39-40. 1998.
There are approximately thirty known species of seahorses, nearly all of which are included in the genus Hippocampus. During 1989, I carried out an investigation of the reproduction and spawning of the Western Australian seahorse (Hippocampus angustus) in captivity. What follows is a summary of my research and the methods used to successfully raise a number of these fish.
- The case of the pregnant males.
Aquarist & Pondkeeper [AQUAR. PONDKEEP.]. Vol. 62, no. 9, pp. 15-19. Dec 1997.
Very few marine fish reach the heights of appeal generated by the Seahorse. Their almost prehistoric appearance, graceful nature and unique reproduction, make them irresistible to many hobbyists. Their attraction is not limited to the aquarist, they capture the imagination of the public to such an extent that the Seahorse has starred in a prime time television programme. Unfortunately this appeal has led to them becoming one of the most long suffering fish in the marine hobby. I dread to think how may have wastes away to a premature death at the hands of the aquarist. Seahorses can be successfully kept in the home aquarium, they have even been bred and reared, but they have certain essential requirements and are therefore definitely not for the beginner. Seahorses have two essential requirements that must be catered for in the home aquarium. To ignore either of these requirements will result in heavy casualties. If the hobbyist cannot provide these requirements Seahorses should not be considered as an option. The crucial requirements are: 1. A constant supply of small live food. 2. A quiet aquarium without any boisterous competition.
- NZ seahorse potential.
Fish Farming International [Fish Farm. Int.], vol. 24, no. 8, p. 37, Aug 1997
Two new aquaculture ventures could become big export earners for the marine farming industry based in New Zealand's Marlborough Sounds. The region looks set to become the first in New Zealand to test farming the tiny seahorse, while a controlled experimental crop of undaria seaweed has been harvested successfully and samples are being analysed. Seahorses are in huge demand in Asia for treating a range of medical conditions, and Steve Yealands, director of the firm which is carrying out the research, believes they could have health and financial spin-offs at home. "Obviously, clinical trials need to be done here to establish the effectiveness of seahorses for medicinal purposes," he told FFI, "but recently a great deal of oriental medicine has proved very useful." Mr Yealands said the seahorse's external skeleton, made of tough cartilage-type tissue, was used in China to treat a broad range of conditions and for general health.
- Studies on the captive breeding of the Knysna seahorse, Hippocampus capensis.
Lockyear, J; Kaiser, H; Hecht, T
Aquarium Sciences and Conservation [AQUARIUM SCI. CONSERV.]. Vol. 1, no. 2, pp. 129-136. Jun 1997.
Seahorse populations throughout the world are vulnerable to exploitation for use in traditional Chinese medicines. Various captive breeding ventures have been established in attempts to meet the demand and to reduce the pressure on the natural populations. Many of these programmes have relied on the capture of wild pregnant males which then give birth under captive conditions. This would however limit production during the non-breeding season. In this study Knysna seahorses, Hippocampus capensis, were bred in captivity during the non-breeding season (winter) using photothermal manipulation. Three constant photoperiods (20L:4D, 16L:8D & 12L:12D) were tested in combination with three temperatures (22 degree C, 25 degree C & 28 degree C). All combinations tested were successful in extending the breeding season of H. capensis. The frequency of pregnancies as well as the number of young produced /pregnancy was not affected by the different photoperiod/temperature combinations. Each male gave birth to 39.38 plus or minus 20.81 juveniles every 34.03 plus or minus 17.25 days during a four month period. The mean juvenile weight and length was influenced by the photoperiod and/or temperature regimes. Juvenile length decreased with increasing temperature (p less than or equal to 0.0001), while an increase in the light phase of the photoperiod regime at 20L:4D resulted in a significant increase (p less than or equal to 0.0006) in length when compared to the 16L:8D and 12L:12D photoperiods. Juvenile weight decreased with increasing temperature, while the combination of photoperiod 16L:8D and the lowest water temperature (22 degree C) yielded the highest mean weights. Further studies are necessary to determine whether mean juvenile weight or length influences juvenile survival.
- The plight of the seahorse.
Today's Aquarist [TODAY'S AQUAR.]. Vol. 6, no. 10, pp. 6-8. 1997.
The first major study of the international trade in seahorses recently released by TRAFFIC (Trade Records Analysis of Flora and Fauna in Commerce) forecasts that seahorse populations in the wild could crash if the rising and unlimited demand for them goes unchecked. The new Species in Danger report "The International Trade In Seahorses", authored by Amanda C. J. Vincent of Oxford University, notes that at least 32 nations around the world are involved in trading dead and live seahorses-from Ecuador to Australia. The largest importers are China, Hong Kong and Taiwan, while the largest exporters are India (annual sales at least 1.3 million seahorses or 3,000 kg.), the Philippines, Thailand and Vietnam. The global trade involves at least 20 million seahorses a year. The majority of the seahorses, Hippocampus sp., go into traditional Chinese medicine (TCM) and its derivatives. (e.g., Japanese and Korean traditional medicines). European use of seahorses for medicines continued until at least the 18th century. Treatments including seahorses as ingredients are believed to benefit a range of conditions, including respiratory disorders such as asthma, sexual dysfunctions such as impotence, and general lethargy and pain. Seahorses are also used as aquarium fishes, curios, and even tonics. "Although we don't yet have a complete picture of the effect of this trade on seahorse populations, the evidence that is available is extremely alarming," said Steven Broad, Executive Director of TRAFFIC International. "A comprehensive program of conservation measures needs to be implemented urgently if seahorses and the fisheries that depend upon them are to avoid a crisis." Seahorses can be expensive. In 1995, the preferred large, bleached seahorses sold for up to US$1,200 per kilo in one Hong Kong outlet. Japanese consumers appear to pay the most for a much smaller seahorse. Dried seahorses of similar size cost at least US$11.49 each in Japan compared to about US$2.80 in Taiwan. Countries that sell imported seahorses as curios or aquarium pets include Canada, Germany, the Netherlands and UK. Some importers are also exporters, such as the USA.
- Keeping a myth alive.
Western Fisheries (Western Australia) [WEST. FISH.]. pp. 20-23. 1997.
The international conservation group TRAFFIC dropped a bombshell at the 1996 World Fisheries Congress conference when it revealed to delegates that seahorses were under threat worldwide, due to a booming demand for them in the traditional medicine, curio and aquarium trades. Seahorses are members of the family Syngnathidae, along with pipefish and seadragons, and are thought to have existed for at least 40 million years. In WA, we have four varieties of seahorse, of which the best known is the Western Australian seahorse, Hippocampus angustus, found on reefs and seagrass meadows between Exmouth and Augusta.
- Community-based management for a sustainable seahorse fishery.
Vincent, ACJ; Pajaro, MG
Developing and sustaining world fisheries resources. The state of science and management. pp. 761-766. 1997.
The seahorse (Hippocampus) fishery is large, global and economically important. It also appears to be unsustainable, with seahorse numbers declining markedly where fished. Handumon village, in the central Philippines, where the first seahorse conservation and management project was implemented in January 1995, is particularly dependent on seahorses. Early socio-economic study provides the template for current co-management efforts. These include protective measures, fishery modifications and enhancement efforts: 1) the barangay established and now enforces a 33-ha no-exploitation sanctuary and an adjacent traditional fishing zone; 2) fishers place newly caught pregnant males into sea cages whence newborn young can escape before the male is sold; 3) fishers re-seed areas depleted of seahorses and have begun developing seahorse culturing skills. The eventual goal is for the barangay to take full responsibility for the project.
- The international trade in seahorses.
SPECIES IN DANGER, TRAFFIC INTERNATIONAL, CAMBRIDGE (UK), 1996, 170 pp
Seahorses represent a hitherto unexplored genre of fisheries, those intended primarily for medicine rather than food. The majority of seahorses go to traditional Chinese medicine and its derivatives. China's economic growth since the mid-1980s is probably the principal agent in a surge in demand for seahorses. In response, and in part because other marine resources are declining, subsistence and small-scale fishers in Asia target seahorses and many obtain the majority of their annual income from these fishes. At least 32 nations around the world are involved in trading seahorses. Information obtained during interviews, in combination with the few published customs statistics available, suggest that annual consumption just within Asian nations may amount to 45 t of dried seahorses annually. Totals and rankings, however, should be interpreted with great caution because data are still tentative and because it was not possible to investigate nations expected to be large consumers (Japan, Korea, Malaysia, Singapore...). Extracting seahorses at current rates appears to be having a serious effect on their populations. Demand far exceeds supply, according to almost all those interviewed. Available evidence indicates that consumption should be reduced if long-term persistence of their population is to be assured. Conservation and management of seahorses would benefit from a series of integrated measures. Recent small-scale conservation initiatives in the Philippines and Vietnam are experiencing initial success.
- Faithful pair bonds in wild seahorses, Hippocampus whitei.
Vincent, ACJ; Sadler, LM
Animal Behaviour [ANIM. BEHAV.], vol. 50, no. 6, pp. 1557-1569, 1995
Genetic evidence has revealed that sexual fidelity is rather rare in supposedly monogamous animals. Pairing, whether sexually faithful or not, is very uncommon in fish and has not previously been confirmed in fish from seagrass habitats. Here, the first underwater study of seahorse reproduction reveals that males and females of an Australian species (Hippocampus whitei) form pairs that mate repeatedly and exclusively. Partners greet each other daily an eschew interactions with non-partners. Seahorses are unusual in that both sexes provide clear visual evidence of having mated (the male becomes pregnant as the female transfers hydrated eggs) allowing confidence that these fish are sexually faithful to one another. Pairs do not divorce and a pair bond only terminates when one partner disappears. Intra-sexual competition appears not to be important in maintaining pair bonds.
- Seahorses exhibit conventional sex roles in mating competition, despite male pregnancy.
Behaviour, vol. 128, no. 1-2, pp. 135-152, 1994
In seahorses, only males undergo a pregnancy. It had been tacitly and explicitly assumed that seahorses were sex role reversed (that females competed more intensely than males for access to mates), on the basis that male pregnancy so limited male reproduction as to produce a female-biased operational sex ratio (OSR). However, this supposition had never been investigated. The laboratory experiments in this paper demonstrate that, contrary to expectations, seahorses exhibit conventional sex roles: male seahorses compete more intensely than females for access to mates, on both the first and final days of courtship. Competing males are more active than competing females in those courtship and competitive behaviours common to both sexes, and only males exhibit uniquely competitive behaviours (wrestling and snapping). Males which succeeded in copulating are heavier than their rivals and copulating seahorses of both sexes generally are more active in courtship and competition than are their unsuccessful rivals. The finding that seahorses maintain conventional sex roles requires us to reconsider the impact of male pregnancy on the OSR.
- Pipefishes and seahorses: are they all sex role reversed?
Vincent, A; Ahnesjoe, I; Berglund, A; Rosenqvist, G
Trends in Ecology & Evolution [TRENDS ECOL. EVOL.], vol. 7, no. 7, pp. 237-241, 1992
The male pregnancy of pipefishes and seahorses has led to the inference that females compete most intensely for access to mates, because males limit female reproduction. However, recent work has shown that in different species either sex may be the predominant competitor for mates. In this family, there is an apparent association between the mating pattern and the sex roles: polygamous species show reversed sex roles whereas monogamous species exhibit "conventional" sex roles. These studies emphasize that sex role reversal is not synonymous with male parental care.
- On seahorse locomotion.
J. Mar. Biol. Assoc. U. K. Vol. 56, no. 4, pp. 939-949. 1976.
Four modes of progression (slow forward, fast forward, turning and up and down movements) are defined and characteristic postures are described for Hippocampus hudsonius. Cinematographic analysis of the fins showed waves to be initiated at the anterior. Variation in amplitude, wavelength, velocity and wave number is noted. Displacements of parts of the fins relative to others are initiated at the posterior. The force produced by the fins when cruising at 3.6 cm s Super(-1) is calculated as 820 dynes for the dorsal fin and 200 dynes for one pectoral fin (1220 dynes for all of the fins active). The work done by 1 fin ray inclinator muscle per stroke when cruising at 5.5 cm s Super(-1) is calculated to be 7.5 x 10 Super(2) ergs for the dorsal fin and 1.5 x 10 Super(2) ergs for one pectoral fin. The total amount of work done by all of the fin ray inclinators is 2.7 x 10 Super(4) ergs for the dorsal fin and 4.8 x 10 Super(3) ergs for one pectoral fin. The power from the dorsal fin is calculated to be 4.2 x 10 Super(5) ergs s Super(-1), the value for one pectoral fin is 1.5 x 10 Super(4) ergs s Super(-1). The value for all fins active is 8.95 x 10 Super(5) ergs s Super(-1). The force produced by the action of a pair of respiratory pores is calculated to be 46 dynes, a significant force which is reduced during upward movement by the reduction of opercular pulsation.
- The spawning behavior of the pipefish Syngnathus acusimilis.
Russian Journal of Marine Biology/Biologiya Morya [Russ. J. Mar. Biol./Biol. Morya]. Vol. 27, no. 1, [np]. 2001.
Parental care in representatives of the family Syngnathidae is carried out exclusively by the males and may restrict the reproductive success of the females, resulting in a reversal of their sexual roles. The reversal of the roles of the sexes is specific to polygamous species of the family; it has not been recorded in monogamous species. We describe the spawning behavior of the Primor's pipefish Syngnathus acusimilis. We show that fish of this species, although polygamous, have no roles reversal between the sexes, and the males are more active during courtship and mate selection.
- Reproduction and food habits of the lined seahorse, Hippocampus erectus (Teleostei: Syngnathidae) of Chesapeake Bay, Virginia.
Teixeira, RL; Musick, JA
Brazilian Journal of Biology [Brazilian J. Biol.]. Vol. 61, no. 1, pp. 79-90. Feb 2001.
The reproductive and feeding biology of the lined seahorse, Hippocampus erectus, was studied in Chesapeake Bay. Seahorses are monogamous, and males incubate the eggs received from females in a closed brood pouch (= marsupium). Females do not play any parental care after mating. Total sex ratio and the operational sex ratio was strongly skewed toward females. Males and females had similar number of eggs/embryos and hydrated oocytes, respectively. The number of eggs/embryos found in the male brood pouch varied from 97 to 1,552 (fish from 80 to 126 mm TL), whereas the number of hydrated oocytes in female varied from 90 to 1,313 (fish from 60 to 123 mm TL). Both, the number of eggs/embryos and hydrated oocytes were better linearly correlated to total weight than to total length. The small snout and mouth size limits the feeding of the lined seahorse to small prey size. Amphypods were the predominant food items found in the guts, especially Ampithoe longimana, Gammarus mucronatus, and Caprella penantis. The lined seahorse is not abundant in Chesapeake Bay, but keeps a breeding population which is probably brought inside the bay by currents on drifting vegetation. Chances to find a partner may be difficult because of its low abundance, due to turbid waters, and its sedentary behavior.
- Monogamous pair bonds and mate switching in the Western Australian seahorse Hippocampus subelongatus.
Kvarnemo, C; Moore, GI; Jones, AG; Nelson, WS; Avise, JC
Journal of Evolutionary Biology [J. Evol. Biol.]. Vol. 13, no. 6, pp. 882-888. Nov 2000.
Apparently monogamous animals often prove, upon genetic inspection, to mate polygamously. Seahorse males provide care in a brood pouch. An earlier genetic study of the Western Australian seahorse demonstrated that males mate with only one female for each particular brood. Here we investigate whether males remain monogamous in sequential pregnancies during a breeding season. In a natural population we tagged males and sampled young from two successive broods of 14 males. Microsatellite analyses of parentage revealed that eight males re-mated with the same female, and six with a new female. Thus, in this first study to document long-term genetic monogamy in a seahorse, we show that switches of mates still occur. Polygynous males moved greater distances between broods, and tended to have longer interbrood intervals, than monogamous males, suggesting substantial costs associated with the breaking of pair bonds which may explain the high degree of social monogamy in this fish genus.
- Exploitation of seahorses and pipefishes.
Naga [Naga]. Vol. 18, no. 1, pp. 18-19. 1995.
Indicators on the exploitation of Syngnathidae (seahorses and pipefishes) are presented together with a brief discussion of syngnathid biology.
- Aquaculture potential of seahorses and pipefishes.
Naga [Naga]. Vol. 18, no. 1, pp. 20-21. 1995.
The characteristics, food and feeding, reproduction and breeding of sea horse and pipefishes (Synanthidae) are presented together with the aspects of syngnathid culture.
- Sex role reversal in a pipefish.
Behavioural Ecology of Fishes, 1993, pp. 219-230, Mar. Behav. Physiol., vol. 23, no. 1-4
The biology of the pipefish Nerophis ophidion offers insights into the evolution of parental care and sex roles, and sex role reversal. Pipefishes have exclusive male care, with males that undergo a long pregnancy and females that provide no care of the young at all. This extreme case of parental investment by males leads to the prediction that males should limit female reproductive rate and that females should be the predominant competitors for mates.
- Genetic evidence for extreme polyandry and extraordinary sex-role reversal in a pipefish.
Jones, AG; Walker, D; Avise, JC
Proceedings of the Royal Society of London, Series B: Biological Sciences [Proc. R. Soc. Lond., Ser. B: Biol. Sci.]. Vol. 268, no. 1485, pp. 2531-2535. 22 Dec 2001.
Due to the phenomenon of male pregnancy, the fish family Syngnathidae (seahorses and pipefishes) has historically been considered an archetypal example of a group in which sexual selection should act more strongly on females than on males. However, more recent work has called into the idea that all species with male pregnancy are sex-role reversed with respect to the intensity of sexual selection. Furthermore, no studies have formally quantified the opportunity for sexual selection any natural breeding assemblage of pipefishes or seahorses in order to demonstrate conclusively that sexual selection acts most strongly on females. Here, we use a DNA-based study of parentage in the Gulf pipefish Syngnathus scovelli in order to show that sexual selection indeed acts more strongly on females than on males in this species. Moreover, the Gulf pipefish exhibits classical polyandry with the greatest asymmetry in reproductive roles (as quantified by variances in mating success) between males and females yet documented in any system. Thus, the intensity of sexual selection on females in pipefish rivals that of any other taxon yet studied.
- Brooding season, sex ratio, and brood pouch development in the seaweed pipefish, Syngnathus schlegeli, in Otsuchi Bay, Japan.
Watanabe, Satoshi; Watanabe, Yoshiro
Ichthyological Research [Ichthyol. Res.]. Vol. 48, no. 2, pp. 155-160. 25 May 2001.
Males of the seaweed pipefish, Syngnathus schlegeli, take care of their eggs in the brood pouch. These pipefish were periodically collected from the shallow seagrass beds in Otsuchi Bay on the Pacific coast of northern Honshu, Japan, from spring to autumn to investigate the basic reproductive ecology. Appearance of the pipefish in the coastal seagrass beds coincided with the initiation of reproduction. The reproductive season was from May to at least October, with its peak in July. A rearing experiment revealed that the brooding period of the male had a negative correlation with water temperature, and it was estimated to last about 1 month in the bay. Almost all males were brooding during the peak of the reproductive season. Although, the brood pouch of most males was either full or devoid of eggs, 6.2% of the males had a partially filled (20%-90%) brood pouch, and multiple clutches were identified in the brood pouch of some males, indicating that the mating system of the pipefish is polygamous, perhaps polygynous. Sex ratio fluctuated among months, and the overall sex ratio tended to be biased to male. Body size of males with an immature brood pouch had a wide range, from 133 to 215mm standard length (SL). The smallest brooding male was 134mm SL. Mean SL of brooding males was significantly larger than that of nonbrooding mature males. The number of males with an immature brood pouch was greater at the beginning than later in the reproductive season. The results seem to collectively indicate that the occurrence of a larger proportion of immature males at the onset of the reproductive season may be ascribed to both new recruitment and larger body size at maturation, resulting from the males trading the reproductive effort to somatic growth, perhaps to increase future reproductive success.
- Mariculture of aquarium fishes.
Encyclopedia of Ocean Sciences - Vol. 3 (I-M). pp. 1560-1567. 2001.
Marine fishes and invertebrates have been kept in aquaria for decades. However, attempts to maintain marine species in a captive environment have been dependent on trial and error for the most part but it has been mainly through the attention and care of aquarists that our knowledge about many marine species has been obtained. This is particularly true of the charismatic syngnathids, which includes at least 40 species of sea horses. During the past 30 years, technological advances in corrosion resistant materials together with advances in aquaculture systems have brought about a rapid increase in demand for large public marine aquarium displays, oceanariums and hobby aquaria suitable for colorful and exotic ornamental species. These developments have led to the establishment of important export industries for live fishes, invertebrates and so-called 'living rocks'. Attempts to reduce dependence on wild harvesting through the development of marine fish and invertebrate hatcheries met with limited success. The availability of equipment, which greatly assists in meeting the water quality requirements for popular marine organisms, has turned the attention of aquarists towards maintaining increasingly complex living marine ecosystems and more exotic species. A fundamental requirement for the success of such endeavors is the need to understand species biology and interspecific relationships within the tank community. Modern marine aquarists must draw increasingly on scientific knowledge and this is illustrated below with reference to sea horse and coral reef aquaria, respectively.
- Reproductive ecology of five pipefish species in one eelgrass meadow.
Vincent, ACJ; Berglund, A; Ahnesjo, I
Environmental biology of fishes. The Hague [Environ. Biol. Fish.]. Vol. 44, no. 4, pp. 347-361. 1995.
Pipefishes have rarely been watched in the wild and have never before been followed in their common seagrass habitats. This study explores the reproductive ecology of five species of pipefishes living in a Swedish eelgrass meadow during parts of four breeding seasons, tagging four of the species. Pipefish are remarkable for their specialised paternal care: Only males aerate, osmoregulate and nourish the developing embryos. Two of the species (Entelurus aequoreus and Nerophis ophidion) have simple ventral gluing of eggs on the trunk while three species (Syngnathus acus, S. rostellatus and S. typhle) have fully enclosed brood pouches on their tails. Males of the former species receive eggs from one female while males of the genus Syngnathus receive partial clutches from several females. Sex ratios of adults on the site differed from equal to male-biased to female-biased, according to species. S. typhle were most numerous and were resighted most often. They were present throughout the breeding season whereas there were temporal shifts in the presence of the other species on the meadow and in some sex ratios. Most species occurred in the deeper, denser part of the meadow but there was some habitat separation by species and sex. All species tended to stay low in the eelgrass, primarily coming up above the eelgrass to display and mate. No species showed site fidelity either to a home range or to the meadow, with E. aequoreus adults spending least time on the meadow. Sexual size dimorphism differed: Males were larger in S. rostelltus, the same size in S. acus and smaller in the other species. Although the species overlap in habitat requirements and breeding season, the only observed interspecific interactions were abortive courtships between Syngnathus species.