Studies on the captive breeding of the Knysna seahorse, Hippocampus capensis

Seahorse populations throughout the world are vulnerable toexploitation for use in traditional Chinese medicines. Variouscaptive breeding ventures have been established in attempts tomeet the demand and to reduce the pressure on the naturalpopulations. Many of these programmes have relied on the captureof wild pregnant males which then give birth under captiveconditions. This would however limit production during the non-breeding season. In this study Knysna seahorses, Hippocampuscapensis, were bred in captivity during the non-breeding season(winter) using photothermal manipulation. Three constantphotoperiods (20L:4D, 16L:8D & 12L:12D) were tested incombination with three temperatures (22 °C, 25 °C& 28 °C). All combinations tested were successful inextending the breeding season of H. capensis. The frequency ofpregnancies as well as the number of young produced/pregnancy wasnot affected by the different photoperiod/temperaturecombinations. Each male gave birth to 39.38 ± 20.81juveniles every 34.03 ± 17.25 days during a four monthperiod. The mean juvenile weight and length was influenced by thephotoperiod and/or temperature regimes. Juvenile length decreasedwith increasing temperature (p 0.0001), while an increasein the light phase of the photoperiod regime at 20L:4D resultedin a significant increase (p 0.0006) in length whencompared to the 16L:8D and 12L:12D photoperiods. Juvenile weightdecreased with increasing temperature, while the combination ofphotoperiod 16L:8D and the lowest water temperature (22 °C)yielded the highest mean weights. Further studies are necessaryto determine whether mean juvenile weight or length influencesjuvenile survival     

Assessing East African trade in seahorse species as a basis for conservation under international controls

• 1. Seahorses (Hippocampus spp.), many of which are listed as Vulnerable or Endangered on the IUCN Red List, are traded worldwide as souvenirs, aquarium fish and, primarily, for use in traditional medicines. Given concern over the sustainability of this trade, the genus was added to Appendix II of the Convention on International Trade in Endangered Species of Wild Fauna and Flora (CITES) in May 2004.
• 2. This paper reports findings of the first ever survey of seahorse trade in Africa, conducted in Kenya and Tanzania in May and June 2000.
• 3. Seahorse trade in Kenya was found to be negligible, with approximately 10 live seahorses exported as aquarium fish annually. Until 1998, however, Kenya may have imported somewhere from 1 to 2.3 t of dried seahorses annually from Tanzania for re‐export to Asian medicine markets. Seahorse trade in Tanzania remained substantial, with at least 630–930 kg of dried seahorse exported directly to Asia each year.
• 4. Accounts of declines in seahorse availability and seahorse size, although few in number, could be early warning signs that wild populations are suffering, at least locally. Close monitoring of future developments in the trade will be essential to allow for timely conservation action as and when necessary, and would contribute to our understanding of the ecological and economical implications of small‐scale, non‐food fisheries.

Copyright © 2004 John Wiley & Sons, Ltd.     

海马网箱养殖试验

本文报道海马网箱养殖试验。海马可以进行网箱养殖，需要选择合适的养殖水环境，改进网箱设置，采用适当的饵料和投喂方式，防治病害，提高成活率。     

Growth and survival of juvenile lined seahorse,Hippocampus erectus (Perry), at different stocking densities

The lined seahorse, Hippocampus erectus (Perry), is an important species in both medicinal and aquarium trades. The aim of this study was to evaluate the effects of stocking density (1, 3 and 5 individuals L⁻¹) on the growth performance and survival of the early-stage juvenile H. erectus. The height (HT), wet weight, weight gain (WG) and specific growth rate (SGR) were affected significantly by the stocking density during the 40-day study. The HT, WG and SGR of the seahorse at 1 and 3 juveniles L⁻¹ were significantly higher than that at 5 juveniles L⁻¹. The survival of juveniles at the three stocking densities was not significantly different at day 25 (90.3 ± 4.5%, 86.7 ± 4.2% and 86.2 ± 3.8% for 1, 3 and 5 juveniles L⁻¹ respectively), but was significantly different at day 40 (87.8 ± 3.9%, 69.6 ± 4.2% and 52.9 ± 2.8% for 1, 3 and 5 juveniles L⁻¹ respectively). For the early-stage juvenile H. erectus, we recommend a stocking density of 3 juveniles L⁻¹, but the density should be reduced to 1–2 juveniles L⁻¹ to avoid reduced and variable growth and high mortality after 25 days.     

三斑海马的人工生态养殖

通过构建三斑海马的生态养殖环境、培育天然活体饵料,形成人工生态系统,提高了幼体的成活率。通过施用发酵鸡粪(即把备用的晒干鸡粪,加水发酵使其熟化)50g/m3或尿素10g/m3,5～7d后,投放海马幼体200ind/m3;放苗28d后,栽培菊花江蓠(密度0.5～2kg/m3)作为水质调控、遮光及养殖海马的缠绕物。江蓠的栽培构建了海马天然饵料的培育场所,藻丛中的小型甲类生物密度达450个/100g以上,形成了良好的养殖三斑海马的人工生态环境,经146d的养殖,生态养殖与投饵养殖模式比较,收获的三斑海马成活率和标准体长分别为70.8%、42.5%,11.13cm、10.04cm。     

Effects of Varying Dietary Fatty Acid Composition on Growth and Survival of Seahorse, Hippocampus Sp., Juveniles

Three commercially available fatty acid enrichment emulsions (DC Selco, DC DHA Selco and DC Super Selco) were used to enrich Artemia nauplii fed to seahorse, Hippocampus sp. fry. The emulsions varied in their n-3 highly unsaturated fatty acid (HUFA) composition. Total n-3 HUFA content ranged from 200 to 450mgg^-1 between the three emulsions while levels of eicosapentaenoic acid (EPA, 20:5n-3) and docosahexaenoic acid (DHA, 22:6n-3) ranged between 47–220 and 80–190mgg^-1, respectively. Survival and growth of seahorses at the end of the 30 day growth trial were greater in treatments receiving enriched Artemia. Seahorses receiving Artemia enriched with DC DHA Selco and DC Super Selco showed significantly (p < 0.05) greater mean survival (71.6 ± 6.0% and 78.3 ± 6.0%, respectively) than those receiving unenriched Artemia (48.3 ± 6.0%). Mean standard length was also significantly greater (p < 0.05) in fry fed DC DHA Selco and DC Super Selco enriched Artemia (20.2 ± 0.3 and 19.7 ± 0.3mm, respectively) compared to those fed unenriched Artemia (18.1 ± 0.3mm). The results show that dietary n-3 HUFA are essential for optimal growth and survival of Hippocampus sp. and, based on the fatty acid compositions of the enriched Artemia used in this study, indicate that the level of dietary DHA supporting optimal growth and survival is greater than 9.3mgDHAg^-1 dry weight.     

DNA条形码技术在海马物种鉴定中的应用分析

海马具有重要的药用和观赏价值,但因其可供鉴定的形态特征较少,应用形态学对海马进行种水平的鉴定时经常会遇到很多困难。DNA条形码技术为海马物种鉴定提供了重要的鉴定方法。通过检索生命条形码数据库（BOLD）和GenBank数据库中海马的DNA条形码信息,应用MEGA软件计算海马种间遗传距离,分析DNA条形码在海马物种鉴定中的应用效果。结果表明,COI基因条码可以有效鉴别大部分种以上阶元的海马,但对亲缘关系较近的海马难以获得准确的鉴定结果。还有一些海马尚无相关的基因信息,也无法通过基因条形码进行鉴别。因此,应用DNA条形码鉴定海马物种尚有一定的局限性。     

Effects of acute and chronic zinc exposure on steroid hormone receptor expression in the lined seahorse,Hippocampus erectus

The element zinc (Zn) can elicit a variety of physiological responses in animals, particularly through its effects on steroid hormone receptor expression. Here, we evaluated the effects of Zn on the expression profiles of steroid hormone receptors in the lined seahorse, Hippocampus erectus, following experimental acute and chronic Zn exposure. Complex response patterns were observed; however, steroid hormone receptor expression in liver and kidney following 12‐day Zn injection (acute exposure) differed significantly from the control treatments. Apparent effects on hepatic lipid metabolism and osmotic regulation in the kidney need detailed investigation. Furthermore, 49‐day (chronic) waterborne Zn exposure produced a significant decrease in both estrogen receptor (ER) expression levels and estradiol concentrations. In additional, chronic exposure led to a substantial reduction of hepatic adipose cells, implying that Zn may regulate hepatic lipid metabolism via ER and estradiol. Our study demonstrated the effects of both acute and chronic Zn exposure on expression patterns of steroid hormone receptors, which will contribute to understanding the mechanism of Zn‐induced hepatic lipid metabolism and other physiological responses in seahorses.