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