A comparison of the growth and development of pyjama sharks (Poroderma africanum) in wild and captive populations.

The pyjama shark (Poroderma africanum) is a Scyliorhinid species endemic to South Africa. Even though it is kept in captivity in many aquaria, there is a lack of research on its growth and development. In this study, we investigated the fertilization rate of eggs and the age at female sexual maturation in captive sharks and compared their growth to that of wild individuals. This is the first study to compare the growth of captive and wild catsharks as well as the first study to compare growth in male and female pyjama sharks and benefits from a much larger sample size than has previously been collected. The mean incubation rate (±standard error of the mean [SE]) was 239.46 ± 4.97 days, the mean Lt of hatchlings (±SE) was 14.65 ± 0.24 cm, and the mean Wt (±SE) was 17.19 ± 0.75 g. The observed ratio of male to female offspring (1:3.5) was also significantly different from 1:1. One female laid fertilized eggs 6.6 years after hatching and was considered sexually mature. Both in captivity and in the wild, males showed negative allometric growth and females showed isometric growth. The growth performance (Φ') was also greater in captive sharks compared to wild sharks regardless of sex. However, there was significant variation in growth between individuals of the same sex. The similar growth patterns (i.e., allometry and isometry) found in wild and captive populations are a very useful tool for informing future conservation management if the population of this shark species were to decline in the future and also prove that captive studies for this species are transferable to wild populations with regard to sexual differences. This study also provides a benchmark for further captive studies in other lesser-studied catshark species and raises interesting questions concerning sexual differences in growth for other shark species.

Conservation benefits of a marine protected area on South African chondrichthyans.

Chondrichthyans are threatened worldwide due to their life-history traits combined with a plethora of anthropogenic impacts that are causing populations to collapse. Marine Protected Areas (MPAs) are a conservation option, but their efficacy for chondrichthyans is still unclear. Conservation efforts might be challenging especially in developing countries, due to a lack of resources and monitoring and limited data and stakeholder support. Here Baited Remote Underwater Stereo-Video systems (stereo-BRUVs) were deployed inside and outside a small partially protected MPA (Robberg MPA, Western Cape, South Africa) to assess the status of cartilaginous fishes' assemblages and to investigate the potential benefits derived from the presence of a marine reserve. Overall, 19 chondrichthyan species in 11 different families were observed. Chondrichthyans were observed in 78.5% of the sites and, of these, 89.7% of the MPA sites showed at least one chondrichthyan, while only in the 67.5% of surrounding exploited sites a cartilaginous fish was sighted. The presence of the MPA had a significant effect on the relative abundance of batoids, threatened species and local endemics, with more observations inside the MPA than outside, indicating the potential benefit of marine reserves on species that are more vulnerable to fishing pressure. Relative abundance was generally higher inside the bay than in the exposed area, and both relative abundance and species richness decreased significantly with depth. The analysis of the body length showed that the 35.5% of species had an average body length below maturity length, indicating that the area might be used as nursery ground for different species. This study provides evidence that MPAs, even though small and partially protected, can provide benefits for chondrichthyans, specifically to threatened species, endemic species and lesser-known species. Importantly, different environmental parameters must be considered to maximize the benefits an MPA can provide.