ANNOUNCEMENTS
Elasmobranchs today are reported to be one of the most threatened species globally because of poor management strategies pertaining to fisheries. Activities like over-fishing, unaccounted bycatch, international trade of elasmobranchs related commodities such as fins, liver oil and skin are some of the key contributors to this decline. In order to conserve these species, it is important to understand their biological characteristics because management plans need to be species-specific. The present study aims at exploring the life-history traits of the sharks and rays which are commonly landed on the coast of Malvan, Maharashtra. The life history traits measured include “length-weight relationship”, reproductive biology in terms of maturity stages and the size at first maturity. The four species considered for this study include: Scoliodon laticaudus, Brevitrygon walga, Chiloscyllium griseum and Chiloscyllium arabicum. We found that females have larger variance in terms of length and weight. Three species, S. laticaudus, C. arabicum, C. griseum were found to show isometric growth whereas B.walga showed positive allometric growth. Overall, the average of lengths at different maturity stages were found to be significantly different from each other. Size at first maturity (L50) in the case of C. arabicum was reported to be higher for females compared to that of males and vice versa for B. walga. Further studies are required to better understand the population dynamics of these species. Furthermore, to bring about sustainability in fisheries, consumption patterns of the landed elasmobranchs can be studied at local level by conducting questionnaire surveys with the local traders, fisher community and tourists (to explore their preferences). Elasmobranchs play a vital role in marine ecosystems as top and mesopredators. Any change in the fishing pressures can lead to significant decline in their populations thereby effecting other organisms along with the communities which rely on them as resources.
Key words: chondrichthyans, length-weight relationship, maturity, threats, reproductive biology.
