Seychelles harbors various elasmobranch species, such as sharks and rays, fulfilling crucial roles in boosting tourism and maintaining ecological balance. Seeing the need to protect these fish stocks and following several international obligations, Seychelles has enacted several national legislative measures and action plans. These measures aimed to evaluate the status of elasmobranch populations, plan and implement conservation interventions, and promote their sustainable use.
In its first National Plan of Action for the Conservation and Management of Sharks 2007-2010, the country has tagged its national elasmobranch fishery as overexploited and depleted. Meanwhile, the second iteration of this planning initiative resulted in the listing of 82 species of elasmobranch occurring in Seychelles, with the number later refined to 73 species after undergoing review and taxonomic revisions. Of the 73 species, the International Union for Conservation of Nature (IUCN) has classified 46 (63%) as threatened worldwide, i.e., species listed as Vulnerable, Endangered, or Critically Endangered on the IUCN Red List. Meanwhile, five other species are classified as Data Deficient. Despite these factors, the country only lists the whale shark (Rhincodon typus) as protected under Seychelles law.
While published data on the species-specific elasmobranch species in Seychelles are scarce, according to the Seychelles Fishing Authority, the general information indicates that some species populations have declined from historical levels, and others may have been locally extinct. As such, in aid of the accounting of elasmobranch species in Seychelles, the current project aims to assess the catch of threatened species in the local artisanal fishery industry and formulate recommendations grounded on existing national legislation and international commitments. The project conducted catch surveys in Victoria Market, fisher partner landing sites, and several key landing sites from August 2021 to September 2022. The assessment also used separate standardized measurement protocols for sharks and rays to identify the species. The assessment results led to the development of morphological and length-weight models to enable a rapid monitoring protocol for similar activities in the future.
During the survey period, the study recorded 20 elasmobranch species, consisting of 12 shark, 7 ray, and 1 guitarfish species. Eighty-four percent of the shark catch belonged to 3 species, namely, blacktip (C.limbatus), grey reef (C. amblyrhynchos), and scalloped hammerheads (S. lewini). This figure translates to 83% by weight. Meanwhile, ray catch consisted mainly of 2 species, with ocellated eagle ray (A. ocellatus) and shortfin devil ray (M. kuhlii) constituting 95% of the catch numerically and 92% by weight.
For the species that exhibited a good population spread, from juvenile to adult, in the catch surveys, namely C. amblyrhynchos, C. limbatus, S. Lewin, R. australiae, A. ocellatus, and M. kuhlii, the mean size of the specimens caught for each species was substantially lower below the size of maturity. This crucial finding suggests that growth overfishing or the excessive fishing of juveniles occurs in Seychelles’ waters. Except for C. amblyrhynchos, the study also found that the catch of juveniles predominantly resulted from illegal fishing for sharks with nets. Furthermore, the study also found a separate unpublished survey conducted from 2013 to 2018, which showed a decrease in mean sizes for C. amblyrhynchos and a significant decline of mature females, indicating potential excessive catch of breeders or recruitment overfishing.
The survey and literature review findings support the current understanding of a depleted shark fishery and ongoing catch decline and highlight the need for a more precautionary approach toward elasmobranch fishery management. Given these considerations, the current study provides the following recommendations:
Fishery management and monitoring recommendations:
Species-based recommendations:
Some facts for potential highlighting: