R. C. Wakeford1 and D. J. Agnew
1Present address: MRAG Ltd., 18 Queen Street, London, W1J 5PN
Renewable Resources Assessment Group, Imperial College
Prince Consort Road, London SW7 2BP, United Kingdom
D. A. J. Middleton, J. H. W. Pompert and V. V. Laptikhovsky
Fisheries Department, Falkland Islands Government
P. O. Box 598, Stanley, Falkland Islands
Publication (Upload) date: 17 November 2004
WAKEFORD, R. C., D. J. AGNEW, D. A. J. MIDDLETON, J. H. W. POMPERT, and V. V. LAPTIKHOVSKY. Management of the Falkland Islands Multispecies Ray Fishery: Is Species-specific Management Required? J. Northw. Atl. Fish. Sci., 35: 309-324. doi:10.2960/J.v35.m497
A multispecies commercial fishery for rajids has been managed in Falkland Islands waters since 1987. In the absence of detailed biological knowledge and catch-at-age data, management policies currently consider a single assemblage rather than individual species. Simple production models with aggregated catch and effort data are used to estimate sustainable levels of exploitation. Biological data, now available from recent research surveys and an ongoing observer program, provide an opportunity to examine the potential impact of the rajid fishery at a species level. This in turn will help determine whether current management policies are still appropriate.
An updated assessment of the northern ray population indicates that the assemblage has been surprisingly robust to fluctuations in fishing pressure. A spatial analysis of the relative abundance of animals showed no evidence of local depletions in biomass. At a species level, a declining trend in the relative abundance of three species (Bathyraja griseocauda, B. multispinus, and an undescribed Bathyraja sp. 3) was found at the same time as an increase in two Rajid species (R. doellojuradoi and R. flavirostris). A preliminary analysis of the distribution and movements of R. flavirostris, coupled with length frequency and maturity data, suggest that this species has a broad distribution, which, unlike B. griseocauda, may not form a resident population within Falkland Island waters. While no loss of diversity has been reported, closure of the once heavily exploited area to the south of the Islands provides at least one refuge for species such as B. griseocauda.
Key words: ray, fishery, Falkland Islands, catch trends, stock assessment, distribution, sustainable management