The IUCN/SSC Shark Specialist Group
Shark News 8: December 1996
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US Management of Large Coastal Sharks
There is widespread concern among US shark scientists and the conservation community over the overfished status of large coastal sharks in the Western Atlantic and Gulf of Mexico (Camhi 1995). Large coastal sharks comprise between 75% and 92% of the annual reported US commercial shark landings in the Atlantic and Gulf (NMFS 1996). Available data indicate that many species had already declined by 50% to 75% between the early 1970s and mid-1980s. Overfishing continued through the early 1990s with the rapid expansion of the commercial shark fishery, largely in response to the increased demand for shark fins. More recently, implementation of the Fishery Management Plan for Atlantic Sharks (FMP), which has imposed an annual commercial quota and recreational bag limits on 22 species of large coastal sharks since 1993, has stemmed additional increases in shark catches (NMFS 1993). Sandbar Carcharhinus obscurus and blacktip C. limbatus sharks constitute 75%-95% of the large coastal landings, depending on location and season (GSAFDF 1996).
In June 1996, the US National Marine Fisheries Service held a scientific assessment to re-evaluate the status of these sharks. A number of disturbing trends were highlighted (NMFS 1996):
- three population models and a wide array of CPUE data sets (including fishery-dependent, fishery-independent, recreational and commercial data) confirmed that abundance in large coastal sharks had declined by 50%-80% since the early 1970s;
- although implementation of the FMP in 1993 may have stemmed the decline, there are still no clear signs that these populations have started to rebuild;
- current level of fishing mortality is about twice that necessary to produce the maximum sustainable catch; and
- demographic analyses indicate that fishing mortality exceeds - by at least twice - the maximum intrinsic rates of increase of the dominant species.
The assessment report indicates that large quota cuts - and even a closure of the large coastal fishery - will not ensure an increase in shark abundance in this century, given the low reproductive capacity of these sharks. The assessment scientists concluded that a 50% reduction or more in fishing mortality may be needed if these sharks are to begin to recover (NMFS 1996).
The Shark Operations Team (OT), an advisory panel comprised mainly of representatives from the US fishery management councils on the Atlantic and Gulf, met in August to consider the findings of the assessment and make management suggestions to NMFS for 1997. OT members recognised the need to reduce fishing mortality, but there was disagreement over the size of the quota cuts needed and what other actions, such as minimum size limits and area closures, could be implemented to offset quota reductions. Although these options have merit, they will first require rigorous scientific review to determine their value in reducing effective fishing mortality and promoting recovery. NMFS is behind schedule in publishing a proposed rule to solicit public comment and establish management options for the large coastal shark fishery in 1997. An update on US management of this fishery will appear in a forthcoming issue of Shark News.
References
Camhi, M. 1995. Risk prone management of the US Atlantic Shark Fishery Shark News 4: 6-7
GSAFDF (Gulf and South Atlantic Fisheries Development Foundation) 1996. Commercial shark fishery observer program. MARFIN Final Report. Tampa, FL. 33pp.
NMFS 1996. Report of the Shark Evaluation Workshop, June 1996. NOAA/NMFS, Southeast Fisheries Science Center, Miami, FL.
NMFS 1993. Fishery Management Plan for sharks of the Atlantic Ocean. NOAA/NMFS, US Dept. of Comm. Feb. 25, 1993.
Merry Camhi, National Audubon Society.
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