An Integrated Approach to Determining the Risk of Over-exploitation for Data-poor Pelagic Atlantic Sharks

Report of an expert working group held June 3–6, 2008, in Washington, D.C. Working group members:

• Colin Simpfendorfer*, Fishing and Fisheries Research Centre, School of Earth and Environmental Sciences, James Cook University, Queensland, Australia
• Enric Cortés*, NOAA/NMFS/SEFSC/PanamaCity Laboratory, Panama City, Florida
• Michelle Heupel*, School of Earth and Environmental Sciences, James Cook University, Queensland, Australia
• Elizabeth Brooks*, NOAA/NMFS/Northeast Fisheries Science Center, Woods Hole, Massachusetts
• Elizabeth Babcock, Rosenstiel School of Marine and Atmospheric Science, University of Miami, Florida
• Julia Baum, Scripps Institution of Oceanography, University of California, San Diego, La Jolla, California
• Rory McAuley, Shark Section, Department of Fisheries, Western Australia, WA Fisheries and Marine Research Laboratory, North Beach, Washington, Australia
• Sheldon Dudley, Natal Sharks Board, KwaZulu Natal, South Africa
• John D. Stevens, CSIRO Division of Marine and Atmospheric Research, Hobart, Australia
• Sonja Fordham, Shark Alliance and Shark Conservation Program Director, Ocean Conservancy, Brussels, Belgium
• Alen Soldo, Centre of Marine Studies, University of Split, Split, Croatia

* working group members who contributed to data analysis

Note: The views expressed herein are solely those of the individuals and do not necessarily reflect the opinions of NOAA Fisheries Service.

SUMMARY

We assessed the risk of over-exploitation for pelagic shark species taken in Atlantic longline fisheries based on three main metrics: ecological risk assessment; the inflection point of the population growth curve (a proxy for B_MSY); and status on the IUCN Red List of Threatened Species. The results were analyzed using multivariate statistics to provide an integrated measure of the risk of overexploitation. The integrated risk approach is not a substitute for stock assessment, but rather a method to aid in making science-based management recommendations in the face of data limitations.

Findings for individual species were compared to that of the blue shark, a species that current stock assessments is not over-exploited under the International Commission for the Conservation of Atlantic Tunas (ICCAT). All examined pelagic shark and ray species had higher levels of risk than the blue shark. All species had substantially lower biological productivity than the blue shark and had inflection points above 50% of virgin biomass.

According to our analyses, species at highest risk are the bigeye thresher, shortfin mako, longfin mako, and, to lesser extent, the silky shark. The porbeagle, oceanic whitetip and common thresher were grouped and identified as having the next greatest risk. The pelagic stingray and scalloped hammerhead ranked in line with the blue shark. Conclusions about the crocodile shark and smooth hammerhead could not be made due to a lack of data.

To access the full report, click the download button.