E6-8049. Stock Assessment of Dusky Shark in the U.S. Atlantic and Gulf of Mexico

AGENCY:

National Marine Fisheries Service (NMFS), National Oceanic and Atmospheric Administration (NOAA), Commerce.

ACTION:

Notice of availability.

SUMMARY:

NMFS announces the availability of a stock assessment report on dusky sharks in the Atlantic and Gulf of Mexico, prepared by the NMFS Southeast Fisheries Science Center. The stock assessment summarizes the relevant biological data, discusses the fisheries affecting the species, and details the data and methods used to assess stock status. Some recommendations were also made regarding future avenues of research and issues to consider in future stock assessments.

ADDRESSES:

Requests for copies of the report should be sent to Sarah McTee, Highly Migratory Species Management Division (F/SF1), National Marine Fisheries Service (NMFS), 1315 East-West Highway, Silver Spring, MD 20910, or may be sent via facsimile (fax) to 301-713-1917 or phone [phone]. Electronic copies of the stock assessment may also be obtained on the internet at: http://www.sefscpanamalab.noaa.gov/​shark/​pdf/​Dusky_​Shark_​Assessment.zip.

FOR FURTHER INFORMATION CONTACT:

For information on the methods, data, and results of the stock assessment, contact Enric Cortes by phone at [phone] or by fax at [phone].

SUPPLEMENTARY INFORMATION:

The dusky shark (Carcharhinus obscurus) is one of 19 species for which retention is prohibited under the Fishery Management Plan for Atlantic Tunas, Swordfish, and Sharks implemented and amended in 1999 and 2003, respectively. Due to potential identification problems and catch data originating from a variety of sources, the magnitude of dusky shark catch has been difficult to ascertain. The dusky shark has not previously been individually assessed; however, low population growth rates, coupled with declines in both the catch per unit effort (CPUE) and size of individuals landed since the early 1990s, created concern that the dusky shark was being heavily exploited.

Using recent biological data on the growth and reproduction of dusky sharks, landing estimates from recreational and commercial fisheries, commercial bycatch estimates, four fishery-dependent and one fishery-independent relative abundance indices, a stock assessment was recently completed for the dusky shark. Results from the models used were very similar with all models showing the stock has been heavily exploited. The baseline analyses using surplus production models indicate that current depletions are over 80 percent of virgin biomass. The age-structured model provided the most optimistic results and indicated that the dusky shark population has been depleted by 62 to 80 percent of the unfished virgin biomass. The stock assessment summarizes the relevant biological data, discusses the fisheries affecting the species, and details the data and methods used to assess stock status. Some recommendations were also made regarding future avenues of research and issues to consider in future stock assessments.

Authority: 16 U.S.C. 971 et seq. and 1801 et seq.

Dated: May 22, 2006.

James P. Burgess,

Acting Director, Office of Sustainable Fisheries, National Marine Fisheries Service.