Implementation of this assumption began in 1982 for member nations. Since 1991, international management of the two stocks has been separated to the degree that each stock is alternately reviewed every second year by the commission. Because of the perceived decline in abundance of western Atlantic bluefin tuna, the two stocks have been subject to different regulations, the most striking difference being the absence of a quota for the eastern fishery and the imposition of a strict harvest quota, allowing catches only for scientific monitoring, for the western fishery.
The United States is represented in ICCAT by three commissioners. An official from the U.S. Department of Commerce's National Oceanic and Atmospheric Administration (NOAA) serves as one of the U.S. commissioners; of the other two, one is required to have experience with commercial fishing and the second with recreational fishing. In preparation for the November 1994 ICCAT meeting, Douglas K. Hall, Assistant Secretary for Oceans and Atmosphere in the Department of Commerce, asked the National Research Council's Ocean Studies Board to conduct a peer reviewed study within six months to enable NOAA to use the results for the ICCAT meeting.
Accordingly, the Ocean Studies Board established the Committee to Review Atlantic Bluefin Tuna to review and evaluate the scientific basis of U.S. management of fisheries for Atlantic bluefin tuna and to recommend research to resolve remaining stock structure issues. The report focuses primarily on the scientific basis for assumptions about stock structure and for indices of abundances used in the stock assessments for western Atlantic bluefin tuna. The issue of stock structure of Atlantic bluefin tuna is discussed in Chapter 2, and movement of Atlantic bluefin tuna is discussed in Chapter 3. Information on the indices of abundances and the results of sensitivity analyses conducted by the committee using data sets obtained from NOAA's National Marine Fisheries Service (NMFS) and the industry are presented and discussed in Chapter 4. In addition, the committee makes specific recommendations to address the detailed problems that are identified and discussed in each section of Chapters 2 through 4.
In response to its charge and based on the analyses presented in Chapters 1 through 4, the committee presents in Chapter 5 the following major conclusions and recommendations for improving the scientific basis of management of Atlantic bluefin tuna:
Available biological evidence of stock structure although sparse is consistent with a single stock hypothesis for bluefin tuna in the North Atlantic Ocean, with at least two spawning areas. Furthermore, the committee's reevaluation of tagging results confirms that movement of bluefin tuna between the western and eastern Atlantic Ocean is sufficient to alter the previous ICCAT