Improving Stock Assessments And Management Advice For Bluefin Tunas And Other Highly Migratory Species

For years bluefin tuna has been the poster child for overfishing and poor management. However, recent improvements in data collection, catch monitoring and international cooperation are providing an opportunity to reverse the perception of a fishery that is doomed to collapse. Stock assessments are conducted routinely to monitor the abundance and productivity of exploited fish stocks so managers can determine how many fish can be sustainably harvested each year. Should a stock be declared overfished or under-going overfishing, the science behind stock assessments also equip managers with the knowledge necessary to make decisions about what short-term and long-term management measures should be taken to help reverse these trends. in that light, the goal of my research has been to use newly available age data to improve the quality and reliability of assessments for Atlantic bluefin tuna by reducing uncertainty about the data and methods used to infer growth and age composition. A secondary goal has been to provide managers with the knowledge necessary to implement effective stock rebuilding programs for Pacific bluefin tuna. Chapter 2 is focused on cohort slicing, a method routinely used in the Atlantic bluefin tuna assessment to estimate catch-at-age from catch-at-size information. This chapter explores how errors in cohort sliced catch-at-age data can bias estimates of total mortality rate derived from catch curve analysis. Recommendations are provided concerning the appropriate mortality estimator and plus group to use depending on the parameters characterizing the stock. Chapter 3 provides updated growth estimates for western Atlantic bluefin tuna, which were adopted in 2017 as the basis for defining growth in the assessment. Chapter 4 provides an overview of the theory behind age-length keys with particular emphasis on the assumptions that govern each method and provides notes of caution concerning their applications to real data. Chapter 5 evaluates through simulation the relative performance of different methods for estimating age composition of western Atlantic bluefin tuna catches and applies the best performing technique, the combined forward-inverse age-length key, to actual western Atlantic bluefin tuna data. Chapter 6 moves over to the Pacific and focuses on evaluating the potential impacts of different minimum size regulations on the stock of Pacific bluefin tuna and explores ways in which to minimize short-term pain to the industry while still achieving long-term yield and conservation goals. Overall, this work has contributed major improvements to the stock assessment process of Atlantic bluefin tuna and implications of this work resonate beyond the bluefin tuna world to other highly migratory species faced with similar problems.

Ocean harvests have plateaued worldwide and many important commercial stocks have been depleted. This has caused great concern among scientists, fishery managers, the fishing community, and the public. This book evaluates the major models used for estimating the size and structure of marine fish populations (stock assessments) and changes in populations over time. It demonstrates how problems that may occur in fisheries dataâ€"for example underreporting or changes in the likelihood that fish can be caught with a given type of gearâ€"can seriously degrade the quality of stock assessments. The volume makes recommendations for means to improve stock assessments and their use in fishery management.

The Law Library presents the complete text of the Atlantic Highly Migratory Species - Atlantic Bluefin Tuna Quotas and Atlantic Tuna Fisheries Management Measures (US National Oceanic and Atmospheric Administration Regulation) (NOAA) (2018 Edition). Updated as of May 29, 2018 NMFS is modifying Atlantic bluefin tuna (BFT) base quotas for all domestic fishing categories; establishing BFT quota specifications for the 2011 fishing year; reinstating pelagic longline target catch requirements for retaining BFT in the Northeast Distant Gear Restricted Area (NED); amending the Atlantic tunas possession-at-sea and landing regulations to allow removal of Atlantic tunas tail lobes; and clarifying the transfer-at-sea regulations for Atlantic tunas. This action is necessary to implement recommendations of the International Commission for the Conservation of Atlantic Tunas (ICCAT), as required by the Atlantic Tunas Convention Act (ATCA), and to achieve domestic management objectives under the Magnuson-Stevens Fishery Conservation and Management Act (Magnuson-Stevens Act). This ebook contains: - The complete text of the Atlantic Highly Migratory Species - Atlantic Bluefin Tuna Quotas and Atlantic Tuna Fisheries Management Measures (US National Oceanic and Atmospheric Administration Regulation) (NOAA) (2018 Edition) - A dynamic table of content linking to each section - A table of contents in introduction presenting a general overview of the structure

This book reviews and evaluates the scientific basis of U.S. management of fisheries for Atlantic bluefin tuna. In particular, it focuses on the issues of stock structure and stock assessments used by the National Oceanic and Atmospheric Administration's National Marine Fisheries Service for management under the International Convention for the conservation of Atlantic Tunas.

"In this action, the National Marine Fisheries Service (NMFS) would adjust regulations governing the U.S. BFT fishery to : (1) Increase the General category maximum BFT daily retention limit from three to five fish (with limit adjustments to be executed via inseason actions when and if appropriate): (2) Allow the BFT General category season to remain open until the January subquota is reached or March 31 (whichever happens first): and (3) Increase the Harpoon category daily retention limit of BFT measuring 73 to 81 inches from two to four fish. This action is intended to enable more thorough utilization of the available U.S. BFT quota for the General and Harpoon permit categories: minimize bycatch and bycatch mortality to the extent practicable: expand fishing opportunities for participants in the commercial winter General category fishery: and increase NMFS' flexibility for selling the General category retention limit depending on available quota. This action would be consistent with the Magnuson-Stevens Fishery Conservation and Management Act, the Atlantic Tunas Convention Act, and the 2006 Consolidated Atlantic Highly Migratory Species Fishery Management Plan. This action is not expected to significantly alter current fishing practices and bycatch mortality rates, or increase fishing effort, and it is not expected to change previously analyzed endangered species or marine mammal interaction rates or magnitudes."--Cover letter; Portfolio comprised of two related PDF documents digitized and organized by: NOAA Office of Program Planning and Integration (PPI) National Environmental Policy Act (NEPA) staff.