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.

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.

Historically, whenever tuna was hauled ashore, the sounds of battle were never far away. ‘Tuna Wars’ tells the untold story of the power struggles emerging around tuna, from the distant past to your present-day dinner table. In the ancient past, the giant tuna was the first fish to become the basis of a large-scale industry and a ‘global’ trade that created fortunes: Hannibal was able to finance his elephant campaign on Rome thanks to tuna. From the Middle Ages on, a tuna fishing monopoly on Spain’s southern coast allowed the nobility to completely dominate the area and even lead the ‘invincible’ Armada. When the markets for tuna increased exponentially thanks to technical advances, tuna eventually became a billion-dollar business and one of the most-consumed fish species worldwide. But this massive expansion came at a price. An 18th century monk in Madrid was the first to warn that tuna fisheries needed to be run sustainably for the sake of future generations. And the issue of sustainability would go on to become a game-changer in the modern tuna wars, characterized by new alliances and partnerships, hybrid warfare and commercial power struggles. In addition to accompanying you through the history of tuna and sharing insights into fisheries science and approaches to sustainably managing fisheries, Tuna Wars offers practical guidance on choosing sustainably fished tuna. In short, it will tell you everything you ever wanted to know about tuna, but were afraid to ask.

The most thorough and current account of scientific research on bluefin tunas—the largest, most sought-after tunas in the world Bluefin tunas are dominant keystone predators known for their impressive size, strength, endurance, and speed. Electronic tags have revealed that they can dive to great depths (over 6000 feet) and migrate vast distances—from frigid subpolar seas to warm tropical waters—for spawning. Prized for their rich taste and unique texture, bluefin tunas are also a worldwide commodity of great value. However, over the past few decades, overfishing throughout their range has led to significant population reductions. In The Future of Bluefin Tunas, Barbara A. Block brings together renowned bluefin experts from 15 different countries to share the latest information on the science, fisheries policy, and management decisions related to each of the three species within the Thunnus group—Atlantic, Pacific, and Southern. Synthesizing basic and applied research, the book delves into every aspect of these majestic fish, from their life history and genetic makeup to their ecology and migrations. Ichthyologists and marine scientists dedicated to the study of these fishes report on the latest stock assessments, explore the results of advances such as biologging and DNA sampling, and assess the potential of bluefin tuna aquaculture. The Future of Bluefin Tunas provides critical research findings to inform decisions that will impact tunas and the ocean ecosystems they affect. Scientists, fisheries managers, policymakers, and marine conservationists will take away key data from this timely volume to help them ensure these remarkable fish continue in perpetuity.

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.