This volume comprises the proceedings of a symposium on marine mammal survey assessment methods, which took place in Seattle, Washington, USA.

Marine mammals face a large array of stressors, including loss of habitat, chemical and noise pollution, and bycatch in fishing, which alone kills hundreds of thousands of marine mammals per year globally. To discern the factors contributing to population trends, scientists must consider the full complement of threats faced by marine mammals. Once populations or ecosystems are found to be at risk of adverse impacts, it is critical to decide which combination of stressors to reduce to bring the population or ecosystem into a more favorable state. Assessing all stressors facing a marine mammal population also provides the environmental context for evaluating whether an additional activity could threaten it. Approaches to Understanding the Cumulative Effects of Stressors on Marine Mammals builds upon previous reports to assess current methodologies used for evaluating cumulative effects and identify new approaches that could improve these assessments. This review focuses on ways to quantify exposure-related changes in the behavior, health, or body condition of individual marine mammals and makes recommendations for future research initiatives.

The Guidelines to Prevent and Reduce Bycatch of Marine Mammals in Capture Fisheries were produced by FAO in response to the request from the Committee on Fisheries at its Thirty-third Session in 2018 to develop technical guidelines on this subject, and are directed at decision-makers, planners, managers and all those involved in developing and implementing policy and technical interventions which relate to the bycatch of marine mammals in fisheries.The guidelines were drafted and developed through a series of activities undertaken by FAO, including the Expert Workshop on Means and Methods for Reducing Marine Mammal Mortality in Fishing and Aquaculture Operations and the Expert Meeting to Develop Technical Guidelines to Reduce Bycatch of Marine Mammals in Capture Fisheries. They outline options for marine mammal bycatch reduction through the application of technical measures, including: spatial closures, the use of acoustic deterrents or alerting devices, modifications to fishing gear, changes in fishing operations and other strategies. The document refers to policy instruments and institutional frameworks that support the implementation of the guidelines and the conservation of marine mammals, in addition to awareness raising, communication and capacity-building actions, together with the special requirements of developing States. Finally, the guidelines address the future research and development needs for the prevention and reduction of marine mammal bycatch in capture fisheries.

The Expert Meeting to “Develop Technical guidelines to reduce bycatch of marine mammals in capture fisheries” was held in Rome, Italy, on 17-19 September 2019. Twenty-nine fisheries and bycatch experts and observers from FAO Members participated in the meeting: Argentina, Australia, Brazil, Canada, Chile, Denmark, Iceland, Japan, Norway, Russian Federation, Sweden, and the United States of America. The meeting was also attended by experts from various regional and international organizations. The meeting aimed to prepare “Technical guidelines to reduce bycatch of marine mammals in capture fisheries” that are directed at decision-makers, planners, managers, and all those involved in developing and implementing policy and technical interventions relevant to the bycatch of marine mammals in fisheries. The meeting was organized by FAO in response to the request from the Committee on Fisheries at its 33rd session in 2018 to develop technical guidelines on this subject. At the meeting the experts reviewed and discussed technical measures that can be applied for the reduction of bycatch of marine mammals in fisheries, including: time-area closures, acoustic deterrents, modifications to fishing gears and changes in fishing operations.

A key goal of fisheries management is to regulate extractive pressure on a resource so as to ensure social, economic and ecological sustainability. This text provides an accessible entry point for students and professionals to management science as developed in fisheries, in order to facilitate uptake of the latest ideas and methods. Traditional management approaches have relied upon a stock assessment based on existing understanding of resource status and dynamics, and a prediction of the likely future response to a static management proposal. However all such predictions include an inherent degree of uncertainty, and the last few decades have seen the emergence of an adaptive approach that uses feedback control to account for unknown future behaviour. Feedback is achieved via a control rule, which defines a relationship between perceived status of the resource and a management action. Evaluations of such rules usually include computer simulation testing across a broad range of uncertainties, so that an appropriate and robust rule can be selected by stakeholders and managers. The book focuses on this approach, which is usually referred to as Management Strategy Evaluation. The book is enriched by case study examples from different parts of the world, as well as insights into the theory and practice from those actively involved in the science of fisheries management.