Little Fish, Big Impact: Managing a Crucial Link in Ocean Food Webs

little fish BIG IMPACT Managing a crucial link in ocean food webs A report from the Lenfest Forage Fish Task Force The Lenfest Ocean Program invests in scientific research on the environmental, economic, and social impacts of fishing, fisheries management, and aquaculture. Supported research projects result in peer-reviewed publications in leading scientific journals. The Program works with the scientists to ensure that research results are delivered effectively to decision makers and the public, who can take action based on the findings. The program was established in 2004 by the Lenfest Foundation and is managed by the Pew Charitable Trusts (www.lenfestocean.org, Twitter handle: @LenfestOcean). The Institute for Ocean Conservation Science (IOCS) is part of the Stony Brook University School of Marine and Atmospheric Sciences. It is dedicated to advancing ocean conservation through science. IOCS conducts world-class scientific research that increases knowledge about critical threats to oceans and their inhabitants, provides the foundation for smarter ocean policy, and establishes new frameworks for improved ocean conservation. Suggested citation: Pikitch, E., Boersma, P.D., Boyd, I.L., Conover, D.O., Cury, P., Essington, T., Heppell, S.S., Houde, E.D., Mangel, M., Pauly, D., Plagányi, É., Sainsbury, K., and Steneck, R.S. 2012. Little Fish, Big Impact: Managing a Crucial Link in Ocean Food Webs. Lenfest Ocean Program. Washington, DC. 108 pp. Cover photo illustration: shoal of forage fish (center), surrounded by (clockwise from top), humpback whale, Cape gannet, Steller sea lions, Atlantic puffins, sardines and black-legged kittiwake. Credits Cover (center) and title page: © Jason Pickering/SeaPics.com Banner, pages ii–1: © Brandon Cole Design: Janin/Cliff Design Inc. Diagrams, pages 19, 63, 70, 78, 86: Sue-Lyn Erbeck little fish BIG IMPACT Managing a crucial link in ocean food webs A report from the Lenfest Forage Fish Task Force April 2012 CONTENTS Task Force Members iv CHAPTER 3 Approaches and Strategies for Forage Fish Acknowledgements v Management: Lessons Learned 16 Management Based on Precaution: Moratoriums �� 17 Preface vi Management Based on Empirical Reference Points �� 17 Our Mission ��vi Prey length and age �� 17 Our Approach �� vii Reproductive output �� 18 Workshops ��vii Predator condition and reproductive success �� 18 Review of existing theory and practice ��vii Management Based on Reference Points Case studies ��vii from Stock Assessments �� 20 Quantitative methods ��viii Reference points based on age-structured approaches �� 20 Developing Conclusions and Recommendations ��viii Constant targeted yield or fishing mortality: CHAPTER 1 MSY approaches �� 21 Introduction: Little Fish, Big Impact 2 Spawning potential approaches �� 21 Fishing a Moving Target�� 3 Variable F determined from a biomass-fishing mortality control rule �� 22 Current Demand for Forage Fish �� 4 Management Based on the Use of The Need for Precautionary Management �� 5 Biomass Thresholds��23 Statement of Problem �� 9 Krill in the Antarctic: The use of precautionary biomass thresholds �� 23 CHAPTER 2 Biological and Ecological Characteristics Herring in Alaska: The use of a harvest threshold of Forage Fish and their Implications for biomass based on egg surveys �� 23 Fisheries Management 10 Sardines in California, Oregon, and Washington: The use of a harvest biomass threshold with an Catchability �� 11 explicitly coupled environmental variable �� 24 Age-Structure Truncation and Conservation Management Based on Potential Biological of Fecundity �� 11 Removal Principles �� 24 Assessment of the Resilience and Recovery Management Based on Temporal and Potential of a Population �� 12 Spatial Approaches �� 26 Steepness of the Stock-Recruitment Relationship �� 12 Steller sea lions in the Sources of Mortality and Management Implications �� 13 Aleutian Islands and eastern Bering Sea �� 27 Sustainability of Other Ecosystem Components �� 13 African penguins in the Benguela �� 27 Localized Depletion �� 14 North Sea sand eel �� 28 Accounting for Interacting Species �� 14 Antarctic krill �� 29 Summary �� 15 Summary �� 29 ii little fish BIG IMPACT CHAPTER 4 CHAPTER 6 Case Studies of Forage Fisheries 30 Comparison of Fisheries Management Antarctic Ecosystems: The Central Role of Krill �� 32 Strategies and Ecosystem Responses to The Baltic Sea: An Impoverished Ecosystem �� 34 the Depletion of Forage Fish 66 Methods �� 67 Barents Sea: The “Capelin Limit Rule”�� 36 The Benguela Upwelling System: Harvest control rules �� 69 A Tale of Two Fisheries �� 38 Parameters for stochastic runs �� 71 The California Current: Supporting Multiple Presentation of the results �� 71 Forage Fish and Invertebrates �� 40 Predator response prediction �� 72 Chesapeake Bay: Undervalued Forage Species Results �� 72 and Concerns of Localized Depletion �� 42 Deterministic model results using the Gulf of Maine: A Trophic and constant yield control rule �� 72 Socioeconomic Cornerstone �� 44 Deterministic model results using the The Humboldt Current and the World’s constant fishing control rule �� 72 Largest Fishery �� 48 Stochastic constant fishing control rules �� 77 The North Sea: Lessons from Forage Fish Stochastic step function rules �� 78 Collapses in a Highly Impacted Ecosystem �� 50 Stochastic hockey stick control rule �� 79 Comparison of control rules using deterministic CHAPTER 5 and stochastic models �� 79 Direct and Supportive Roles of Forage Fish 54 Comparison of control rules with stochastic models �� 79 Methods �� 55 Major Findings and Conclusions �� 83 Importance of forage fish to predators �� 56 Calculating the direct and supportive roles CHAPTER 7 of forage fish to commercial fisheries �� 57 Key Findings and Recommendations 84 Global estimate of forage fish economic value Key Findings �� 84 to fisheries ��

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