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Guide to Fisheries Science and Stock Assessments

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Guide to Fisheries Science and Stock Assessments ATLANTIC STATES MARINE FISHERIES COMMISSION Guide to Fisheries Science and Stock Assessments von Bertalanffy Growth Curve Maximum 80 Yield 70 60 50 40 Carrying 1/2 Carrying Length (cm) 30 Fishery Yield Fishery Capacity Capacity Observed 20 Estimated 10 0 Low Population Population size High Population 0 1 2 3 4 5 6 7 8 9 10 Age (years) June 2009 Guide to Fisheries Science and Stock Assessments Written by Patrick Kilduff, Atlantic States Marine Fisheries Commission John Carmichael, South Atlantic Fishery Management Council Robert Latour, Ph.D., Virginia Institute of Marine Science Editor, Tina L. Berger June 2009 i Acknowledgements Reviews of this document were provided by Doug Vaughan, Ph.D., Brandon Muffley, Helen Takade, and Kim McKown, as members of the Atlantic States Marine Fisheries Commission’s Assessment Science Committee. Additional reviews and input were provided by ASMFC staff members Melissa Paine, William Most, Joe Grist, Genevieve Nesslage, Ph.D., and Patrick Campfield. Tina Berger, Jessie Thomas-Blate, and Kate Taylor worked on design layout. Special thanks go to those who allowed us use their photographs in this publication. Cover photographs are courtesy of Joseph W. Smith, National Marine Fisheries Service (Atlantic menhaden), Gulf States Marine Fisheries Commission (fish otolith) and the Northeast Area Monitoring and Assessment Program. This report is a publication of the Atlantic States Marine Fisheries Commission pursuant to National Oceanic and Atmospheric Administration Grant No. NA05NMF4741025, under the Atlantic Coastal Fisheries Cooperative Management Act. ii Table of Contents Guide to Fisheries Science and Stock Assessments ACKNOWLEDGEMENTS ....................................................................................................................................... II ACRONYMS ................................................................................................................................................................... V PREFACE ........................................................................................................................................................................ VI INTRODUCTION ......................................................................................................................................................... 1 WHY ASSESS FISH STOCKS? ................................................................................................................................. 1 CHAPTER 1. SOME BASIC CONCEPTS ......................................................................................................... 3 STOCKS AND POPULATIONS ............................................................................................................................. 3 STOCK AND RECRUITMENT ............................................................................................................................... 3 SURPLUS PRODUCTION AND CARRYING CAPACITY ............................................................................. 4 HOW TO READ A GRAPH ................................................................................................................................... 5 CHAPTER 1: “SOME BASIC CONCEPTS” SUMMARY ................................................................................... 6 CHAPTER 2. DATA SOURCES ............................................................................................................................ 7 WHAT ARE FISHERY-DEPENDENT DATA? ..................................................................................................... 7 WHY COLLECT FISHERY-DEPENDENT DATA? ............................................................................................ 8 HOW ARE FISHERY-DEPENDENT DATA COLLECTED? ............................................................................ 9 COMMERCIAL FISHERY DATA ..................................................................................................................... 9 RECREATIONAL FISHERY DATA .............................................................................................................. 10 BIOLOGICAL DATA ...................................................................................................................................... 11 WHAT ARE FISHERY-INDEPENDENT DATA AND WHY ARE THEY COLLECTED? ..................... 12 SEAMAP & NEAMAP ...................................................................................................................................... 12 HOW ARE SURVEYS DESIGNED & HOW ARE FISHERY-INDEPENDENT DATA USED? .............. 14 WHAT GEARS ARE USED TO CAPTURE FISH? ........................................................................................... 14 WEIRS AND POUND NETS ........................................................................................................................ 14 POTS ................................................................................................................................................................... 15 GILL NETS ......................................................................................................................................................... 15 TRAWLS AND DREDGES ............................................................................................................................ 15 SEINES................................................................................................................................................................. 16 HOOK-AND-LINE .......................................................................................................................................... 17 USING DIFFERENT GEARS AT DIFFERENT TIMES AND PLACES ......................................................... 17 CHAPTER 2: “DATA SOURCES” SUMMARY ................................................................................................ 18 CHAPTER 3. LIFE HISTORY & BIOLOGY .................................................................................................. 19 AGE & GROWTH ................................................................................................................................................... 19 FEEDING ................................................................................................................................................................... 22 iii REPRODUCTIVE BIOLOGY ........................................................................................................................ 23 HABITAT AND MIGRATION ..................................................................................................................... 25 NATURAL MORTALITY ............................................................................................................................... 26 CHAPTER 3. “LIFE HISTORY AND BIOLOGY” SUMMARY .............................................................. 26 CHAPTER 4. POPULATION CONCEPTS ........................................................................................... 27 RECRUITMENT ................................................................................................................................................ 28 GROWTH ......................................................................................................................................................... 28 MORTALITY ..................................................................................................................................................... 28 CHAPTER 4. “POPULATION CONCEPTS” SUMMARY ..................................................................... 29 CHAPTER 5. STOCK ASSESSMENT MODELS ................................................................................. 30 INTRODUCTION TO MATHEMATICAL MODELS ............................................................................. 31 CATCH CURVE ANALYSIS ......................................................................................................................... 33 SURPLUS PRODUCTION MODELS .......................................................................................................... 35 VIRTUAL POPULATION ANALYSIS ......................................................................................................... 35 RETROSPECTIVE PATTERNS IN FISHERIES STOCK ASSESSMENT MODELS ............................. 37 STATISTICAL CATCH-AT-AGE ................................................................................................................. 39 MULTISPECIES VIRTUAL POPULATION ANALYSIS (MSVPA-X) ..................................................... 40 TAGGING MODELS ....................................................................................................................................... 42 ASMFC STOCK ASSESSMENT TRAINING WORKSHOPS................................................................. 43 CHAPTER 5. “STOCK ASSESSMENT MODELS” SUMMARY ............................................................. 43 CHAPTER 6. REFERENCE POINTS ........................................................................................................ 44 YIELD-BASED REFERENCE POINTS ......................................................................................................... 44 SPAWNING STOCK BIOMASS PER RECRUIT & SPAWNING POTENTIAL RATIO ................. 46 REPLACEMENT ...............................................................................................................................................
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