ECOSYSTEM BASED FISHERIES MANAGEMENT FOR CHESAPEAKE BAY Crab Species Team Background and Issue Briefs Blue Crab Species Team Background and Issue Briefs Ecosystem Based Fisheries Management for Chesapeake Bay: Blue Crab Background and Issues Briefs Written by the EBFM Blue Crab Species Team Eric G. Johnson George Abbe Anson H. Hines Desmond M. Kahn Romuald N. Lipcius John C. McConaugha Gretchen A. Messick Thomas J. Miller Eric Schott Jeffrey D. Shields Jacques van Montfrans Yonathan Zohar Gina M. Ralph Other Contributors Rochelle D. Seitz Published by Maryland Sea Grant Publication Number UM-SG-TS-2010-04 ECOSYSTEM BASED FISHERIES MANAGEMENT FOR CHESAPEAKE BAY Blue Crab Species Team Background and Issues Briefs Contents Introduction .............................................................................................................................. B-iii Acknowledgments .....................................................................................................................B-v Blue Crab Species Team ..........................................................................................................B-vii Blue Crab Species Team Workplan.......................................................................................... B-ix BACKGROUND Early Life History: The Larval Phase of a Complex Life History .....................................B/1-1 John R. McConaugha Early Life History: Post-larvae and Young Juveniles ........................................................B/1-5 Gina Ralph, Romuald N. Lipcius, Jacques van Montfrans, and Rochelle Seitz Life History of Late Juveniles and Adults........................................................................B/1-11 Anson H. Hines References ........................................................................................................................B/1-17 HABITAT Predictions for Climate Change Effects on Blue Crabs .....................................................B/2-1 Anson H. Hines and Eric G. Johnson Habitat Degradation and Blue Crabs..................................................................................B/2-5 Jacques van Montfrans and Romuald N. Lipcius Effects of Fishing Pressure on Habitat ............................................................................B/2-10 Eric G. Johnson, Anson H. Hines, Romuald N. Lipcius, and Gina M. Ralph Diseases and Blue Crab Habitat .......................................................................................B/2-13 Eric Schott and Gretchen A. Messick References ........................................................................................................................B/2-18 FOODWEB Predation.............................................................................................................................B/3-1 Jacques van Montfrans, Eric G. Johnson, Romuald N. Lipcius Cannibalism........................................................................................................................B/3-7 Anson H. Hines, Desmond M. Kahn, and Eric G. Johnson B-i Prey...................................................................................................................................B/3-11 Gina M. Ralph, Romuald N. Lipcius, Rochelle D. Seitz, and Jacques van Montfrans Impacts of Fishery Exploitation on Foodweb Dynamics .................................................B/3-15 Eric G. Johnson and Thomas J. Miller Invasive Species ...............................................................................................................B/3-21 Anson H. Hines and Jacques van Montfrans Disease Impacts on Predators and Prey............................................................................B/3-25 Gretchen A. Messick, Eric Schott, and Jeffrey D. Shields References ........................................................................................................................B/3-29 STOCK ASSESSMENT Blue Crab Stock Assessment..............................................................................................B/4-1 Thomas J. Miller, Eric G. Johnson, Gina M. Ralph, Gretchen A. Messick, Anson H. Hines, Desmond M. Kahn, Romuald N. Lipcius, John C. McConaugha, Eric J. Schott, Jeffrey D. Shields, and Jacques van Montfrans Patterns and Processes........................................................................................................B/4-3 Recruitment Variability ......................................................................................................B/4-7 Environmental Drivers of Recruitment ..............................................................................B/4-9 Juvenile and Adult Mortality............................................................................................B/4-11 Fishery Impacts.................................................................................................................B/4-15 Indicators and Issues.........................................................................................................B/4-19 References ........................................................................................................................B/4-25 SOCIOECONOMICS Topics to be addressed: Ecosystem Services, Competition with Imports, Equitable Management Alternatives, Regional and National Economic Value, Management Options and Models ..........................................................................B/5-1 Authors to be determined B-ii Introduction Eric Johnson, Chair, Blue Crab Species Team The blue crab, Callinectes sapidus, is perhaps the Bay’s most iconic species. Blue crabs exhibit a complex life history with large-scale dispersal between estuarine and marine habitats during larval, juvenile and adult phases. Within Chesapeake Bay, blue crabs utilize key nearshore habitats including seagrass, tidal salt marshes and woody debris that are particularly vulnerable to a suite of anthropogenic stressors. The blue crab is an integral component of the complex estuarine foodweb, and serves important roles as both predator and prey in the Chesapeake Bay ecosystem (Baird and Ulanowicz 1989). The blue crab supports both a thriving recreational fishery and Chesapeake Bay’s most lucrative commercial fishery. The fishery is complex with commercial and recreational sectors, regional variation in fishing gear and effort, multi-juris- dictional management, and a variety of markets including “live hard crab”, “soft and peeler” and “processed crab meat” industries (Kennedy et al. 2007). Recent declines in blue crab popula- tions, female spawning stock and harvest have resulted in coordinated single-species manage- ment efforts. However, given the ecological, economic and sociological importance of the blue crab to the region, this species is perhaps the ideal candidate for ecosystem-based fishery management (EBFM) in Chesapeake Bay. Fisheries researchers, managers and policy makers have become increasingly aware of the importance of adopting multi-species and EBFM in Chesapeake Bay (Chesapeake Bay Fisheries Ecosystem Advisory Panel 2006). These approaches provide a more holistic framework that recognizes the complex interactions among species, habitat and environment that combine to regulate the population dynamics of exploited fishery stocks. Further, EBFM approaches recognize that the biological and socioeconomic systems to be managed are inexorably linked. Despite this awareness, effective development and implementation of EBFM plans have been hampered because this approach requires not only traditional fisheries data sources such as standardized surveys of abundance, effort and harvest, but a detailed knowledge of multi-species interactions, complex ecological processes and the impacts of environmental stressors. In Chesapeake Bay, the need for multi-species and EBFM approaches has been acknowledged for more than a decade (Miller et al. 1996; Houde et al. 1998; CBFEAP 2006). As a critical step towards advancing EBFM in Chesapeake Bay, Maryland Sea Grant assembled teams of experts to develop detailed background and issue briefs for five of the bay’s most important fishery species including the blue crab. Herein, we provide briefing documents that summarize the major ecological, environmental, and socioeconomic issues facing managers seeking to develop an EBFM plan for the blue crab in Chesapeake Bay. B-iii Blue Crab Species Team Background and Issues Briefs Issue briefs are subdivided into five major sections: 1. Biological Background (Larval Biology, Post-larvae and Young Juveniles, Late Juveniles and Adults) 2. Habitat (Climate Change, Habitat Degradation, Fishing Pressure, Disease) 3. Food Web (Predation, Cannibalism, Prey, Fishing Pressure, Invasive Species, Disease) 4. Stock Assessment (Population Dynamics, Connectivity, Recruitment Variability, Environmental Drivers, Mortality, Exploitation) 5. Socioeconomics (Ecosystem Services, Competition With Imports, Equitable Management Alternatives, Regional and National Economic Value, Aquaculture, Management Options and Models) The background and issue briefs developed by the blue crab species team will be provided to the fisheries managers and Quantitative Ecosystem Teams (QETs) and used to identify relevant EBFM metrics and generate appropriate target and threshold reference points for the blue crab fishery in Chesapeake Bay. References Baird, D. and R.E. Ulanowicz. 1989. The seasonal dynamics of the Chesapeake Bay ecosystem. Ecological Monographs 59:329-364. Chesapeake Bay Fisheries Ecosystem Advisory Panel