NOAA s Role in Chesapeake Bay

Transcription

1 NOAA s Role in Chesapeake Bay NOAA Chesapeake Bay Office Mission To understand, predict and explain changes in the Chesapeake Bay ecosystem, and to coordinate efforts to conserve and manage coastal and estuarine resources to meet the Region s economic, social and environmental needs. NOAA Activities related to Blue Crab Coordination for Chesapeake Bay Stock Assessment Committee Produces Annual Blue Crab Advisory Report Marine Debris Program Chesapeake Bay Study on Derelict Fishing Gear Blue Crab Advanced Research Consortium

2 Blue Crab Advisory Report Annual report summarizing technical information to assist resource managers in evaluating management options Completed annually - in the spring from 1997 through 2005 Full Blue Crab Stock Assessment (Fall 2005) Internationally peerreviewed by the Center for Independent Experts and accepted by the Fisheries Steering Committee 2006 report completed in the fall found that preparing report in the fall didn t provide additional data so moving back to spring 2007 report (this report) mid-term timeline Fall 2007 CBSAC workshop being planned to review analyses to improve assessment even further 2008 report to be issued again in spring (May/June timeframe)

3 Pot Survey

4 Storyline for 2007 Abundance of fishery size crabs (Age 1+) remains low compared to historical levels Decline seen since 1993 ended in 2001 however, the abundance stabilized below the survey average Recruitment (Age 0) was low second lowest since survey began in 1989 Low recruitment has persisted since Female spawning potential (biomass of crabs available to spawn) was below average Exploitation Levels Exploitation fraction (% of crabs removed by fishing) was estimated at 50% for 2006 Threshold is 53% Target 46%

5 Harvest Chesapeake Bay Blue Crab harvest , adjusted for changes in reporting methods. 120 Landings (Millions of Pounds) Bay-wide harvest adjusted for reporting changes 20 Mean Year

6 Projected Harvest 95% Prediction intervals for harvest 120 Predicted annual harvest Observed annual harvest Baywide Harvest (Millions of Pounds) Observed 2006 harvest (48.9 million lbs) Predicted 2007 harvest (48.7 million lbs) y = x R 2 = Crab Abundance (Millions of Crabs)

7 Winter Dredge Survey exploitable stock Winter dredge survey density of blue crabs aged one year and older (age 1+) These are crabs measuring greater than 60mm across the carapace and are considered the exploitable stock. Crabs per 1,000 Square Meters Annual Crab Density 3-year average Survey Average Upper Prediction Bound Lower Prediction Bound Upper and Lower Bounds of Average Range for the Survey Year represents the calendar year at the beginning of the survey. The 1989 value represents results for the winter of Year

8 Winter Dredge Survey - Recruitment Winter dredge survey density of age 0 blue crabs (recruits) These are crabs measuring less than 60mm (2.4 inches) across the carapace. Age -0 crabs per 1,000 Square Meters Annual Crab Density 3-year average Survey Average Upper and Prediction Lower Bounds of Lower Average Prediction Range for Bound the Survey Year represents the calendar year at the beginning of the survey. The 1989 value represents results for the winter of Year

9 Winter Dredge Survey - SSB Winter dredge survey density of female spawning potential These are immature and mature female crabs measuring greater than 60mm (2.4 inches) across the carapace. Mature female crabs per 1,000 Square Meters Annual Crab Density 3-year average Survey Average Upper and Prediction Lower Bounds of Average Range for the Survey Lower Prediction Bound Year represents the calendar year at the beginning of the survey. The 1989 value represents results for the winter of Year

10 Exploitation Annual Measures of Fishing Pressure (Exploitation Fraction) on Blue Crabs in Chesapeake Bay, as Compared to Target and Threshold Levels Exploitation Fraction annual exploitation fraction target exploitation fraction = 0.46 overfishing threshold = Year

11 Management Control Rule Adopted by Bi-State Blue Crab Advisory Committee in 2001 and updated in the NOAA 2005 Stock Assessment (Miller et. al.) Control Rule is the foundation upon which sustainable management of the blue crab fishery in Chesapeake Bay is built Represents the relationship between adult blue crab abundance, exploitation, and management reference points

12 Summary 2006 Harvest just under 50 million pounds Baywide Harvest predicted to be about 48.7 million pounds Baywide Blue crab fishery is recruitment driven upcoming harvest dependent upon the influx of age 0 crabs from the previous year The reduction in recruitment apparent after 1996, combined with continued low levels of adult abundance, indicate that the blue crab stock and associated fisheries are cause for concern Given the current estimate of total abundance and the projected harvest for 2007, the predicted exploitation for 2007 could exceed the exploitation threshold (high variance) Draft Report excerpt: CBSAC recommends that management jurisdictions work with the multiple stakeholder groups to: define goals for the fishery; Develop a comprehensive management plan for achieving these goals; Implement plan to assure sustainability of resource.

13 Other Management Considerations Ghost Fishing

14 Derelict Crab Traps Side Scan Sonar Surveys performed out of the crab fishing season in MD revealed very high numbers of trap-like targets Efforts to identify and validate these targets via random subsampling indicated > 90% survey accuracy Sonar Identifies Traps

15 Concerns with Trap Loss Equipment Replacement Costs? Impacts to the Crab Fishery? Impacts to Bycatch? Impacts to Habitat? Potential for Management Action?

16 Are Derelict Crab Traps a Problem? Derelict Fishing Gear Project Objectives Determine the number of derelict traps in the Bay at a given point in time Determine the potential effects of derelict traps on the Baywide management of crabs and other living marine resources Ghost Fishing Mortality Blue Crabs By-catch Species Habitat Value/Degradation Socioeconomic and cultural impacts Develop retrieval & prevention methods and assess feasibility

17 How Are We Assessing Effects? Studies in Maryland and Virginia Partners include MDNR, VIMS, UMD, COL, and SERC Quantify the Number of Actively Fishing Derelict Traps Side scan sonar Direct retrieval/groundtruthing Estimates of fishing effort Estimates of trap loss rate Estimates of ghost fishing mortality Document Effects on Living Resources Through Field Experiments

18 Status of our Efforts NCBO derelict trap abundance surveys are underway in Maryland and Virginia data will yield baywide estimate NCBO transect surveys in Maryland Bay NCBO-funded VIMS study in Virginia Bay Preliminary results imminent Retrieval feasibility study underway Retrieval methods development and testing Derelict trap accretion experiment Collaboration with watermen and other stakeholders Ghost fishing impact field study (underway for 12 months this October) Ghost fishing simulation Quantification of animal entrapment and mortality rates Estimation of trap degradation rates preliminary analyses Spring 08

19 Closing Review and adoption of the Blue Crab Advisory Report by the Fisheries Steering Committee later this month Additional data and findings from the Derelict Fishing Gear study released in the same timeframe Continued baywide monitoring of blue crab stock critical to assessing management efforts Future briefings of the Commission