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Published byMarco Mendenhall Modified over 10 years ago
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Stock Assessment for Central Southern Management Area (CSMA) Striped Bass Stocks Marine Fisheries Commission Business Meeting February 11, 2011
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Overview Available Data Methods Results Conclusions Research Recommendations
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Assessment Review Internal Review External Peer Review
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Available Data Fishery-independent –NCWRC Spawning Grounds Surveys Catch rates Scales (Tar River) –NCDMF Program 915 Catch rates
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Available Data Fishery-dependent –Trip ticket program (landings) –Creel survey –Biological samples not used (too few samples)
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Data Limitations The input data limitations for these analyses are twofold: –Limitations inherent in the surveys collecting the data Examples: Lack of defined spawning areas, use of multispecies survey –Analytical limitations resulting from data that are not complete or that were not collected Examples: Incomplete age data by system, lack of system specific life history parameters
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Methods Despite data limitations, multiple methods were applied to attempt to determine stock status –Trend analysis –Catch curves Ultimately, none of the methods were able to determine stock status reliably
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Trend Analysis Catch-per-unit-effort (CPUE) –NCWRC Spawning Grounds Survey: number of striped bass collected per hour of sampling effort –NCDMF Program 915: number of striped bass collected per 160 sets in a year (12 hr net set of 240 yds) Examined CPUE by age (cohort) over time
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CPUE Ages 3 to 6 Neuse River-Spawning Grounds, 1994-2009 CPUE = number of fish per electrofishing hr
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CPUE Ages 3 to 6 Neuse River-Program 915, 2003-2009 CPUE = number of fish in 160 gill net sets
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CPUE Ages 3 to 7 Tar/Pamlico River-Spawning Grounds, 1996-2009 CPUE = number of fish per electrofishing hr
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CPUE Ages 3 to 7 Tar/Pamlico River-Program 915, 2003-2009 CPUE = number of fish in 160 gill net sets
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Catch Curves Used to estimate mortality from catch or survey age data Total mortality (Z) is the sum of fishing (F) and natural (M) mortality Z = F + M
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Catch Curves
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Annual Total Mortality (Z) Neuse River-Spawning Grounds
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Annual Total Mortality (Z) Neuse River-Program 915
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Annual Total Mortality (Z) Tar/Pamlico River-Spawning Grounds
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Annual Total Mortality (Z) Tar/Pamlico River-Program 915
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Size Distribution Changes in length and age distribution can be indicative of stock trends –Expanding distribution rebuilding –Truncated distribution declining
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Neuse River Commercial Length Frequency
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Neuse River Spawning Grounds Survey Length Frequency
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Neuse River Program 915 Length Frequency
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Pamlico River Commercial Length Frequency
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Tar/Pamlico River Spawning Grounds Survey Length Frequency
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Pamlico River Program 915 Length Frequency
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Conclusions Total mortality (Z) estimates vary without trend providing little information for stock status determination Length distributions provide no substantial evidence of a viable stock The size and age distributions, low abundance, and the absence of older fish support continued management efforts to promote enhancement of the striped bass fisheries in each system
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Research Recommendations Since the 2004 FMP, significant efforts were made to fill CSMA data gaps, but critical data are still needed –Life history parameters –Additional fishery-dependent data –Improved fishery-independent data Above data necessary to perform a reliable, quantitative assessment –Funding and staff needed to collect needed data
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