Stock Assessment for Central Southern Management Area (CSMA) Striped Bass Stocks Marine Fisheries Commission Business Meeting February 11, 2011

Overview Available Data Methods Results Conclusions Research Recommendations

Assessment Review Internal Review External Peer Review

Available Data Fishery-independent –NCWRC Spawning Grounds Surveys Catch rates Scales (Tar River) –NCDMF Program 915 Catch rates

Available Data Fishery-dependent –Trip ticket program (landings) –Creel survey –Biological samples not used (too few samples)

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

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

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

CPUE Ages 3 to 6 Neuse River-Spawning Grounds, CPUE = number of fish per electrofishing hr

CPUE Ages 3 to 6 Neuse River-Program 915, CPUE = number of fish in 160 gill net sets

CPUE Ages 3 to 7 Tar/Pamlico River-Spawning Grounds, CPUE = number of fish per electrofishing hr

CPUE Ages 3 to 7 Tar/Pamlico River-Program 915, CPUE = number of fish in 160 gill net sets

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

Catch Curves

Annual Total Mortality (Z) Neuse River-Spawning Grounds

Annual Total Mortality (Z) Neuse River-Program 915

Annual Total Mortality (Z) Tar/Pamlico River-Spawning Grounds

Annual Total Mortality (Z) Tar/Pamlico River-Program 915

Size Distribution Changes in length and age distribution can be indicative of stock trends –Expanding distribution rebuilding –Truncated distribution declining

Neuse River Commercial Length Frequency

Neuse River Spawning Grounds Survey Length Frequency

Neuse River Program 915 Length Frequency

Pamlico River Commercial Length Frequency

Tar/Pamlico River Spawning Grounds Survey Length Frequency

Pamlico River Program 915 Length Frequency

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

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