Figure 15.1 Statistical Areas Used

Distribution, Biology and Management

Scup or porgy, Stenotomus chrysops, is a demersal, schooling species distributed in the Mid Atlantic Bight from Cape Cod, MA to Cape Hatteras, NC. Previous tagging studies have indicated the possibility of two stocks, one in Southern New England waters and the other extending south from New Jersey. However, the lack of definitive tag return data from these studies, coupled with distributional information from NEFSC trawl surveys, support the concept of a single unit stock from New England to Cape Hatteras (Figure 15.1). A new industry-cooperative tagging study for scup, designed to evaluate fish movement and estimate mortality rates, was initiated in 2005.

Scup undertake extensive migrations between coastal waters in summer and offshore waters in winter, migrating north and inshore to spawn in spring. Sexual maturity is essentially complete by age 3 at a total length of 21 cm (O’Brien et al. 1993). Scup attain a maximum fork length of about 40 cm, and ages of up to at least 14 years.

Research Vessel Survey Indices and Assessment

NEFSC spring and autumn survey biomass indices for scup have exhibited similar trends during the survey time series. The assessment for scup is currently index-based, and relies on the NEFSC spring survey spawning stock biomass (SSB) kg per tow index as the primary measure of stock biomass (Figure 15.4 [Fig 15.4 Data]).

SSB indices peaked in the late-1970s and then declined until the late 1990s. SSB indices have increased since 1999 but have been highly variable. As stock biomass declined during the 1980s, the age structure of the scup population became truncated, with a low proportion of fish at ages 3 and older (Figure 15.5 [Fig 15.5 Data]). Since 2000, the age structure of the population has expanded to approximate that observed in the late-1970s (Figure 15.5 [Fig 15.5 Data]).

Biological Reference Points

Yield and SSB per recruit based reference points for scup (Figure 15.6 [Fig 15.6 Data]) were last calculated in the 1998 assessment (NEFSC 1998) and are presented in Table 15.2. The lack of an analytical assessment for scup has prevented the estimation of MSY based reference points. The fishing mortality threshold of F_msy is defined to be F_max, currently at F = 0.26, and the index-based biomass threshold is set at the 1977-1979 average of the NEFSC spring trawl survey Spawning Stock Biomass (SSB) kg per tow value of 2.77.

Summary

Recent NEFSC spring SSB indices indicate that the stock is in an overfished condition; stock status with respect to the overfishing threshold (F_msy = F_max) cannot currently be evaluated as there is no reliable estimate of fishing mortality available for scup.