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Table of Contents
Executive Summary
Background
Commercial Fishery Landings
Commercial Fishery Discards
Recreational Fishery Catch
Recreational Fishery Discards
Total Fishery Catch
Research Survey Indices of Adbundance
2011 Updated Fishing Mortality Rate and Stock Size Estimates
2008 DPS Assessment Biological Reference Points
2011 Updated Stock Status
Assessment Uncertainty Considerations
Projection of the Overfishing Limit for 2013
Acknowledgements
References Cited

Northeast Fisheries Science Center Reference Document 12-25

Stock Assessment of Scup (Stenotomus chrysops) for 2012

by Mark Terceiro
National Oceanic Atmospheric Administration, National Marine Fisheries Service, Northeast Fisheries Science Center, 166 Water Street, Woods Hole, MA, 02543 USA

Web version posted October 31, 2012

Citation: Terceiro M. 2012. Stock Assessment of Scup (Stenotomus chrysops) for 2012. US Dept Commer, Northeast Fish Sci Cent Ref Doc. 12-25; 104 p. Available from: National Marine Fisheries Service, 166 Water Street, Woods Hole, MA 02543-1026, or online at http://www.nefsc.noaa.gov/nefsc/publications/

Information Quality Act Compliance: In accordance with section 515 of Public Law 106-554, the Northeast Fisheries Science Center completed both technical and policy reviews for this report. These predissemination reviews are on file at the NEFSC Editorial Office.

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Executive Summary

This assessment of the scup (Stenotomus chrysops) stock along the Atlantic coast (Massachusetts to North Carolina) is an update through 2011 of commercial and recreational fishery (MRIP) catch data, research survey indices of abundance, and the analyses of those data. The stock was not overfished and overfishing was not occurring in 2011 relative to the biological reference points established in the 2008 Northeast Data Poor Stocks (DPS) assessment. The fishing mortality rate (F) was estimated to be 0.034 in 2011, below the fishing mortality threshold reference point = Fishing mortality producing Maximum Sustainable Yield (FMSY) = F40% = 0.177. Spawning Stock Biomass (SSB) was estimated to be 190,424 metric tons (mt) = 420 million lbs in 2011, above the biomass target reference point = SSBMSY = SSB40% = 92,044 mt = 203 million lbs.

Reported 2011 landings in the commercial fishery were 6,819 mt = 15.033 million lbs, about 73% of the commercial quota. Estimated 2011 landings in the recreational rod-and-reel fishery (as estimated by the MRIP) were 1,632 mt = 3.598 million lbs, about 61% of the recreational harvest limit. Total commercial and recreational landings in 2011 were 8,451 mt = 18.631 million lbs and total commercial and recreational discards were 2,086 mt = 4.599 million lbs, for a total catch in 2011 of 10,537 mt = 23.230 million lbs.

Spawning stock biomass decreased from about 100,000 mt in 1963 to about 50,000 mt in 1969, then increased to about 75,000 mt during the late 1970s. SSB declined through the 1980s and early 1990s to less than 5,000 mt in the mid-1990s. SSB increased to above 100,000 mt = 220 million lbs since 2004 due to improved recruitment and low fishing mortality. SSB was estimated to be 190,424 mt = 420 million lbs in 2011. There is a 50% probability that SSB in 2011 was between 185,000 and 198,000 mt (408 and 436 million lbs). Fishing mortality calculated from the average of the currently fully recruited ages (2-7+) varied between F = 0.1 and F = 0.3 during the 1960s and 1970s. Fishing mortality increased during the 1980s and early 1990s, peaking at about F = 1.0 in the mid-1990s. Fishing mortality decreased after 1994, falling to less than F = 0.1 since 2001, with F in 2011 = 0.034. There is a 50% probability that F in 2011 was between 0.026 and 0.042.

Recruitment at age 0 averaged 92 million fish during 1963-1983, the period in which recruitment estimates are influenced mainly by the assessment model stock-recruitment relationship. Since 1984, recruitment estimates from the model are influenced mainly by the fishery and survey catches at age, and averaged 110 million fish during 1984-2011. The 1999, 2000, and 2008 year classes are estimated to be the largest of the time series, at 207, 226, and 215 million age 0 fish. After below average recruitment in 2009 and 2010, the 2011 year class is estimated to be above average at 154 million age 0 fish.

There is no consistent internal retrospective pattern in F, SSB, or recruitment evident in the 2012 updated assessment model. A between-assessment comparison provides another measure of assessment uncertainty due to changes in model estimates. The 2012 assessment estimates of SSB and F are intermediate with respect to the 2008 DPSWG assessment and 2009 update for the same years, and are very similar to those from 2010 and 2011 updates. The 2012 assessment estimates of the size of the 2007 through 2010 year classes are in general larger compared to the 2011 assessment.

If the landings of scup in 2012 equal the specified Total Allowable Landings (TAL) = 16,749 mt = 36.925 million lbs, the 2012 median (50% probability) discards are projected to be 3,334 mt = 7.350 million lbs, and the median total catch is projected to be 20,083 mt = 44.275 million lbs. The median F in 2012 is projected to be 0.158, below the fishing mortality threshold = FMSY = F40% = 0.177. The median SSB on June 1, 2012 is projected to be 203,982 mt = 450 million lbs, above the biomass target of SSBMSY = SSB40% = 92,044 mt = 203 million lbs.

If the stock is fished at the fishing mortality threshold = FMSY = F40% = 0.177 in 2013, median landings are projected to be 17,981 mt = 39.641 million lbs, with median discards of 3,721 mt = 8.203 million lbs, and median total catch = 21,680 mt = 47.796 million lbs. This projected median total catch is equivalent to the Overfishing Limit (OFL) for 2013, and is greater than MSY = 16,161 mt (35.629 million lbs) of total catch (13,134 mt = 28.956 million lbs of landings plus 3,027 mt = 6.673 million lbs of discards). The median SSB on June 1, 2013 is projected to be 196,236 mt = 432 million lbs, above the biomass target of SSBMSY = SSB40% = 92,044 mt = 203 million lbs. The projected catch estimates in the following table are medians of the catch distributions for fixed F in 2013.

Total Catch (OFL), Landings, Discards, Fishing Mortality (F)

and Spawning Stock Biomass (SSB) in 2013

Catches and SSB in metric tons

Total Catch

Landings

Discards

F

SSB

         

21,680

17,981

3,721

0.177

196,236

Background

Biology

Scup (Stenotomus chrysops) is a schooling continental shelf species of the Northwest Atlantic that is distributed primarily between Cape Cod and Cape Hatteras (Morse 1978). Scup undertake extensive migrations between coastal waters in summer and offshore waters in winter. Scup migrate north and inshore to spawn in spring, with larger fish (age 2 and older) tending to arrive in spring first, followed by smaller fish (Neville and Talbot 1964; Sisson 1974). Larger scup are found during the summer near the mouth of large bays and in the ocean within 20-fathoms (120 feet = 37 meters), and often inhabit rough bottom areas. Smaller scup are more likely to be found in shallow, smooth bottom areas of bays during summer (Morse 1978). Scup migrate south and offshore in the fall as the water temperature decreases, arriving in offshore wintering areas by December (Hamer 1970; Morse 1978).

Spawning occurs from May through August and peaks in June. About 50% of age-2 scup are sexually mature (about 17 cm total length; Morse 1978), while nearly all scup of age 3 and older are mature. Scup reach a maximum fork length of at least 41 cm and a maximum age of at least 14 years, with a likely maximum of 20 years (Dery and Rearden 1979). The largest and oldest scup sampled in Northeast Fisheries Science Center (NEFSC) surveys (1973, 1976, 1978) were fish 38-41 cm (fork length) and 14 years old. The largest and oldest scup in NEFSC commercial fishery samples (1974) was 40 cm (fork length) and 14 years old. The instantaneous natural mortality rate (M) for scup has been assumed to be 0.20 (Crecco et al. 1981, Simpson et al. 1990) in this and all previous stock assessments.

Fishery Management

The Mid-Atlantic Fishery Management Council (MAFMC) and Atlantic States Marine Fisheries Commission (ASMFC) jointly manage scup under Amendment 8 (1997) to the Scup, Scup, and Black Sea Bass Fishery Management Plan (FMP). The assessment and management unit includes all scup from Cape Hatteras, NC north to the US-Canada border. Tagging studies (e.g., Neville and Talbot 1964; Cogswell 1960, 1961; Hamer 1970, 1979) have indicated the possibility of two stocks of scup, one in Southern New England waters and another extending south from New Jersey waters. However, the lack of definitive locations for tag return data coupled with distributional data from the NEFSC bottom trawl surveys supports the concept of a single unit stock (Mayo 1982).

Amendment 8 to the FMP established a recovery plan for scup under which exploitation rates were to be reduced to 47% (F=0.72) during 1997-1999, to 33% (F=0.45) during 2000-2001, and to 21% (F=0.26) during 2002-2007. These goals were to be attained through implementation of a Total Allowable Catch (TAC) that included a commercial quota and a recreational harvest limit, commercial fishery minimum net mesh, trap vent and fish sizes and closed areas, and recreational fishery minimum fish sizes, possession limits, and closed seasons.

Amendment 12 (1998) to the FMP established a biomass threshold (a proxy for one-half BMSY) for scup based on the three-year moving average of the NEFSC spring bottom trawl survey index of Spawning Stock Biomass (SSB) during 1977-1979, which was perceived to be a period when the stock was near one-half BMSY. The scup stock was considered to be overfished when the SSB index fell below a value of 2.77 SSB kg per tow. Amendment 12 defined overfishing for scup to occur when the fishing mortality rate exceeded the threshold fishing mortality of Fmax = 0.26 (as a proxy for FMSY).

Broad scale Gear Restricted Areas (GRAs) for scup were implemented in November 2000 under the framework provisions of the FMP to reduce discards of scup in the small mesh fisheries for Loligo squid and silver hake. Two Northern Areas off Long Island were implemented for November through January, while a Southern Area off the mid-Atlantic coast was implemented for January through April. The size and boundaries of the GRAs were modified in late 2000 and again in 2005 in response to commercial fishing industry recommendations.

Amendment 14 (2007) to the FMP defined the biomass target and implemented a stock rebuilding plan for scup. The stock was to fully rebuild to the biomass target by January 1, 2015. The proxy for BMSY was two times the 3-year moving average of the NEFSC spring index of SSB during 1977-1979 noted earlier, or 2*2.77 = 5.54 SSB kg per tow. A target fishing mortality rate of F = 0.10 was to be applied in each year of a 7 year rebuilding period beginning in 2008. A TAC of 4,491 mt = 9.901 million lbs and corresponding Total Allowable Landings (TAL) of 3,329 mt = 7.339 million lbs were established for 2008 to achieve the target F.

The current overfished and overfishing definitions are based on revisions to the FMP through Framework 7 (2007) and use the values established in Amendments 12 (1998) and 14 (2007) as follows:

The maximum fishing mortality threshold for each of the species under the FMP is defined as FMSY (or a reasonable proxy thereof) as a function of productive capacity, and based upon the best scientific information consistent with National Standards 1 and 2. Specifically, FMSY is the fishing mortality rate associated with MSY. The maximum fishing mortality threshold (FMSY) or a reasonable proxy may be defined as a function of (but not limited to): total stock biomass, spawning stock biomass, total egg production, and may include males, females, both, or combinations and ratios thereof which provide the best measure of productive capacity for each of the species managed under the FMP. Exceeding the established fishing mortality threshold constitutes overfishing as defined by the Magnuson-Stevens Act.

The minimum stock size threshold for each of the species under the FMP is defined as one-half BMSY (or a reasonable proxy thereof) as a function of productive capacity, and based upon the best scientific information consistent with National Standards 1 and 2. The minimum stock size threshold (one-half BMSY) or a reasonable proxy may be defined as a function of (but not limited to): total stock biomass, spawning stock biomass, total egg production, and may include males, females, both, or combinations and ratios thereof which provide the best measure of productive capacity for each of the species managed under the FMP. The minimum stock size threshold is the level of productive capacity associated with the relevant one-half MSY level. Should the measure of productive capacity for the stock or stock complex fall below this minimum threshold, the stock or stock complex is considered overfished. The target for rebuilding is specified as BMSY (or reasonable proxy thereof) at the level of productive capacity associated with the relevant MSY level, under the same definition of productive capacity as specified for the minimum stock size threshold.

Stock Assessment

A peer-reviewed assessment including an analytical population model was accepted in 1995 by SAW 19 (NEFSC 1995). The assessment featured a virtual population analysis (VPA) modeled in the ADAPT framework (Conser and Powers 1990), with commercial and recreational landings and discards at age estimates, and with state and NEFSC abundance indices used for calibration. The 1995 SAW 19 assessment indicated that F in 1993 was 1.3, and SSB was 4,600 mt = 10.141 million lbs. A yield per recruit (YPR) analysis indicated that Fmax = 0.236.

The VPA was updated through 1996 and reviewed by the 1997 SAW 25 (NEFSC 1997), but due to concerns over the low intensity of fishery length sampling in the 1990s, uncertainty about the magnitude of commercial discards in the late 1990s, and the ongoing high variability and imprecision of survey indices, the VPA was not accepted as a basis for management decisions. Assessment conclusions were therefore based primarily on trends in NEFSC and state agency survey indices and catch curve analyses using those survey data. The 1997 SAW 25 was able to conclude that in 1996 scup were over-exploited and near record low abundance levels.

The scup assessment was next updated through 1997 and reviewed by the 1998 SAW 27 (NEFSC 1998). Several configurations of a surplus production model (ASPIC; Prager 1994) were reviewed in addition to an updated VPA, but like the VPA, the production model results were not accepted due to concerns over the validity of the input fishery and survey data. An updated YPR analysis was accepted and indicated that Fmax = 0.26. The 1998 SAW 27 concluded that a VPA or other analytical model formulation for scup would not be feasible until the quality of the input data, particularly the precision of discard estimates, was significantly improved and that scup was over exploited and at a low biomass level.

The 1998 SAW 27 Panel recommended the scup assessment be based on the long-term time series of NEFSC trawl survey indices and fishery catches. The Panel noted that commercial landings were sustained at about 19,000 mt = 41.888 million lbs annually during the mid-1950s to mid-1960s, and concluded that the stock was likely near BMSY during that period (Figure 1). The nearest subsequent peak in NEFSC survey indices occurred in the late 1970s. Commercial and total fishery catches in the late 1970s were about one-half of those in the 1950s to 1960s, and so the late 1970s were identified as a period when the stock was likely to have been near one-half of BMSY. The Panel considered the NEFSC spring survey series to be most representative of SSB, since older ages were better represented in the age structure than in the NEFSC fall survey or other state agency surveys. The 1998 SAW 27 Panel recommended that the three-year moving average of the NEFSC spring bottom trawl survey index of SSB during 1977-1979 (2.77 SSB kg per tow) be used as the proxy biomass threshold (one-half BMSY) and that Fmax = 0.26 be used as the proxy fishing mortality threshold (FMSY). Those recommendations were subsequently adopted for the biological reference points in Amendment 12 to the FMP.

The scup assessment was next updated through 1999 and reviewed by the 2000 SAW 31 (NEFSC 2000). The assessment continued to be based on trends in research survey indices and fishery catches and indicated that the stock was overfished and that overfishing was occurring. The stock assessment was reviewed again by the 2002 SAW 35 and included fishery data through 2001 (NEFSC 2002). The assessment was again based on trends in research survey indices and fishery catches, but indicated that the stock was no longer overfished, although the 2002 SAW 35 Panel concluded that stock status with respect to the overfishing definition could not be evaluated due to the uncertainty of F estimates derived from research survey catch curve calculations. The 2002 SAW 35 Panel found sufficient evidence to conclude that the relative exploitation rates had declined in recent years and that survey observations indicated strong recruitment and some rebuilding of age structure.

During 2002-2008, the status of the stock was evaluated by the MAFMC Monitoring Committee using trends in research survey indices and fishery catches. A relative exploitation index based on the annual total fishery landings and the NEFSC spring three-year average SSB index was used as a proxy for F to monitor status with respect to overfishing and provide guidance to the specification of the annual TAC. A projection of the NEFSC spring survey SSB index using assumptions about maturity, partial recruitment to the survey, and the level of future recruitment as indexed by the NEFSC spring survey at age 1 was used in Amendment 14 to the FMP to forecast stock rebuilding and set the F target for 2008-2105. An update to the status monitoring metrics was completed in 2008 to aid in the specification of fishery regulations for 2009. The update indicated that while the stock was overfished in 2007, the exploitation rate was at about the F target, suggesting that overfishing was not occurring in 2007. However, the stock rebuilding progress was slower than forecast by the Amendment 14 projection, with the NEFSC spring 2007 SSB index (three-year average = 1.16 kg per tow) at only 56% of the projected 2007 index (2.08 kg per tow).

The most recent peer review of the scup assessment was conducted by the 2008 Northeast Data Poor Stocks (DPS) Peer Review Panel (NEFSC 2009), which accepted an Age Structured Assessment Program (ASAP) statistical catch at age (SCAA) model (NFT 2008) as the basis for biological reference points and status determination, with fishery and survey catch data through 2007. The new model of scup population dynamics was expected to provide a more stable tool for monitoring stock status and specifying annual fishery regulations than the previous single index-based model. The assessment indicated that the stock was not overfished and overfishing was not occurring in 2008, relative to the revised biological reference points. Fishing mortality was estimated to have decreased rapidly after 1994, with F in 2007 = 0.054. With greatly improved recruitment and relatively low fishing mortality rates since 1998, SSB was estimated to have steadily increased to about 119,300 mt = 263 million lbs in 2007. There was no consistent retrospective pattern in F, SSB, or recruitment evident in the 2008 assessment model. Following the 2008 DPS stock assessment, the NMFS declared scup to be officially rebuilt in 2009.

This 2012 assessment update uses the same model configuration as the 2008 DPS (NEFSC 2009) benchmark and 2009-2011 assessment updates (Terceiro 2009, 2010, 2011). The updated population model includes with fishery and survey catch information through 2011. The 2012 evaluation of stock status is made with respect to the 2008 DPS biological reference points.

Commerical Fishery Landings

United States total commercial landings averaged over 18,000 mt per year from 1950 to 1965, peaking at over 22,000 mt in 1960, and then decreased to less than 10,000 mt per year in the late 1960s. Landings fluctuated between about 5,000 and 10,000 mt from 1970 to the early 1990s and then decreased to about 1,200 mt in 2000, less than 6% of the peak observed in 1960. Commercial landings have since increased to average about 4,000 mt during 2003-2011 (Figure 1). Reported 2011 landings in the commercial fishery were 6,819 mt = 15.033 million lbs, about 73% of the commercial quota. About eighty percent of the commercial landings of scup since 1979-2011 were in Rhode Island (38%), New Jersey (26%), and New York (16%; Table 1). The otter trawl is the principal commercial fishing gear, accounting for about 75% of the total catch since 1979 (Table 2). The remainder of the commercial landings is taken by floating trap (11%) and hand lines (7%), with paired trawl, pound nets, and pots and traps each contributing between 1 and 4%.

Commercial Fishery Discards

The NEFSC Fishery Observer Program has collected information on landings and discards in the commercial fishery since 1989. Northeast Region (NER; ME-VA) discard estimates were raised to account for North Carolina landings. A discard mortality rate of 100% was assumed because there are no published estimates of scup discard mortality rates. This assumption is based on limited observations and is a point of contention between scientists and fishermen. Previous peer reviews of the assessment have recommended that research be conducted to better characterize the discard mortality rate of scup in different gear types in order to more accurately quantify the absolute magnitude of scup discard mortality (NEFSC 1995, 1997, 1998, 2000, 2002, 2009). Quantifying discards from the commercial fishery is necessary for a reliable scup assessment, but low sample sizes in the past have resulted in uncertain estimates. Despite the uncertainty of the discard data, recent peer review panels have concluded that commercial discarding of scup has been high during most of the last 20 years, generally approaching or exceeding the commercial landings. Since the implementation of the GRAs in 2000, estimated discards have averaged 35%-40% of the total commercial catch.

Commercial discards for scup are estimated using geometric mean discards to landings (GMDL) ratios. Ratios of discards to landings are stratified by landings level (for trip landings < 300 kg (661 lbs), the bycatch fishery; or => 300 kg, the directed fishery) and half-year and multiplied by corresponding observed scup landings from the NEFSC Dealer Report database to provide estimates of scup discards. Geometric mean rates (re-transformed, uncorrected, mean ln-transformed Discards to Landings per trip) are used because the distributions of landings, discards and the ratio of discards to landings on a per-trip basis in the scup fishery are highly variable and positively skewed. Observed trips with both scup landings and discard were used to calculate per trip discard to landings ratios. Only trips with both non-zero landings and discards could be used for this approach to avoid division by zero. The number of trawl gear trips used to calculate the geometric mean discard-to-landings ratios (GMDL) by half year for 1997-2008 ranged from 1 to 104 for trips < 300 kg and from 1 to 35 for trips =>300 kg, with the best sampling occurring since 2003. No trawl gear trips were available for half year two in 1997 and 1999 for trips < 300 kg and for half year two in 1997-2001 for trips => 300 kg. The ratio calculated for half year one was used to estimate discards for half year two when no trawl gear trips were available in half year two. The ratios ranged from 0.03 in 2004 (half year two, trips => 300 kg) to 121.71 in 1998 (half year one, trips => 300 kg; Table 3).

The large 1998 directed fishery ratio and subsequent very high annual discard estimate (111,973 mt) was based on a single trawl gear trip. About 93% of the discard from that trip was attributable to a single tow in which an estimated 68.2 mt (150,000 lbs.) of scup were captured. This tow was not lifted from the water and the captain of the vessel estimated the weight of the catch. There has been debate concerning the validity of the catch weight estimate and whether or not it was representative of other vessels or trips in the fishery. However, the observation was reported by a trained NEFSC observer and was therefore included in the initial calculation of the estimate of scup discards (Table 3). Peer reviews of the assessment have since concluded that the 1998 estimate (173,690 mt) is infeasible, and it has been replaced by the mean of the 1997 and 1999 estimates (3,331 mt; Table 4).

Recreational Fishery Catch

Scup is the object of a major recreational fishery, with the greatest proportion of catches taken in the states of Massachusetts, Rhode Island, Connecticut and New York. Estimates of the recreational catch in numbers were obtained from the NMFS Marine Recreational Fishery Statistics Survey (MRFSS) for 1981-2011, and from the NMFS Marine Recreational Information Program (MRIP) for 2004-2011. These estimates were available for three categories: type A - fish landed and available for sampling, type B1 - fish landed but not available for sampling and type B2 - fish caught and released. The estimated recreational landings (types A and B1) in weight during 1981-2011 as estimated by the MRFSS averaged about 2,000 mt per year (Table 5). MRFSS estimated 2011 landings in the recreational rod-and-reel fishery were 1,593 mt = 3.512 million lbs, about 61% of the recreational harvest limit. Since 1981, the recreational landings have averaged 33% of the commercial and recreational landings total.

The commercial fishery VTR system provides an alternative set of reported recreational landings by the party/charter boat sector. A comparison of VTR reports and MRFSS estimates indicates that MRFSS estimates were on average about 50% higher over the 1995-2011 period, ranging from a factor of 0.34 in 1998 to 2.43 in 2009 (Table 6). It is unclear if this is due mainly to under-reporting of party/charter boat recreational landings in the VTR system, or a systematic positive bias of MRFSS landings estimates for the party/charter boat sector.

The estimated recreational live discard in weight during 1984-2011 ranged from 39 mt in 1999 to a high of 2,031 mt in 2010, averaging about 600 mt per year (Table 7). The weight of discards has been directly calculated only for those years (1984 and later) for which recreational catch at age has been compiled. In compilations of total fishery catch for earlier years, the recreational discards was assumed to be approximately 2% of the estimated recreational landings, based on the mean discard percentage for 1984-1996, the time period with catch at age estimates before the implementation of the FMP. The discard mortality rate in the recreational fishery has been reported to range from 0-15% (Howell and Simpson 1985) and from 0-14% (pers. comm, Williams E., University of Rhode Island, Department of Fisheries and Aquaculture. November 1, 1994). Howell and Simpson (1985) found mortality rates were positively correlated with size, due mainly to the tendency for larger fish to take the hook deep in the esophagus or gills. Williams more clearly demonstrated increased mortality with depth of hook location, as well as handling time, but found no association with fish size. Based on these studies, a discard mortality rate in the recreational fishery of 15% has been used in this and previous assessments, resulting in a time series average discard mortality of about 100 mt per year.

Marine Recreational Information Program Estimates of Recreational Fishery Catch

The NMFS Marine Recreational Fishery Statistics Survey (MRFSS) was replaced by the Marine Recreational Information Program (MRIP) in 2012 to provide improved recreational fishing statistics. The MRIP implemented a new statistical method for calculating recreational catch estimates, with many survey elements related to both data collection and analysis updated and refined to address issues such as data gaps, bias, consistency, accuracy, and timeliness. As part of the implementation of the MRIP, recreational fishery catch estimates for 2004-2011 have been directly replaced by those using the MRIP estimation methods. For earlier years, a constant "ratio of means" of the MRFSS and MRIP estimates has been used to adjust the recreational catch estimates (Table 5 and Table 7).

For the recreational fishery harvest number (catch types A + B1), the largest change was for the commonwealth of MA, with a cumulative 2004-2011 increase of about 4 million fish, about +67% and also the largest cumulative percentage increase amongst the states. The largest absolute decrease was for the state of RI with a cumulative 2004-2011 decrease of about 289,000 fish, or about -7%. The state of MD had the largest cumulative percentage decrease at -67%; however, MD's cumulative harvest (now about 3,600 fish) is only 0.1% of the coastal total. Over all states, the cumulative harvest in numbers increased by about 5.3 million fish (about +19%), ranging from a decrease of 174,000 fish in 2007 (-5%) to an increase of 2.5 million fish in 2004 (+52%; Table 8). Therefore, for the years 1963-2003 recreational harvest numbers were increased by 19% for this assessment update.

For the recreational fishery harvest weight (catch types A + B1, mt), the most important change was for the commonwealth of MA with a cumulative 2004-2011 increase of about 1,713 mt, or about +67%. The state of DE had the largest cumulative percentage increase at +112%; however, DE's cumulative harvest (now about 4 mt) is less than 0.1% of the coastal total. The largest absolute decrease was for the state of RI with a cumulative 2004-2011 decrease of about 108 mt, about -6%. The state of MD had the largest cumulative percentage decrease at -30%, a cumulative decrease of about 1 mt. Over all states, the cumulative harvest in weight (mt; metric tons) increased by about 2,433 mt (about +18%), ranging from a decrease of 122 mt in 2008 (-7%) to an increase of 1,356 mt fish in 2004 (+71%; Table 9). Therefore, for the years 1963-2003 recreational harvest weight was increased by 18% for this assessment update (Table 5, Table 21, and Table 24).

For the recreational fishery live releases in numbers (catch type B2), the largest change was for the commonwealth of MA, with a cumulative 2004-2011 increase of about 3.1 million fish, about +38% and also the largest cumulative percentage increase amongst the states. The largest absolute decrease was for the state of NJ with a cumulative 2004-2011 decrease of about 410,000 fish, or about -12%. The state of MD had the largest cumulative percentage decrease at -47%, a cumulative decrease of about 45,000 million fish. Over all states, the cumulative live release in numbers increased by about 4.5 million fish (about +11%), ranging from a decrease of 239,000 fish in 2008 (-3%) to an increase of 1.7 million fish in 2004 (+36%; Table 10). Therefore, for the years 1963-2003 recreational live release and discard mortality estimates were increased by 11% for this assessment update (Table 7, Table 21, and Table 24).

Commercial Fishery Landings at Length and Age

The NER commercial fishery length frequency sampling is summarized in Table 11. Annual sampling intensity has varied from 18 to 687 mt per 100 lengths, with sampling exceeding the informal threshold criterion of 200 mt per 100 lengths since 1995. For this assessment, commercial fishery landings at age beginning in 1984 have been updated through 2011, with samples generally pooled by market category (pins/small, medium, large/mix, jumbo, and unclassified) and by half-year (January-June, July-December); samples were pooled on a quarterly basis (e.g., January-March) since 2004. Estimates of commercial fishery landings at age (Figure 2) and mean weights at age are presented in Table 12 and Table 13.

Commercial Fishery Discards at Length and Age

The intensity of length sampling of discarded scup from the NEFSC Fishery Observer Program declined in 1992-1995 relative to 1989-1991 (Table 14). Sampling intensity ranged from 489 to 335 mt per 100 lengths sampled in 1992-1995, failing to meet the informal criterion of 200 mt per 100 lengths. Sampling intensity improved to 100 mt per 100 lengths in 1996, but then declined to over 200 mt per 100 lengths in 1997-1999. Sampling intensity has generally met the 200 mt per 100 lengths threshold since 2000. The mean weight of the discard was estimated from length frequency data using a length-weight equation, total numbers discarded were then estimated by dividing total weight by mean weight, and numbers at length were then calculated from the length-frequency distribution. Discards at length were aged using a combination of commercial and survey age-length keys, with discards at age dominated by fish aged 0, 1, or 2, depending on the year under consideration. Estimates of commercial fishery discards at age (Figure 3) and mean weights at age are presented in Table 15 and Table 16.

Recreational Fishery Landings at Length and Age

For the recreational fishery, length sampling intensity has varied from 45 to 471 mt per 100 lengths. Sampling in all years except 1984 during 1981-1987 failed to meet the informal criterion of 200 mt per 100 lengths, but since 1988 the criterion has been met except for 1999-2000 (Table 5). Numbers at length for recreational landings were determined from recreational fishery length samples pooled by half-years (January-June; July-December) over all regions and fishing modes, and were converted to numbers at age by applying half-year age-length keys constructed from NEFSC commercial and survey samples. Age-length keys from spring surveys and first and second quarter commercial samples were applied to numbers at length from the first half of the year, while age-length keys from fall surveys and third and fourth quarter commercial samples were applied to numbers at length from the second half of the year. Estimates of recreational fishery landings at age (Figure 4) and mean weights at age are presented in Table 17 and Table 18.

Recreational Fishery Discards at Length and Age

No length frequency samples of the scup discard were collected under the MRFSS program before 2005, so recreational discards were assumed to be fish aged 0 and 1, in the same relative proportions and with the same mean weight as the landed catch less than state regulated minimum fish sizes. An inspection of discard length frequency samples from the New York recreational fishery for 1989-1991 indicated that this assumption was reasonable. Since 2005, the MRFSS/MRIP For-Hire Survey discard samples have been used in concert with the MRFSS/MRIP sub-legal landed lengths to characterize the length frequency of the recreational discard. The informal sampling criterion of 200 mt per 100 lengths has been consistently met since 2007 (Table 7). Numbers at length were converted to numbers at age by applying half-year (January-June; July-December) age-length keys constructed from NEFSC commercial and survey samples. As noted earlier, a 15% discard mortality rate is assumed. Estimates of recreational fishery discards at age (Figure 5) and mean weights at age are presented in Table 19 and Table 20.

Total Fishery Catch

Total commercial and recreational landings in 2011 were 8,451 mt = 18.631 million lbs and total commercial and recreational discards were 2,086 mt = 4.599 million lbs, for a total catch in 2011 of 10,537 mt = 23.230 million lbs (Table 21). Estimates of the total fishery catch at age and mean weights at age for 1984-2011 (the time series is limited by the availability of sampled fishery ages) are presented in Table 22 and Table 23. An extended time series of the total catch of scup has been estimated to provide an historical perspective of the exploitation of scup in the years before fishery aging data were available (Table 24). These estimates include commercial and recreational landings and discards. The recreational fishery catch for 2004-2011 has been estimated using the MRIP methods. For earlier years, a constant "ratio of means" of the MRFSS and MRIP estimates has been used to adjust the recreational catch estimates.

The catches before 1981 are the least reliable due to uncertainty about a) the magnitude of domestic commercial fishery discards, b) the magnitude of the distant water fleet (DWF) catch and c) the uncertainty of assumptions made to estimate the recreational catch (50% reduction from interpolations made in Mayo 1982 for 1960-1978; recreational discards assumed to be 2% of the adjusted recreational landings). For years in which no commercial fishery observer data were collected (prior to 1989), commercial discards were estimated using the mean of landings to discards ratios for 1989-2001.

Research Survey Indices of Abundance

Northeast Fisheries Science Center

The NEFSC spring and fall bottom trawl surveys provide long time series of fishery-independent indices for scup. The NEFSC spring and fall surveys are conducted annually during March-May and September-November, ranging from just south of Cape Hatteras, NC to Canadian waters. NEFSC spring and fall abundance and biomass indices for scup exhibit considerable inter-annual variability (Table 25; Figure 6). NEFSC spring survey catches are characterized mainly by scup of ages 1 and 2 (Figure 7), while the fall survey often captures large numbers of age 0 and 1 fish (Figure 8).

The Fisheries Survey Vessel (FSV) Albatross IV (ALB) was replaced in spring 2009 by the FSV Henry B. Bigelow (HBB) as the main platform for NEFSC research surveys, including the spring and fall bottom trawl surveys. The size, towing power, and fishing gear characteristics of the HBB are significantly different from the ALB, resulting in different fishing power and therefore different survey catchability. Calibration experiments to estimate these differences were conducted during 2008 (Brown 2009), and the results of those experiments were peer reviewed by a Panel of three non-NMFS scientists during the summer of 2009 (Anonymous 2009, Miller et al. 2010). The terms of reference for the Panel were to review and evaluate the suite of statistical methods used to derive calibration factors by species before they were applied in a stock assessment context. Following the advice of the August 2009 Peer Review (Anonymous 2009), the methods proposed in Miller et al. (2010), and the precedents set in peer-reviews of stock assessments for haddock (Van Eeckhaute and Brooks 2010), yellowtail flounder (Legault et al. 2010), silver and red hake (NEFSC 2011a), and winter flounder (NEFSC 2011b), aggregate and length-based calibration factors were used to convert 2009-2011 spring and fall HBB survey catch number and weight indices to ALB equivalents for use in this stock assessment update (Tables 26-28; Figure 6).

The NEFSC survey indices sometimes appear to mainly reflect the availability of scup to the survey, rather than true abundance, making it difficult to interpret large inter-annual changes in the indices. For example, the 2002 spring biomass index was about twice the second highest spring index, which was observed in 1977 (Figure 6). The spring numeric abundance indices are similar; the 2002 index is the highest observed in the series and about twice the 1970 index. These dramatic increases were evident across all ages in the estimated 2002 spring numbers at age (Table 29; Figure 7). However, the previous fall survey estimates of numbers at age in 2001 had not reflected relatively large values from which the corresponding 2002 spring numbers at age might have been expected to derive (Table 30; Figure 8) nor did they subsequently translate to exceptional indices of biomass in fall 2002 or spring 2003. Spring survey biomass and abundance indices decreased subsequent to 2002, but are still above the low values of the late 1990s. Fall survey abundance and biomass, although highly variable, have about doubled since the late 1990s.

The NEFSC winter survey was started in 1992 primarily as a flatfish survey, was conducted during February, and ranged from Cape Hatteras, NC to the southwestern part of Georges Bank. The winter survey 2002 abundance and biomass indices were, like the spring survey, the largest of the time series (Table 31; Figure 6). Similar to the spring estimates, numbers at age estimated for the 2002 winter survey were also exceptionally large (Table 32; Figure 9). Winter survey abundance and biomass decreased subsequent to 2002, but were still above the low values of the late 1990s. The winter trawl series ended in 2007.

The large differences in the absolute magnitude of NEFSC survey catches of ages 0-2 compared to those of fish at ages 3 and older suggests a substantial difference in survey selection at age between these two aggregate age groups. In the 2008 DPS assessment (NEFSC 2009), aggregate biomass indices retracted to the lengths of fish ages 0-2 were constructed for calibration of those ages in the population model (maximum length of 22 cm in the winter, 20 cm in the spring, and 23 cm in the fall series). The 2009-2011 HBB values for these aggregate indices have also been converted to ALB equivalents using length calibration factors (Table 33).

Massachusetts Division of Marine Fisheries

The Massachusetts Division of Marine Fisheries (MADMF) has conducted spring and fall bottom trawl surveys of Massachusetts territorial waters in May and September since 1978. Survey coverage extends from the New Hampshire to Rhode Island boundaries and seaward to three nautical miles, including Cape Cod Bay and Nantucket Sound. The study area is stratified into geographic zones based on depth and area. The MADMF spring survey catches are characterized mainly by scup of ages 1 and 2, while the fall survey often captures large numbers of age 0 fish. The spring biomass and abundance indices decreased sharply from a high in the early 1980s to relatively low levels through the 1990s, and have since exhibited a variable but increasing trend (Table 34; Figure 10). The MADMF fall abundance index can include large numbers of age 0 fish and therefore can be more variable as it reflects inter-annual variance in recruitment. The fall biomass index exhibits an increasing trend since the mid 1990s (Table 34; Figure 10).

Rhode Island Division of Fish and Wildlife

The Rhode Island Division of Fish and Wildlife (RIDFW) has conducted spring and fall bottom trawl surveys based on a stratified random sampling design since 1979. Three major fishing grounds are considered in the spatial stratification, including Narragansett Bay, Rhode Island Sound, and Block Island Sound. Stations are either fixed or randomly selected for each stratum. The RIDFW spring survey mainly catches scup of ages 1 and 2. The spring index shows relatively low scup abundance and biomass through 1999 followed by a steep increase during 2000-2002, in common with the NEFSC and MADMF indices, and high variability since then (Table 35; Figure 11). The RIDFW fall survey is dominated by age 0 scup, and the fall indices show a general increase to a 1993 peak, followed by a steep decline until 1998, and a steady increase since then. The fall biomass series reached a time series peak in 2011 (Figure 11).

The RIDFW implemented a ventless trap survey in cooperation with commercial fishermen beginning in 2005. The cooperative trap survey has a fixed station format, and survey catches are expressed as catch per trap soak hour. The index of age 0 scup from the trap indicates strong recruitment in 2007 and 2010, while the aggregate index of scup abundance has increased steadily since 2005 (Table 36; Figure 11 and Figure 12). The RIDFW cooperative trap survey data have not yet been included in the calibration of the assessment population model.

Connecticut Department of Environmental Protection

The Connecticut Department of Environmental Protection (CTDEP) trawl survey program was initiated in May 1984 and encompasses both New York and Connecticut waters of Long Island Sound. The stratified random design survey is conducted in the spring (April-June) and fall (September-October). The CTDEP spring index indicates relatively low abundance through most of the survey period, but has increased substantially since 1999 (Table 37; Figure 13). The CTDEP fall survey, which often catches large numbers of age-0 scup, indicates that recruitment was relatively stable during most of the survey period, but the aggregate fall indices have also increased substantially since 1999 (Table 38; Figure 12 and Figure 13). Due to vessel engine failure, a complete fall survey was not conducted in 2010. The age compositions of the CTDEP spring and fall surveys generally include a higher proportion of age 2 and older fish than the other state or NEFSC surveys (Figure 14 and Figure 15).

New York Department of Environmental Conservation

The New York Department of Environmental Conservation (NYDEC) initiated a small mesh trawl survey in 1985 to collect fisheries-independent data on the age and size composition of scup in local waters. This survey is conducted in the Peconic Bays, the estuarine waters which lie between the north and south forks of eastern Long Island. The NYDEC survey provides age 0, 1, and 2+ indices of scup abundance. The age 0 indices are generally low over the survey period, with peaks in 2000, 2002, 2003, 2006, and 2007 that may indicate recruitment of strong cohorts in those years (Table 39; Figure 12). In the early years of the survey there often has not been a strong correspondence between the age 0 indices and age 1 and 2+ indices in the following years (Figure 16).

New Jersey Bureau of Marine Fisheries

The New Jersey Bureau of Marine Fisheries (NJBMF) conducts a stratified random bottom trawl survey of New Jersey coastal waters from Ambrose Channel south to Cape Henlopen Channel. Latitudinal strata boundaries correspond to those in the NEFSC trawl survey; longitudinal boundaries correspond to the 30, 60, and 90 foot isobaths. Each survey includes two tows per stratum plus one additional tow in each of nine larger strata for a total of 39 tows. The NJBMF survey indices exhibit variable patterns over the early part of the time series. The biomass index reached a minimum in 1996 and then generally increased, peaking in 2007 (Table 39; Figure 17).

University of Rhode Island Graduate School of Oceanography

University of Rhode Island Graduate School of Oceanography (URIGSO) has conducted a standardized, two-station trawl survey in Narragansett Bay and Rhode Island Sound since the 1950s, with consistent sampling since 1963. Irregular length-frequency samples for scup indicate that most of the survey catch is of fish from ages 0 to 2. The aggregate numbers-based index reached a peak in the late 1970s, was relatively low during the late 1990s, and has since generally increased. The 2009 index was the second highest of the time series, after the 1976 and 1989 indices (Table 40; Figure 18).

Virginia Institute of Marine Science

Juvenile Fish Trawl Survey

The Virginia Institute of Marine Science (VIMS) has conducted a juvenile fish trawl survey in lower Chesapeake Bay during June-September since 1988. The VIMS age-0 scup indices show a general decline in recruitment from relatively high levels with peaks in the late 1980s to early 1990s, to relatively low levels from the late 1990s to early 2000s, and the indication of several recent strong year classes (Table 39; Figure 12).

Chesapeake Bay Multispecies Monitoring and Assessment Program Trawl Survey

The VIMS Chesapeake Bay Multispecies Monitoring and Assessment Program (ChesMMAP) trawl survey is designed to support stock assessment activities at both a single and multispecies scale. While no single gear or monitoring program can collect all of the data necessary for quantitative assessments, ChesMMAP was designed to fill data gaps by maximizing the biological and ecological data collected for several recreationally and commercially important species in the bay. Total abundance and biomass indices composed mainly of age 0 and 1 fish are available since 2002, and suggest strongest recruitment in 2007 and 2010 (Table 41; Figure 19).

Northeast Area Monitoring and Assessment Program (NEAMAP) Trawl Survey

The VIMS Northeast Area Monitoring and Assessment Program (NEAMAP) industry-cooperative survey was started in fall 2007, providing research survey samples in the spring and fall seasons along the Atlantic coast from Rhode Island to North Carolina, in depths of 20-90 feet (9-43 meters). The NEAMAP survey data have not yet been included in the calibration of the assessment population model (Table 42; Figure 19).

2011 Updated Fishing Mortality Rate and Stock Size Estimates

Fishing mortality rates and stock sizes were estimated using the ASAP SCAA model (NFT 2008a). The catch at age, mean weight at age, maturity at age, and survey index calibration time series were input as in the 2008 DPS and 2009-2011 assessment updates (NEFSC 2009, Terceiro 2009, 2010, 2011). Winter, spring, and mid-year survey indices and all survey recruitment (age-0) indices were compared to population numbers of the same age at the beginning of the same year. Fall survey indices were compared to population numbers one year older at the beginning of the next year. Lognormal error distributions were assumed for the total catch in weight, research survey catch at age calibration indices, internal Beverton-Holt stock-recruitment relationship and parameters, selectivity parameters, annual fishing mortality parameters, survey catchability parameters, and estimated stock numbers at age. A multinomial distribution was assumed for fishery catch at age. Additional model settings including specification of likelihood component emphasis factors (lambdas), size of the deviation factors expressed as standard deviations and penalty functions for extreme fishing mortality estimates were left at the consensus values set in the 2008 DPS assessment.

Summary estimates, estimated January 1 stock size at age in numbers, and estimated fishing mortality (F) at age from the updated model for 1984-2011 (the years with input fishery catches at age) are provided in Tables 43-45. Spawning stock biomass (SSB) decreased from about 100,000 mt in 1963 to about 50,000 mt in 1969, then increased to about 75,000 mt during the late 1970s. SSB declined through the 1980s and early 1990s to less than 5,000 mt in the mid-1990s. With greatly improved recruitment and low fishing mortality rates since 1998, SSB increased to about greater than 100,000 mt = 220 million lbs since 2004. SSB was estimated to be 190,424 mt = 420 million lbs in 2011 (Figure 20 and Figure 21). There is a 50% probability that SSB in 2011 was between 185,000 and 198,000 mt (408 and 436 million lbs; Figure 22). Fishing mortality calculated from the average of the currently fully recruited ages (2-7+) varied between F = 0.1 and F = 0.3 during the 1960s and 1970s. Fishing mortality increased during the 1980s and early 1990s, peaking at about F = 1.0 in the mid-1990s. Fishing mortality decreased after 1994, falling to less than F = 0.1 since 2004, with F in 2011 = 0.034 (Figure 23). There is a 50% probability that F in 2010 was between 0.026 and 0.042 (Figure 24).

Recruitment at age 0 averaged 92 million fish during 1963-1983, the period in which recruitment estimates are influenced mainly by the assessment model stock-recruitment relationship. Since 1984, recruitment estimates from the model are influenced mainly by the fishery and survey catches at age, and averaged 110 million fish during 1984-2011. The 1999, 2000, and 2008 year classes are estimated to be the largest of the time series, at 207, 226, and 215 million age 0 fish. After below average recruitment in 2009 and 2010, the 2011 year class is estimated to be above average at 154 million age 0 fish (Figure 20 and Figure 21).

There is no consistent internal retrospective pattern in F, SSB, or recruitment evident in the 2012 updated assessment model (Figures 25-27). A between-assessment comparison provides another measure of assessment uncertainty due to changes in model estimates. The 2012 assessment estimates of SSB and F are intermediate with respect to the 2008 DPSWG assessment and 2009 update for the same years, and are very similar to those from 2010 and 2011 updates. The 2012 assessment estimates of the size of the 2007 through 2010 year classes are in general larger compared to the 2011 assessment (Figures 28-30).

2008 DPS Assessment Biological Reference Points

The 2008 DPS Peer Review Panel accepted the ASAP SCAA model results as the basis for biological reference points and status determination for scup (NEFSC 2009). Reference points were calculated using the non-parametric yield and SSB per recruit/long-term projection approach adopted for summer flounder (NEFSC 2008a) and the New England groundfish stocks (NEFSC 2008b). In the yield and SSB per recruit calculations, the most recent five year averages were used for mean weights and fishery partial recruitment pattern. For the estimation of MSY and SSBMSY, the cumulative distribution function of the 1984-2007 recruitments (corresponding to the period of input fishery catches at age) was re-sampled to provide future recruitment estimates (mean = 117 million age 0 fish). The 2008 DPS Peer Review Panel recommended F40% as the proxy for FMSY, and the corresponding SSBF40% as the proxy for SSBMSY. The F40% proxy for FMSY = 0.177, the proxy estimate for SSBMSY = SSB40% = 92,044 mt = 202.922 million lbs, and the proxy estimate for MSY = MSY40% = 16,161 mt = 35.629 million lbs (13,134 mt = 28.956 million lbs of landings and 3,027 mt = 6.673 million lbs of discards).

2011 Updated Stock Status

The scup stock was not overfished and overfishing was not occurring in 2011 relative to the biological reference points established in the 2008 Northeast Data Poor Stocks (DPS) assessment. The fishing mortality rate (F) was estimated to be 0.034 in 2011, below the fishing mortality threshold reference point = FMSY = F40% = 0.177. Spawning Stock Biomass (SSB) was estimated to be 190,424 metric tons (mt) = 420 million lbs in 2011, above the biomass target reference point = SSBMSY = SSB40% = 92,044 mt = 203 million lbs (Figure 31).

Assessment Uncertainty Considerations

The 2012 assessment indicates that the stock was well above the biomass target and being fished at well below the fishing mortality threshold in 2011. The high level of 2011 stock abundance is the result of historically low fishing mortality rates and historically high levels of recruitment since the late 1990s. The MSY proxy in terms of total catch is 16,161 mt (35.628 million lbs), with total landings of 13,134 mt (28.956 million lbs) and total discards of 3,027 mt (6.673 million lbs). Total fishery catch is estimated to have averaged about 34,000 mt (~75 million lbs) during 1960-1965, while reported commercial landings alone averaged about 19,000 mt (~42 million lbs) in that period (Table 24). Therefore, the MSY estimate appears feasible given historical evidence from the fishery. The 2008 DPS Peer Review Panel (NEFSC 2009) advised that a gradual increase in the ABC toward the MSY level would facilitate an evaluation of the performance of the new assessment model and reference points in monitoring stock status, while reducing the risk to the stock due to rapidly increased catch.

Projection of the Overfishing Limit (OFL) for 2013

Stochastic projections were made to provide forecasts of stock size and catches in 2012-2013 consistent with the 2008 DPS assessment biological reference points. The projections assume that recent (2006-2011) patterns of discarding will continue over the time span of the projections. Different patterns that could develop in the future due to different trip and bag limits and fishery closures have not been evaluated. One hundred projections were made for each of the 1000 Markov Chain Monte Carlo (MCMC) realizations of 2012 stock sizes from the updated assessment results using NFT AGEPRO version 4.0.5 (NFT 2011). Future recruitment at age 0 was generated randomly from a cumulative density function of the updated recruitment series for 1984-2011 (mean recruitment = 110 million fish).

If the landings of scup in 2012 equal the specified Total Allowable Landings (TAL) = 16,749 mt = 36.925 million lbs, the 2012 median (50% probability) discards are projected to be 3,334 mt = 7.350 million lbs, and the median total catch is projected to be 20,083 mt = 44.275 million lbs. The median F in 2012 is projected to be 0.158, below the fishing mortality threshold = FMSY = F40% = 0.177. The median SSB on June 1, 2012 is projected to be 203,982 mt = 450 million lbs, above the biomass target of SSBMSY = SSB40% = 92,044 mt = 203 million lbs.

If the stock is fished at the fishing mortality threshold = FMSY = F40% = 0.177 in 2013, median landings are projected to be 17,981 mt = 39.641 million lbs, with median discards of 3,721 mt = 8.203 million lbs, and median total catch = 21,680 mt = 47.796 million lbs. This projected median total catch is equivalent to the Overfishing Limit (OFL) for 2013, and is greater than MSY = 16,161 mt (35.629 million lbs) of total catch (13,134 mt = 28.956 million lbs of landings plus 3,027 mt = 6.673 million lbs of discards). The median SSB on June 1, 2013 is projected to be 196,236 mt = 432 million lbs, above the biomass target of SSBMSY = SSB40% = 92,044 mt = 203 million lbs. The projected catch estimates in the following table are medians of the catch distributions for fixed F in 2013.

Total Catch (OFL), Landings, Discards, Fishing Mortality (F)

and Spawning Stock Biomass (SSB) in 2013

Catches and SSB in metric tons

Total Catch

Landings

Discards

F

SSB

         

21,680

17,981

3,721

0.177

196,236

Acknowledgements

Special thanks to Daphne Cassidy, Grace Thornton, and the staff of the NOAA Fisheries NEFSC Population Biology Branch for their timely preparation of the 2011 scup ages used in this assessment update.

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