Northeast Fisheries Science Center Reference Document 11-11



# 52nd Northeast Regional Stock Assessment Workshop (52nd SAW):

Assessment Summary Report

by Northeast Fisheries Science Center

## Recent Issues in This Series

10-11 Northeast Fisheries Science Center Cetacean Biopsy Training Manual
, by F Wenzel, J Nicolas, F Larsen, and RM Pace III. July 2010.

10-12 A Survey of Social Capital and Attitudes toward Management in the New England Groundfish Fishery
, by DS Holland, P Pinto da Silva, and J Wiersma. July 2010.

10-13 Black Sea Bass 2010 Stock Assessment Update
, by GR Shepherd and J Nieland. July 2010.

10-14 Stock Assessment of Summer Flounder for 2010
, by M Terceiro. July 2010.

10-15 Bluefish 2010 Stock Assessment Update
, by GR Shepherd and J Nieland. July 2010.

10-16 Stock Assessment of Scup for 2010
, by M Terceiro. July 2010.

10-17 50th Northeast Regional Stock Assessment Workshop (50th SAW) Assessment Repor t, by Northeast Fisheries Science Center. August 2010.

10-18	 An Updated Spatial Pattern Analysis for the Gulf of Maine-Georges Bank Atlantic Herring Complex During 1963-2009, by JJ Deroba. August 2010.

10-19	 Northeast Fisheries Science Center publications, reports, abstracts, and web documents for calendar year 2009, by A Toran. September 2010.

10-20	 Northeast Fisheries Science Center publications, reports, abstracts, and web documents for calendar year 2009, by A Toran. September 2010.

10-21	 12th Flatfish Biology Conference 2010 Program and Abstracts, by Conference Steering Committee. October 2010.
10-22	 Update on Harbor Porpoise Take Reduction Plan Monitoring Initiatives: Compliance and Consequential Bycatch Rates from June 2008 through May 2009, by C D Orphanides. November 2010.

11-01 51st Northeast Regional Stock Assessment Workshop (51st SAW): Assessment Summary Report
, by Northeast Fisheries Science Center. January 2011.

11-02 51st Northeast Regional Stock Assessment Workshop (51st SAW): Assessment Report
, by Northeast Fisheries Science Center. March 2011.

11-03 Preliminary Summer 2010 Regional Abundance Estimate of Loggerhead Turtles (Caretta caretta) in Northwestern Atlantic Ocean Continental Shelf Waters
, by the Northeast Fisheries Science Center and the Southeast Fisheries Science Center. April 2011.

11-04 Proration of Loggerhead Sea Turtle (Caretta caretta) Interactions in US Mid-Atlantic Bottom Otter Trawls for Fish and Scallops, 2005–2008, by Managed Species Landed, by M L Warden. March 2011.

11-05 North Atlantic Right Whale Sighting Survey (NARWSS) and Right Whale Sighting Advisory System (RWSAS) 2010 Results Summary
, by C Khan, T Cole, P Duley, A Henry, and J Gatzke. March 2011.

11-06 NOAA NEFSC Stellwagen Bank National Marine Sanctuary Program 2009 Aerial Survey Results Summary , by J Gatzke, C Khan, T Cole, P Duley, A Henry, S Van Parijs, and D Wiley. March 2011.

11-07 Interim Report for Fishing Year 2010 on the Performance of the Northeast Multispecies (Groundfish) Fishery (May 2010 – January 2011)
, by Andrew Kitts, Evan Bing-Sawyer, Matthew McPherson, Julia Olson, and John Walden. May 2011.

11-08	 Estimates of Cetacean and Pinniped Bycatch in the 2009 New England Sink Gillnet and Mid-Atlantic Gillnet Fisheries
, by CD Orphanides. April 2011.

11-09	 Standardized Bycatch Reporting Methodology 3-year Review Report 2011

- Part 1 by SE Wigley, J Blaylock, PJ Rago, J Tang, HL Haas, and G Shield. June 2011.
11-10	 Evaluating Sea Turtle Injuries in Northeast Fishing Gear by C Upite. July 2011.

### Northeast Fisheries Science Center Reference Document 11-11

US DEPARTMENT OF COMMERCE National Oceanic and Atmospheric Administration National Marine Fisheries Service Northeast Fisheries Science Center Woods Hole, Massachusetts

July 2011 

# 52nd Northeast Regional Stock Assessment Workshop (52nd SAW):

Assessment Summary Report

by Northeast Fisheries Science Center

NOAA National Marine Fisheries Service, 166 Water St., Woods Hole, MA 02543.

# Northeast Fisheries Science Center Reference Documents

This series is a secondary scientific series designed to assure the long-term documentation and to enable the timely transmission of research results by Center and/or non-Center researchers, where such results bear upon the research mission of the Center (see the outside back cover for the mission statement). These documents receive internal scientific review, and most receive copy editing. The National Marine Fisheries Service does not endorse any proprietary material, process, or product mentioned in these documents. All documents issued in this series since April 2001, and several documents issued prior to that date, have been copublished in both paper and electronic versions. To access the electronic version of a document in this series, go to http://www.nefsc.noaa.gov/nefsc/publications/ . The electronic version is available in PDF format to permit printing of a paper copy directly from the Internet. If you do not have Internet access, or if a desired document is one of the pre-April 2001 documents available only in the paper version, you can obtain a paper copy by contacting the senior Center author of the desired document. Refer to the title page of the document for the senior Center author’s name and mailing address. If there is no Center author, or if there is corporate ( i.e. , non-individualized) authorship, then contact the Center’s Woods Hole Labora

tory Library (166 Water St., Woods Hole, MA 02543-1026). Editorial Treatment: To distribute this report quickly, it has not undergone the normal tech

nical and copy editing by the Northeast Fisheries Science Center’s (NEFSC’s) Editorial Office as have most other issues in the NOAA Technical Memorandum NMFS-NE series. Other than the four covers and first two preliminary pages, all writing and editing have been performed by the authors listed within. This report was reviewed by the Stock Assessment Review Commit

tee, a panel of assessment experts from the Center for Independent Experts (CIE), University of Miami. 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. This document may be cited as:

Northeast Fisheries Science Center. 2011. 52nd Northeast Regional Stock Assessment Workshop (52nd SAW) Assessment Summary Report. US Dept Commer, Northeast Fish Sci Cent Ref Doc. 11-11; 51 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/52 nd SAW Assessment Summary Report iii 

## Table of Contents

Introduction

.............................................................................................................................. .. 1 Outcome of Stock Assessment Review Meeting .........................................................................2 Glossary ...................................................................................................................... ..................3 A. SOUTHERN NEW ENGLAND/MID-A TLANTIC (SNE/MA) WINTER FLOUNDER ASSESSMENT SUMMARY FOR 2011

................................................... 11 State of Stock ................................................................................................................ .............11 Projection .................................................................................................................... ...............11 Catch ......................................................................................................................... ..................11 Catch and Status Table ........................................................................................................ .......12 Stock Distribution and Identification ......................................................................................... 12 Data and Assessment ........................................................................................................... .......12 Biological Reference Points ................................................................................................... ....13 Fishing Mortality ............................................................................................................. ...........13 Recruitment ................................................................................................................... .............13 Spawning Stock Biomass ........................................................................................................ ...13 Special Comments .............................................................................................................. ........13 References .................................................................................................................... ..............14 Figures ....................................................................................................................... .................15 B. GEORGES BANK (GBK) WINTER FL OUNDER ASSESSMENT SUMMARY FOR 2011

.............................................................................................................................. ....... 27 State of Stock ................................................................................................................ .............27 Projections ................................................................................................................... ...............27 Catch ......................................................................................................................... ..................27 Catch and Status Table ........................................................................................................ .......28 Stock Distribution and Identification ......................................................................................... 28 Data and Assessment ........................................................................................................... .......28 Biological Reference Points ................................................................................................... ....29 Fishing Mortality ............................................................................................................. ...........29 Spawning Stock Biomass ........................................................................................................ ...29 Recruitment ................................................................................................................... .............29 Special Comments .............................................................................................................. ........30 References ................................................................................................................... ..............30 Tables ....................................................................................................................... .................31 Figures ...................................................................................................................... .................32 C. GULF OF MAINE (GOM) WINTER FLOUNDER ASSESSMENT SUMMARY FOR 2011

............................................................................................................................ 36 State of Stock ................................................................................................................ .............36 Projections ................................................................................................................... ...............36 Catch ......................................................................................................................... ..................3652 nd SAW Assessment Summary Report iv 

### Catch and Status Table ........................................................................................................ .......37 Stock Distribution and Identification ......................................................................................... 37 Data and Assessment ........................................................................................................... .......37 Biological Reference Points ................................................................................................... ....38 Fishing Mortality ............................................................................................................. ...........38 Recruitment ................................................................................................................... .............38 Spawning Stock Biomass ........................................................................................................ ...38 Special Comments .............................................................................................................. ........38 References .................................................................................................................... ..............39 Figures ....................................................................................................................... .................40 Appendix: Terms of Reference

................................................................................................ 4852 nd SAW Assessment Summary Report 1 

## SAW-52 ASSESSMENT SUMMARY REPORT

**Introduction** The 52 nd 

### SAW Assessment Summary Report cont ains summary and detailed technical information on three stock assessments reviewed in June 2011 at the Stock Assessment Workshop (SAW) by the 52 nd 

### Stock Assessment Review Committee (SARC-52): three stocks of winter flounder ( Pseudopleuronectes americanus ) from Southern New England/Mid-Atlantic, Georges Bank, and Gulf of Maine. The SARC-52 c onsisted of 3 external, independent reviewers appointed by the Center for Independent Expert s [CIE], and an external SARC chairman from the NEFMC SSC. The SARC evaluated whether each Term of Reference (listed in the Appendix) was completed successfully based on whether the work provided a scientifically credible basis for developing fishery manage ment advice. The reviewers’ reports for SAW/SARC-52 are available at website: http://www.nefsc.noaa.gov/nefsc/saw/under the heading “SARC 52 Panelist Reports”. An important aspect of any assessment is th e determination of current stock status. The status of the stock relates to both the rate of removal of fish from the population – the exploitation rate – and the current stock size. The exploitation ra te is the proportion of the stock alive at the beginning of the year that is ca ught during the year. When that proportion exceeds the amount specified in an overfishing definition, overfishing is occurring. Fishery removal rates are usually expressed in terms of the instantane ous fishing mortality rate, F, and the maximum removal rate is denoted as F THRESHOLD. 

### Another important factor for classifying the stat us of a resource is the current stock level, for example, spawning stock biomass (SSB) or total stock biomass (TSB). Overfishing definitions, therefore, characteristically include specification of a minimum biomass threshold as well as a maximum fishing threshold. If the biom ass of a stock falls below the biomass threshold (B THRESHOLD 

### ) the stock is in an overfished conditi on. The Sustainable Fisheries Act mandates that a stock rebuilding plan be deve loped should this s ituation arise. As there are two dimensions to stock status – the rate of removal and the biomass level – it is possible that a stock not curr ently subject to overfishing in term s of exploitation rates is in an overfished condition, that is, has a biomass level less than the thresh old level. This may be due to heavy exploitation in the past, or a result of other f actors such as unfavorable environmental conditions. In this case, future recruitment to th e stock is very important and the probability of improvement may increase greatly by increasing the stock size. Conversely, fishing down a stock that is at a high biomass level should generally increase the long- term sustainable yield. Stocks under federal jurisdiction are managed on the basi s of maximum sustainable yield (MSY). The biomass that produces this yield is called B MSY 

### and the fishing mortality rate that produces MSY is called F MSY


### . Given this, federally managed stocks under revi ew are classified with respect to current overfishing definitions. A stock is overfished if its current biomass is below B THRESHOLD 

### and overfishing is occurring if cu rrent F is greater than F THRESHOLD. 

### The table below depicts status criteria.52 nd SAW Assessment Summary Report 2 BIOMASS

B <B THRESHOLD B THRESHOLD < B < B MSY B > B MSY

EXPLOITATION RATE F>F THRESHOLD Overfished, overfishing is occurring; reduce F, adopt and follow rebuilding plan Not overfished, overfishing is occurring; reduce F, rebuild stock F = F TARGET <= F MSY

F<F THRESHOLD Overfished, overfishing is not occurring; adopt and follow rebuilding plan Not overfished, overfishing is not occurring; rebuild stock F = F TARGET <= F MSY


### Fisheries management may take into account the precautionary approach, and overfishing guidelines often include a control rule in the overfishing definition. Generically, the control rules suggest actions at various le vels of stock biomass and incor porate an assessment of risk, in that F TARGETS 

### are set so as to avoid exceeding F THRESHOLDS


### . **Outcome of Stock Assessment Review Meeting**

Based on the Review Panel reports (available at http://www.nefsc.noaa.gov/nefsc/saw/ under the heading “SARC 52 Panelis t Reports”), the SARC review co mmittee concluded that for the SNE/MA winter flounder assessment all Terms of Reference were addressed satisfactorily. The statistical catch-age model us ed for SNE/MA assessment is cons idered to be a scientifically credible approach and provides a reasonable basi s for fisheries management advice. In 2010, this stock was overfished but overf ishing was not occurring.

The Terms of Reference for the GBK winter flounder assessment were satisfactorily addressed. The VPA model used was a scientifically credible approach and provides a reasonable basis for fisheries management advice. A statistical catc h-age model should be considered for the GBK stock as there may be more uncer tainty here associated with ca tch and discards than would be appropriate for the assumption of true known catch es as is made in a VPA analysis. In 2010 the GBK winter flounder stock wa s not overfished and overfishing was not occurring.

The Terms of Reference for the GOM winter flounder assessment were partially addressed. The GOM statistical catch-age model c ould not account for conflicting tr ends in the catch and survey information, and was not accepted. However, the accepted fall back analysis of the area-swept method provides a reasonable gauge of overfishing status and provides time trends in biomass. Overfishing does not appear to be taking place in 2010. It was not possible at the meeting to determine whether or not the stock is overfished.

For all of these assessments, the SARC felt that th e discussion of stock vulnerability could have addressed biological issues more directly (e.g., life history, longe vity, fecundity, productivity, or whether the species or stock is overly susceptibl e to fishing or environmental conditions). While the length-based calibrations be tween vessels were informative and appeared appropriate, this method might be considered for additional peer review. A met hod was developed for combining information on winter flounder acro ss regions to help inform the spawner-recruit relationships used in developing projections a nd biological reference points (for details on the method see the Review Panel Summary Report and the A ppendix of the Stock Assessment Report).52 nd SAW Assessment Summary Report 3 

### Glossary

ADAPT . A commonly used form of computer program used to optimally fit a Virtual Population Assessment (VPA) to abundance data.

ASAP . The Age Structured Assessment Program is an age-structured model that uses forward computations assuming separability of fishing mortality into year and age components to estim ate population sizes given observed catches, catch-at-age, and indices of abundance. Discards can be treated explicitly. The separabilityassumption is relaxed by allowing for fleetspecific computations and by allowing the selectivity at age to change smoothly over time or in blocks of years. The software can also allow the catchabil ity associated with each abundance index to vary smoothly with time. The problem’s dimensions (number of ages, years, fleets and abundance indices) are defined at input and limited by hardware only. The input is arrang ed assuming data is available for most years, but missing years are allowed. The model currently does not allow use of length data nor indices of survival rates. Dia gnostics include index fits, residuals in catch and catch-at-age, and effective sample size calculations. Weights are input for different components of the objective function and allow for relatively simple age-structured production model type models up to fully parameterized models.

ASPM . Age-structured production models, also known as statistical catch-at-age (SCAA) models, are a technique of stock assessment that integrate fishery catch and fishery-independent sampling information. The procedures are flexible, allowing for uncertainty in the absolute magnitudes of catches as part of the estimation. Unlike virtual population analysis (VPA) that tracks the cumulative catches of various year classes as they age, ASPM is a forward projection simulation of the exploited population. ASPM is similar to the NOAA Fishery Toolbox applications ASAP (Age Structured Assessment Program) and SS2 (Stock Synthesis 2) Availability . Refers to the distribution of fish of different ages or sizes relative to that taken in the fishery. Biological reference points . Specific values for the variables that describe the state of a fishery system which are used to evaluate its status. Reference points are most often specified in terms of fishing mortality rate and/or spawning stock biomass. The reference points may indicate 1) a desired state of the fishery, such as a fishing mortality rate that will achieve a high level of sustainable yield, or 2) a state of the fishery that should be avoided, such as a high fishing mortality rate which risks a stock collapse and long-term loss of potential yield. The form er type of reference points are referred to as “target reference points” and the latter ar e referred to as “limit reference points” or “thresholds”. Some common examples of reference points are F 0.1 

### , F MAX 

### , and F MSY 

### , which are defined later in this glossary.

B 0 

### . Virgin stock biomass, i.e., the long-term average biomass value expected in the absence of fishing mortality.

B MSY 

### . Long-term average biomass that would be achieved if fi shing at a constant fishing mortality rate equal to F MSY


### . Biomass Dynamics Model . A simple stock assessment model that tracks changes in stock using assumptions about growth and can be tuned to abundance data such as commercial catch rates, research survey trends or biomass estimates. Catchability . Proportion of the stock removed by one unit of effective fishing effort (typically age-specific due to52 nd SAW Assessment Summary Report 4 

### differences in selectivity and availability by age).

Control Rule . Describes a plan for preagreed management actions as a function of variables related to the status of the stock. For example, a control rule can specify how F or yield should vary with biomass. In the National Standard Guidelines (NSG), the “MSY control rule” is used to determine the limit fishing mortality, or Maximum Fishing Mortality Threshold (MFMT). Control rules are also known as “decision rules” or “harvest control laws.” Catch per Unit of Effort (CPUE)

. Measures the relative success of fishing operations, but also ca n be used as a proxy for relative abundance based on the assumption that CPUE is linearly related to stock size. The use of CPUE that has notbeen properly standardized for temporalspatial changes in ca tchability should be avoided. Exploitation pattern . The fishing mortality on each age (or group of adjacent ages) of a stock relative to the highest mortality on any age. The exploitation pattern is expressed as a series of values ranging from 0.0 to 1.0. The pattern is referred to as “flat-topped” when the values for all the oldest ages are about 1.0, and “dome-shaped” when the values for some intermediate ages are about 1.0 and those for the oldest ages are significantly lower. This pattern often varies by type of fishing gear, area, and seasonal distribution of fishing, and the growth and migration of the fish. The pattern can be changed by modifications to fishing gear, for example, increasing mesh or hook size, or by changing the proportion of harvest by gear type. Mortality rates . Populations of animals decline exponentially. This means that the number of animals that die in an "instant" is at all times proportional to the number present. The decline is defined by survival curves such as: N t+1 

### = N t 

### e -z



### where N t 

### is the number of animals in the population at time t and N t+1 

### is the number present in the next time period; Z is the total instantaneous mortality rate which can be separated into deaths due to fishing (fishing mortality or F) and deaths due to all other causes (natural mortality or M) and e is the base of the natural logarithm (2.71828).To better understand th e concept of an instantaneous mortality rate, consider the following example. Suppose the instantaneous total mortality rate is 2 (i.e., Z = 2) and we want to know how many animals out of an in itial population of 1 million fish will be alive at the end of one year. If the year is a pportioned into 365 days (that is, the 'instant' of time is one day), then 2/365 or 0.548% of the population will die each day. On the first day of the year, 5,480 fish will die (1,000,000 x 0.00548), leaving 994,520 alive. On day 2, another 5,450 fish die (994,520 x 0.00548) leaving 989,070 alive. At the end of the year, 134,593 fish [1,000,000 x (1 - 0.00548) 365 

### ] remain alive. If, we had instead selected a smaller 'instant' of time, say an hour, 0.0228% of the population would have died by the end of the first time interval (an hour), leaving 135,304 fish alive at the end of the year [1,000,000 x (1 - 0.00228) 8760 

### ]. As the instant of time becomes shorter and shorter, the exact answer to th e number of animals surviving is given by the survival curve mentioned above, or, in this example:

N t+1 

### = 1,000,000e -2 

### = 135,335 fish Exploitation rate . The proportion of a population alive at the beginning of the year that is caught during the year. That is, if 1 million fish were alive on January 1 and 200,000 were caught during the year, the exploitation ra te is 0.20 (200,000 / 1,000,000) or 20%.52 nd SAW Assessment Summary Report 5 

### F MAX 

### . The rate of fishing mortality that produces the maximum level of yield per recruit. This is the point beyond which growth overfishing begins.

F 0.1 

### . The fishing mortality rate where the increase in yield per recruit for an increase in a unit of effort is only 10% of the yield per recruit produced by the first unit of effort on the unexploited stock (i.e., the slope of the yield-per-recruit curve for the F 0.1 

### rate is only one-ten th the slope of the curve at its origin).

F 10% 

### . The fishing mortality rate which reduces the spawning stock biomass per recruit (SSB/R) to 10% of the amount present in the absence of fishing. More generally, Fx%, is the fishing mortality rate that reduces the SSB/R to x% of the level that would exist in the absence of fishing.

F MSY 

### . The fishing mortality rate that produces the maximum sustainable yield. Fishery Management Plan (FMP) . Plan containing conservation and management measures for fishery resources, and other provisions required by the MSFCMA, developed by Fishery Management Councils or the Secretary of Commerce.

Generation Time . In the context of the National Standard Guidelines, generation time is a measure of the time required for a female to produce a reproductively-active female offspring for use in setting maximum allowable rebuilding time periods. Growth overfishing . The situation existing when the rate of fishing mortality is above F MAX 

### and when fish are harvested before they reach their growth potential.

Limit Reference Points . Benchmarks used to indicate when harvests should be constrained substantiall y so that the stock remains within safe biological limits. The probability of exceeding limits should be low. In the National Standard Guidelines, limits are referred to as thresholds. In much of the international literature (e.g., FAO documents), “thresholds” are used as buffer points that signal when a limit is being approached. Landings per Unit of Effort (LPUE)

. Analogous to CPUE and measures the relative success of fish ing operations, but is also sometimes used a proxy for relative abundance based on the assumption that CPUE is linearly related to stock size.

MSFCMA . (Magnuson-Stevens Fishery Conservation and Management Act). U.S. Public Law 94-265, as amended through October 11, 1996. Available as NOAA Technical Memorandum NMFS-F/SPO-23, 1996. Maximum Fishing Mortality Threshold (MFMT, F THRESHOLD 

### ) . One of the Status Determination Criteria (SDC) for determining if overfishing is occurring. It will usually be equivalent to the F corresponding to the MSY Control Rule. If current fishing mortality rates are above F THRESHOLD, 

### overfishing is occurring. Minimum Stock Size Threshold (MSST, B THRESHOLD 

### ) . Another of the Status Determination Criteria. The greater of (a) 1⁄2B MSY 

### , or (b) the minimum stock size at which rebuilding to B MSY 

### will occur within 10 years of fishing at the MFMT. MSST should be measured in terms of spawning biomass or other appropriate measures of productive capacity. If current stock size is below B THRESHOLD 

### , the stock is overfished. Maximum Spawning Potential (MSP)

. This type of reference point is used in some fishery management plans to define overfishing. The MSP is the spawning stock biomass per recruit (SSB/ R) when fishing mortality is zero. The degree to which fishing reduces the SSB/R is expressed as a percentage of the MSP (i.e., %MSP). A stock is considered overfished when the52 nd SAW Assessment Summary Report 6 

### fishery reduces the %MSP below the level specified in the overf ishing definition. The values of %MSP used to define overfishing can be derived from stock-recruitment data or chosen by analogy using available information on the level required to sustain the stock. Maximum Sustainable Yield (MSY) . The largest average catch that can be taken from a stock under existing environmental conditions. Overfishing . According to the National Standard Guidelines, “overfishing occurs whenever a stock or stock complex is subjected to a rate or level of fishing mortality that jeopardizes the capacity of a stock or stock complex to produce MSY on a continuing basis.” Overfishing is occurring if the MFMT is exceeded for 1
year or more. Optimum Yield (OY) . The amount of fish that will provide the greatest overall benefit to the Nation, particularly with respect to food production and recreational opportunities and taking into account the protection of marine ecosystems. MSY constitutes a “ceiling” for OY. OY may be lower than MSY, depending on relevant economic, social, or ecological factors. In the case of an overfished fishery, OY should provide for rebuilding to B MSY


### . Partial Recruitment . Patterns of relative vulnerability of fish of different sizes or ages due to the combined effects of selectivity and availability. Rebuilding Plan . A plan that must be designed to recover stocks to the B MSY 

### level within 10 years when they are overfished (i.e. when B < MSST). Normally, the 10 years would refer to an expected time to rebuilding in a probabilistic sense.

Recruitment . This is the number of young fish that survive (from birth) to a specific age or grow to a specific size. The specific age or size at which recruitment is measured may correspond to when the young fish become vulnerable to capture in a fishery or when the number of fish in a cohort can be reliably estimated by a stock assessment. Recruitment overfishing . The situation existing when the fishing mortality rate is so high as to cause a reduction in spawning stock which causes recruitment to become impaired. Recruitment per spawning stock biomass (R/SSB) . The number of fishery recruits (usually age 1 or 2) produced from a given weight of spawners, usually expressed as numbers of recruits pe r kilogram of mature fish in the stock. This ratio can be computed for each year class and is often used as an index of pre-recruit survival, since a high R/SSB ratio in one ye ar indicates aboveaverage numbers resulting from a given spawning biomass for a pa rticular year class, and vice versa.

Reference Points . Values of parameters (e.g. B MSY 

### , F MSY 

### , F 0.1 

### ) that are useful benchmarks for guiding management decisions. Biological re ference points are typically limits that sh ould not be exceeded with significant probability (e.g., MSST) or targets for management (e.g., OY).

Risk . The probability of an event times the cost associated with the event (loss function). Sometimes “r isk” is simply used to denote the probability of an undesirable result (e.g. the risk of biomass falling below MSST). Status Determination Criteria (SDC)

. Objective and measurable criteria used to determine if a stock is being overfished or is in an overfished state according to the National Standard Guidelines. Selectivity . Measures the relative vulnerability of differ ent age (size) classes to the fishing gears(s).52 nd SAW Assessment Summary Report 7 

### Spawning Stock Biomass (SSB) . The total weight of all sexually ma ture fish in a stock. Spawning stock biomass per recruit (SSB/R or SBR) . The expected lifetime contribution to the spawning stock biomass for each recruit. SSB/R is calculated assuming that F is constant over the life span of a year class. The calculated value is also dependent on the exploitation pattern and rates of growth and natural mortality, all of which are also assumed to be constant. Stock Synthesis (SS). This application provides a statistical framework for calibration of a population dynamics model using a diversity of fishery and survey data. SS is designed to accommodate both age and size structure and with multiple stock sub-areas. Selectivit y can be cast as age specific only, size-specific in the observations only, or si ze-specific with theability to capture the major effect of sizespecific survivorship. The overall model contains subcomponents which simulate the population dynamics of the stock and fisheries, derive the expected values for the various observed data, and quantify the magnitude of difference between observed and expected data. Parameters are searched for which will maximize the goodness-of-fit. A management layer is also included in the model allowing uncertainty in estimated parameters to be propagated to the management quantities, thus facilitating a description of the risk of various possible management scenarios. The structure of SS allows for building of simple to complex models depending upon the data available.

Survival Ratios . Ratios of recruits tospawners (or spawning biomass) in a stockrecruitment analysis. The same as the recruitment per spawning stock biomass (R/SSB), see above. TAC . Total allowable catch is the total regulated catch from a stock in a given time period, usually a year. Target Reference Points . Benchmarks used to guide management objectives for achieving a desirable outcome (e.g., OY). Target reference points should not be exceeded on average. Uncertainty . Uncertainty results from a lack of perfect knowle dge of many factors that affect stock assessments, estimation of reference points, and management. Rosenberg and Restrepo (1994) identify 5 types: measurement error (in observed quantities), process error (or natural population variability), model error (misspecification of assumed values or model structure), estimation error (in population parameters or reference points, due to any of the preceding types of errors), and implementation error (or the inability to achieve targets exactly for whatever reason) Virtual population analysis (VPA) (or cohort analysis) . A retrospective analysis of the catches from a given year class which provides estimates of fishing mortality and stock size at each age over its life in the fishery. This technique is used extensively in fishery assessments. Year class (or cohort) . Fish born in a given year. For example, the 1987 year class of cod includes all cod born in 1987. This year class would be age 1 in 1988, age 2 in 1989, and so on. Yield per recruit (Y/R or YPR) . The average expected yield in weight from a single recruit. Y/R is calculated assuming that F is constant over the life span of a year class. The calculated value is also dependent on the exploitation pattern, rate of growth, and natural mortality rate, all of which are assumed to be constant.52 nd SAW Assessment Summary Report 8 

### Figure 1. Offshore depth strata sa mpled during Northeast Fisherie s Science Center bottom trawl research surveys. 73 74 76 3 4

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3552 nd SAW Assessment Summary Report 9 

### Figure 2. Inshore depth strata sampled during No rtheast Fisheries Science Center bottom trawl research surveys. 45 47 51 50

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74 75 76 79

77 78 80 81 82

83 84

85 86

87 88 90

89

57 71 70 69 68 67 45

44

43

42

41

47 45

3

2 1

4 5 6

7 8 9

10 11 14

16 12
13

17 15

20 18

19

23 21

22 24 25 26 71 72 73 74 75

39 40 41 75 76 39

38

37

36

35 21 24 22

23 25
26

27

28 29

30
31

38

39 40 37 34

33 35 32

36

41

44

43 4252 nd SAW Assessment Summary Report 10 

### Figure 3. Statistical areas used for reporting commercial catches.52 nd SAW A. Southern New England W inter Flounder 11 

### A. SOUTHERN NEW ENGLAND / MID-ATLA NTIC (SNE/MA) WINTER FLOUNDER ASSESSMENT SUMMARY FOR 2011

State of Stock: In 2010 the SNE/MA winter flounder st ock was overfished but overfishing was not occurring. The current assessment provides a new assessment model, a new assumption for the instantaneous natural mortality rate (M), and new biological reference points. The recommended biological reference points are F MSY 

### = F THRESHOLD 

### = 0.290, SSB MSY 

### = B TARGET 

### = 43,661 mt, 1/2 SSB MSY 

### = B THRESHOLD 

### = 21,831 mt, and MSY = 11,728 mt. The 2010 estimate of Spawning Stock Biomass (SSB) is 7,076 mt, 16% of B TARGET 

### and 32% of B THRESHOLD 

### . The 2010 estimate of fishing mortality (F , ages 4-5) is 0.051, 18% of F THRESHOLD 

### (Figures A1-A3).

Given the new model and assumptions in th e current assessment, comparison of the 2010 estimates of SSB and F estimates with th e existing 2008 GARM III reference points (NEFSC 2008) is not appropriate. The existing biol ogical reference points from the 2008 GARM III assessment are F 40% 

### = F THRESHOLD 

### = 0.248, SSB 40% 

### = B TARGET 

### = 38,761 mt, 1/2 SSB 40% 

### = B THRESHOLD 

### = 19,381 mt, and MSY 40% 

### = 9,742 mt.

Projections: Projections of future stock status were made based on the current assessment results using mean weight, matur ity, and fishery selectivity pattern s at age estimated for the most recent 5 years in the assessment (2006-2010) to reflect current conditions in the stock and fishery. Recruitment was projected using the st ock-recruitment model for the MSY-based BRPs. The projections assumed the FMP Framework 44 fish ing year (May 1) catch of 842 mt would be landed as a calendar year (Jan 1) catch in 2011. A catch of 842 mt in 2011 is projected to provide median F in 2011 = 0.100 and median SSB in 2011 = 9,177 mt. Projections at F = 0.000 in 2012- 2014 indicate less than a 1% chance that the stock will rebuild to SSB MSY 

### = 43,661 mt by 2014.

Catch: Commercial fishery landings reached an hi storical peak of 11,977 metric tons (mt) in 1966, then decreased through the 1970s, peaked again at 11,176 mt in 1981, and then steadily decreased to 2,128 mt in 1994. Commer cial landings then increased to 4,556 mt in 2001 but have decreased since then to only 174 mt in 2010 (Figure A4). The Propor tional Standard Error (PSE) of commercial landings has averaged less than 1%. Recreational fish ery landings peaked in 1984 at 5,510 mt, but decreased s ubstantially thereafter, with only 28 mt estimated for 2010. The PSE of the recreational landings has averaged about 27%. Commercial fishery discards for 1981 to 1993 were estimated from length frequency data from the NEFSC and MADMF trawl surveys, commercial port sampling of landings at length and Fishery Observer sampling of landings and discards at length. The Standardized Bycatch Reporting Method (SBRM) has been used for estimation of SNE/MA winter flounder commercial fishery discards for 1994 and later years. Commercial fishery discard losses peak ed in the early 1980s at 1,000-1,500 mt per year and then decreased to less than 200 mt per year since 1997. A discard mort ality rate of 50% was applied to the commercial live discard estimates. The PSE of the commercial fishery discards has averaged 27%. Recreationa l fishery discard losses p eaked in 1984-1985 at about 700,000- 750,000 fish or 150-200 mt and then decreased to le ss than 100,000 fish or 20 mt per year since 2000. A discard mortality rate of 15% was applie d to recreational live discard estimates. The PSE of the recreational di scards has averaged 30%

.52 nd SAW A. Southern New England W inter Flounder 12 

### Catch and Status Table (weights in 000s mt, recruitment in millions, arithmetic means): SNE/MA Winter Flounder

Year 2001 2002 2003 2004 2005 2006 2007 2008 2009 2010 Max 1 Min 1 Mean 1

Commercial landings 4.6 3.1 2.3 1.6 1.3 1.7 1.6 1.1 0.3 0.2 11.1 0.2 3.9 Commercial discards <0.1 0.1 0.2 0.1 0.1 0.2 0.1 0.1 0.2 0.2 1.5 <0.1 0.5 Recreational landings 0.5 0.2 0.3 0.2 0.1 0.1 0.1 0.1 0.1 <0.1 5.5 <0.1 1.4 Recreational discards <0.1 <0.1 <0.1 <0.1 <0.1 <0.1 <0.1 <0.1 <0.1 <0.1 <0.1 <0.1 <0.1 Catch used in
assessment 5.1 3.4 2.8 1.9 1.6 2.0 1.9 1.3 0.5 0.4 15.8 0.4 5.9

Spawning Stock Biomass 2 8.1 6.0 5.6 4.9 4.5 5.2 6.2 5.9 5.7 7.1 20.1 3.9 8.0 Recruitment (age 1) 15.1 7.4 7.5 15.6 14.2 8.3 7.5 13.5 8.7 8.7 71.6 7.4 25.2 F (ages 4-5) 0.70 0.63 0.55 0.46 0.37 0.42 0.34 0.24 0.09 0.05 1.16 0.05 0.65

1: Over the period 1981-2010 2: On March 1 annually



### Stock Distribution and Identification: Winter flounder ( Pseudopleuronectes americanus ) is a demersal flatfish species commonly found in No rth Atlantic estuaries and on the continental shelf. The species is distributed between the Gu lf of St. Lawrence, Canada and North Carolina, U.S., although it is not abundant south of Delaware Bay. Inform ation from tagging, meristics, and life history studies suggest extensive mi xing occurs among the localized Southern New England and Mid-Atlantic populations, and so the populations in the region are combined into a single stock complex for assessment purposes. Within the SNE/MA st ock complex, winter flounder undergo annual migrations from estuaries, where spawning occurs in the late winter and spring, to offshore shelf areas of less than 60 fa thoms (110 meters). The current SNE/MA stock complex extends from the coastal shelf east of Provincetown, MA sout hward along the Great South Channel (separating Nantucket Shoals a nd Georges Bank) to the southern geographic limits of winter flounder off Delaware.

Data and Assessment: The age-structured assessment model for SNE/MA winter flounder has changed from an ADAPT VPA model to an AS AP SCAA model (NFT 2011). A new value for natural mortality has been adopte d, changing from M = 0.20 to M = 0.30 for all ages and years. New biological reference points have th erefore also been estimated, with F MSY 

### , SSB MSY 

### , and MSY now based on a stock-recruitment model. Indices of recruitm ent and stock abundance from the NEFSC winter, spring, and fall, Massachus etts spring, Rhode Isla nd spring, University of Rhode Island, Connecticut spri ng, Delaware and New Jersey tr awl surveys were used in the ASAP calibration.52 nd SAW A. Southern New England W inter Flounder 13 

### Biological Reference Points (BRP): F MSY 

### , SSB MSY 

### , and MSY were estimated from a stockrecruitment model using a range of values for steepness (slope of the stock recruitment curve near the origin) which was consistent with the stock-recruitment data. It is anticipated that steepness should be similar betw een the three stocks. Therefore, when computing the BRPs, values of steepness were chosen which were cons tructed to be as similar as possible between stocks, while also providing good fits to the st ock recruitment data for each stock. For the SNE/MA stock, steepness was set at 0.6. These BRP estimates are direct MSY based estimates. The recommended biological reference poi nts for SNE/MA winter flounder are F MSY 

### = F THRESHOLD 

### = 0.290, SSB MSY 

### = B TARGET 

### = 43,661 mt, 1/2 SSB MSY 

### = B THRESHOLD 

### = 21,831 mt, and MSY = 11,728 mt. For comparison, F 40% 

### computed using the same biological and fishery characteristics is 0.327, with SSB 40% 

### = 29,045 mt and MSY 40% 

### = 8,903 mt (Figures A5-A7).

Fishing Mortality: During 1981-1993, fishing mortality (F ages 4-5) varied between 0.61 (1982) and 0.95 (1993) and then decreased to 0.47 by 1999. Fishing mortality then increased to 0.70 by 2001, and then decreased to 0.05 in 2010, genera lly tracking the decrea se in fishery catch (Figure A8). The fishery sel ectivity pattern during 1981-1993 was estimated to be 0.01 at age 1, 0.24 at age 2, 0.75 at age 3, was fixed at 1.00 at ag e 4, was estimated at 1.00 at age 5, 0.99 at age 6, and 1.00 at age 7+. The patt ern during 1994-2010 was estimated to be 0.01 at age 1, 0.19 at age 2, 0.70 at age 3, was fixed at 1.00 at age 4, was estimated at 0.97 at age 5, 0.89 at age 6, and 0.67 at age 7+. There is an 80% probability that F for ages 4-5 in 2010 was between 0.04 and 0.06 (Figure A9). Retrospective an alysis for the 2003-2010 terminal years indicates retrospective error in fishing mortality ranged fr om -38% in 2006 to -13% in 2009.

Recruitment: Recruitment at age 1 decreased nearly continuously from 71.6 million age-1 fish in 1981 (1980 year class) to 7.5 million fish in 2002 (2001 year class). Recruitment has averaged 10.5 million during 2003-2010 (Figure A10). Retrospective error in recruitment at age 1 ranged from +78% in 2005 (2004 year clas s) to -11% in 2009 (2008 year class).

Spawning Stock Biomass: SSB decreased from 20,100 mt in 1982 to a record low of 3,900 mt in 1993 and then increased to 8,900 mt by 2000. SSB has varied between 4,500-8,000 mt during 2001-2009 and was 7,076 mt in 2010 (Figure A10). Th ere is an 80% probability that SSB in 2010 was between 6,433 mt and 8,590 mt (Figure A11) . Retrospective error in SSB ranged from +42% in 2004 to +12% in 2009.

Special Comments: A considerable source of vulnerability for SNE/MA winter flounder is the continued weak recruitment and low reproductive rate (e.g., recruits per spawner). Recruitment estimates for the last decade are lower than those predicted by the stock recruitment model (Figures A5 and A12). If the w eak recruitment and low reproductiv e rate continues, productivity and rebuilding of the stock w ill be less than projected.

Stock-recruit modeling suggests that warm winter temperatures can have a negative effect on recruitment of SNE/MA winter flounder.52 nd SAW A. Southern New England W inter Flounder 14 

### References:

NEFSC. 2008. Assessment of 19 Northeast groun dfish stocks through 2007. Report of the 3 rd 

### Groundfish Assessment Review Meeting (GAR M III), Northeast Fisheries Science Center, Woods Hole, Massachusetts. Augus t 4-8, 2008. NEFSC Ref Doc. 08-15. 884 p.

NOAA Fisheries Toolbox (NFT) 2011. Age Struct ured Assessment Program (ASAP), version 2.0.21. [Internet address: http://n ft.nefsc.noaa.gov/ASAP.html ].52 nd SAW A. Southern New England W inter Flounder 15 

## SNE/MA Winter flounder stock status

Spawning Stock Biomass (000s mt) 0 2 4 6 8 10 12 14 16 18 20 22 24 26 28 30 32 34 36 38 40 42 44 46 48 50Fishing Mortality (F ages 4-5)

0.0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1.0 1/2 SSBMSY = Bthreshold = 21,831 mt

FMSY = Fthreshold = 0.290 SSBMSY = Btarget = 43,661 mt

SAW 52



### A1. 2011 SAW 52 stock status in 2010 for SNE/ MA winter flounder with respect to MSY-based BRPs; error bars on SSB a nd F are 80% confidence intervals.52 nd SAW A. Southern New England W inter Flounder 16 

### A2. Estimated trend in Fishing Mortality and associated BRPs for SNE/MA winter flounder. ASAP CAT10 is the 2011 SAW 52 final a ssessment model. The MSY-based BRP is recommended for stock status determination. 0.0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1.0 1.1 1.2 1.3 1.4Fishing Mortality (age 4-5)

Year 

### SNE/MA Winter Flounder

ASAP CAT10 FMSY F40%52 nd SAW A. Southern New England W inter Flounder 17 

### A3. Estimated trend in Spawning Stock Bioma ss (SSB) and associated BRPs for SNE/MA winter flounder. ASAP CAT10 is the 2011 SA W 52 final assessment model. The MSY-based BRP is recommended for stock status determination. 0 5,000 10,000 15,000 20,000 25,000 30,000 35,000 40,000 45,000 50,000SSB (metric tons)

Year 

### SNE/MA Winter Flounder

ASAP CAT10 SSBMSY SSB40%52 nd SAW A. Southern New England W inter Flounder 18 

# SNE/MA Winter flounder

Landings and Discards

Year 1960 1965 1970 1975 1980 1985 1990 1995 2000 2005 2010000s mt



## 0 2000 4000 6000 8000 10000 12000 14000 16000

Comm Land Comm Disc Rec Land Rec Disc Total Catch



### A4. Commercial landings (1964-2010) , commercial discards (1981- 2010), recreational landings (1981-2010), recreational discar ds (1981-2010), and total fi shery catch (1981-2010) for SNE/MA winter flounder.52 nd SAW A. Southern New England W inter Flounder 19 

### A5. Final stock-recruitment model for SNE/MA winter flounder. Spawning stock is in mt; recruitment is in thousands of age-1 fish.52 nd SAW A. Southern New England W inter Flounder 20 

### A6. Comparison of fishing mortality versus total yield relationship for st ock-recruitment model based BRPs (F MSY 

### , MSY) and yield per recruit model based BRPs (F 40%, 

### MSY 40% 

### ).52 nd SAW A. Southern New England W inter Flounder 21 

### A7. Comparison of fishing mortality versus SSB re lationship for stock-recruitment model based BRPs (F MSY 

### , SSB MSY 

### ) and yield per recruit model based BRPs (F 40% 

### , SSB 40% 

### ).52 nd SAW A. Southern New England W inter Flounder 22 

# Year 1960 1970 1980 1990 2000 2010000s mt



# 0 5 10 15 20F (age 4-5)



# 0.0 0.5 1.0 1.5 

# Total Catch and Fishing Mortality

Total Catch

F (age 4-5) 

# SNE/MA Winter flounder

Comm. Land.

A8. Total catch (landings and discards, 000s mt ), commercial landings (000s mt) and fishing mortality rate (F, age 4-5) for SNE/MA winter flounder.52 nd SAW A. Southern New England W inter Flounder 23 

### A9. MCMC distribution of the es timate of the 2010 Fishing Mo rtality of SNE/MA winter flounder.52 nd SAW A. Southern New England W inter Flounder 24 

# Recruitment and Biomass Year 1980 1985 1990 1995 2000 2005 2010SSB (000s mt)



# 0 5 10 15 20 25Recruitment (age 1, millions)



# 0 10 20 30 40 50 60 70 

# SSB and Recruitment

Recruitment

SSB 

# SNE/MA Winter flounder

A10. Spawning stock biomass (SSB, 000s mt, solid li ne) and recruitment (millions of fish at age-1, vertical bars) fo r SNE/MA winter flounder.52 nd SAW A. Southern New England W inter Flounder 25 

### A11. MCMC distribution of the estimate of the 2010 Spawni ng Stock Biomass (SSB) of SNE/MA winter flounder.52 nd SAW A. Southern New England W inter Flounder 26 

### A12. Time series trend in Recruits per Spawner (R/S) for SNE/MA winter flounder; most recent years are on the right side of the plot.52 nd SAW B. Georges B ank Winter Flounder 27 

### B. GEORGES BANK WINTER FLO UNDER ASSESSMENT SUMMARY FOR 2011

State of Stock: In 2010, the stock was not overfished a nd overfishing was not occurring, based on the new biological reference point (BRP) estimates of: F MSY 

### (F THRESHOLD 

### ) = 0.42, SSB MSY 

### (B TARGET 

### ) = 10,100 mt, and 1/2 SSB MSY 

### (B THRESHOLD 

### ) = 5,050 mt, MSY = 3,700 mt. The 2010 estimate of spawning stock biomass (SSB ) is 9,703 mt, which is well above the B THRESHOLD 

### and at 96.1% of the B TARGET 

### . The 2010 estimate of fishing mortality (average F on ages 4-6) is 0.15 and is well below the F THRESHOLD 

### of 0.42 (Figure B1). There wa s an 80% probability that the 2010 average F was between 0.12 and 0.21 and th at the 2010 SSB estimate was between 7,304 mt and 12,578 mt.

Given the new model and assumptions in th e current assessment, comparison of the 2010 estimates of SSB and F with the existing refere nce points is not appropriate. The BRPs derived from the 2008 assessment (NEFSC 2008) were: F 40% 

### (F THRESHOLD 

### ) = 0.26, SSB 40% 

### (B TARGET 

### ) = 16,000 mt, 1/2 SSB 40% 

### (B THRESHOLD 

### ) = 8,000 mt, and MSY 40% 

### = 3,500 mt.

Projections: A projection of future st ock status was made based on the VPA results using mean weights, maturity, and fishery selectivity patter ns at age estimated for the most recent 5 years (2006-2010) to reflect current conditions in the stock and fisher y. Stochastic projections were run for 2011-2017 because rebuilding of the stock, with at least 75% probability, is required by 2017. Recruitment was projected using the results fr om a Beverton-Holt stoc k-recruitment model, which fixed steepness ( h ) at 0.78, resulting in an F MSY 

### estimate of 0.42. The projections assumed the FMP Framework 44 fishing year (May 1) cat ch of 2,118 mt would be landed as a calendar year (Jan 1) catch in 2011.

The projection results indi cate that rebuilding to SSB MSY 

### (= 10,100 mt) is expected to be achieved with 76% probability in the current year (2011), assuming a 2011 catch of 2,118 mt.

Catch: Total landings during 1964-2010 were predominately from the U.S groundfish trawl fishery, with lesser amounts re ported by the USSR (during 1965-1977), for the U.S scallop dredge fishery, and as bycatch in the Canadian bottom trawl fi sheries for cod and haddock (1- 24% of the total). Total landings reached a peak of 4,500 mt in 1972, and averaged 3,200 mt during 1973-1984, but then declined to their lo west level (780 mt) in 1995 (Figure B2). Following an increase to 3,100 mt in 2003, landing s declined to 800 mt in 2007. Landings were 1,000 mt in 2008 and 1,300 mt in 2010. During 1995- 2010, the proportional standard error (%) due to the allocation of Georges Bank winter fl ounder landings to Statistical Areas using Vessel Trip Reports, ranged between 0.7 and 1.3%.

U.S. discards during 1989-2010 were estimated using the Standardized Bycatch Reporting Methodology (Wigley et al. 2007) and were hind cast for 1964-1988. Discards for the Canadian scallop dredge fleet were estimated by the CA Division of Fisheries and Oceans for 2004-2010 and were hindcast for 1982-2003. Discards from the Canadian groundfish trawl fleet were not available. During the assessment period, 1982-2010, to tal discards of wint er flounder averaged 15% of the total landings. Discards were hi gher during 1982-1991 than thereafter and were primarily from U.S. fisheries (i.e., primarily from the large mesh ( ≥ 5.5 in. codend mesh size) fleet during 1964-1975 and the sc allop dredge fleet during 1976-2010). However, after 1991,52 nd SAW B. Georges B ank Winter Flounder 28 

### discards were primarily from the Canadian sca llop dredge fishery. Total discards have slowly increased since 1995. The precision (CVs) of U.S. discard estimates for 1992-2010 ranged between 0.09 and 0.49 (average = 0.26), but the precision of the Canadian estimates is unknown.

Catches during 1964-2010 and were dominated by landings fro m the U.S. groundfish bottom trawl fleet. Catches increased during 1964-1972, reaching a peak of 4,600 mt in 1972, but then declined to 2,000 mt in 1976 (Figure B3). Du ring 1977-1984 catches ranged between 3,300 and 4,300 mt then gradually declined to a time seri es low of 800 mt in 1995. Catches increased again to 3,300 mt in 2003 then declined to 1,000 mt in 2007, followed by a slight increase to 2,000 mt in 2009. Total catch in 2010 was 1,500 mt. Catches pr ior to 1964 were likely higher because U.S. landings alone reached a peak of 4,100 mt in 1945, close to the 1964-2010 peak catch of 4,600 mt and without accounting for discards or landings from international fleets.

Catch and Status Table (weights in 000s mt, recruitment in millions , arithmetic means): Georges Bank Winter flounder

Year 2001 2002 2003 2004 2005 2006 2007 2008 2009 2010 Max 1 Min 1 Mean 1

U.S. landings 1.7 2.1 2.8 2.7 2.0 0.8 0.8 0.9 1.7 1.3 4.0 0.7 2.1 CA landings 0.5 0.2 0.3 0.2 0.1 0.1 <0.1 <0.1 <0.1 <0.1 0.5 <0.1 0.1 Total 2.2 2.3 3.1 2.9 2.1 0.9 0.8 0.9 1.7 1.3 4.5 0.8 2.3 U.S. discards <0.1 <0.1 <0.1 0.1 0.1 0.1 0.2 0.1 0.1 0.1 0.3 <0.1 0.1 CA discards 0.2 0.2 0.2 0.1 0.1 0.1 <0.1 0.1 0.3 0.1 0.3 <0.1 0.1 Total 0.2 0.2 0.2 0.2 0.2 0.2 0.2 0.2 0.4 0.2 0.5 0.1 0.2 U.S. catch 1.7 2.1 2.8 2.8 2.1 0.9 1.0 1.0 1.8 1.4 4.3 0.7 2.2 CA catch 0.7 0.4 0.5 0.3 0.2 0.2 <0.1 0.1 0.3 0.1 0.7 0.0 0.2 Total 2.4 2.5 3.3 3.1 2.3 1.1 1.0 1.1 2.1 1.5 4.3 0.8 2.4 Spawning Stock Biomass 2 10.7 10.2 9.5 5.5 5.3 5.9 6.2 6.5 7.9 9.7 17.4 26.3 1.2 10.7 Recruitment (age 1) 9.0 7.3 6.1 5.5 5.6 10.5 15.6 18.8 4.0 22.5 3.4 4.0 0.2 9.0 F (ages 4-6) 0.52 0.55 0.85 0.63 0.56 0.20 0.21 0.23 0.23 0.15 7.9 13.4 0.5 0.52

1 During 1964-2010 for landings (includes pre- 2001 USSR landings), discards (no CA disc ards available prior to 1982) and catches ; during 1982- 2010 for F, SSB and R

2 On April 1 annually



### Stock Distribution and Identification: Winter flounder ( Pseudopleuronectes americanus ) is a demersal flatfish species commonly found in Nort h Atlantic estuaries a nd on the continental shelf. The species is distributed between the Gu lf of St. Lawrence, Canada and North Carolina, U.S., although it is not abundant south of Dela ware Bay. On Georges Bank, winter flounder are generally found at depths less than 82 m (Co llette and Klein-MacPhee 2002). Tagging studies (e.g., Howe and Coates 1975) indicate that th ere is limited mixing of fish among the three current stock units, with about 1%-3% between the GOM and SNE/MA, about 1% between GBK and SNE/MA, and <1% between GOM and GBK. Meristics studies base d mainly on fin ray counts also indicate a separate Georges Bank st ock (Kendall 1912; Perl mutter 1947; Lux et al 1970). Growth and maturity studies also support the distin ction of at least th ree stock areas (Lux 1973; Howe and Coates 1975; Witherell and Burne tt 1993), with Georges Bank fish growing and maturing the fastest. The stock area extends fr om Georges Bank westward to about midway along the Great South Channel.

Data and Assessment: Similar to the 2008 assessment (NEFSC 2008), an ADAPT VPA model was run with catch-at-age data (ages 1-7+) for 1982-2010. Swept-area stock abundance from the52 nd SAW B. Georges B ank Winter Flounder 29 

### NEFSC spring and fall surveys (1982-2010) and the Canadian spring surveys (1987-2010), for ages 1-7+, were used in the VPA calibration. Fo r the U.S. surveys, length-based, stock-specific calibration coefficients were used to convert catches by the SRV H.B. Bigelow to SRV Albatross IV catches. Major model changes included: the a ddition of discards from the Canadian scallop dredge fleet, a new maturity schedule, a new as sumption for the instantaneous natural mortality rate (M = 0.3 instead of 0.2), and new MSY-ba sed biological reference points (BRPs).

Biological Reference Points: F MSY 

### , SSB MSY 

### , and MSY were estimated from a stock-recruitment model using a range of fixed values (Table B1 ) for steepness (slope of the stock recruitment curve near the origin) which was consistent w ith the stock and recru itment data. Based on the assumption that steepness should be similar between the three winter flounder stocks, values of steepness were chosen which were constructed to be as similar as possi ble between stocks, but which also provided good fits to the stock-recrui tment data for each stock. For the Georges Bank stock, steepness was set at 0.78 (further deta ils in Appendix of the 2011 SAW-52 Stock Assessment Report). The new BRP estimates are direct MSY-based estimates. The recommended biological re ference points are: F MSY 

### = F THRESHOLD 

### = 0.42, SSB MSY 

### = B TARGET 

### = 10,100 mt, 1/2 SSB MSY 

### = B THRESHOLD 

### = 5,050 mt, and MSY = 3,700 mt. For comparison, F 40% 

### , computed using the same biological a nd fishery characteristics, is 0.32, SSB 40% 

### is 11,300 mt, and MSY 40% 

### is 3,200 mt.

The existing biological reference points fr om the 2008 assessment (NEFSC 2008) are: F 40% 

### (F THRESHOLD 

### ) = 0.26, SSB 40% 

### (B TARGET 

### ) = 16,000 mt, 1/2 SSB 40% 

### (B THRESHOLD 

### ) = 8,000 mt, MSY 40% 

### = 3,500 mt. However, given the new model assumptions in the current assessment (assumed M = 0.3 rather than 0.2), comparison of the 2010 estimates of SSB and F estimates with the existing reference points is not appropriate.

Fishing Mortality: Fishing mortality (fully recruited F, ages 4-6) increased from 0.42 in 1982 to a peak of 1.2 in 1984, and then ranged between 0.57 and 0 .92 during 1985-1993 (Figure B4). Fishing mortality decreased to 0.26 in 1999, but then increased again to 0.85 in 2003. Following a decline to 0.20 in 2006, fishing mortality remain ed stable at low le vels (0.21-0.23) during 2007-2009, and then declined to a record low of 0.15 in 2010. A retrospec tive analysis for the 2001-2009 terminal years indicated th at the retrospective error in fishing mortality ranged from -48% in 2002 to +42% in 2009.

Spawning Stock Biomass: SSB decreased from a peak of 17 ,400 mt in 1982 to a record low of 3,400 mt in 1995, and then increased again to 13,800 mt in 2000. SSB varied between 5,300 and 10,700 mt during 2001-2009, and was 9,703 mt in 2010 (Fi gure B5). Retrospective error in SSB ranged from -13% in 2008 to +43% in 2002.

Recruitment: Recruitment at age 1 increased from 13.8 million fish in 1982 to a peak of 26.3 million fish in 1988, but then declined to 5.2 milli on fish in 1993 (Figure B6). Recruitment has averaged 10.5 million during 2003-2010. Retrospectiv e error in recruitment at age 1 (R) ranged from +78% in 2005 (2004 year class) to -11% in 2009 (2008 year class).52 nd SAW B. Georges B ank Winter Flounder 30 

### Special Comments: Stock-recruitment data showed no significant relationship with temperature or other environmental factors examined, unlik e the SNE/MA winter flounder stock.

The stock-recruitment data for this stock are less informative than the SNE/MA data for predicting recruitment at low spawner levels making estimation of the spawner-recruit relationship difficult without extern al information (Table B1).

The revised assessment model alters the historical perception of stock status. Four changes from the previous assessment are: 1) a change of M fr om 0.2 to 0.3 and 2) a new maturity schedule, 3) the addition of Canadian discards , and 4) a change to MSY-base d BRPs rather than proxies. The assessment indicates that the st ock has not been overfished sinc e 1996. This contrasts with the 2008 assessment which indicated the stock was overfished in 2007.

References:

Collette, B. and G. Klein-MacPhee. 2002. Bigelow a nd Schroeder’s Fishes of the Gulf of Maine. 3 rd 

### Ed. Smithsonian Institution Pre ss. Washington, D.C., USA. 748 p.

Howe, A.B. and P.G. Coates. 1975. Winter fl ounder movements, growth, and mortality off Massachusetts. Trans. Am. Fish. Soc. 104(1):13-29.

Kendall, W.C. 1912. Notes on a new species of flatfish from off the coast of New England. Bull. U.S. Bureau Comm. Fish. 30: 391-394.

Lux, F.E. 1973. Age and growth of the winter flounder, Pseudopleuronectes americanus , on Georges Bank. Fish. Bull

. 71(2): 505-512.

Lux, F.E., A.E. Peterson, Jr., and R.F. Hutton. 1970. Geographical variation in fin ray number in winter flounder, Pseudopleuronectes americanus (Walbaum) off Massachusetts. Trans. Am. Fish. Soc. 99: 483-488.

NEFSC. 2008. Assessment of 19 Northeast groun dfish stocks through 2007. Report of the 3 rd 

### Groundfish Assessment Review Meeting (GAR M III), Northeast Fisheries Science Center, Woods Hole, Massachusetts. Augus t 4-8, 2008. NEFSC Ref Doc. 08-15. 884 p.

Perlmutter, A. 1947. The blackback flounder and its fishery in New England and New York.Bull. Bingham Oceanog. Collection, Yale University 11(2), 92 p.

Wigley, S.E., P.J. Rago, K.A. Sosebee, and D.L. Palka. 2007. The analytic component to the Standardized Bycatch Reporting Methodol ogy Omnibus Amendment: sampling design and estimation of precision and accuracy (2 nd 

### ed.). Northeast Fish. Sci Cent. Rec. Doc. 07-09. 156 p.

Witherell DB, Burnett J. 1993. Growth and maturation of winter flounder, Pseudopleuronectes americanus, in Massachusetts. Fish. Bull. 91: 816-820.52 nd SAW B. Georges B ank Winter Flounder 31 

### Table B1. AIC profile for unfished steepness ( h ) values from Beverton-Holt stockrecruitment models for the 1982-2009 year classes of Georges Bank winter flounder.

Fixed

AIC

( h ) F MSY 

### SSB MSY 

### MSY 0.60 583.217 0.26 19,785 4,910 0.65 581.230 0.30 15,144 4,318 0.70 579.698 0.34 12,437 4,003 0.75 578.518 0.38 10,673 3,824 0.76 578.317 0.39 10,341 3,799 0.77 578.126 0.41 9,798 3,777 0.78 577.945 0.42 9,524 3,757 0.79 577.774 0.43 9,269 3,740 0.80 577.611 0.44 9,030 3,725 0.85 576.917 0.51 7,742 3,678 0.90 576.390 0.60 6,621 3,672
0.95 575.996 0.74 5,476 3,70652 nd SAW B. Georges B ank Winter Flounder 32 

### B1. Stock status for Georges Bank wint er flounder, during 2010, based on F MSY 

### and SSB MSY 

### reference points. 80% confidence intervals are shown for the 2010 SSB and F estimates.52 nd SAW B. Georges B ank Winter Flounder 33 

### B2. Landings of Georges Bank winter flounder, by country, during 1964-2010.

B3. U.S. landings of Georges Bank winter fl ounder during 1937-1950 and total landings and catches during 1964-2010.52 nd SAW B. Georges B ank Winter Flounder 34 

### B4. Trends in average fishing mortality rates (age s 4-6) for Georges Bank winter flounder during 1982-2010. The MSY-based BRP is recommen ded for stock status determination.

B5. Trends in spawning stock biomass (SSB, 000s mt) for Georges Bank winter flounder during 1982-2010. The MSY-based BRP is recommen ded for stock status determination.52 nd SAW B. Georges B ank Winter Flounder 35 

### B6. Trends in age 1 recruitment (Jan. 1 stock numbers in millions) for Georges Bank winter flounder during 1982-2011.52 nd SAW C. Gulf of M aine Winter Flounder 36 

### C. GULF OF MAINE (GOM) WINTER FLOUNDER ASSESSMENT SUMMARY FOR 2011

State of Stock: The assessment of GOM winter flounder stock is based on an empirical swept-area model utilizing data from the 2010 NEFSC fall surve y, the MADMF fall survey, and the Maine-New Hampshire fall inshore survey. Using a survey tr awl efficiency value of 0.6 the estimated stock biomass in 2010 of fish greater than 30 cm was 6,341 mt (80% CI 4,230 - 8,800 mt). The overfished status remains unknown because a biomass reference point or proxy could not be determined and an analytical assessment model was not accepted.

In 2010 overfishing was not occurring for the stock (Figure C1). A proxy BRP value of the overfishing threshold was derived fr om a length-based yield per recr uit analysis that assumes all fish above 30 cm are fully recruited to the fish ery and that natural mortality is 0.3. Using F 40% 

### (0.31) as a proxy for F MSY 

### , the corresponding threshold exploita tion rate is 0.23. The overfishing status is based on the ratio of 2010 catch (195 mt) to survey based swept area estimate of biomass for winter flounder exce eding 30 cm in length (6,341 mt). Exploitation rate in 2010 was estimated at 0.03 (80% CI 0.02 - 0.05), which is le ss than the threshold ex ploitation rate (0.23). The conclusion that overfishing was not occurring in 2010 is robust to the range of uncertainty in the biomass estimate (Figures C7 and C8).

The biomass estimate for 2010 is 16% lower than that for 2009 using the same survey methods but this difference is not statistica lly significant (Figures C3 and C5).

The most recent biological referenc e points for this stock were F MSY 

### =0.43 and B MSY 

### =4,100 mt; these estimates came from the assessment at SA RC 36 in 2003. It is not appropriate to compare the 2010 exploitation rate and stoc k size estimates to those earl ier BRP values which should no longer be used.

Projections: Projections were not possible.

Catch: Commercial landings were near 1,000 mt from 1964 to the mid 1970s. Thereafter commercial landings increased to a peaked of 2,793 mt in 1982, and then steadily declined to 350 metric tons (mt) in 1999 (Figure C2). La ndings have been near 650 mt from 2000 to 2004 and about 300 mt from 2005 to 2009. Landings have d eclined to a record low of 140 mt in 2010. Recreational landings reached a p eak in 1981 with 2,554 mt but declin ed substantially thereafter. Recreational landings have generally been le ss than 100 mt since 1994, with exception of 2008 where the landings were estimated at 103 mt. A discard mortality of 15% was assumed for recreational discards. Discards were estimat ed for the large mesh trawl (1982-2010), gillnet (1986-2010), and northern shrimp fishery (1982- 2010). A discard mortality of 50% was assumed for commercial fishery. In general the total discards are a small percentage (time series average 11%) of the total catch (Figure C2). There has been a substantial decline in the total catch compared to the early 1980s (recent catch is roughly 5% of the 1980s catch).52 nd SAW C. Gulf of M aine Winter Flounder 37 

### Catch Table (weights in 000s mt,): GOM Winter Flounder

Year 2001 2002 2003 2004 2005 2006 2007 2008 2009 2010 Max 1 Min 1 Mean 1

Commercial landings 0.7 0.7 0.8 0.6 0.3 0.2 0.3 0.3 0.3 0.1 2.8 0.1 0.9 Commercial discards <0.1 <0.1 <0.1 <0.1 <0.1 <0.1 <0.1 <0.1 <0.1 <0.1 0.4 <0.1 0.1 Recreational landings <0.1 <0.1 <0.1 <0.1 <0.1 <0.1 <0.1 0.1 0.1 <0.1 3.0 <0.1 0.5 Recreational discards <0.1 <0.1 <0.1 <0.1 <0.1 <0.1 <0.1 <0.1 <0.1 <0.1 <0.1 <0.1 <0.1 Catch used in
assessment 0.8 0.7 0.8 0.7 0.4 0.2 0.3 0.4 0.4 0.2 6.2 0.2 1.3

1: Over the period 1982-2010



### Stock Distribution and Identification: Winter flounder ( Pseudopleuronectes americanus ) is a demersal flatfish species commonly found in No rth Atlantic estuaries and on the continental shelf. The species is distributed between the Gu lf of St. Lawrence, Canada and North Carolina, U.S., although it is not abundant south of Delaware Bay. Gulf of Maine winter flounder undergo annual migrations from estuaries an d near shore areas, where spawni ng occurs in th e late winter and early spring, to offshore shelf areas of less th an 60 fathoms (110 meters). The current Gulf of Maine stock extends from the coastal shelf ea st of Provincetown, MA northward to the Bay of Fundy, including NEFSC sta tistical areas 511-515.

Data and Assessment: GOM winter flounder models deve loped in ADAPT VPA, SCALE, and ASAP (NFT 2011) were too unre liable for stock status determ ination. The population models have difficulty with the conflicting data trends within the assessment, specifically the large decrease in the catch over the time series with very little change in the indi ces or age structure in both the catch and surveys. A new value for natural mortality has been adopted, changing from M = 0.20 to M = 0.30 which was used in the estimation of the F 40% 

### reference point. A combined survey 30+ cm biomass area swept estimate using the NEFSC, MADMF and the Maine-New Hampshire surveys was used to estimate biomass. The fall surveys were selected over the spring surveys because some portion of the stock is lo cated within estuaries, which are not surveyed during the spring.

Uncertainty in the individual estim ates of survey abundance and swep t area trawl footprints were characterized empirically and used to construc t an overall estimate of uncertainty in the aggregate biomass estimate. The efficiency value of 0.6 was supported by comparison of VPA estimates of efficiency for the Georges Bank winter flounder while making the assumption that the same fraction of each stock is available to the respective surveys. The NEFSC fall survey (expressed in Albatross equivale nts) had an efficiency estimat e of 0.3. Calibration experiments between the FSV Bigelow and the R/V Albatross revealed a biomass conversion coefficient of ~2. Thus an efficiency estimate for the Bigelo w survey estimate in 2010 of 0.6 was supported. An analysis of catch rates in overlappi ng areas by the NEFSC and MADMF surveys demonstrated similar catchabilities for winter flounder by the two surveys. Sensitivity analyses were conducted with efficiencies of 0.8 and 1.0. The sampling distributions of biomass and fishing mortality are approximated by integratin g over the factors which constitute the primary sources of uncertainty. These factors include the sampling variability in the NEFSC, MADMF and the Maine-New Hampshire spring and fall bottom surveys for 2009 and 2010. The second major source of variability for the survey estimate s is the variation in th e size of the area swept by an average tow.52 nd SAW C. Gulf of M aine Winter Flounder 38 

### Biological Reference Points (BRP): Biological reference poi nts for stock biomass are unknown.

A proxy value of the overfishing threshold wa s derived for the 2011 assessment from a lengthbased yield per recruit (N FT 2011) analysis that assumes all fi sh above 30 cm are fully recruited to the fishery and that natural mortality is 0.3 (Figure C4). Von Bertalanffy parameters were estimated from the spring and fall NEFSC surv ey age data (n = 2,035) from 2006 to 2010. Maturity at length information is estim ated from the spring MDMF survey (L 50 

### =29cm). The reference points were converted to exploitation rates to be consis tent with the swept area biomass approach. Using F 40% 

### (0.31) as a proxy for F MSY 

### , the corresponding threshol d exploitation rate is 0.23. This serves as a proxy for th e overfishing threshold (Figure C1 ). Current prac tice is to set catch advice based on 75% F MSY 

### . 75% of the estimated F 40% 

### exploitation rate is 0.17. The previous estimates of F MSY 

### (from SARC 36 in 2003) used an M of 0.2 and observed average weights at age.

MSY could not be estimated.

Fishing Mortality: Exploitation rate in 2010 was estim ated at 0.03 (80% CI 0.02 - 0.05) using the 2010 ratio of catch (195 mt) to the 30+ area swept biomass (6,341 mt; 80% CI 4,230 - 8,800 mt) from the fall surveys (Figure C6). An assume d efficiency of 60% was used to construct this estimate from the NEFSC fall survey, the MADMF fall survey, and the Maine-New Hampshire fall inshore survey.

Recruitment: Recruitment is unknown.

Spawning Stock Biomass: Spawning stock biomass is unknown.

Special Comments: There is considerable uncertain ty with the GOM winter flounder assessment. There was a major effort to deve lop an ASAP assessment model for GOM winter flounder; however, no version of the model was satisfactory. The attempted analytical models had difficulty estimating population scale due to the conflicting data trends within the assessment, specifically the larg e decrease in the catch over the time series with very little change in the indices or age structure in bot h the catch and surveys. The scaling of the population estimates was sensitive to the weightin g imposed on the catch at age compositions. The ASAP model did allow errors in the fit to the catch at age and improved fit to the survey indices without the split in survey catchability (See GARM III). However this resulted in a lack of fit to the plus group in the catch at ag e composition. The stock assessment report will summarize the ASAP model applic ation, but its results are not used for the determination of stock status.

An analytic assessment was not accepted in GAR M III (NEFSC 2008) resulting in the status of the stock being unknown in 2008.52 nd SAW C. Gulf of M aine Winter Flounder 39 

### References:

NEFSC. 2008. Assessment of 19 Northeast groun dfish stocks through 2007. Report of the 3 rd 

### Groundfish Assessment Review Meeting (GAR M III), Northeast Fisheries Science Center, Woods Hole, Massachusetts. Aug. 4-8, 2008. NEFSC Ref Doc. 08-15. 884 p.

NOAA Fisheries Toolbox (NFT) 2011. [Interne t address: http://nft.nefsc.noaa.gov/].52 nd SAW C. Gulf of M aine Winter Flounder 40 

### GOM Winter Flounder Overfishing status

30+ cm Exploitable Biomass (000s mt) 0123456789Exploitation Rate

0.00 0.05 0.10 0.15 0.20 0.25 0.30



### 2010 Exploitation Rate Threshold = 0.23

C1. Stock status for GOM winter flounder in 2010 with respect to a proxy for F MSY 

### . 80% confidence intervals are shown for biomass and exploitation rate. F 40% 

### = 0.31, which corresponds to an exploitation rate of 0.23.52 nd SAW C. Gulf of M aine Winter Flounder 41 

### C2. GOM winter flounder composition of the catc h by weight in metric tons from 1982 to 2010. 

## Catch Weight

0 1,000 2,000 3,000 4,000 5,000 6,000198219841986198819901992199419961998200020022004200620082010metric tons 

### Shrimp Disc
LG Mesh Disc
Gillnet Disc
Rec Disc
Rec
Com52 nd SAW C. Gulf of M aine Winter Flounder 42 

### Area Swept 30+ cm Biom ass Survey Components

Sp r in

g 2009
Sp r in

g

2010 Fall 2

009 Fall 2

01030+ cm Area Swept Biomass (mt)



### 0 2000 4000 6000 8000

MENH NEFSC MDMF



### C3. 30+ cm area swept biomass estimates for the spring and fall surveys from 2009 to 2010 assuming efficiency is 0.6. The NEFSC survey used a TOGA tow criteria of 132x.52 nd SAW C. Gulf of M aine Winter Flounder 43 

### C4. Length-based yield per recruit analysis usin g von Bertalanffy parameters estimated from the spring and fall 2006-2010 NEFSC surveys, matur ity at length from the MDMF survey and assuming a natural mortality of 0.3. F 40% 

### was estimated at 0.31. The SSB/R line (red) decreases as F increases.Yield per RecruitSpawning Stock Biomass per Recruit52 nd SAW C. Gulf of M aine Winter Flounder 44 

### C5. Sensitivity of swept area 30+ cm biomass es timates for Gulf of Maine winter flounder for varying seasons and years under thre e alternative assumed values of trawl efficiency for all three
surveys . 

# B Estimates vs Assumed Efficiency

Fall2009

0.5 0.6 0.7 0.8 0.9 1.0 EFFIC 0 5000 10000 15000 20000

B i o m a s s ( m t ) 

### Fall2010

0.5 0.6 0.7 0.8 0.9 1.0 EFFIC 0 5000 10000 15000 20000

B i o m a s s ( m t )



### Spring2009

0.5 0.6 0.7 0.8 0.9 1.0 EFFIC 0 5000 10000 15000 20000

B i o m a s s ( m t ) 

### Spring2010

0.5 0.6 0.7 0.8 0.9 1.0 EFFIC 0 5000 10000 15000 20000

B i o m a s s ( m t )52 nd SAW C. Gulf of M aine Winter Flounder 45 

### C6. Estimated exploitation rates for Gulf of Maine winter flounder for Fall 2010 based on three assumed gear efficiencies (0.6, 0.8, and 1.0) and 5 levels of catch (the 2010 catch of 195 mt, an assumed quota of 500 mt, assumed quota of 700 mt, 75% OFL of 1,078 mt and the OFL of 1,458 mt based on F 40% 

### ). Dashed lines represent length-base d exploitation rate estimates of F 40% 

### (0.23) and 75% of F 40% 

### (0.17). SSB per recruit is derive d using GOM winter flounder growth and maturation relationships and an assume d knife edge selection curve at 30 cm. 

# Exploitation Estimates: Fall 2010

0.6

0 500 1000 1500 QUOTA 0.0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9

E x p l o i t a t i o n R a t e 

### 0.8

0 500 1000 1500 QUOTA 0.0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9

E x p l o i t a t i o n R a t e



### 1

0 500 1000 1500 QUOTA 0.0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9

E x p l o i t a t i o n R a t e52 nd SAW C. Gulf of M aine Winter Flounder 46 

### C7. Estimated probability of exceeding F MSY 

### proxy (F 40% 

### ), expressed as an exploitation rate of 0.23, and assuming efficiencies of 60%, 80% and 100% based of the fall 2010 survey across a range of quotas. 

## Probability of Exceeding Fmsy Proxy=0.23

0 500 1000 1500 Quota (mt) 0.0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1.0

P r o b a b i l i t y F > F m s y P r o x y



### 60% 80% 100% Efficiency52 nd SAW C. Gulf of M aine Winter Flounder 47 

### C8. Estimated probability of exceeding 75% of F MSY 

### proxy (F 40% 

### ), expressed as an exploitation rate of 0.17, and assuming efficiencies of 60% , 80% and 100% based of the fall 2010 survey across a range of quotas. 

# Probability of Exceeding 75% Fmsy Proxy=0.17

0 500 1000 1500 Quota (mt) 0.0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1.0

P r o b a b i l i t y F > 7 5 % F m s y P r o x y



### 60% 80% 100% Efficiency52 nd SAW Assessment Summary Report Appendix: Terms of Referen ce 48 

### Appendix: Assessment Terms of Reference 

## TORs for SAW/SARC52 (June 6-10, 2011) (file vers.: 12/17/2010)

A. Winter flounder (Southern New England Stock) 1. Estimate catch from all sources including landings and discards. Characterize the uncertainty in these sources of data.

2. Present survey data being considered and/or used in the assessment (e.g., regional indices of abundance, recruitment, state and other surveys, ag e-length data, etc.). Characterize uncertainty in these sources of data.

3. Estimate annual fishing mortality, recruitment and stock biomass (both total and spawning stock) for the time series (integrating results from TOR- 5), and estimate their uncertainty. Include areaswept biomass estimates. Investigate if imp lied survey gear or catchability estimates are reasonable. Include a historical retrospective analysis to allow a comparison with previous assessment results.

4. Perform a sensitivity analysis which examines th e impact of allocation of catch to stock areas on model performance (in TOR-3).

5. Examine the effects of incorporating envir onmental factors in models of population dynamics (e.g., spring water temperatures in an environmentally-explicit stock recruitment function).

6. State the existing stock status definitions fo r “overfished” and “overfi shing”. Then update or redefine biological reference points (BRPs; point estimates or proxies for B MSY , B THRESHOLD , and F MSY ) and provide estimates of their uncertainty. If analytic model-based estimates are unavailable, consider recommending alternative me asurable proxies for BRPs. Comment on the scientific adequacy of existing BRPs and the “new ” (i.e., updated, redefined, or alternative) BRPs.

7. Evaluate stock status (overfished and overfish ing) with respect to the “new” BRPs (from TOR 6), and with respect to the existing BRPs (from a prev ious accepted peer review) whose values have been updated.

8. Develop and apply analytical approaches and data that can be used for conducting single and multi-year stock projections and for computing candidate ABCs (Acceptable Biological Catch; see Appendix to the TORs) under a set of alternative harvest scenarios. If the stock needs to be rebuilt, take that into account in these projections.

a. Provide numerical short-term projections (3-5 yrs, or through the end of the rebuilding period, as appropriate). Each projection s hould estimate and report annual probabilities of exceeding threshold BRPs for F, and probabilities of falling below threshold BRPs for biomass. In carrying out projections, cons ider a range of assumptions about the most important uncertainties in the assessment (e.g ., terminal year abundance, variability in recruitment). b. Take into consideration uncertainties in the assessment and the species biology to describe this stock’s vulnerability (see “Appe ndix to the SAW TORs”) to becoming or remaining overfished, and how this could affect the choice of ABC.

c. Develop plausible hypotheses (e.g., mixing among the three stocks) which might explain any conflicting trends in th e data and undertake scenario analyses to evaluate the consequences of these alternate hypotheses on ABC determination.52 nd SAW Assessment Summary Report Appendix: Terms of Referen ce 49 9. Review, evaluate and report on the stat us of the SARC and Working Group research recommendations listed in recent SARC reviewed asse ssments and review panel reports. Identify new research recommendations.

B. Winter flounder (Georges Bank Stock)

1. Estimate catch from all sources including landings and discards. Characterize the uncertainty in these sources of data.

2. Present survey data being considered and/or used in the assessment (e.g., regional indices of abundance, recruitment, state and other surveys, ag e-length data, etc.). Characterize uncertainty in these sources of data.

3. Estimate annual fishing mortality, recruitment and stock biomass (both total and spawning stock) for the time series (integrating results from TOR- 5), and estimate their uncertainty. Include areaswept biomass estimates. Investigate if imp lied survey gear or catchability estimates are reasonable. Include a historical retrospective analysis to allow a comparison with previous assessment results.

4. Perform a sensitivity analysis which examines th e impact of allocation of catch to stock areas on model performance (in TOR-3).

5. Examine the effects of incorporating envir onmental factors in models of population dynamics (e.g., spring water temperatures in an environmentally-explicit stock recruitment function).

6. State the existing stock status definitions fo r “overfished” and “overfi shing”. Then update or redefine biological reference points (BRPs; point estimates or proxies for B MSY , B THRESHOLD , and F MSY ) and provide estimates of their uncertainty. If analytic model-based estimates are unavailable, consider recommending alternative me asurable proxies for BRPs. Comment on the scientific adequacy of existing BRPs and the “new ” (i.e., updated, redefined, or alternative) BRPs.

7. Evaluate stock status (overfished and overfish ing) with respect to the “new” BRPs (from TOR 6), and with respect to the existing BRPs (from a prev ious accepted peer review) whose values have been updated.

8. Develop and apply analytical approaches and data that can be used for conducting single and multi-year stock projections and for computing candidate ABCs (Acceptable Biological Catch; see Appendix to the TORs) under a set of alternative harvest scenarios. If the stock needs to be rebuilt, take that into account in these projections.

a. Provide numerical short-term projections (3-5 yrs, or through the end of the rebuilding period, as appropriate). Each projection s hould estimate and report annual probabilities of exceeding threshold BRPs for F, and probabilities of falling below threshold BRPs for biomass. In carrying out projections, cons ider a range of assumptions about the most important uncertainties in the assessment (e.g ., terminal year abundance, variability in recruitment). b. Take into consideration uncertainties in the assessment and the species biology to describe this stock’s vulnerability (see “Appe ndix to the SAW TORs”) to becoming or remaining overfished, and how this could affect the choice of ABC.52 nd SAW Assessment Summary Report Appendix: Terms of Referen ce 50 c. Develop plausible hypotheses (e.g., mixing among the three stocks) which might explain any conflicting trends in th e data and undertake scenario analyses to evaluate the consequences of these alternate hypotheses on ABC determination.

9. Review, evaluate and report on the stat us of the SARC and Working Group research recommendations listed in recent SARC reviewed asse ssments and review panel reports. Identify new research recommendations.

C. Winter flounder (Gulf of Maine Stock)

1. Estimate catch from all sources including landings and discards. Characterize the uncertainty in these sources of data.

2. Present survey data being considered and/or used in the assessment (e.g., regional indices of abundance, recruitment, state and other surveys, ag e-length data, etc.). Characterize uncertainty in these sources of data.

3. Estimate annual fishing mortality, recruitment and stock biomass (both total and spawning stock) for the time series (integrating results from TOR- 5), and estimate their uncertainty. Include areaswept biomass estimates. Investigate if imp lied survey gear or catchability estimates are reasonable. Include a historical retrospective analysis to allow a comparison with previous assessment results.

4. Perform a sensitivity analysis which examines th e impact of allocation of catch to stock areas on model performance (in TOR-3).

5. Examine the effects of incorporating envir onmental factors in models of population dynamics (e.g., spring water temperatures in an environmentally-explicit stock recruitment function).

6. State the existing stock status definitions fo r “overfished” and “overfi shing”. Then update or redefine biological reference points (BRPs; point estimates or proxies for B MSY , B THRESHOLD , and F MSY ) and provide estimates of their uncertainty. If analytic model-based estimates are unavailable, consider recommending alternative me asurable proxies for BRPs. Comment on the scientific adequacy of existing BRPs and the “new ” (i.e., updated, redefined, or alternative) BRPs.

7. Evaluate stock status (overfished and overfish ing) with respect to the “new” BRPs (from TOR 6), and with respect to the existing BRPs (from a prev ious accepted peer review) whose values have been updated.

8. Develop and apply analytical approaches and data that can be used for conducting single and multi-year stock projections and for computing candidate ABCs (Acceptable Biological Catch; see Appendix to the TORs) under a set of alternative harvest scenarios. If the stock needs to be rebuilt, take that into account in these projections.

a. Provide numerical short-term projections (3-5 yrs, or through the end of the rebuilding period, as appropriate). Each projection should estimate and report annual probabilities of exceeding threshold BRPs for F, and probabilities of falling below threshold BRPs for biomass. In carrying out projections, consider a52 nd SAW Assessment Summary Report Appendix: Terms of Referen ce 51 range of assumptions about the most im portant uncertainties in the assessment (e.g., terminal year abundance, variability in recruitment). b. Take into consideration uncertainties in the assessment and the species biology to describe this stock’s vulnerability (see “Appendix to the SAW TORs”) to becoming or remaining overfished, and how this could affect the choice of ABC.

c. Develop plausible hypotheses (e.g., mixing among the three stocks) which might explain any conflicting trends in the data and undertake scenario analyses to evaluate the consequences of these alternate hypotheses on ABC determination.

9. Review, evaluate and report on the stat us of the SARC and Working Group research recommendations listed in recent SARC reviewed asse ssments and review panel reports. Identify new research recommendations.



## Appendix to the SAW TORs:

Clarification of Terms used in the SAW/SARC Terms of Reference

(The text below is from DOC National Standard Guidelines, Federal Register, vol. 74, no. 11, January 16, 2009)

On “Acceptable Biological Catch”:

Acceptable biological catch (ABC) is a level of a stock or stock comple x’s annual catch that accounts for the scientific uncertainty in the estimate of [overfish ing limit] OFL and any other scientific uncertainty...” (p. 3208) [In other words, OFL ≥ ABC.]

ABC for overfished stocks. For overfished stocks and stock complexes, a rebuilding ABC must be set to reflect the annual catch that is consistent with the schedule of fishing mortality rates in the rebuilding plan. (p. 3209)

NMFS expects that in most cases ABC will be reduced fr om OFL to reduce the probability that overfishing might occur in a year. (p. 3180)

ABC refers to a level of ‘‘catch’’ that is ‘‘acceptable’’ given the ‘‘biological’’ characteristics of the stock or stock complex. As such, [optimal yield] OY does not equate with ABC. The specification of OY is required to consider a variety of factors, including social and economic factors, and the protection of marine ecosystems, which are not part of the ABC co ncept. (p. 3189)

On “Vulnerability”:

“Vulnerability. A stock’s vulnerability is a combination of its productivity, which depends upon its life history characteristics, and its susceptibility to the fishery. Productivity refers to the capacity of the stock to produce MSY and to recover if the population is depleted, and susceptibility is the potential for the stock to be impacted by the fishery, which includes direct captures, as well as indirect impacts to the fisher y (e.g., loss of habitat quality).” (p. 3205)

## Procedures for Issuing Manuscripts in the Northeast Fisheries Science Center Reference Document (CRD) Series

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script/abstract/webpage preparation, review, and dis

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### Organization Manuscripts must have an abstract and table of contents, and (if applicable) lists of figures and tables. As much as possible, use traditional scientific manu

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### Style The CRD series is obligated to conform with the style contained in the current edition of the United States Government Printing Office Style Manual. That style manual is silent on many aspects of scientific manuscripts. The CRD series relies more on the CSE Style Manual. Manuscripts should be prepared to conform with these style manuals. The CRD series uses the American Fisheries Soci

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### Preparation Once your document has cleared the review pro

cess, the Editorial Office will contact you with publica

tion needs – for example, revised text (if necessary) and separate digital figures and tables if they are embedded in the document. Materials may be submitted to the Editorial Office as files on zip disks or CDs, email attachments, or intranet downloads. Text files should be in Microsoft Word, tables may be in Word or Excel, and graphics files may be in a variety of formats (JPG, GIF, Excel, PowerPoint, etc.).



### Production and Distribution The Editorial Office will perform a copy-edit of the document and may request further revisions. The Editorial Office will develop the inside and outside front covers, the inside and outside back covers, and the title and bibliographic control pages of the docu

ment. Once both the PDF (print) and Web versions of the CRD are ready, the Editorial Office will contact you to review both versions and submit corrections or changes before the document is posted online. A number of organizations and individuals in the Northeast Region will be notified by e-mail of the availability of the document online.Research Communications Branch Northeast Fisheries Science Center National Marine Fisheries Service, NOAA 166 Water St. Woods Hole, MA 02543-1026



# Publications and Reports of the Northeast Fisheries Science Center

The mission of NOAA’s National Marine Fisheries Service (NMFS) is “stewardship of living marine resources for the benefit of the nation through their science-based conservation and management and promotion of the health of their environment.” As the research arm of the NMFS’s Northeast Region, the Northeast Fisheries Science Center (NEFSC) supports the NMFS mission by “conducting ecosystem-based research and assess

ments of living marine resources, with a focus on the Northeast Shelf, to promote the recovery and long-term sustainability of these resources and to generate social and economic opportunities and benefits from their use.” Results of NEFSC research are largely reported in primary scientific media ( e.g. , anonymously-peer-reviewed scientific journals). However, to assist itself in providing data, information, and advice to its constituents, the NEFSC occasionally releases its results in its own media. Currently , there are three such media:

NOAA Technical Memorandum NMFS-NE -- This series is issued irregularly. The series typically includes: data reports of long-term field or lab studies of important species or habitats; synthesis reports for important species or habitats; annual reports of overall assessment or monitoring programs; manuals describing program-wide surveying or experimental techniques; literature surveys of important species or habitat topics; proceedings and collected papers of scientific meetings; and indexed and/or annotated bibliographies. All issues receive internal scientific review and most issues receive technical and copy editing.

Northeast Fisheries Science Center Reference Document -- This series is issued irregularly. The series typically includes: data reports on field and lab studies; progress reports on experiments, monitoring, and assessments; background papers for, collected abstracts of, and/or summary reports of scientific meetings; and simple bibliographies. Issues receive internal scientific review and most issues receive copy editing.

Resource Survey Report (formerly Fishermen’s Report ) -- This information report is a regularly-issued, quick-turnaround report on the distribution and relative abundance of selected living marine resources as derived from each of the NEFSC’s periodic research ves

sel surveys of the Northeast’s continental shelf. This report undergoes internal review, but receives no technical or copy editing.

TO OBTAIN A COPY of a NOAA Technical Memorandum NMFS-NE or a Northeast Fisheries Science Center Reference Document

, either contact the NEFSC Editorial Office (166 Water St., Woods Hole, MA 02543-1026; 508-495-2350) or consult the NEFSC webpage on “Reports and Publications” (http://www.nefsc.noaa.gov/nefsc/publications/). To access Resource Survey Report , consult the Ecosystem Surveys Branch webpage (http://www.nefsc.noaa.gov/femad/ecosurvey/mainpage/).

ANY USE OF TRADE OR BRAND NAMES IN ANY NEFSC PUBLICATION OR REPORT DOES NOT IMPLY ENDORSE

MENT. 

### MEDIA MAIL