Intended to provide our own search engines and external engines with highly rich, chapter-representative searchable text on the opening pages of each chapter. Because it is UNCORRECTED material, please consider the following text as a useful but insufficient proxy for the authoritative book pages.
Do not use for reproduction, copying, pasting, or reading; exclusively for search engines.
OCR for page 7
1 INTRODUCTION If we only knew all the laws of Nature, we should need only one fact, or the description of one actual phenomenon, to infer all the particular results at that point. Now we know only a few laws, and our result is vitiated, not, of course, by any confusion or irregularity in Nature, but by our ignorance of essential elements in the calculation. Henry David Thoreau GROUNDFISH RESOURCES OF THE NORTHWESTERN ATLANTIC Fisheries for groundfish off the shores of the Northeast United States and Southeast Canada have played a major role in the development of regional commerce, trade, and society in the United States and Canada. Cod fishing became a major source of income and food for the early colonists (Kurlansky, 1997). The export of salt cod to Europe, and later to the West Indies, in the infamous "golden triangle" trade of cod, rum, and slaves, provided hard currency for the developing nation (Jensen, 1972). In the past 10 years, many traditionally important stocks have fallen to their lowest levels in recorded history and, consequently, many of the fishing communities that relied on these once rich fisheries for their economic livelihood have experienced reduced landings. Attempts to limit the current fishing effort and implement other restrictive regulations in order to promote the rebuilding of these stocks have led to major socioeconomic, ecological, and political concerns for coastal communities in New England. The well-being of fish and harvesters is likely to continue to be a critical issue for fishery management in the Northeast in the future. In particular, three of the most important commercial fish species, cod (Gadus morhua ), haddock (Melanogrammus aeglefinus), and yellowtail flounder (Pleuronectes ferruginea), have all experienced substantial reductions in catch and stock (Figures 1.1 and 1.2). HISTORICAL EXPLOITATION AND ASSESSMENT Early groundfish fisheries, characterized by small fishing vessels that targeted cod, were largely unregulated until this century. These fisheries were located in inshore waters, but trips offshore to Georges Bank began in the mid-1700s. Georges Bank became a principal harvesting ground by the late 1800s (Jensen, 1972). Prior to the early 1900s, most cod were captured by handlining from schooners or longlining from small dories that delivered their catch to larger schooners at the end of the day. By
OCR for page 8
using these simple, but labor-intensive methods, nearly 50,000 tons of cod were harvested from Georges Bank in 1893. This was the first year for which a relatively accurate record of commercial landings was kept (Serchuk and Wigley, 1992). FIGURE 1.1 Commercial Landings (metric tons, live) of cod, haddock, and yellowtail flounder from Gulf of Maine (GOM) (NAFO Division 5Y), Georges Bank (GB) and southern New England (SNE) (NAFO Division 5Z and Subarea 6). SOURCE: NEFSC, 1997a. NOTE: NAFO = Northwest Atlantic Fisheries Organization. FIGURE 1.2 Spawning stock biomass (metric tons) at the start of the spawning season of cod, haddock, and yellowtail flounder from Gulf of Maine (GOM), Georges Bank (GB), southern New England (SNE). Based on ADAPT-tuned VPA. SOURCE: NEFSC, 1997a. NOTE: VPA = virtual population analysis.
OCR for page 9
The groundfish fishery developed rapidly with the introduction of steam- and diesel-powered vessels, otter trawling, and on-board refrigeration around the turn of the century (Clark et al., 1982; Serchuk and Wigley, 1992; Kurlansky, 1997). Otter trawling, which used large planks or doors to pull the net open, was developed in England and introduced to the Northeast fishery in 1905 (Jensen, 1972). This technique, when combined with motorized vessels, was much more efficient than traditional dory fishing, and fishing effort and fleet size in the Northeast groundfish fishery increased rapidly after its introduction (Jensen, 1972; Clark et al., 1982). However, fishing efforts in the Northeast declined, and heavily targeted cod stocks appeared to recover due to the reduction in fishing during World War I. Between World Wars I and II, effort in the groundfish fishery again increased and shifted from cod to Georges Bank haddock. The harvest of haddock peaked at 132,200 tons in 1929, then dropped to 28,000 tons by 1934 (Clark et al., 1982). In the mid-1930s, another commercially important fishery developed around yellowtail flounder. The winter flounder that had previously supported the New England trawl fleet declined drastically, and yellowtail flounder became a substitute for trawlers and filleting plants (Royce et al., 1959). The higher demand for food during World War II increased fishing effort generally and, specifically, effort on yellowtail flounder. Yellowtail flounder quickly became an important target species, and harvesting rates rose rapidly: a peak of nearly 29,000 metric tons was harvested in the southern New England fishery in 1942 (Royce et al., 1959). The effort in this fishery increased and the price per pound received by harvesters in 1947 had more than doubled since 1942 (Royce et al., 1959). The stock subsequently collapsed, and less than 15,000 tons were harvested in the southern New England fishery in 1949. An international convention established the International Commission for the Northwest Atlantic Fisheries (ICNAF) in 1949 to provide a forum for the management of northwest Atlantic fish stocks shared by more than one nation. A method of dividing fishing grounds into statistical areas based on ecological and oceanographic characteristics was formalized under ICNAF, and critical data were organized by managers (Hennemuth and Rockwell, 1987). The exploitation of cod, haddock, and yellowtail flounder by distant-water factory trawler fleets from the Soviet Union, Spain, and other European countries began in 1961 and expanded rapidly in the early and late 1960s (Clark et al., 1982; Serchuk and Wigley, 1992; Murawski et al., 1997). Fishing effort increased and cod landings rose more than fivefold, from 11,000 tons in 1960 to 53,000 tons in 1966 (Serchuk and Wigley, 1992). The catch of northern cod stocks off Newfoundland and Labrador peaked at 810,000 metric tons in 1968 then diminished rapidly under similarly intensive fishing by distant-water fleets (Hutchings and Myers, 1994). Standardized catch sampling was initiated for haddock in 1931, and for other species on a case-by-case basis thereafter, until 1963 when a multispecies sampling program was implemented (Serchuk and Wigley, 1992). In the same year, surveys were conducted by the United States in autumn, and by 1968, they had been expanded to include both autumn and spring surveys. MODERN EXPLOITATION AND ASSESSMENT The arena for fisheries management changed drastically in the 1970s. Depletion of fish stocks by the foreign fishing fleets off U.S. coasts, in part, motivated the United States to extend its fishing jurisdiction out to 200 nautical miles from shore. The need to manage fisheries in this extended jurisdiction and to improve the management of rapidly declining fish stocks led to new federal legislation. The Fishery Conservation and Management Act of 1976 (P.L. 94-265, 16 U.S.C. 1801 et seq.) established regions within which fish populations would be managed and mechanisms for controlling fishing activities. The Magnuson Fishery Conservation and Management Act (MFCMA), as it was later renamed,
OCR for page 10
called for the formation of regional fishery management councils. The New England Fishery Management Council (NEFMC) was formed in 1977 and the modern era of management of the groundfish stock off the northeastern coast began. Recent stock assessment activities and actions are summarized in Table 1.1. Although joint U.S. and Canadian management of shared Georges Bank and Gulf of Maine groundfish stocks had been somewhat successful under ICNAF, cooperative management faltered quickly due to disagreements over national boundaries. By 1978, each country set total allowable catches (TACs) individually, although scientific information continued to be shared among fishery scientists. The NEFMC approved the first fishery management plan (FMP) for the Northeast groundfish fishery in 1977 (Serchuk and Wigley, 1992). However, it quickly became apparent that groundfish stocks were not rebuilding (Serchuk and Wigley, 1992). The individual trip limit system that had been implemented to reduce fishing effort had proven unsuccessful due to difficulties in accurately monitoring daily landings of vessels, misreporting of areas in which fish were caught, illegal landings at many ports along the coast, and mislabeling of fish species (NEFMC, 1994). NEFMC began work on a new interim plan to replace the existing FMP in 1978 (Serchuk and Wigley, 1992). In 1982, NEFMC abandoned the use of the TAC quota system established by ICNAF, in favor of indirect effort control measures such as minimum mesh size restrictions, area closures, and minimum fish size regulations for cod, haddock, and yellowtail flounder (Serchuk and Wigley, 1992; Clark et al., 1982; NEFSC, 1994b). Canadian efforts to improve stock assessment methods increased with its extended jurisdiction to 200 miles offshore. In 1977, the Canadian Atlantic Fisheries Scientific Advisory Committee (CAFSAC) was formed to provide scientific advice for the management of Canadian groundfish stocks. The exclusive economic zones (EEZs) of the United States and Canada overlapped in the region of Georges Bank. Unfortunately, the allocation of fishing privileges within this zone could not be negotiated between the two nations, and the United States and Canada submitted to binding arbitration by the International Court of Justice (ICJ). In 1984, a maritime boundary was determined by the ICJ, and implemented by the two nations in 1985. The first Canadian assessment of Georges Bank cod was conducted in 1983, and annual assessments have been performed in most years since (Hunt and Buzeta, 1996). Canadian harvests increased until the mid-1980s, after which they declined rapidly (Hutchings and Myers, 1994). In July 1992, the northern cod fishery off Newfoundland and Labrador was closed. Canadian management had been based primarily on setting a single-species annual TAC, but it also includes other methods of control such as seasonal and area closures (Mayo et al., 1992). Since 1992, Canada has dramatically altered the management of Atlantic groundfish (Fordham, 1996). The most significant changes have been the implementation of a strict dockside monitoring program, an enhanced at-sea observer program, and an individual transferable quota (ITQ) program for many stocks. In 1988, environmental groups and the Technical Monitoring Group established by NEFMC to review the multispecies groundfish FMP raised concerns about the status of groundfish stocks and the effectiveness of management in rebuilding stocks (Serchuk and Wigley, 1992). In 1991, the Conservation Law Foundation and the Massachusetts Audubon Society sued the National Marine Fisheries Service (NMFS) for failing to prevent overfishing as defined in Amendment 4 to the multispecies groundfish FMP implemented in January 1991. A consent decree was reached between the parties in 1991, requiring that the overfishing levels for groundfish species established under Amendment 4 be met, and the implementation of a new plan to rebuild cod and yellowtail flounder stocks within five years and the haddock stock within ten years (NEFMC, 1994). NEFMC began to develop a new amendment to the groundfish multispecies FMP soon after Amendment 4 was implemented to increase the declining biomass of important commercial stocks, and to meet the requirements of the consent decree.
OCR for page 11
TABLE 1.1 Management Actions and Stock Assessments for Cod, Haddock, and Yellowtail Flounder from 1960 to 1997 Year Cod Haddock Yellowtail Flounder 1960 —First modern recreational survey in Northeast— 1963 —Standardized research vessel multispecies trawl surveys (autumn)— Early 1960s —Commercial fishery weigh-out, interview, and catch sampling (ICNAF)— 1965 —Second recreational survey— 1965-1969 —Peak harvests by foreign distant-water fleets— 1968 —Standardized research vessel multispecies trawl surveys (spring and autumn)— 1970 Spawning area closures from March-April. ICNAF sets TAC at 12,000 tons (Georges Bank) 1971 —First formal stock assessment under ICNAF— Assessment indicates Subarea 5 cod exceeded MSY since 1965 1972 Spawning area closures March-May. ICNAF sets TAC at 6,000 tons (Georges Bank) 1973 ICNAF sets TAC of 35,000 tons 1975 Spawning area closures February-May. ICNAF sets incidental catch only TAC 1976 —Magnuson Fishery Management and Conservation Act (MFCMA) passed— —Preliminary VPA conducted— VPA-based recommendation of 15,000-ton TAC
OCR for page 12
Year Cod Haddock Yellowtail Flounder 1977 —Fishery Management Council established— —Reciprocal Fishing Agreement (U.S.-Canada)— —CAFSAC formed and F0.1 established as long-term harvesting goal (Canada)— —TAC and indirect effort control measures used (Canada)— VPA conducted using commercial and recreational data. Indicates high F (0.55-0.65) and low biomass 1978 —Groundfish Fishery Management Plan (FMP)— —Minimum mesh size 5.125"— —Trip limits, mandatory reporting, quotas set, recreational catch under FMP— —End of Reciprocal Fishing Agreement— Minimum fish size 16" 1979 —Recreational surveys standardized and conducted annually— —"Interim Plan" for groundfish— —Catch controls eliminated, closed areas, minimum fish and mesh sizes retained— 1982 Minimum fish size 17" (15" recreational) Peak Canadian harvest of 18,000 tons under TAC 1983 —First Canadian assessment of Georges Bank multispecies complex— —SPA performed using 1960-1976 data (Canada)— Minimum fish size 17" (15" recreational) Minimum mesh size 5.5" Minimum fish size 11" 1984 —International Court of Justice ends U.S.-Canada boundary dispute— —Court delineates Hague Line— 1985 —Multispecies FMP implemented— —Increased gear and effort controls— Minimum mesh size 5.5" Minimum mesh size 5.5" 1986 Area closures extend from February-May Area closures enacted in southern New England 1987 —Canadian SPA updated using ADAPT model—
OCR for page 13
Year Cod Haddock Yellowtail Flounder 1988 —Canadian DFO suggests improved U.S.-Canada controls— —VPA updated— Minimum fish size 12" 1989 —Canada establishes new management efforts, focuses efforts on cod— —VPA updated— 1991 —Amendment 4— —CLF and Massachusetts Audubon sue NMFS for lack of enforcement of overfishing definition— —Consent decree (NMFS) to prevent overfishing and rebuild stocks— —5-year (cod and yellowtail) and 10-year (haddock) rebuilding stocks— —Stricter effort control measures enacted (area closures increased)— —Canada introduces ITQs and dockside monitoring of catch— —Area closures extended— 1992 —U.S. and Canadian stock assessments completed— —Canada increases at-sea monitoring— 1994 —Canada establishes minimum catch history for ITQ vessels in Georges Bank— —Amendment 5— —Amendment 6— —Area closures in key areas now year round— 1996 —Amendment 7— 1997 —U.S. and Canadian stock assessments completed— NOTE: CAFSAC = Canadian Atlantic Fisheries Scientific Advisory Committee CLF = Conservation Law Foundation DFO = Department of Fisheries and Oceans FMP = fishery management plan ICNAF = International Commission for Northwest Atlantic Fisheries ITQ = individual transferable quota MSY = maximum sustainable yield NMFS = National Marine Fisheries Service SPA = sequential population analysis TAC = total allowable catch VPA = virtual population analysis
OCR for page 14
In 1993, NMFS reported that the haddock stock on Georges Bank was the lowest on record and that landings of Gulf of Maine haddock had decreased by 96% from 1983 to 1992 (Fordham, 1996). Emergency regulations were implemented. These included haddock closed area regulations, prohibition of transfer of fish at sea, and a ban on pair trawling. Some of these emergency measures were included the following year in Amendment 5. Those that were not included in this amendment became part of Amendment 6, prepared by the Secretary of Commerce. In 1994, NEFMC produced Amendment 5 (Table 1.2). This new amendment called for a 50% reduction in fishing effort divided equally over a five- to seven-year period (MMC, 1996). This effort reduction was to be accomplished by a moratorium on new permits for the groundfish fishery, stricter area closures (Figure 1.3), minimum mesh and fish sizes, a mandatory logbook reporting system, and a days at sea (DAS) program (MMC, 1996). The DAS program was designed to reduce effort by limiting the number of days that a fishing vessel could fish. The number of days allocated to a vessel was determined by one of two methods depending on the preference of the vessel owner (1) as a fraction of that vessel's historical effort or (2) by assigning a ''fleet" value, based on averaged values from the groundfish fleet (MMC, 1996). Amendment 5 specified a five-year schedule for reducing DAS by 10 percent per year for vessels under the individual vessel DAS program with the goal of a 50% reduction in by 1999 (Table 1.2). This reduction translates into 88 DAS in 1999 (MMC, 1996). In 1994, the United States conducted a stock assessment for Northeast groundfish stocks. This assessment concluded that Georges Bank and Gulf of Maine cod, haddock, and yellowtail flounder stocks were at or near record low levels of spawning biomass and that cod and yellowtail flounder fishing mortality levels were far in excess of fishing mortality levels needed to rebuild the stocks (NEFSC, 1994a, 1995; O'Brien and Brown, 1995). Canadian assessments from 1995 indicated similarly low levels of spawning biomass for stocks on Georges Bank (Gavaris and VanEckhaute, 1996; Hunt and Buzeta, 1996). The Stock Assessment Review Committee (SARC) convened by NMFS in June 1994 concluded that "measures provided in Amendment 5 are clearly inadequate" (NEFSC, 1994b) and that fishing mortality for cod and yellowtail "should be reduced to levels approaching zero" (NEFSC, 1994b). Amendment 7 was implemented in July 1996 and is similar in many respects to Amendment 5. However, Amendment 7 accelerated the reductions in total fleet DAS to 88 days in 1997 and reduced individual vessel DAS by 50% by 1997 (MMC, 1996). For the first time since 1982, Amendment 7 set a target TAC for groundfish species (MMC, 1996). This target provided a recommended catch, although reaching the target TAC would not necessarily trigger management action as TACs in other fisheries do. Amendment 7 increased the number and duration of area closures (Figure 1.4), reduced the number of exemptions to the DAS program, and established a Multispecies Monitoring Committee (MMC). The MMC was to review progress toward meeting the fishing mortality reduction goals established under provisions of Amendment 7. DESCRIPTION OF 1997 U.S. STOCK ASSESSMENT FOR COD, HADDOCK, AND YELLOWTAIL FLOUNDER Terms of Reference By the end of 1996, the status of Gulf of Maine cod, Georges Bank cod, haddock, and yellowtail flounder, and southern New England yellowtail flounder fisheries was of major concern. Subsequently, the scheduled stock assessments took on a special significance. The terms of reference for these stock assessments were (1) assess the stock status through 1996 and characterize the variability of estimates of stock abundance and fishing mortality rates; (2) provide projected estimates of catch for 1997-1998
OCR for page 15
FIGURE 1.3 Regulated areas in the northeast fishery recommended in Amendment 5 of the Multispecies Fisheries Management Plan. SOURCE: NEFMC, 1994.
OCR for page 16
FIGURE 1.4 Regulated areas in the northeast fishery recommended in Amendment 7 of the Multispecies Fisheries Management Plan. SOURCE: NEFMC, 1996.
OCR for page 17
TABLE 1.2 Management Measures Implemented by Amendments 5, 6, and 7. Amendment 5 (1994) Amendment 6 (1994) Amendment 7 (1996) Moratorium on new vessel permits during stock rebuilding period. Vessels retaining less than 500 pounds of groundfish, with fewer than 4,500 hooks or fishing with sink gillnet gear, are exempted from the moratorium. Moratorium on new vessel permits during stock rebuilding period. No exemptions for commercial vessels to the moratorium. Days at sea (DAS) program enacted to reduce fishing vessel effort to 50% of 1993 levels, 10% per year, within 5 years (1999) of enactment of the plan by reducing the number of days available for fishing. Vessels less than 45 feet, longline vessels with fewer than 4,500 hooks set per day, and certain types of gillnet vessels exempted. DAS program accelerated to reduce fishing vessel effort to 50% of 1993 levels within 2 years (1997). Vessels of more than 30 feet, longline vessels with fewer than 4,500 hooks set per day, and certain types of gillnet vessels are no longer exempt from days at sea program. Vessels under 30 feet may fish under small vessel exemption permit. 6-inch minimum mesh size applies to most vessels retaining more than 500 pounds of groundfish, certain exemptions for purse seiners and midwater-trawl vessels. Seasonal 6-inch square mesh for juvenile cod protection on Stellwagen Bank and Jeffreys Ledge from March-July. 6-inch mesh size applies to all vessels, unless the bycatch of regulated groundfish species is less than 5% of the weight of the total catch. No retention of groundfish species allowed. 6-inch minimum mesh size for juvenile cod protection on Stellwagen Bank and Jeffreys Ledge year round. 6-inch minimum mesh size also expanded in southern New England east of 72°30' consistent with other areas. Mandatory logbook reporting required. Mandatory logbook reporting required. Target total allowable catch (TAC) established. Multispecies Monitoring Committee (MMC) formed to monitor effectiveness of Amendment 7. 500-pound trip limit for haddock. 500-pound trip limit for haddock. 1,000-pound trip limit for haddock. Closed areas for haddock, cod, and southern New England yellowtail flounder expanded. Time frames of closures for haddock and yellowtail flounder (Areas I, II, and Nantucket Lightship) expanded from February-May to January-June, except haddock in Closed Area II has February-May closure. Time frames of closures for haddock and yellowtail flounder (Areas I, II, and Nantucket Lightship) expanded year-round by emergency action in December. Scallop dredging prohibited year-round in closed areas. Scallop dredges prohibited from possessing or landing haddock from January-June. Pair trawling banned. Closed areas for haddock, cod, and southern New England yellowtail flounder expanded. Time frames of closures for haddock and yellowtail flounder (Areas I, II, and Nantucket Lightship) year-round. Scallop dredging prohibited year-round in closed areas.
OCR for page 18
and spawning stock biomass (SSB) for 1998-1999 at various levels of F (fishing mortality), including all relevant biological reference points; and (3) advise on the assessment and management implications of incorporating recreational catch and commercial discard data in the assessment. United States and Canadian Stock Assessment Process Stock assessments are conducted jointly by teams of scientists from the Department of Fisheries and Oceans of Canada (DFO) and the U.S. National Marine Fisheries Service (NMFS). The assessments are subsequently peer reviewed by federal, state, provincial, and academic scientists. In Canada the assessments are reviewed during the regional advisory process (RAP), and in the United States the stock assessments are reviewed during the SARC process. Final assessment advice is formulated at the last step in the process, the Stock Assessment Workshop (SAW) in the United States, and in Canada, by the Fisheries Resource Conservation Council (FRCC). Stock Assessment Procedure and Timing in 1997 Scientists at the NMFS Northeast Fisheries Science Center (NEFSC) in Woods Hole, Massachusetts conduct the stock assessments, which incorporate landings, survey, and observer data. The stock assessment process in 1997 started with assembly of data as early as February 1996, preliminary runs of the ADAPT model (Conser and Powers, 1990; Conser et al., 1991) in March 1997, and ended with the final distribution of stock assessment documents to the SARC at its meeting in May 1997 (Figure 1.5). Scientists from NEFSC also participated in the Canadian's regional assessment process in Moncton, New Brunswick, Canada. The SARC met during the 24th Northeast Regional Stock Assessment Workshop (Figure 1.5). This committee peer-reviewed the stock assessment. The SARC considered the reports of the Northern and Southern Demersal Working Groups (NEFSC, 1997a), peer-reviewed the assessments, and developed management advice. The SARC's advice is published in a report (NEFSC, 1997b) and was presented at meetings of the regional fishery management councils. Dealer and Vessel Data The data used in each of the assessments are summarized in Appendix D. Beginning in 1994, personal interviews were no longer used to determine fishing effort, catch location, and discards. Instead, a program of mandatory vessel logbooks and dealer reports was implemented. Vessel trip reports for 1994, 1995, and 1996 were available for these stock assessments, but all data are provisional. Vessel trip report data include information on area fished and on retained and discarded catch and effort. There is no direct link between dealer report data and the vessel trip report, since there is no unique identifier that associates a vessel trip with a dealer transaction. Fields common to both data sets were used as an indirect link and provide some information on landings by market category and stock area (area fished). Observations that had zeros in either data set were eliminated to avoid erroneous matches. Because it was uncertain whether live or landed weight was given in a vessel report, the dealer and vessel trip reports were retained in matching sets to assist in determining the precision of allocations of species catches to stock groups. Effort is estimated from the logbook and interview data. Catch per unit effort (CPUE; i.e., total pounds landed per days absent) is estimated from commercial weigh-out and logbook data. There is undoubtedly a difference in the effort recorded by the earlier method that used port agents' interviews and the current method that uses self-reporting by harvesters. Discard and effort information were evaluated by the SARC, and the results were compared to information obtained from corresponding
OCR for page 19
observer data. The Northeast groundfish stocks reviewed are not managed by a TAC, but inaccuracies in reported removals should be expected nevertheless. Trawl Surveys Surveys have been conducted in the autumn since 1963 and in the spring since 1968 by NEFSC. The region is separated into 65 strata (Figure 1.6), and trawls are conducted at sites randomly chosen in each area. Beginning in 1985, trawl doors were changed from wood and steel to all steel. Conversion factors are used to adjust catches to make them comparable. In addition, surveys conducted by Canada are used in the stock assessment for Georges Bank cod and haddock. Data from scallop surveys are also used in stock assessments on southern New England yellowtail flounder. Recreational data are evaluated, but not used in the final VPA assessments of cod. Age Sampling Age composition is estimated by market category from length frequency and age samples. Data were pooled by calendar quarter, except that when samples were insufficient within a quarter, they were pooled semiannually. Most samples were obtained during port sampling. However, for Georges Bank yellowtail flounder and haddock, port samplings were low and were supplemented by uncategorized (no market category) samples collected during sea sampling conducted by NMFS. Models Used In recent years, both Canadian and U.S. managers have used the adaptive framework or age-structured model (ADAPT) (Conser and Powers, 1990; Gavaris and VanEeckhaute, 1996). The advantage of the ADAPT model over previously used virtual population analyses (VPA) and sequential population analysis (SPA) models is that it permits the accommodation of other data and can weight data sources based on their variability, reliability, and relative importance (Conser and Powers, 1990). The ADAPT models used by CAFSAC and NMFS differ in some of the equations used for weighting the reliability of ageing data and the incorporation of other observations, but they are essentially similar implementations (Conser and Powers, 1990). Results The results of the stock assessments were summarized in the advisory report on stock status (Table 1.3). Some of their conclusions are that (1) fishing mortality for cod, haddock, and yellowtail flounder in all areas except the Gulf of Maine has been reduced below the level of overfishing and is near or below the levels for rebuilding established by the fishery management plan; (2) recruitment is low relative to historical levels; (3) the spawning stock biomass has shown some rebuilding in all stocks except Gulf of Maine cod; and (4) except for Gulf of Maine cod, short-term projections indicate that spawning stock biomass will be maintained or rebuilt. Projections for Gulf of Maine cod indicate a continued decline.
OCR for page 20
FIGURE 1.5 Time line for United States and Canadian data analysis and stock assessments in 1997. NOTE: ND = Northern Demersal, NRC = National Research Council.
OCR for page 21
FIGURE 1.6 Map showing the sampling strata for NEFSC bottom trawl survey. SOURCE: NEFSC, 1997a.
OCR for page 22
FIGURE 1.7 Map showing statistical unit areas off Northeast U.S. and Canada. SOURCE: NEFSC, 1997a.
OCR for page 23
TABLE 1.3 Status of Five New England Groundfish Stocks Reviewed at SAW-24 Stock Current Fishing Mortality 1994-1996 Recruitment 1994-1996 Spawning Stock Biomass Biomass Threshold Gulf of Maine cod Well above target Low Low declining Threshold not well defined Georges Bank cod Near target Low Low increasing Well below Georges Bank haddock Below target Low Low increasing Below Georges Bank yellowtail flounder Below target Average Low increasing Near Southern New England yellowtail flounder Below target Low Low increasing Below Status of each stock is summarized in terms of current (1996) fishing mortality, 1994-1996 recruitment, 1994-1996 spawning stock biomass (SSB), and minimum SSB thresholds established for management purposes in the multispecies FMP. Fishing mortality in 1996 is characterized relative to the F0.1 or Fmax (Gulf of Maine cod) rebuilding targets. Minimum SSB thresholds were established for Georges Bank cod (70,000 metric tons), Georges Bank haddock, (80,000 metric tons), Georges Bank yellowtail flounder (10,000 metric tons), and southern New England yellowtail flounder (10,000 metric tons) from Table 2 of NEFSC, (1997b). HISTORY AND PURPOSE OF THIS STUDY In the most recent reauthorization of the Magnuson-Stevens Fishery Conservation and Management Act (P.L. 104-293, 16 U.S.C. 1801 et seq.), Congress mandated that the National Academy of Sciences "shall conduct a peer review of Canadian and U.S. stock assessments, information collection methodologies, biological assumptions and projections, and other relevant scientific information used as the basis for conservation and management in the Northeast multispecies fishery" (see Appendix A). The National Research Council (NRC) has been charged with the review and has formed a committee to fulfill this mandate (see Appendix B for biographies of committee members). This report is a review of the 1997 stock assessments of cod, haddock, and yellowtail flounder conducted by NMFS. The committee also examined the stock assessments conducted by Canada for cod and haddock. The committee's approach was to (1) attempt to replicate NMFS stock assessments; (2) compare the current stock assessment with other assessments around the world; (3) evaluate the stock assessment of cod, haddock, and yellowtail flounder according to the guidelines outlined in the Improving Fish
OCR for page 24
Stock Assessments (NRC, 1998); (4) evaluate the status of stocks of cod, haddock, and yellowtail flounder; and (5) evaluate the role of stock assessment in the fishery management process. In Chapter 2, the committee reviews the Northeast groundfish fish stock assessments in general to address whether they provide a valid scientific basis for decisionmaking. Included in this chapter is the committee's attempt to provide a more realistic depiction of uncertainty in forecasts of stock condition. In Chapter 3, a detailed review of the 1997 NMFS stock assessments in particular is provided to show where improvements could be made. An appraisal of the role of stock assessment in the management process is outlined in Chapter 4. The committee's findings and conclusions are summarized in Chapter 5. NMFS provided background material and the 1997 stock assessments both before and after these had undergone its own review process. NMFS personnel made a presentation of the stock assessment to the committee. Personnel from the Canadian Department of Fisheries and Oceans also provided background material and stock assessments and presented the stock assessments to the committee. The NRC retained a consultant, Marine Resources Assessment Group (MRAG) America, Inc. to assist the committee in its task. The committee requested that the consultant replicate analyses conducted by NMFS and carry out an alternative set of projections. These results were used to judge the quality of the stock assessment conducted by NMFS. In addition, the consultant was asked to extend the stock assessments by using data from more years than are typically used by NMFS. The results of the consultant's work were considered by the committee, and some results appear in this report. The committee met in July 1997 in Bedford and Gloucester, Massachusetts. During this meeting, the committee heard presentations from invited speakers, other interested parties, and stakeholders to understand the context in which stock assessments are made.
Representative terms from entire chapter: