CONTENTS Introduction The Fishery Bottom Trawl Survey Results Estimation of Fishing Mortality and Stock Size Biological Reference Points Conclusions Acknowledgments References
Northeast Fisheries Science Center Reference Document 07-06
Ralph K. Mayo1, Jon K.T. Brodziak, John M. Burnett, Michele L. Traver, and Laurel A. Col
The 2005 Assessment of Acadian Redfish, Sebastes fasciatus Storer, in the Gulf of Maine/Georges Bank Region
1National Marine Fisheries Serv., Woods Hole Lab., 166 Water St., Woods Hole MA 02543-1026
2National Marine Fisheries Serv., 2570 Dole St., Honolulu HI 96822-2396
Web version posted April 26, 2007Citation: Mayo RK, Brodziak JKT, Burnett JM, Traver ML, Col LA. 2007. The 2005 Assessment of Acadian redfish, Sebastes fasciatus Storer, in the Gulf of Maine/Georges Bank region. US Dep Commer, Northeast Fish Sci Cent Ref Doc 07-06; 32 p.
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.
The 2005 assessment is based on several sources of information, including: (a) the age composition of USA 1969–1985 commercial landings; (b) Northeast Fisheries Science Center spring and autumn research vessel survey data; and (c) standardized USA commercial fishing effort data. Information on total landings is available since the inception of the fishery in the mid 1930s, and a measure of commercial catch per unit of effort was derived for most of the period when the directed fishery operated (1942–1989). Trends in total biomass and exploitable biomass are illustrated, and additional information on the age structure of the stock is presented, including the age composition of the commercial landings (1969–1985) and an index of the age composition of the stock based on research vessel survey data (1975–2004). Fishery-dependent and fishery-independent information are integrated using an age-structured biomass dynamics model to generate estimates of instantaneous fishing mortality, stock biomass, and recruitment on an annual basis from 1934 through 2004.
Acadian redfish have supported a substantial domestic fishery in the Gulf of Maine and the Georges Bank (Great South Channel) regions off the northeast coast of the United States (Northwest Atlantic Fisheries Organization [NAFO] Subarea 5) since the 1930s, when the development of freezing techniques enabled a widespread distribution of the frozen product throughout the country. Landings rose rapidly from less than 100 metric tons (mt) in the early 1930s to over 20,000 mt in 1936, peaked at 56,000 mt in 1942, then declined throughout the 1940s and 1950s. Landings from the Gulf of Maine increased during the 1970s, but have been declining throughout the 1980s and 1990s. Since the mid 1990s, landings from this stock have remained at their lowest level since the directed fishery commenced in the 1930s.
Fishing mortality in 2004 is estimated at 0.00239, a substantial decline from 2001. Spawning stock biomass increased from 124,400 mt in 2001 to 175,800 mt in 2004. The estimate of the 2000 spawning stock biomass based on the present assessment is within 5% of the estimate obtained from the 2001 assessment.
Spawning stock biomass in 2004 was 175,800 mt, 74% of SSBMSY (236,700 mt) and F in 2004 is estimated at 0.002, well below FMSY (0.04). Thus, the stock is not overfished and overfishing is not occurring.
Three species of Sebastes are common in the Northwest Atlantic. The Acadian redfish, S. fasciatus Storer (Robins et al. 1991a), and the deepwater redfish, S. mentella Travin, are virtually indistinguishable from each other based on external characteristics. Both species are considered beaked redfish based on the presence of a prominent symphyseal tubercle on the anterior mandible (Klein-MacPhee and Collette 2002). The third species, the golden redfish, S. norvegicus Ascanius (formerly S. marinus; see Robins et al. 1991b) can be distinguished from the beaked redfishes based on external characteristics, notably a greatly diminished symphyseal tubercle.
Visual separation of Acadian redfish and deepwater redfish can be accomplished reliably by counting the number of soft rays in the anal fin (Ni 1982) and internal examination of the passage of the extrinsic gas bladder musculature between the second, third, and fourth ventral ribs (Ni 1981; see Hallacher 1974). The two species can also be distinguished genetically by the genotype at the malate dehydrogenase locus (MDH-A*) (Payne and Ni 1982; McGlade et al. 1983). In general, deepwater redfish are predominant in the northernmost reaches of the Northwest Atlantic, extending from the Gulf of St. Lawrence and the Grand Banks of Newfoundland across the North Atlantic to European waters. (See Atkinson 1987 for a general review.) Acadian redfish and deepwater redfish co-occur in the Gulf of St. Lawrence and the Laurentian Channel, where introgressive hybridization occurs between the two species (Roques et al. 2001), and on the Grand Banks and the Flemish Cap. Morphometric studies have shown that within the Gulf of St. Lawrence, deepwater redfish have a more fusiform body shape than Acadian redfish (Valentin et al. 2002). Deepwater redfish are less prominent in the more southerly regions of the Scotian Shelf and appear to be virtually absent from the Gulf of Maine, where Acadian redfish appear to be the sole representative of the genus Sebastes (Sevigny et al. 2003).
Acadian redfish are long-lived, exhibit ovoviviparous reproduction, and are characterized by low fecundity and a low natural mortality rate. The testes of the males ripen in the autumn and mating occurs in late autumn and early winter (Kelly and Wolf 1959; Pikanowski et al. 1999). Fertilization of the ripe eggs is delayed until spring and larval extrusion generally occurs from late spring through July and August, as incubation requires between 45 and 60 days (Kelly et al. 1972; Kelly and Wolf 1959). Generally, between 15,000 and 20,000 extruded larvae are produced per female during each spawning cycle (Kelly et al. 1972).
Acadian redfish have supported a substantial domestic fishery in the Gulf of Maine and the Georges Bank (Great South Channel) regions off the northeast coast of the United States (Northwest Atlantic Fisheries Organization [NAFO] Subarea 5) since the 1930s, when the development of freezing techniques enabled a widespread distribution of the frozen product throughout the country. Landings rose rapidly from less than 100 metric tons (mt) in the early 1930s to over 20,000 mt in 1936, peaked at 56,000 mt in 1942, then declined throughout the 1940s and 1950s (Table 1, Figure 1). As landings declined in local waters, fishing effort began to expand to the Scotian Shelf and the Gulf of St. Lawrence (NAFO Subarea 4), and finally to the Grand Banks of Newfoundland (NAFO Subarea 3). This expansion continued throughout the 1940s and early 1950s, culminating in a peak USA catch of 130,000 mt in 1952. By the mid 1950s, redfish stocks throughout the Northwest Atlantic were heavily exploited (Atkinson 1987), and total landings began to decline in all Subareas. Landings from the Gulf of Maine increased temporarily during the 1970s, but have been declining throughout the 1980s and 1990s. Since the mid 1990s, landings from this stock have remained at their lowest level since the directed fishery commenced in the 1930s.
United States commercial fisheries for Acadian redfish are managed under the New England Fishery Management Council's Northeast Multispecies Fishery Management Plan (FMP). Under this FMP, redfish are included in a complex of 15 groundfish species managed by time/area closures, gear restrictions, minimum size limits, and – since 1994 – by direct effort controls including a moratorium on permits and days-at-sea restrictions under Amendments 5, 7, and 13 to the FMP. Amendment 9 established initial biomass rebuilding targets (Anon. 1998) and defined control rules which specify target fishing mortality rates and corresponding rebuilding time horizons. Amendment 13 implemented formal rebuilding plans within specified time frames based on revised biomass and fishing mortality targets derived by the Working Group on Re-evaluation of Biological Reference Points for New England Groundfish (NEFSC 2002b). The goal of the management program is to reduce fishing mortality to levels which will allow stocks within the complex to initially rebuild above minimum biomass thresholds, then to attain and remain at or near target biomass levels.
The dynamics of this stock have been evaluated using a variety of techniques including production models (Schaefer 1954, 1957; Pella and Tomlinson 1969; Fox 1975), yield per recruit (Thompson and Bell 1934; Beverton and Holt 1957), and virtual population analysis (VPA). A preliminary production model estimate suggested a long-term potential yield of between 14,000 and 20,000 mt, depending on model formulation (Mayo 1975, 1980). A yield per recruit analysis performed with M=0.05 and a partial recruitment of 50% at age 6 and full recruitment at ages 9 and older indicated FMAX at 0.13 and F0.1 at 0.06 (Mayo 1993). VPA, which was first performed on this stock using catch at age data from 1969–1980, indicated that age 9+ fishing mortality rates (in the range of 0.18 to 0.28 throughout most of the 1970s) were accompanied by a 62% decline in exploitable biomass (ages 5+) between 1969 and 1980 (Mayo et al. 1983). A subsequent analysis which included additional catch at age data through 1983 indicated that, although F had begun to decline from a maximum value of 0.28 in 1979 to 0.17 in 1983, exploitable biomass had been reduced by 75% from the 1969 level by 1984 (NEFC 1986). The VPA was discontinued after 1986, but further declines in redfish landings since then suggest that F is now likely to be rather low (at or below M), rendering the convergence of VPAs unlikely.
An index-based assessment of this stock was presented at the 15th Northeast Regional Stock Assessment Workshop (SAW) in December 1992 (Mayo 1993; NEFSC 1993a, 1993b) and an interim assessment was reviewed by the Northern/Southern Demersal Working Group in August 2000 (NEFSC 2001a). However, the index-based results were not relevant to the then existing biological reference points (see Anon. 1998). The initial peer review of an age-based dynamics model assessment for this stock (Mayo et al. 2002) occurred at the 33rd Northeast Regional SAW in June 2001 (NEFSC 2001b), and an updated index assessment was reviewed at the Groundfish Assessment Review Meeting (GARM) in October 2002 (NEFSC 2002a; Mayo and Col 2002). The present age-based dynamics model assessment was reviewed at the second GARM in August 2005 (NEFSC 2005; Mayo et al. 2005).
The potential for Acadian redfish to return to conditions observed in the 1960s is limited in part by their combination of slow growth and low fecundity. Even at relatively low levels of F (0.03–0.05), restoration of the 1969 age structure is not likely to occur except under extremely favorable recruitment conditions over several decades (Mayo 1987). The recent appearance of just such favorable recruitment during the past decade suggests that restoration of age structure is underway.
Trends in Catch and Effort
Landings of Acadian redfish from Subarea 5 from 1934 through 2004 are given in Table 1 and illustrated in Figure 1. This fishery has been prosecuted almost exclusively by large (>150 gross registered tons) otter trawlers fishing out of Maine and Massachusetts ports. Landings by domestic vessels rose rapidly from less than 100 mt in the early 1930s to over 20,000 mt in 1936, peaked at 56,000 mt in 1942, then declined throughout the 1940s and 1950s. Although Acadian redfish have been harvested primarily by domestic vessels, distant water fleets took considerable quantities for a brief period during the early 1970s (Table 1, Figure 1), at times accounting for 25-30% of the total Subarea 5 redfish catch. The distant water fleet effort, combined with increased domestic fishing effort, resulted in a brief increase in total catch to about 20,000 mt during the early 1970s. With the declaration of exclusive economic zones (EEZ) by the USA and Canada in 1977, USA vessels could no longer access redfish stocks on the Scotian Shelf and the Grand Banks. The fishery for Acadian redfish was then restricted almost exclusively to the Gulf of Maine except for a small portion of the Scotian Shelf off Southwest Nova Scotia. Landings from the Gulf of Maine increased temporarily during the late 1970s, but declined throughout the 1980s and have averaged less than 500 mt per year during the 1990s and the early part of the 21st century.
Commercial catch per unit effort (CPUE) indices from 1942–1989 for directed redfish trips, standardized by vessel tonnage class as described by Mayo et al. (1979), are listed in Table 1 and illustrated in Figure 2. The resulting calculated fishing effort values were derived by dividing total annual landings by the directed CPUE index. Directed CPUE has declined steadily from about 6 tons per standard day fished during the late 1960s to less than 2 tons per day fished after 1980 (Table 1, Figure 2). This decline is consistent with the 60–70% decline in exploitable biomass estimated by previous VPAs (Mayo et al. 1983; NEFC 1986). Total fishing effort, after nearly tripling between 1969 and 1979 (coincident with the highest estimates of fishing mortality [NEFC 1986]), appeared to stabilize during the mid 1980s before declining markedly through 1989.
Traditionally, the directed fishery for redfish in the Gulf of Maine was prosecuted by vessels using otter trawls with relatively small mesh in the range of 70–80 mm. After the 1980s, under domestic management plans, minimum mesh size regulations were imposed on vessels fishing for the major demersal species off the New England coast, including Acadian redfish. In 1977, following implementation of the Magnuson Fishery Conservation and Management Act, the minimum allowable mesh size increased from 114 to 130 mm; by 1994 the minimum mesh size had increased to 152 mm. These mesh restrictions, combined with low biomass and truncated size and age structure of the redfish stock, have effectively eliminated the prosecution of a fishery since the mid 1980s.
Age Composition of the 1969–1985 Landings
Estimates of the number of fish landed at age were derived from biological sampling data collected in the ports during the period 1969 through 1985 (Table 2, Figure 3). With the sharp decline in landings during the 1980s, ageing of commercial samples was discontinued after 1985. For the period 1969–1985, however, estimates of numbers landed at age were derived by applying quarterly age/length keys, separately by sex, to the estimated numbers landed at length by sex. The overall age composition was then obtained by addition of the estimates by sex.
Landings at age and mean weight at age matrices based on all available commercial length and age data from 1969 through 1985 are given in Table 3. The sharp discontinuity in the age structure of the population created by infrequent recruitment after the 1960s can be inferred from the age composition of the landings; this is in contrast to a more uniform age structure in the 1970s resulting from a series of moderate year classes produced in the 1950s and 1960s. The most striking feature is the singular presence of the 1971 year class advancing through the fishery since 1976, followed by the entrance of the 1978 year class during 1983–1985. By the early 1980s the fishery had become dependent on a few relatively strong year classes and recruitment appeared to have diminished considerably.
BOTTOM TRAWL SURVEY RESULTS
Bottom trawl surveys have been conducted by the Northeast Fisheries Science Center (NEFSC) in the Gulf of Maine/Georges Bank region since autumn 1963 and spring 1968 (Azarovitz 1981). The NEFSC spring and autumn bottom trawl survey data were analyzed to evaluate trends in total and exploitable abundance and biomass of Acadian redfish, and trends in the age composition of the population.
Trends in Total Abundance and Biomass
Abundance (stratified mean number per tow) and biomass (stratified mean weight per tow) indices were calculated from NEFSC spring and autumn surveys based on strata encompassing the Gulf of Maine and portions of the Great South Channel (strata 24, 26–30, 36–40; Table 4 and Table 5; Figure 4 and Figure 5). Trends in total abundance and biomass are similar in both spring and autumn surveys. Relative abundance of redfish has declined sharply in both survey series, from peak levels over of 100 fish per tow in the late 1960s and early 1970s to generally between 10 and 30 fish per tow during the mid 1980s through mid 1990s. The decline in biomass has been of the same order. Both series suggest a slight increase in abundance and biomass between the mid 1980s and 1990s followed by a sharp increase in autumn 1996 and spring 1997, and relative stability at these higher levels during the past decade.
Trends in Exploitable Abundance and Biomass
Indices of exploitable abundance and biomass were derived by applying a series of mesh selection ogives to the time series of bottom trawl survey data. First, a catch-weighted average mesh size was calculated for each year from 1964–1993. The average mesh size increased from 2.5–3 in (64–76 mm) during the 1960s to about 5.5 in (140 mm) during the late 1980s and early 1990s (Figure 6), then to 6–6.5 in (152–165 mm) at present. Five periods were identified and data from early mesh selection studies (Clark 1963; Clay 1979; McKone 1979; Nikeshin et al. 1981) were used to construct mesh selectivity curves based on estimates of alpha and beta derived by fitting logistic curves to published data.
These selectivity factors (alpha and beta) were applied to the NEFSC spring and autumn survey data to ‘filter out’ those fish that would not have been retained by the approximate mesh size in use by the commercial fleets during each period. The same stratified mean calculations of abundance and biomass were performed on the ‘filtered’ data as for the total abundance and biomass indices.
During the 1960s, most of the population of redfish was above the size that would be retained by the 2.5–3 in (64–76 mm) mesh used by the commercial fleets. During the late 1990s and early 2000s, most of the population of redfish was below the size that would be retained by the 5.5–6 in (140–152 mm) mesh used by the commercial fleets. Thus, recent increases in total abundance and biomass are not reflected in the exploitable component of the stock under the present management regulations (Figure 7 and Figure 8). At present the portion of the total biomass stock that is exploitable is very small compared to the earlier periods (Table 6).
Age Composition Indices
Stratified mean indices of abundance at age were calculated from NEFSC autumn survey data from 1975 through 2004 and from NEFSC spring survey data from 1975 through 1990 with some exceptions. The survey otolith collection is routinely aged to the maximum possible age. For this analysis, all ages greater than 50 years were binned at 50+. As the autumn survey has provided the most consistent set of abundance and biomass indices, priority was given to ageing of the autumn survey otolith collection. Annual age compositions from all available spring and autumn surveys are depicted in Figure 9, and the composite age distribution from the autumn survey is illustrated in Figure 10. The age composition data clearly illustrate recruitment patterns and changes in age structure of the population. In 1975, the population still appeared to exhibit a relatively broad age structure. The 1971 year class is prominently featured in 1975, followed by the 1978 year class in the early 1980s; these two year classes continued to dominate the demographics of the population through the 1980s.
More recently, the 1985 and 1992 year classes appear most prominent. Despite this improvement in recent recruitment, the age structure of the population during the late 1990s and early 2000s remains severely truncated compared to 1975 and earlier.
Accuracy and Precision of Survey Ages
For Acadian redfish, age-reader precision was estimated once from second readings of random subsamples from the NEFSC 2004 autumn bottom trawl survey. The precision level was 89% agreement, with a total CV of 1.0%, between first and second readings (Figure 11), indicating a moderate level of consistency in age determinations for this long-lived species.
ESTIMATION OF FISHING MORTALITY AND STOCK SIZE
Population dynamics model
In this section, an age-structured assessment model is developed for redfish. Age-structured population dynamics of redfish were modeled in a standard manner using forward-projection methods for statistical catch-at-age analyses (Fournier and Archibald 1982; Methot 1990; Ianelli and Fournier 1998; Restrepo and Legault 1998). The age-structured model (RED) employed at the last peer review of this assessment in 2001 (SAW 33) was updated with NEFSC spring and autumn bottom trawl survey biomass indices and NEFSC autumn bottom trawl survey age compositions through 2004. The population dynamics model is briefly described below and a full description of the age-structured model is provided in Mayo et al. 2002.
The age-structured model is based on forward projection of population numbers at age. This modeling approach is based on the principle that population numbers through time are determined by recruitment and total mortality at age through time. The population numbers at age matrix N=(Ny,a)YxA has dimensions Y by A, where Y is the number of years in the assessment time horizon and A is the number of age classes modeled. The oldest age (A) comprises a plus-group consisting of all fish age A and older. The time horizon for redfish is 1934–2004 (Y=71). The number of age classes is 26, representing ages 1–26+. Input data to the model includes the total landings (1934–2004), commercial CPUE index (1942–1989), commercial landings at age (1969–1985), NEFSC spring and autumn total biomass indices, and the autumn survey age composition (1975–2004).
Forward Projection Model Results
Fishing mortality on Acadian redfish has generally remained quite low compared to many other species. Average fully recruited fishing mortality (ages 9+) remained between 0.05 and 0.15 from the 1940s through the 1960s even as landings also declined (Figure 12). Fishing mortality increased substantially during the 1970s and early 1980s, peaking at 0.29 in 1979 and 1982. These results are very similar to those obtained using VPA during the early 1980s (Mayo et al. 1983, NEFSC 1986). With the subsequent disappearance of the directed fishery, fishing mortality declined sharply, reaching extremely low levels during the 1990s and 2000s.
The spawning stock biomass of redfish declined from over 500,000 mt in the early 1940s, shortly after exploitation commenced, to 120,000–130,000 mt between 1957 and 1971 (Figure 13). Spawning biomass declined further to very low levels of less than 30,000 mt during most of the 1980s and early 1990s before increasing to almost 180,000 mt in 2004. The estimate of the 2000 spawning stock biomass based on the present assessment is within 5% of the estimate obtained from the 2001 assessment.
Recruitment at age 1 remained relatively constant for about two decades from the mid 1940s through the mid 1960s, averaging about 60 million fish (Figure 13). Following this period of relative stability, strong or moderate year classes appeared infrequently until the 1990s, when moderate to strong year classes once again appeared on a more regular basis. The largest year classes in the almost 60-year series are the 1971 (246 million fish at age 1) and 1992 (281 million fish at age 1) cohorts. Survival ratios (recruits per unit of spawning biomass) also illustrate the relatively high survival of the dominant 1971 and 1992 year classes, as well as the moderate 1978 and 1989 year classes (Figure 14).
The initial version of the age-structured forward projection model (RED) was refined after 2001, and is now a component of the NOAA Fisheries Toolbox (NFT) stock assessment software, STATCAM. This version, while identical to RED in most approaches, provides for additional weighting of input data, depending on the length of the time series. Comparative runs of both models were conducted on data sets available at the previous peer review meeting (1934–2000) and at the present meeting (1934–2004) to determine whether differences in modeling approaches produced different estimates of spawning biomass and F. While both models produce very similar estimates of spawning stock biomass and fishing mortality over time (Figure 15), the STATCAM model (STATCAM 2005) is generating a higher rate of increase in SSB during the past decade than the biomass produced by the original RED model. Both models produce the same status determination for this stock, but because the results from the original RED model were used to derive the biomass reference point, the update from this model is used for current status determination.
BIOLOGICAL REFERENCE POINTS
Estimates of recruitment obtained from the age-structured biomass dynamics model reviewed at SAW 33 were used to infer the probable recruitment that could be produced by a rebuilt stock as described in NEFSC (2002b). Recruitment estimates derived by the model from the1952–1999 year classes served as the basis for evaluating trends and patterns in recruitment. The stock recruitment data suggest an increase in the frequency of larger year classes (>50 million fish) at higher biomass levels (Figure 16); therefore, recruitment estimates corresponding to the upper quartile of the SSB range served as the basis for deriving mean and median recruitment estimates. In accordance with the recommendation of the Stock Assessment Review Committee (SARC) at SAW 33, the estimate of F50% (0.04) is taken as a proxy for FMSY. This fishing mortality rate produces 4.1073 kg of spawning stock biomass per recruit and 0.1429 kg of yield per recruit. The resulting mean recruitment of 57.63 million fish results in an SSBMSY estimate of 236,700 mt when multiplied by the SSB per recruit, and an MSY estimate of 8,235 mt when multiplied by the yield per recruit.
Reference points derived from the non parametric approach are:
It was determined (NEFSC 2002b) that the stock could not be rebuilt to BMSY by 2009 even at F=0.0. Therefore, the rebuilding scenario invoked a 10 year plus 1 mean generation time (31 years for Acadian redfish) to achieve rebuilding. This results in an Frebuild = 0.013. Based on the results from the present assessment, spawning stock biomass in 2004 is estimated at 175,800 mt, 74% of BMSY and F in 2004 is estimated at 0.002, well below FMSY. Thus, the stock is not overfished and overfishing is not occurring.
Anon. 1998. Evaluation of existing overfishing definitions and recommendations for new overfishing definitions to comply with the Sustainable Fisheries Act. Final Report, Overfishing Definition Review Panel, June 17, 1998.
Atkinson DB. 1987. The redfish resources off Canada’s East coast. Proc Int Rockfish Symp., October, 1986, Anchorage Alaska. Alaska Sea Grant Rep No. 87-2, p 15-34.
Azarovitz TR. 1981. A brief historical review of the Woods Hole Laboratory trawl survey time series. In: Doubleday WG, Rivard D, eds. Bottom Trawl Surveys. Can Spec Sci Publ Fish Aquat Sci. 58:62-67.
Beverton RJ, Holt SJ. 1957. On the dynamics of exploited fish populations. Fish Invest Lond. (2)19:533 p.
Clark JR. 1963. Size selection of fish by otter trawls, Part I. Escapement of redfish through codend meshes. Int Comm Northw Atl Fish Spec Publ. No. 5, p 85-88.
Clay D. 1979. Synthesis of Selection Curves for Atlantic Redfish, Sebastes mentella. Northw Atlant Fish Org SCR Doc. 79/VI/113 (Revised), 7 p.
Fournier DA, Archibald CP. 1982. A general theory for analyzing catch at age data. Can J Fish Aquat Sci. 39:1195-1207.
Fox WW. 1975. Fitting the generalized stock production model by least squares and equiblibrium approximation. Fish Bull US. 73(1):23-27
Hallacher LE. 1974. The comparative morphology of extrinsic gasbladder musculature in the scorpoinfish genus Sebastes (Pisces: Scorpaenidae). Proc Calif Acad Sci., 4th Series, Vol XL, No. 3, p 59-86.
Ianelli JN, Fournier DA. 1998. Alternative age-structured analyses of NRC simulated stock assessment data. NOAA Tech Memo NMFS-F/SPO-30, p. 81-96.
Kelly GF, Earl PM, Kaylor JD, Lux FE, MacAvoy HR, McRae ED. 1972. Fishery Facts-1. Redfish. NMFS Extension Publ. No. 1.
Kelly GF, Wolf RS. 1959. Age and growth of redfish, Sebastes marinus, in the Gulf of Maine. Fish Bull US. 60:1-31.
Klein-MacPhee G, Collette BB. 2002. Scorpionfishes. Family Scorpaenidae. In: Collette BB, Klein-MacPhee G, eds. Bigelow and Schroeder’s Fishes of the Gulf of Maine 2nd ed. Smithsonian Institution Press, Washington DC.
Mayo RK. 1975. A preliminary assessment of the redfish fishery in ICNAF Subarea 5. Int Comm Northw Atl Fish Res Doc. 75/59, 31 p.
Mayo RK. 1980. Exploitation of redfish, Sebastes marinus (L.), in the Gulf of Maine-GeorgesBank Region, with particular reference to the 1971 Year-Class. J Northw Atl Fish Sci. 1:21-37.
Mayo RK. 1987. Recent exploitation patterns and future stock rebuilding strategies for Acadian redfish, Sebastes fasciatus Storer, in the Gulf of Maine-Georges Bank region of the Northwest Atlantic. Proc Int Rockfish Symp, October, 1986, Anchorage Alaska. Alaska Sea Grant Report No. 87-2, p. 335-353.
Mayo RK. 1993. Historic and recent trends in the population dynamics of redfish, Sebastes fasciatus Storer, in the Gulf of Maine-Georges Bank Region. Northeast Fish Sci Cent Ref Doc. 93-03, 24 p.
Mayo RK, Bevacqua B, Gifford VM, Griffin ME. 1979. An assessment of the Gulf of Maine redfish, Sebastes marinus (L.), stock in 1978. Northeast Fish Cent Woods Hole Lab Ref Doc. 79-20, 63 p.
Mayo RK, Brodziak JKT, Thompson M, Burnett JM, Cadrin SX. 2002. Biological characteristics, population dynamics, and current status of redfish, Sebastes fasciatus Storer, in the Gulf of Maine-Georges Bank Region. Northeast Fish Sci Cent Ref Doc. 02-05, 130 p.
Mayo RK, Brodziak J, Traver M, Col L. 2005. Gulf of Maine/Georges Bank Acadian Redfish. In: Mayo RK, Terceiro M, eds. Assessment of 19 northeast groundfish stocks through 2004. 2005 Groundfish Assessment Review Meeting (2005 GARM), Northeast Fisheries Science Center, Woods Hole, Massachusetts, 15-19 August, 2005. Northeast Fish Sci Cent Ref Doc. 05-13, p 372-388.
Mayo RK, Col L. 2002. Gulf of Maine-Georges Bank Acadian redfish. In: Assessment of 20 groundfish stocks through 2001, a report of the Groundfish Assessment Review Meeting (GARM), Northeast Fish Sci Cent Ref Doc. 02-16, p 265-274.
Mayo RK, Dozier U, Clark SH. 1983. An assessment of the redfish, Sebastes fasciatus, stock in the Gulf of Maine-Georges Bank Region. Northeast Fisheries Center Woods Hole Laboratory Reference Document 83-22, 55 p.
McGlade JM, Annand MC, Kenchington TJ. 1983. Electrophoretic identification of Sebastes and Helicolenus in the northwestern Atlantic. Can J Fish Aquat Sci. 40:1861–1870.
McKone DM. 1979. Division 3M redfish mesh assessment. Northw Atlant Fish Org SCR Doc. 79/VI/121, 7 p.
Methot RD. 1990. Synthesis model: an adaptive framework for analysis of diverse stock assessment data. Int North Pac Fish Comm Bull. 50:259-277.
NEFC. 1986. Redfish. In: Report of the Second NEFC Stock Assessment Workshop (Second SAW). Northeast Fish Cent Woods Hole Lab Ref Doc. 86-09, p 19-30.
NEFSC. 1993a. Report of the 15th Northeast Regional Stock Assessment Workshop (SAW 15). Stock Assessment Review Committee (SARC) consensus summary of assessments. Northeast Fish Sci Cent Ref Doc. 93-06, 108 p.
NEFSC. 1993b. Report of the 15th Northeast Regional Stock Assessment Workshop (SAW 15). The plenary. Northeast Fish Sci Cent Ref Doc. 93-07, 66 p.
NEFSC. 2001a. Assessment of 19 northeast groundfish atocks through 2000. Northeast Fisheries Science Center, Woods Hole, Massachusetts, August 30-31, 2000. Northeast Fish Sci Cent Ref Doc. 01-20, 217 p.
NEFSC. 2001b. Report of the 33rd Northeast Regional Stock Assessment Workshop (SAW 33). Stock Assessment Review Committee (SARC) consensus summary of assessments. Northeast Fish Sci Cent Ref Doc. 01-18, 281 p.
NEFSC. 2002a. Assessment of 20 northeast groundfish stocks through 2001. Groundfish Assessment Review Meeting (GARM), Northeast Fisheries Science Center, Woods Hole, Massachusetts, October 8-11, 2002. Northeast Fish Sci Cent Ref Doc. 02-16, 522 p.
NEFSC. 2002b. Report of the Working Group on Re-Evaluation of Biological Reference Points for New England Groundfish. Northeast Fish Sci Cent Ref Doc. 02-04, 254 p.
NEFSC. 2005. Assessment of 19 northeast groundfish stocks through 2004. In: Mayo RK, Terceiro M, eds. 2005 Groundfish Assessment Review Meeting (2005 GARM), Northeast Fisheries Science Center, Woods Hole, Massachusetts, 15-19 August 2005. Northeast Fish Sci Cent Ref Doc. 05-13; 499 p.
Ni I-H. 1981. Separation of sharp-beaked redfish, Sebastes fasciatus and S. mentella, from Northeastern Grand Bank by morphology of extrinsic gasbladder musculature. J Northw Atl Fish Sci. 2:7-12.
Ni I-H. 1982. Meristic variation in beaked redfishes, Sebastes mentella and S.fasciatus, in the Northwest Atlantic. Can J Fish Aquat Sci. 39:1664-1685.
Nikeshin KN, Kovalenko VG, Kondratyuk YA, Gorskova AS. 1981. Selectivity of bottom and midwater codends when fishing for deepwater redfish in the Northwest Atlantic. Northw Atlant Fish Org SCR Doc. 81/IX/87, 17 p.
Payne RH, Ni I-H. 1982. Biochemical population genetics of redfishes (Sebastes) off Newfoundland. J Northw Atl Fish Sci. 3:169–172.
Pella JJ, Tomlinson PK. 1969. A generalized stock production model. Bull Inter-Amer Trop Tuna Comm. 13(3):419-496.
Pikanowski RA, Morse WW, Berrien PL, Johnson DL, McMillan DG. 1999. Essential fish habitat document. Redfish, Sebastes spp., life history and habitat characteristics. NOAA Tech Mem NMFS-NE-132, 19 p.
Restrepo VR, Legault CM. 1998. A stochastic implementation of an age-structured production model. University of Alaska Sea Grant College Program, Rep No. 98-01:435-450.
Robins CR, Bailey RM, Bond CE, Brooker JR, Lachner EA, Lea RN, Scott WB. 1991a. Common and scientific names of fishes from the United States and Canada, Fifth Edition. Amer Fish Soc Spec Publ. 20, 183 p.
Robins CR, Bailey RM, Bond CE, Brooker JR, Lachner EA, Lea RN, Scott WB. 1991b. Names of the Atlantic Redfishes, Genus Sebastes. Fisheries, Vol. 11, No.1, p 28-29.
Roques S, Sévigny J-M, Bernatchez K. 2001. Evidence for broadscale introgressive hybridisation between two redfish (genus Sebastes) in the Northwest Atlantic: a rare example in marine environment. Molec Ecol. 10:149-165.
Schaefer MB. 1954. Some aspects of the dynamics of populations important to the management of the commercial marine fisheries. Bull Inter-Amer Trop Tuna Comm. 1(2):25-56.
Schaefer MB. 1957. A study of the dynamics of the fishery for yellowfin tuna in the Eastern tropical Pacific ocean. Bull Inter-Amer Trop Tuna Comm. 2(6):245-285.
Sévigny J-M, Roques S, Bernatchez L, Valentin A, Parent É, Black MN, Chanut J-P, Marcogliese1 D, Arthur R, Albert E, Desrosiers B, Atkinson B. 2003. 2. Species identification and stock structure. In: Gascon D, ed. Redfish multidisciplinary research zonal program (1995-1998): final report. Can Tech Rep Fish Aquat Sci. 2462:xiii + 139 p.
STATCAM. 2005. Statistical catch at age model, version 1.3. NOAA Fisheries Toolbox. NEFSC, Woods Hole, MA. Available at http://nft.nefsc.noaa.gov/beta
Thompson WF, Bell FH. 1934. Biological statistics of the Pacific halibut fishery. 2. Effect of changes in intensity upon yield and yield per unit of gear. Rep Int Fish (Pacific halibut) Comm. 8; 49 p.
Valentin A, Sévigny J-M, Chanut, J-P. 2002. Geometric morphometrics reveals body shape differences between sympatric redfish Sebastes mentella, Sebastes fasdatus and their hybrids in the Gulf of St Lawrence. J Fish Biol. 60:857-875.