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The spatial and temporal distribution patterns of the Atlantic wolffish (Anarhichas lupus) from the Gulf of Maine-Georges Bank region were examined based on bottom trawl survey data from 1963 to 1989. Age composition, growth and food habits were also evaluated from 1983 to 1989. Catches of wolffish were distributed throughout the region, but highest concentrations occurred along the 100 m depth contour of the Gulf of Maine-Georges Bank. Statistical analyses of the depth occurrences revealed a seasonal shift in depth distribution from shallow water ( 50 cm) wolffish migrate to these shallow waters in spring and return to deeper waters in autumn. The oldest wolffish aged was 22 years. Mean length-at-age ranged from 4.7 cm total length for age 0 to 98.0 cm total length for age 22 in spring. Growth was modelled best by the Gompertz function. Bivalve molluscs (primarily Placopecten magellanicus) dominated the diet, followed by echinoderms, gastropods and decapods. Introduction The Atlantic wolffish (Anarhichas lupus) is a commercially important, cold water species found on both sides of the North Atlantic. In the Northwest Atlantic, its distribution extends from off Greenland to the Nantucket Shoals off the eastern United States (Jonsson, 1982). It is typically captured incidental to fishing operations directed toward other benthic species in this region. Commercial landings in USA territorial waters are from the Gulf of Maine and Georges Bank (NAFO Subarea 5), where the total USA nominal catch increased from 200 tons in 1970 to 1 200 tons in 1983 and have since declined to 500 tons (NMFS/NEFC, 1991). Additionally, National Marine Fisheries Service (NMFS), Northeast Fisheries Center, Woods Hole, Massachusetts, bottom trawl surveys indicate a long-term decline in relative abundance since the 1970s (NMFS/NEFC, 1991). Such information suggests that the Atlantic wolffish population of the Gulf of Maine-Georges Bank may be overexploited. However, currently there is no fishery management plan implemented to control fishing mortality on this species. Data on population biology and dynamics of exploited species are essential for proper management strategies. Past research concerning the biology of the Atlantic wolffish has included studies on food habits (Jonsson, 1982; Albikovskaya, 1983; Templeman, 1985; Hawkins and Angus, 1986), distribution and migratory patterns (Albikovskaya, 1982; Jonsson, 1982; Templeman, 1984), reproductive behaviour (Keats et al., 1985), age and growth (Jonsson, 1982) and sexual maturity and fecundity (Templeman, 1986) from Icelandic to Nova Scotian waters. Only descriptive data on depth distribution, food habits and breeding habits (Bigelow and Schroeder, 1953) are available for fishes in United States territorial waters. This study was undertaken to document trends in spatial and temporal distribution patterns based on bottom trawl survey data, and to evaluate quantitatively age, growth and food habits of Atlantic wolffish from the Gulf of MaineGeorges Bank region. Materials and Methods Data used for the spatial and temporal distribution analyses were collected from 1963 to 1989 in the Gulf of Maine-Georges Bank region by NMFS in a synoptic bottom trawl survey. The survey was based on a stratified-random sampling design for continental shelf waters >27 m in depth, partitioned into strata of unequal area based on depth and geographic location (Grosslein, 1969; Azarovitz, 1981). Prior to 1968, sampling was conducted only in autumn. A spring survey was added to the annual schedule in 1968. Sampling effort was expanded in 1972 to include the nearshore waters between 5 and 27 m depth. Sampling during spring and autumn J. Northw. Atl. Fish. Sci., Vol. 13: 53–61 54 J. Northw. Atl. Fish. Sci., Vol. 13, 1992 occurred generally in March to May and September to November, respectively. Sampling stations were randomly selected within each stratum and effort (number of stations) allocated in rough proportion to stratum area. At each station, a # 36 or # 41 Yankee otter trawl with a 1.25 cm stretched mesh codend liner was towed at approximately 3.5 knots for 30 min; bottom depth and near-bottom temperature data were also recorded (Azarovitz, 1981). Changes in spatial distribution between spring and autumn were examined for the 1963–89 survey period. Depth of occurrences, weighted by the number of wolffish captured in each tow, were compared between seasons using Kruskal-Wallis nonparametric ANOVA (Gibbons, 1976). Further, length frequencies were examined by depth ranges for evidence of a seasonal reproductive migration noted by Keats et al. (1986). Due to the low numbers of wolffish captured annually, data from all survey years were combined for these analyses. Age and growth Wolffish were collected opportunistically for the age, growth and food habits analyses from autumn 1983 to spring 1989. Individuals captured in the otter trawl were weighed collectively to the nearest 0.1 kg, measured individually (total length; TL) to the nearest cm, and sexed. The head and entire digestive tract from the esophagus to rectal sphincter were then removed, stored in plastic bags, and frozen. Occasionally, small wolffish (

From collections of Atlantic wolffish in the Northwest Atlantic (West Greenland to the Scotian Shelf) during 1950-67, mean vertebral counts increased gradually from the colder northern to the warmer southern areas (74.19 off Labrador to 75.29 on the southern Scotian Shelf). This is the reverse of the usual pattern in other fishes of the region with pelagic eggs. The pattern for mean dorsal fin-ray counts was similar, but the area coverage and sample sizes were less extensive and the differences were less significant than in the vertebral data. The overall ranges in counts were 72-78 for vertebrae and 71-77 for dorsal fin-rays. Dorsal fin-ray and vertebral numbers were moderately well correlated in a limited number of specimens.

Tagging of 398 Atlantic wolffish, Anarhichas lupus, 81 spotted wolffish, A. minor, and 101 northern wolffish, A. denticulatus, with Petersen disc tags in the Newfoundland area during 1962-66 yielded 5.0, 7.4 and 3.0% returns respectively. Recapture information indicates that migrations are generally short but some rather long migrations were noted. The rate of recapture of Atlantic wolfish declined rapidly from 15.4% for coastal taggings to 6.7% for offshore taggings except Flemish Cap and to 1.1% for Flemish Cap tagging. Depths of recapture of Atlantic wolffish ranged from 20 to 476 m. Fig. 1. Map of the study area with place names mentioned in the text. Materials and Methods Because of the lack of information on movements of wolffishes in eastern Canadian waters, some tagging of the three species off Newfoundland (Fig. 1) was carried out during 1962:66.