CHANGES IN BIOMASS OF FINFISHES AND SQUIDS FROM THE GULF OF MAINE TO CAPE HATTERAS, 1963-74, AS DETERMINED FROM RESEARCH VESSEL SURVEY DATA

摘要: Trends in finfish and squid biomaBB for the 1963·74 period International Commission Northwest Atlantic Fisheries (lCNAF) Subarea 5 Statistical Area 6, as evidenced by autumn bottom trawl survey data, were reviewed. Commercial statistics reported to ICNAF reveal that landings groundfish species of major commercial importance peaked 1965 subsequently declined with shifts directed effort pelagic (for which 1971). le~er primarily reflect increasing throughout this period. Relative abundance indices (stratified mean catch kilograms per tow) from revealed drastic declines haddock, Melanogrammusaeglefinus; silver hake, Merluccius bilinearis; red Urophycis chuss; herring, Clupea harengus, during although decreases observed nearly all importance. Possible evidence ofchanges composition also observed, white tenuis; mackerel, Scomber scombrus; squids, Loligo pealei Illex illecebrosus, have shown pronounced increases relative recent years coincident other occupying similar ecological niches. Analysis four strata sets (Middle Atlantic, southern New England, Georges Bank, GulfofMaine areas) unacijusted biomass ranging 37% on Bank 74% Middle area; combining data strata, a decline 32% was obtained 1967·74 (including section, added 1967), while remaining (1963·74) corresponding figure is 43%. By acijusting components according catchability computing stock size estimates entire biomass, 65% Atlantic) using untransformed indices, 66% computed retransformed indices. For excluded) 47% 46% obtained, respectively. these sets, figures 51% 47%. Stock 1975 approximated 2.0 x 108 tons, one·fourth ofthe estimated virgin biomaBBlevel one·halfofthe level maximum sustainable yield.