Correlations of Fish Catch and Environmental Factors in the Gulf of Maine

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Abstract
In an investigation of catches of 17 commercial marine species of fish and shellfish [Alosa pseudoharengus, Peprilus triacanthus, Gadus morhua, Clupea harengus harengus, Brevoortia tyrannus, Sebastes marinus, Merluccius bilinearis, Morone saxatilis, Limanda ferruginea, Mercenaria mercenaria, Mya arenaria, Placopecten magellanicus, Homarus americanus, Pandalus borealis, Glycera dibranchiata, Scomber scombrus, Hippoglossus hippoglossus] from the Gulf of Maine, 10 showed statistically significant correlations with sea temperatures at St. Andrews, New Brunswick, Canada or Boothbay Harbor, Maine [USA]. Most fish records contained at least 40 yr of data. Descriptive equations are produced for 4 spp. based first on the correlation between catch and sea temperature and second on the correlation between catch and sea temperature allowing for fishing effort. Inclusion of fishing effort, not surprisingly, improved the correlations for all of the species so examined. The equations permitted the prediction of later parts of the records from earlier parts. Considering the fish species collectively, the Gulf of Maine system from 1940-1959 appeared to be in equilibrium with little fluctuation in the total commerical biomass. The large fluctuations in individual species abundance result from a combination of fishing pressure and to a significant degree oceanic climate as represented by sea temperature. The small fluctuations in the total biomass display the species variation, with their differing climatic preferences, as well as possible predator (including man)-prey relationships. Environmentally imposed patterns underlie at least 50% of the fluctuations in catch of many species and the understanding of these fluctuations is basic to effective management.