Sea-surface temperature used to predict the relative density of giant Pacific octopuses (Enteroctopus dofleini) in intertidal habitats of Prince William Sound, Alaska

Abstract

Productivity linked to upwelling strength is an important environmental factor affecting the production and dynamics of octopus populations. This often takes the form of a negative relationship between octopus abundance and sea-surface temperatures (SST). Enteroctopus dofleini (giant Pacific octopuses) is caught as by-catch in several fisheries, but management for octopuses is data-poor. Visual surveys (in Prince William Sound (PWS) and Puget Sound) showed significant negative correlations of octopus counts with winter SST over the previous 30 months in the waters of eastern Gulf of Alaska, as expected on the basis of life-history parameters. In PWS, local octopus densities varied more than six-fold during the study, and correlations with SST accounted for 48-61% of the variance in counts. Octopus by-catch datasets were not similarly significantly correlated with SST. The negative correlation with SST suggests that octopus populations are influenced by factors regulating marine productivity during larval stages of life history far from the site of recruitment to benthic habitats. Targeted visual surveys for E. dofleini may be more predictable than by-catch statistics, and may be better estimators of variation in octopus abundance.