Using historical catch flexibility and fishing ground mobility as measures of the adaptive capacity of fishing communities to future ocean change

Changing ocean characteristics, moving species, and competing ocean uses challenge fishing communities reliant on marine resources. Many communities have diversified what they catch, or where they fish to cope with variation in availability of fish. However, we often lack understanding of the frequency of these adaptation strategies in response to historical variability. Here, we quantitatively evaluate catch flexibility, catch switching, and fishing ground mobility of Communities at Sea (CaS) in the Northeast USA. CaS capacity to change catch composition or shift fishing grounds differed by gear type and with regional drivers. Dredge was highly mobile but species selective, and groundfish trawl either altered their catch or shifted fishing grounds. Lobster and shrimp trawl CaS were largely unable to take advantage of either strategy, while fleets using other pots and traps did both. Differences within gear types often reflected distinct regional strategies in dealing with the loss of target species from historical fishing grounds. Overall, adaptive capacity for a port reflects its portfolio of fleets as well as shared constraints and opportunities of their home port. Understanding the degree to which fishing communities have adapted to historical variability can help prioritize efforts to enhance adaptive capacity for future ocean change.