Modeling nearshore fish habitats using Alaska as a regional case study

Abstract

Abstract Nearshore areas represent important habitats for many species, at least for part of their life cycle. Therefore, modeling and mapping nearshore habitats is essential for natural resource management and conservation, such as determining potential impacts to marine populations and their habitats from human activities and identifying conservation measures. Although fish survey and habitat data are uncommon for nearshore areas, two regional databases, the Nearshore Fish Atlas of Alaska (NFA) and ShoreZone, provide a rare opportunity to evaluate nearshore habitats for Alaska’s shallow, nearshore fish assemblages. In the present study, we used the NFA and ShoreZone databases in a practical approach to model and map Alaska nearshore fish habitats. Specifically, we fitted generalized additive models (GAMs) to NFA and ShoreZone data to map the spatial patterns of probability of encounter and density of Pacific cod (Gadus macrocephalus) early juveniles in the northern southeastern Alaska (NSEA) area and walleye pollock (Gadus chalcogrammus) early juveniles in Prince William Sound (PWS). The density of Pacific cod early juveniles was found to be high in all of the western part of the NSEA area, particularly around Port Alexander. The density hotspots of walleye pollock early juveniles were found to be located in the northern and southernmost parts of PWS. Data inventories and modeling and mapping Alaska nearshore fish habitats provide valuable information to manage marine resources and human activities (e.g., to identify the main nursery areas of commercially important species along the Alaska coastline), and allow for other important ecological and ecosystem issues to be addressed (e.g., producing marine protected area planning scenarios to protect forage fishes used by large marine predators). The NFA and ShoreZone are valuable resources, and our efforts to leverage them to model and map nearshore fish habitats establishes a reference for similar efforts throughout Alaska’s regions and beyond.