Correlating environmental and biogenic factors with abundance and distribution of Pacific ocean perch (Sebastes alutus) in the Aleutian Islands, Alaska

Abstract

Abstract-In the Aleutian Islands, patterns of distribution and abundance of Pacific ocean perch (Sebastes alutus) are influenced by oceanographic processes and biogenic structures. We used generalized additive modeling (GAM) to examine relationships between these predictors and patterns of settled juvenile and adult distribution and abundance from bottom trawl surveys conducted from 1997 through 2010. Depth, temperature, and location had the greatest influence, and biogenic structures co-occurring with this species improved predictions. Model results confirmed previously reported depth-and temperaturedependent patterns of Pacific ocean perch and revealed the elevated presence and abundance of this fish in proximity to Aleutian passes. Adults were more common and abundant in deeper (~225 m) water than were juveniles (~150 m), and the probability of encountering either life stage increased in the presence of fan-and ball-shaped sponges over moderate slopes and decreased with increasing tidal velocities. The GAMs accounted for one-quarter of the deviance for juvenile presenceabsence (24.9%) and conditional abundance (25.0%) and accounted for 38.7% and 42.5% of the deviance for the same adult response variables. Although depth, temperature, and location were the dominant predictor variables of both juvenile presence and abundance, our results indicate that biogenic structures that provide vertical structure in otherwise lowrelief, trawlable habitats may represent refugia for Pacific ocean perch juveniles and adults.Describing essential fish habitat (EFH), defined by the Magnuson-Stevens Fishery Conservation and Management Act (Magnuson-Stevens Act) as "those waters and substrate necessary to fish for spawning, breeding, feeding or growth to maturity," has been the focus of much recent habitat research. Laidig et al. (2009) used the Delta submersible to conduct visual surveys on the central California shelf and found that demersal fishes associated with boulder and cobble substrata occurred in greater numbers than they did with mud or brachiopod beds. Other studies have observed denser and more diverse assemblages of rockfishes in the presence of increased boulder coverage (Marliave and Challenger, 2009) or in association with rocky ridges (Rooper et al., 2010). Greene et al. (2011) demonstrated that rugged seafloor geomorphologies in southeast Alaska can be used to identify suitable habitat for demersal shelf rockfish (Sebastes spp.). Living substrata can also modify seafloor habitats in ways that impact EFH. Others have considered biogenic structures, such as sponges, corals, and bryozoans, to be important habitat-forming organisms in Alaska Malecha et al., 2005; Stone et al., 2011) and other waters (e.g., Barthel, 1997 [Weddell Sea]; Beazley et al., 2013 [the northwest Atlantic]; and Coker et al., 2014 [warm-water coral reefs]). In this study, we attempt to add to the growing body of knowledge used to identify and describe EFH for species of Sebastes in Alaska.The Resource Assessment and Conservation Engin...

Benthic Habitats, as Derived from Classification of Side‐Scan‐Sonar Mapping Data, Are Important Determinants of Reef‐Fish Assemblage Structure in the Eastern Gulf of Mexico

“…In this pilot study, the reef-fish assemblage structure in the Elbow differed significantly relative to the types of reef habitat that were identified through side-scan-sonar imagery. The distribution of fish populations is often related to habitat characteristics ranging from microhabitats (e.g., substrate composition, attached biota) to broad-scale habitat features (e.g., water depth) throughout their range (Anderson and Yoklavich 2007;Purcell et al 2014;Bacheler and Ballenger 2015;Laman et al 2015;Bacheler et al 2016). Determining which measures of habitat are the most important to the statistical design of a fisheries survey requires careful consideration.…”

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Higher Aggregation of Key Prey Species Associated with Diet and Abundance of the Steller Sea Lion Eumetopias jubatus across the Aleutian Islands

“…Invertebrate communities can provide vertical structure for protection from predators and habitat for feeding, especially for juvenile fish (Rooper and Boldt ; Laman et al. ). For example, numbers of adult and juvenile Pacific Ocean Perch S. alutus —another common species in the Aleutian Islands—increased in the presence of certain sponge shapes, which may act as refugia for both life stages (Laman et al.…”

“…Although no consistent effects of TEZs on fish densities were observed, these closures may indirectly benefit fish species by offering greater protection to structure-forming invertebrates. Invertebrate communities can provide vertical structure for protection from predators and habitat for feeding, especially for juvenile fish (Rooper and Boldt 2005;Laman et al 2015). For example, numbers of adult and juvenile Pacific Ocean…”

The effect of random and density‐dependent variation in sampling efficiency on variance of abundance estimates from fishery surveys

“…Survey‐derived abundance indices (AIs) and their variances (AIVs) are used in a wide variety of studies such as population dynamics (e.g. Sibly, Barker, Denham, Hone, & Pagel, ), ecological processes (Aydin & Mueter, ; Laman, Kotwicki, & Rooper, ), experimental design (e.g. Overholtz, Jech, Michaels, Jacobson, & Sullivan, ), stock assessments (e.g.…”