Diet composition and foraging ecology of U.S. Pacific Coast groundfishes with applications for fisheries management

Abstract

Determining the prey composition and foraging habitats of U.S. Pacific Coast groundfishes are specified management directives that have not received much scientific attention. To address this knowledge gap, we conducted a meta-analysis of the feeding ecology of 18 commercially important species and their life stages during a recent review of Pacific Coast groundfish essential fish habitat. A Major Prey Index was developed to evaluate relative importance among 47 prey taxa. Based on this metric, unidentified teleosts, euphausiids, and brachyuran crabs were the most important prey groups. When 14 generalized prey categories were used, fishes represented the dominant taxon (mean % weight or volume = 32.3) followed by shrimps (11.5), crabs (10.0), and euphausiids (9.5). PERMANOVA results indicated that species-specific differences were the primary source of dietary variability among tested variables (life stage, functional group, taxonomic group). Pacific Coast groundfishes mainly were characterized as mesopredators with estimated trophic levels ranging from 3.4 to 4.2. Foraging habitats differed significantly among functional (benthic, demersal, pelagic) and taxonomic (elasmobranch, roundfish, rockfish, flatfish) groups. Using hierarchical agglomerative cluster analysis, we identified a significantly distinct trophic guild that consumes mainly polychaetes and hard-shelled molluscs (juvenile, juvenile-adult Dover Sole; juvenile-adult English Sole) and another that specializes on euphausiids (juvenile Pacific Hake; juvenile-adult Darkblotched Rockfish). Our findings filled substantial data gaps in the trophic ecology and habitatbased management of commercially important species and can be used to inform future reviews of Pacific Coast groundfish essential fish habitat.

Freshwater Predators on the Edge: Assessing the Temporal and Spatial Variation in Diet of Largemouth Bass in Mobile Bay Estuary, Alabama, USA

“…) and have been used effectively for fish (Bizzarro et al. ). Descriptive statistics of diet richness (the number of prey types found in the stomach) and diversity (Shannon's diversity index H′ ) were calculated for each individual and averaged across individuals within both seasons and sites.…”

“…Statistical analysis.-We generated accumulation curves for the overall sample and for each season within our data set to determine whether we reached an asymptote in species richness as a function of diets sampled (Ferry and Cailliet 1996). Similar methods have been used in other studies of vertebrate diet characterization (Balaguera-Reina et al 2018) and have been used 164 effectively for fish (Bizzarro et al 2017). Descriptive statistics of diet richness (the number of prey types found in the stomach) and diversity (Shannon's diversity index H 0 ) were calculated for each individual and averaged across individuals within both seasons and sites.…”

Structure of winter groundfish feeding guilds in Pacific herring Clupea pallasii and walleye pollock Gadus chalcogrammus nursery fjords

“…Because of this connectivity, PWS derives a significant portion of biological productivity from the GoA (Campbell, ; Halverson et al ., ; McKinstry & Campbell, ), including multiple groundfish species ( Bechtol, ). Several studies have examined groundfish feeding habits in the GoA, particularly the important commercial species including Pacific cod Gadus macrocephalus Tilesius 1810, walleye pollock Gadus chalcogrammus Pallas 1814, or Pacific halibut Hippoglossus stenolepis Schimdt 1904 along with other lesser‐fished or ecologically important fish families including skates (Rajidae), other flatfishes (Pleuronectidae), or rockfishes (Sebastidae; Albers & Anderson, ; Adams et al ., ; Bizzarro et al ., ; Jewett, ; Marsh et al ., ; Urban, ; Yang, ).…”

“…The present study was conducted in Prince William Sound (PWS), which is located on the south-central Alaska coast, primarily between 60 and 61 N, and is connected to the nearby Gulf of Alaska (GoA) by a series of entrances and passageways. Because of this connectivity, PWS derives a significant portion of biological productivity from the GoA (Campbell, 2018;Halverson et al, 2013;McKinstry & Campbell, 2018), including multiple groundfish species (Bechtol, 1999 Albers & Anderson, 1985;Adams et al, 2007;Bizzarro et al, 2017;Jewett, 1978;Marsh et al, 2012;Urban, 2012;Yang, 1993).…”

New perspectives on the feeding ecology and trophic dynamics of fishes

“…Regardless, this approach emphasizes the novel use of fish food habits data that can inform data-poor situations, serving as an alternative and creative means to inform fisheries management decisions. Bizzarro et al (2016) conducted a meta-analysis of the diets of 18 commercially-important groundfishes and their life stages from the U.S. Pacific Coast. By developing a Major Prey Index, unidentified fishes, euphausiids, and brachyuran crabs were determined to be important prey.…”