Spatial and temporal variability in feeding and condition of age-0 walleye pollock (Theragra chalcogramma) in frontal regions of the Bering Sea

Brodeur, Richard D.; Wilson, Matthew T.; Ciannelli, Lorenzo

doi:10.1006/jmsc.1999.0525

Cited by 54 publications

(38 citation statements)

References 21 publications

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“…For age-0 walleye pollock, our estimate of gastric evacuation rate was similar to the estimates (0.25 to 0.28% BW h -1 ) of Merati & Brodeur (1996). Daily ration for age-0 walleye pollock was previously estimated to be 1.0 to 2.5% BW (eastern Bering Sea, Brodeur et al 2000) and 7.4 to 8.5% BW (western GOA, Merati & Brodeur 1996); this latter estimate may be relatively high due to the inclusion of samples collected near Kodiak Island where euphausiids were an especially prominent dietary component. Ciannelli et al (2004) estimated a very high daily ration (16 to 21% BW) relative to both our estimate and to the ad libitum (10% BW) ration of laboratory-held fish (Sogard & Olla 1996).…”

Section: Discussionmentioning

confidence: 98%

“…This weight was used to calculate stomach content weight as percent body weight (% BW = stomach content weight / (preserved whole wet body weight -stomach content weight) × 100). The contents were then teased apart and sorted into broad taxonomic categories following Brodeur et al (2000). Each taxonomic category was comprised of subcategories (prey-quality categories) to indicate digestion and fragment size: 1 = < 50% intact and well-digested, 2 = > 50% intact but well-digested, 3 = largely intact but digested, 4 = intact and fresh.…”

Section: Methodsmentioning

confidence: 99%

“…The model can be applied to feeding chronologies that include 1 or 2 feeding periods per 24 h. Brodeur et al (2000) applied the same model to age-0 walleye pollock in the Bering Sea, but our parameter estimates for capelin in the Pacific are new. Following Brodeur et al (2000), the % BW data were grouped into 3 h time bins as a somewhat arbitrary compromise between maximizing both the number of samples in each time bin and the number of time bins. Sample sizes were not sufficient to construct separate time series for each year; therefore, the resulting feeding chronologies integrate potential interannual effects.…”

Section: Methodsmentioning

confidence: 99%

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Comparative analysis of the feeding ecology of two pelagic forage fishes: capelin Mallotus villosus and walleye pollock Theragra chalcogramma

Wilson

Jump²,

Duffy‐Anderson³

2006

Mar. Ecol. Prog. Ser.

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Pelagic forage fishes are an important component in the transfer of trophic energy in marine ecosystems. Capelin Mallotus villosus and age-0 walleye pollock Theragra chalcogramma are pelagic forage fishes whose alternate fluctuations in abundance have been associated with systemwide biotic reorganization of the Gulf of Alaska (GOA) ecosystem. To better understand differences between these fishes, we compared their feeding ecology using samples of similar-sized (39 to 126 mm) individuals collected together in midwater trawl hauls during September 2000 to 2001 in the western GOA. Zooplankton samples were used to characterize prey availability. The comparative analysis focused on diet, feeding chronology, daily ration, and prey selectivity. The diet of both species mostly consisted of small copepods, large copepods, adult and juvenile euphausiids, thecosome pteropods, and larvaceans; consequently, the overall diet overlap was high. The diet overlap of fish from some samples, however, was low. Capelin fed mostly during crepuscular periods while pollock mostly fed at night. The daily ration estimate for capelin was low (1.8% body weight [BW]) relative to pollock (5.2% BW). Chesson's index of selectivity indicated preferential selection of euphausiids (adult and juvenile) by capelin and age-0 pollock. At euphausiid-poor locations, capelin stomachs were mostly empty while pollock stomachs contained alternate prey. Selectivity of amphipods, large copepods, larvaceans, and reptantians was higher for age-0 pollock than for capelin. Consumption of euphausiids increased with their abundance in the plankton, and consumption:biomass ratios indicate that localized depletion could occur. We hypothesize that capelin increase foraging mobility while age-0 pollock switch to alternate prey as a competitive response to limited euphausiid availability.KEY WORDS: Capelin · Age-0 walleye pollock · Diet overlap · Prey selectivity Resale or republication not permitted without written consent of the publisher

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Section: Discussionmentioning

confidence: 98%

Section: Methodsmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

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Comparative analysis of the feeding ecology of two pelagic forage fishes: capelin Mallotus villosus and walleye pollock Theragra chalcogramma

Wilson

Jump²,

Duffy‐Anderson³

2006

Mar. Ecol. Prog. Ser.

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“…This feature, which is evident along the entire southeastern shelf, limits the horizontal flux of salt, nutrients and heat between the middle and coastal domains (Coachman, 1986;Kachel et al, 2002). A similar feature occurs around the Pribilof Islands, where it enhances feeding opportunities for higher trophic level organisms (Kinder, Hunt, Schneider & Schumacher, 1983;Decker & Hunt, 1996;Hunt, Coyle, Hoffman, Decker & Flint, 1996a;Brodeur, Wilson & Ciannelli, 2000).…”

Section: The Eastern Bering Sea Regionmentioning

confidence: 92%

Climate change and the control of energy flow in the southeastern Bering Sea

Hunt

Stabeno

2002

Progress in Oceanography

144

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We examine how coupling between physical and biological processes influences the production and transfer of energy to upper trophic-level species in the southeastern Bering Sea. We review time series that illustrate changes in the marine climate of the southeastern Bering Sea since the mid-1970s, particularly variability in the persistence of sea ice and the timing of its retreat. Time series (1995 -2001) from a biophysical mooring in the middle domain of the southeastern shelf support the hypothesis that retreat of the winter sea ice before mid-March (or the failure of ice to be advected into a region) results in an open water bloom in May or June in relatively warm water (Ն3°C). Conversely, when ice retreat is delayed until mid-March or later, an ice-associated bloom occurs in cold (Յ0°C) water in early spring. These variations are important because the growth and production of zooplankton and the growth and survival of larval and juvenile fish are sensitive to water temperature. The Oscillating Control Hypothesis (OCH) recently proposed by Hunt et al. (2002), predicts that control of the abundance of forage fish, and in the case of walleye pollock (Theragra chalcogramma), recruitment of large piscivorous fish, will switch from bottom-up limitation in extended periods with late ice retreat to top-down in warmer periods when ice retreat occurs before mid-March. In support of this hypothesis, we review recent data from the southeastern Bering Sea that show 2-to 13-fold changes in copepod abundance with changes in spring water temperatures of 3 to 5°C. We also provide indirect evidence that the abundance of adult pollock on the eastern Bering Sea shelf negatively affects the abundance forage fishes (including juvenile pollock) available to top predators. Although there is evidence that pollock year-class strength is positively related to temperature, we lack the time series of pollock populations in extended periods (8 -10 years) of cold-water blooms necessary to test the OCH. 

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“…The inner front limits the horizontal flux of salt, nutrients and heat between the middle and coastal domains (Coachman, 1986;Kachel et al, 2002). Increased production associated with the structural fronts at the Pribilof Islands enhances feeding opportunities for higher trophic level organisms (Sinclair et al, 1994;Decker and Hunt 1996;Hunt et al, 1996a;Brodeur et al, 2000).…”

Section: Study Areamentioning

confidence: 99%

Climate change and control of the southeastern Bering Sea pelagic ecosystem

Hunt

Stabeno

Walters

et al. 2002

Deep Sea Research Part II: Topical Studies in Oceanography

498

385

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We propose a new hypothesis, the Oscillating Control Hypothesis (OCH), which predicts that pelagic ecosystem function in the southeastern Bering Sea will alternate between primarily bottom-up control in cold regimes and primarily top-down control in warm regimes. The timing of spring primary production is determined predominately by the timing of ice retreat. Late ice retreat (late March or later) leads to an early, ice-associated bloom in cold water (e.g., 1995, 1997, 1999), whereas no ice, or early ice retreat before mid-March, leads to an open-water bloom in May or June in warm water (e.g., 1996, 1998, 2000). Zooplankton populations are not closely coupled to the spring bloom, but are sensitive to water temperature. In years when the spring bloom occurs in cold water, low temperatures limit the production of zooplankton, the survival of larval/juvenile fish, and their recruitment into the populations of species of large piscivorous fish, such as walleye pollock (Theragra chalcogramma), Pacific cod (Gadus macrocephalus) and arrowtooth flounder (Atheresthes stomias). When continued over decadal scales, this will lead to bottom-up limitation and a decreased biomass of piscivorous fish. Alternatively, in periods when the bloom occurs in warm water, zooplankton populations should grow rapidly, providing plentiful prey for larval and juvenile fish. Abundant zooplankton will support strong recruitment of fish and will lead to abundant predatory fish that control forage fish, including, in the case of pollock, their own juveniles. Piscivorous marine birds and pinnipeds may achieve higher production of young and survival in cold regimes, when there is less competition from large piscivorous fish for coldwater forage fish such as capelin (Mallotus villosus). Piscivorous seabirds and pinnipeds also may be expected to have high productivity in periods of transition from cold regimes to warm regimes, when young of large predatory species of fish are numerous enough to provide forage. The OCH predicts that the ability of large predatory fish populations to sustain fishing pressure will vary between warm and cold regimes.The OCH points to the importance of the timing of ice retreat and water temperatures during the spring bloom for the productivity of zooplankton, and the degree and direction of coupling between zooplankton and forage fish. in the biomass of large piscivorous fish and a concurrent decline in the biomass of forage fish, including age-1 walleye pollock, particularly over the southern portion of the shelf. Populations of northern fur seals (Callorhinus ursinus) and seabirds such as kittiwakes (Rissa spp.) at the Pribilof Islands have declined, most probably in response to a diminished prey base. The available evidence suggests that these changes are unlikely the result of a decrease in total annual new primary production, though the possibility of reduced post-bloom production during summer remains. An ecosystem approach to management of the Bering Sea and its fisheries is of great importance if all o...

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Spatial and temporal variability in feeding and condition of age-0 walleye pollock (Theragra chalcogramma) in frontal regions of the Bering Sea

Cited by 54 publications

References 21 publications

Comparative analysis of the feeding ecology of two pelagic forage fishes: capelin Mallotus villosus and walleye pollock Theragra chalcogramma

Comparative analysis of the feeding ecology of two pelagic forage fishes: capelin Mallotus villosus and walleye pollock Theragra chalcogramma

Climate change and the control of energy flow in the southeastern Bering Sea

Climate change and control of the southeastern Bering Sea pelagic ecosystem

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