A new method to evaluate the nutritional composition of marine mammal diets from scats applied to harbor seals in the Gulf of Alaska

Geiger, Gretchen L.; Atkinson, Shannon; Waite, Jason N.; Blundell, Gail M.; Carpenter, J. Richard; Wynne, Kate M.

doi:10.1016/j.jembe.2013.09.005

Cited by 9 publications

(5 citation statements)

References 64 publications

(95 reference statements)

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“…FO i was higher than NUM i in all but one species, four-bearded rockling, suggesting that harbour seals in the study area did not specialize on a few selected fish species. Rather, as has been reported in previously mentioned studies Tollit and Thompson 1996;Bromaghin et al 2012;Lance et al 2012;Geiger et al 2013;Luxa and Acevedo-Gutiérrez 2013), their diet appears to be diverse and varied, with high species richness. The switch to a large proportion of herring in winterspring at Tvedestrand (NUM i = 35.4%) may indicate a preference for herring when this species becomes available in the area.…”

Section: Feeding Ecologymentioning

confidence: 57%

“…They inhabit coastal areas around the northern Pacific and Atlantic oceans (Teilmann and Galatius 2018). Between foraging trips harbour seals return to specific haul-out sites to socialize and rest with conspecifics, a behaviour called central place foraging (Geiger et al 2013;Luxa and Acevedo-Gutiérrez 2013). Generally, seals spend most of their time hauled out during daytime and low tide, while most foraging trips take place at night (Thompson et al 1989;Thompson and Miller 1990;Bjørge et al 1995;Ramasco et al 2014).…”

Section: Introductionmentioning

confidence: 99%

“…clupeoids, gadoids, sandeels (Ammodytidae), sculpins and flatfish (e.g. Tollit and Thompson 1996;Bromaghin et al 2012;Lance et al 2012;Geiger et al 2013;Luxa and Acevedo-Gutiérrez 2013). They vary their diets according to season and geographical location, seemingly to prefer the regionally and seasonally most abundant of both benthic and pelagic species (e.g.…”

Section: Introductionmentioning

confidence: 99%

“…They vary their diets according to season and geographical location, seemingly to prefer the regionally and seasonally most abundant of both benthic and pelagic species (e.g. Bromaghin et al 2012;Lance et al 2012;Geiger et al 2013;Luxa and Acevedo-Gutiérrez 2013;Schwarz et al 2018). In some areas, seals seem to favour a small number of prey species but also supplement their diet with other species (Lance et al 2012).…”

Section: Introductionmentioning

confidence: 99%

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Diet composition and biomass consumption of harbour seals in Telemark and Aust-Agder, Norwegian Skagerrak

Sørlie

Nilssen

Bjørge

et al. 2020

Marine Biology Research

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To explore ecosystem dynamics and functions it is vital to obtain knowledge on predator-prey relations. Harbour seals are piscivorous predators that can come into conflict with fisheries. Recently, as the Skagerrak and Kattegat population of harbour seals has increased, claims have emerged that seals are depleting coastal cod populations. The diet of harbour seals in Norwegian Skagerrak was investigated based on otolith identification from scats. The overall seal diet included 20 different fish species/groups. The most important prey (combined index Q i) were haddock/pollack/saithe (32.7%), genus Trisopterus (Norway pout/poor cod/bib, 12.5%), plaice (12.4%) and herring (10.0%). Plaice also had the largest biomass (24.1%). Gadoids and pleuronectids comprised 88.6% of the diet (combined index Q i) and 87.1% in terms of biomass. Cod constituted 0.7% (combined index Q i) of the overall diet and 2.3% in terms of biomass. Fish length estimates showed that seals generally prefer small fish below minimum allowed landing size. Estimated total amount of fish consumed was 315 tons per year and was dominated by non-commercial species. Annual cod consumption was an estimated 7.1 tons, representing 5% of annual cod landings, suggesting that competition between local fisheries and harbour seals is limited.

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Section: Feeding Ecologymentioning

confidence: 57%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

Diet composition and biomass consumption of harbour seals in Telemark and Aust-Agder, Norwegian Skagerrak

Sørlie

Nilssen

Bjørge

et al. 2020

Marine Biology Research

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“…Our study revealed that CSL diet in the southern CCE is highly diverse and variable over time, and to a lesser extent, across space. H', or its derivative N 1 , has been the most common metric used to describe diversity in the diet of pinnipeds (Merrick et al 1997, Garcia-Rodriguez & Aurioles-Gamboa 2004, Trites & Calkins 2008, Geiger et al 2013. Although diversity indices S and N 1 values differed, both indicated that CSL diet at the Channel Islands has a high degree of spatial (i.e.…”

Section: Discussionmentioning

confidence: 99%

Spatio-temporal diet variability of the California sea lion Zalophus californianus in the southern California Current Ecosystem

Lowry

Nehasil

Moore

2022

Mar. Ecol. Prog. Ser.

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Characterizing predator diets is essential to understanding food web dynamics. We investigated the dietary breadth and variation of the California sea lion (CSL) Zalophus californianus at 3 of the California Channel Islands from 1981-2015. Prey species were identified from hard parts and soft-tissue remains of pyrosomes recovered from fecal samples, revealing a diverse diet of fish and cephalopods. Percent frequency of occurrence and percent split-sample frequency of occurrence were used to describe long-term trends, correlations between prey taxa, diet diversity, and diet similarity. The most common of 142 prey taxa identified to species were market squid Doryteuthis opalescens, northern anchovy Engraulis mordax, shortbelly rockfish Sebastes jordani, jack mackerel Trachurus symmetricus, Pacific sardine Sardinops sagax, Pacific hake Merluccius productus, and Pacific mackerel Scomber japonicus. Dietary differences were observed between male and female sea lions, and between animals from different islands and seasons. Intra-island diets at 2 locations were more similar than inter-island diets. Important inter-annual and decadal changes in diet were identified. CSL diet shifted from an anchovy-based diet in the 1980s to a market squid based-diet in the 1990s and 2000s, with other prey taxa being consumed more frequently when consumption of those 2 main prey declined. Prey-switching likely provides flexibility needed in the dynamic California Current Ecosystem, and may allow CSLs to adapt to changes in food supply and availability driven by climate change.

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Enteroctopus dofleini, Giant Pacific octopus

Bower,

Noro,

Sakurai

et al. 2024

Octopus Biology and Ecology

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A new method to evaluate the nutritional composition of marine mammal diets from scats applied to harbor seals in the Gulf of Alaska

Cited by 9 publications

References 64 publications

Diet composition and biomass consumption of harbour seals in Telemark and Aust-Agder, Norwegian Skagerrak

Diet composition and biomass consumption of harbour seals in Telemark and Aust-Agder, Norwegian Skagerrak

Spatio-temporal diet variability of the California sea lion Zalophus californianus in the southern California Current Ecosystem

Enteroctopus dofleini, Giant Pacific octopus

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