Capelin (Mallotus villosus) availability influences the inshore summer diet of Atlantic cod (Gadus morhua) in coastal Newfoundland

Berard, Marissa T.; Davoren, Gail K.

doi:10.1007/s10641-020-00982-9

Cited by 10 publications

(7 citation statements)

References 48 publications

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“…(2017) similarly found a decrease in niche breadth of other non‐breeding marine predators, including Sooty Shearwaters Ardenna grisea , Great Shearwaters Ardenna gravis and Humpback Whales Megaptera novaeangliae , as Capelin availability increased in our study area during summer 2016. Similarly, Berard and Davoren (2020) found that Atlantic Cod G. morhua decreased dietary diversity to focus on a primary diet of Capelin, as Capelin availability increased in our study area during the summers of 2017 and 2018. Additionally, it has been widely documented that seabirds increase Capelin consumption when they arrive inshore to spawn but do not alter their diet when Capelin later arrive inshore to spawn relative to chick‐rearing (Carscadden et al .…”

Section: Discussionsupporting

confidence: 70%

“…gulls, shearwaters, whales, cod; Gulka et al . 2017, Berard & Davoren 2020), and a similar but more marked response is expected among breeding seabird species within the same foraging guild. Three sympatric alcid species, Atlantic Puffins Fratercula arctica (hereafter referred to as Puffins), Razorbills Alca torda and Common Murres Uria aalge (hereafter referred to as Murres), are wing‐propelled divers that consume small fish and invertebrates and have a shared distribution in the North Atlantic.…”

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confidence: 53%

“…Indeed, the inshore arrival of spawning Capelin results in an order of magnitude increase in prey biomass in coastal Newfoundland (Gulka et al . 2019, Berard & Davoren 2020, Carvalho & Davoren 2020). As Capelin also is a high‐quality prey type, with energy density approximately double that of other coastal prey types, e.g.…”

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confidence: 99%

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Seabird species‐ and assemblage‐level isotopic niche shifts associated with changing prey availability during breeding in coastal Newfoundland

Jenkins

Davoren

2020

Ibis

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Shifting prey availability can lead to altered species interactions, indicated by variation in the dietary niche breadth and position of species within an assemblage. On the Newfoundland coast, annual inshore spawning migration of the dominant forage fish, Capelin Mallotus villosus, provides an excellent opportunity to investigate the influence of varying prey availability on dietary niche breadth and position among species. During June–August 2017, we investigated species‐ and assemblage‐level dietary responses to shifting Capelin availability of three Capelin‐eating, sympatrically breeding auk species, the Atlantic Puffin Fratercula arctica, Razorbill Alca torda and Common Murre Uria aalge. The diet of Leach's Storm Petrels Oceanodroma leucorhoa, which breed alongside the three auk species but are not known to rely on Capelin, was also examined to determine dietary shifts throughout breeding that were unrelated to Capelin availability. We quantified stable isotope ratios (δ15N, δ13C) in seabird blood components (plasma, cellular component) collected both before and after spawning Capelin arrived in the study area and compared isotopic niche breadth within a Bayesian framework. At the species level, auk trophic position increased and isotopic niche breadth narrowed after Capelin arrived, suggesting a more Capelin‐based diet. Simultaneously, trophic diversity of the auk assemblage, reflecting the extent of spacing among niches of species, decreased after spawning Capelin arrived inshore. Contrastingly, increased trophic position but broader isotopic niche breadth during higher relative to lower Capelin availability for Leach's Storm Petrel confirm that this species is probably not affected by the inshore arrival of Capelin, but instead that isotopic changes may be more related to a shift in breeding stage to chick‐rearing. Overall, our findings reiterate the importance of Capelin as a prey resource for breeding auks in coastal Newfoundland, but that the degree of reliance on Capelin varies among species, possibly allowing coexistence of these ecologically similar species. The findings highlight potential changing species interactions, such as increased competition, under declines in Capelin biomass.

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Section: Discussionsupporting

confidence: 70%

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confidence: 53%

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Seabird species‐ and assemblage‐level isotopic niche shifts associated with changing prey availability during breeding in coastal Newfoundland

Jenkins

Davoren

2020

Ibis

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“…We considered capelin availability as 'high' when capelin spawning was initiated at one or several spawning sites until capelin spawning had finished and we considered it 'low' outside of this period. Although capelin biomass peaks near the start of spawning [35,36,46], we further corroborated capelin availability periods using published data [36] from a ship-based hydroacoustic survey that quantified capelin biomass (g/m 2 ) over a cluster of subtidal spawning sites (Fig. 1).…”

Section: Study Area and Field Worksupporting

confidence: 78%

“…The degree to which individual great black-backed gulls alter their foraging behaviour and diet in response to changing resource availability, however, is unknown. In Newfoundland, Canada, a key forage fish, capelin (Mallotus villosus), migrates into coastal areas to spawn during the seabird breeding season, causing the inshore prey biomass to double upon arrival at inshore spawning sites [4,35,36]. This dramatic shift in prey availability results in population-level dietary shifts of other seabirds [4,20,21] and reduced seabird predation by gulls [30,31].…”

Section: Introductionmentioning

confidence: 99%

Different individual-level responses of great black-backed gulls (Larus marinus) to shifting local prey availability

Maynard

Gulka

Jenkins

et al. 2021

Preprint

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To grow, survive and reproduce under anthropogenic-induced changes, individuals must respond quickly and favourably to the surrounding environment. A species that feeds on a wide variety of prey types (i.e. generalist diet) may be comprised of generalist individuals, specialist individuals that feed on different prey types, or a combination of the two. If individuals within a population respond differently to an environmental change, population-level responses may not be detectable. By tracking foraging movements of eight great black-backed gulls ( Larus marinus ), a generalist species, we compared group-level and individual-level responses to an increase in prey biomass (capelin; Mallotus villosus ) during the breeding season in coastal Newfoundland, Canada. As hypothesized, shifts in prey availability resulted in significantly different individual responses in foraging behaviour and space use, which was not detectable when data from individuals were combined. Some individuals maintained similar foraging areas, foraging trip characteristics (e.g., trip length, duration) and habitat use with increased capelin availability, while others shifted foraging areas and habitats resulting in either increased or decreased trip characteristics. We show that individual specialization can be non-contextual in some gulls, whereby these individuals continuously use the same feeding strategy despite significant change in prey availability conditions. Findings also indicate high response diversity among individuals to shifting prey conditions that a population- or group-level study would not have detected, emphasizing the importance of examining individual-level strategies for future diet and foraging studies on generalist species.

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Habitat characteristics and diel patterns of sand lance (Ammodytes spp) in coastal Newfoundland

Morrison,

Davoren

2024

Environ Biol Fish

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Capelin (Mallotus villosus) availability influences the inshore summer diet of Atlantic cod (Gadus morhua) in coastal Newfoundland

Cited by 10 publications

References 48 publications

Seabird species‐ and assemblage‐level isotopic niche shifts associated with changing prey availability during breeding in coastal Newfoundland

Seabird species‐ and assemblage‐level isotopic niche shifts associated with changing prey availability during breeding in coastal Newfoundland

Different individual-level responses of great black-backed gulls (Larus marinus) to shifting local prey availability

Habitat characteristics and diel patterns of sand lance (Ammodytes spp) in coastal Newfoundland

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