Prey-switching to fishery discards does not compensate for poor natural foraging conditions in breeding albatross

Kuepfer, Amanda; Votier, Stephen C.; Sherley, Richard B.; Ventura, Francesco; Matias, Rafael; Anderson, Orea R. J.; Brickle, Paul; Arkhipkin, Alexander I.; Catry, Paulo; Scales, ed.

doi:10.1093/icesjms/fsac069

Cited by 4 publications

(1 citation statement)

References 78 publications

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“…Birds were found to feed a lot on discards, e.g. fish guts and heads from fishing vessels (Kuepfer et al ., 2022), resulting in elevated δ 15 N ratios (Mariano-Jelicich et al ., 2014). Another interesting finding was the high niche overlap between adult M. gregaria and benthic omnivorous species (56.58%).…”

Section: Discussionmentioning

confidence: 99%

Unveiling the wasp-waist structure of the Falkland shelf ecosystem: the role of Doryteuthis gahi as a keystone species and its trophic influences

Büring,

van Der Grient,

Pierce

et al. 2024

J. Mar. Biol. Ass.

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The Falkland Shelf is a highly productive ecosystem in the Southwest Atlantic Ocean. It is characterized by upwelling oceanographic dynamics and displays a wasp-waist structure, with few intermediate trophic-level species and many top predators that migrate on the shelf for feeding. One of these resident intermediate trophic-level species, the Patagonian longfin-squid Doryteuthis gahi, is abundant and plays an important role in the ecosystem. We used two methods to estimate the trophic structure of the Falkland Shelf food web, focusing on the trophic niche of D. gahi and its impacts on other species and functional groups to highlight the importance of D. gahi in the ecosystem. First, stable isotope measurements served to calculate trophic levels based on an established nitrogen baseline. Second, an Ecopath model was built to corroborate trophic levels derived from stable isotopes and inform about trophic interactions of D. gahi with other functional groups. The results of both methods placed D. gahi in the centre of the ecosystem with a trophic level of ~ 3. The Ecopath model predicted high impacts and therefore a high keystoneness for both seasonal cohorts of D. gahi. Our results show that the Falkland Shelf is not only controlled by species feeding at the top and the bottom of the trophic chain. The importance of species feeding at the third trophic level (e.g. D. gahi and Patagonotothen ramsayi) and observed architecture of energy flows confirm the ecosystem's wasp-waist structure with middle-out control mechanisms at play.

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Section: Discussionmentioning

confidence: 99%

Unveiling the wasp-waist structure of the Falkland shelf ecosystem: the role of Doryteuthis gahi as a keystone species and its trophic influences

Büring,

van Der Grient,

Pierce

et al. 2024

J. Mar. Biol. Ass.

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Inter-colony and inter-annual variation in discard use by albatross chicks revealed using isotopes and regurgitates

Kuepfer

Catry²,

Bearhop

et al. 2023

Mar Biol

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Effective marine ecosystem monitoring is critical for sustainable management. Monitoring seabird diets can convey important information on ecosystem health and seabird–fishery interactions. The diet of breeding black-browed albatross (Thalassarche melanophris) has previously been assessed using stomach content analysis (SCA) or stable isotope analysis (SIA), but not both methods together. Combining dietary sampling approaches reduces biases associated with using single methods. This study combines SCA and SIA to study the diet of black-browed albatross chicks, with a specific focus on fishery discard consumption, at two Falkland Islands colonies (New Island 51°43′S, 61°18′W and Steeple Jason Island 51°01′S, 61°13′W) during two consecutive breeding seasons (2019 and 2020). SCA provided high taxonomic resolution of short-term diet and priors for stable isotope mixing models, with multiple measures of dietary items (e.g. numeric frequency N%, frequency of occurrence FO%). By contrast, SIA of down feathers provided a single and more integrated dietary signal from throughout chick development. Although the two methods disagreed on the dominant prey group (SCA—crustacean; SIA—pelagic fish), the complementary information suggested a chick diet dominated by natural prey (SCA: 74%–93% [FO], 44%–98% [N]; SIA: minimum 87%–95% contribution). Nonetheless, SCA revealed that a high proportion of breeding adults do take discards. We detected consistent colony-specific diets in relation to prey species, but not in relation to higher discard use. Overall, discard consumption was highest in 2020, the year characterised by the poorest foraging conditions. Our results have implications for fisheries management and future dietary studies assessing discard use.

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The Falkland Islands marine ecosystem: A review of the seasonal dynamics and trophic interactions across the food web

Grient¹,

Morley²,

Arkhipkin³

et al. 2023

Advances in Marine Biology

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Prey-switching to fishery discards does not compensate for poor natural foraging conditions in breeding albatross

Cited by 4 publications

References 78 publications

Unveiling the wasp-waist structure of the Falkland shelf ecosystem: the role of Doryteuthis gahi as a keystone species and its trophic influences

Unveiling the wasp-waist structure of the Falkland shelf ecosystem: the role of Doryteuthis gahi as a keystone species and its trophic influences

Inter-colony and inter-annual variation in discard use by albatross chicks revealed using isotopes and regurgitates

The Falkland Islands marine ecosystem: A review of the seasonal dynamics and trophic interactions across the food web

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