Baleen whale prey consumption based on high-resolution foraging measurements

Savoca, Matthew S.; Czapanskiy, Max F; Kahane-Rapport, Shirel R; Gough, William T.; Fahlbusch, James A.; Bierlich, K. C.; Segre, Paolo S.; Clemente, Jacopo Di; Penry, Gwenith S.; Wiley, David N.; Calambokidis, John; Nowacek, Douglas P.; Johnston, David W.; Pyenson, Nicholas D.; Friedlaender, Ari S.; Hazen, Elliott L.; Goldbogen, Jeremy A.

doi:10.1038/s41586-021-03991-5

Cited by 132 publications

(131 citation statements)

References 120 publications

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“…Indeed, the consumption estimates by Reilly et al (2004) are highly uncertain and vary considerably according to methods used. Using a novel approach combining lunge feeding frequency and prey density, Savoca et al (2021) estimate that the consumption of krill by cetaceans may be up to three times that previously estimated. As krill predator populations continue to recover, their consumption of krill will increase, and potentially increase competition among other krill predators.…”

Section: Discussionmentioning

confidence: 99%

“…Consumption estimates suggest that in the most intensively used areas, humpback whales may consume up to 162 kg km À2 day À1 (Figure 3), and fin whales consume up to 415 kg km À2 day À1 . When alternative consumption estimates described by Reilly et al (2004) and Savoca et al (2021) were combined with the high and low confidence bounds, the amount of krill consumed by humpback and fin whales in the study area varied considerably (Appendix S2: Table S7).…”

Section: Whales-at-sea Surveysmentioning

confidence: 99%

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Using seabird and whale distribution models to estimate spatial consumption of krill to inform fishery management

et al. 2022

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Ecosystem dynamics at the northwest Antarctic Peninsula are driven by interactions between physical and biological processes. For example, baleen whale populations are recovering from commercial harvesting against the backdrop of rapid climate change, including reduced sea ice extent and changing ecosystem composition. Concurrently, the commercial harvesting of Antarctic krill is increasing, with the potential to increase the likelihood for competition with and between krill predators and the fishery. However, understanding the ecology, abundance, and spatial distribution of krill predators is often limited, outdated, or at spatial scales that do not match those desired for effective fisheries management. We update current knowledge of predator dependence on krill by integrating telemetry‐based data, at‐sea observational surveys, estimates of predator abundance, and physiological data to estimate the spatial distribution of krill consumption during the austral summer by three species of Pygoscelis penguin, 11 species of flying seabirds, one species of pinniped, and two species of baleen whale. Our models show that the majority of important areas for krill predator foraging are close to penguin breeding colonies in nearshore areas where humpback whales also regularly feed, and along the shelf‐break, though we caution that not all known krill predators are included in these analyses. We show that krill consumption is highly variable across the region, and often concentrated at fine spatial scales, emphasizing the need for the management of the local krill fishery at relevant temporal and spatial scales. We also note that krill consumption by recovering populations of krill predators provides further evidence in support of the krill surplus hypothesis, and highlight that despite less than comprehensive data, cetaceans are likely to consume a significant proportion of the krill consumed by natural predators but are not currently considered directly in the management of the krill fishery. If management of the krill fishery is to be precautionary and operate in a way that minimizes the risks to krill predator populations, it will be necessary in future analyses, to include up‐to‐date and precise abundance and consumption estimates for pack‐ice seals, finfish, squid, and other baleen whale species not currently considered.

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Section: Discussionmentioning

confidence: 99%

Section: Whales-at-sea Surveysmentioning

confidence: 99%

Using seabird and whale distribution models to estimate spatial consumption of krill to inform fishery management

et al. 2022

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“…2, Supplementary Table S4), typical of waters modified by coastal upwelling. Given fin whale estimated daily average consumption of ~ 8 tons of krill 67 , our abundance estimate (median 2383.8, SD 671, CI 1387.9-5068.5) indicate that this sole species might remove ~ 7 × 10 6 tons of krill a year. Considering that the role of large cetaceans in the ecosystem functioning and biogeochemical cycling of the HCE has been traditionally undermined 1,4,7,61 our results highlight the importance that fin and other baleen whales might elicit in HCE structuring [68][69][70][71] .…”

Section: Discussionmentioning

confidence: 88%

Abundance and distribution patterns of cetaceans and their overlap with vessel traffic in the Humboldt Current Ecosystem, Chile

Bedriñana‐Romano

Zárate

Hucke‐Gaete

et al. 2022

Sci Rep

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The Humboldt Current Ecosystem (HCE) is one of the most productive marine ecosystems, sustaining one of the largest fishing industries in the world. Although several species of cetaceans are known to inhabit these productive waters, quantitative assessments of their abundance and distribution patterns are scarce and patchy. Here, we present the first abundance and distribution estimates for fin whale (Balaenoptera physalus), southeast Pacific blue whales (Balaenoptera musculus), sperm whale (Physeter macrocephalus), dusky dolphin (Lagenorhynchus obscurus), and common dolphin (Delphinus spp.) in the entire Chilean portion of the HCE. Line transect surveys were conducted during 2016–2021 between 18° S and 41° S and up to ~ 200 km offshore, and data were analyzed using distance sampling methods. Group counts were modelled as a function of environmental variables using single step Bayesian Binomial N-mixture model (BNMM), which allows full uncertainty propagation between model components. By using spatially explicit predictions of cetacean densities and observed vessel densities in the HCE, we provide quantitative assessments on the relative probability of cetaceans encountering vessels (RPCEV). Dusky dolphin and fin whale showed the largest distribution overlap with industrial and artisanal fishery fleets. Our results highlight areas where effort should be prioritized to address the extant but unquantified negative interactions between vessels and cetaceans in Chilean HCE.

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“…In practice, the excess krill biomass appears to have been eroded during the last quarter of the 20th century by a decline in the primary productivity of the Southern Ocean [ 4 ]. This has been linked to a reduction in the bioavailability of whale-recycled iron [ 4 , 10 , 11 ], as well as to climate-driven declines in sea ice extent and krill density in the Western Antarctic Peninsula and Scotia Sea [ 8 , 12 , 13 , 16 ]. In the case of the Antarctic fur seal, the number of females breeding at a long-term study population on Bird Island shows tight linkage to local krill availability [ 14 ] and there has also been a recent switch from positive to negative dependent pup mortality [ 77 ].…”

Section: Discussionmentioning

confidence: 99%

“…These hunted whales would have consumed vast amounts of Antarctic krill ( Euphausia superba ), a shrimp-like crustacean that forms the dominant prey of many mammals and birds of the Southern Ocean [ 8 ]. Consequently, whaling activities in the Southern Ocean are estimated to have produced a surplus of around 147–380 million tonnes of uneaten krill per year [ 6 , 11 ]. This competitive release of krill is thought to explain increases in populations of seals and penguins at South Georgia during the 1940s to 1970s, a top-down hypothesis referred to as the ‘krill surplus hypothesis’ [ 6 ].…”

Section: Introductionmentioning

confidence: 99%

Demographic Reconstruction of Antarctic Fur Seals Supports the Krill Surplus Hypothesis

Hoffman

Chen

Vendrami

et al. 2022

Genes

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Much debate surrounds the importance of top-down and bottom-up effects in the Southern Ocean, where the harvesting of over two million whales in the mid twentieth century is thought to have produced a massive surplus of Antarctic krill. This excess of krill may have allowed populations of other predators, such as seals and penguins, to increase, a top-down hypothesis known as the ‘krill surplus hypothesis’. However, a lack of pre-whaling population baselines has made it challenging to investigate historical changes in the abundance of the major krill predators in relation to whaling. Therefore, we used reduced representation sequencing and a coalescent-based maximum composite likelihood approach to reconstruct the recent demographic history of the Antarctic fur seal, a pinniped that was hunted to the brink of extinction by 18th and 19th century sealers. In line with the known history of this species, we found support for a demographic model that included a substantial reduction in population size around the time period of sealing. Furthermore, maximum likelihood estimates from this model suggest that the recovered, post-sealing population at South Georgia may have been around two times larger than the pre-sealing population. Our findings lend support to the krill surplus hypothesis and illustrate the potential of genomic approaches to shed light on long-standing questions in population biology.

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Baleen whale prey consumption based on high-resolution foraging measurements

Cited by 132 publications

References 120 publications

Using seabird and whale distribution models to estimate spatial consumption of krill to inform fishery management

Using seabird and whale distribution models to estimate spatial consumption of krill to inform fishery management

Abundance and distribution patterns of cetaceans and their overlap with vessel traffic in the Humboldt Current Ecosystem, Chile

Demographic Reconstruction of Antarctic Fur Seals Supports the Krill Surplus Hypothesis

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