Spatial association between hotspots of baleen whales and demographic patterns of Antarctic krill Euphausia superba suggests size-dependent predation

Santora, Jarrod A.; Reiss, Christian S.; Loeb, Valerie J.; Veit, Richard R.

doi:10.3354/meps08513

Cited by 115 publications

(111 citation statements)

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“…Fin whales are known to have a broad diet (Reilly et al 2013), opportunistically feeding on aggregated prey species with a preference for areas with complex water circulation, such as in upwelling areas around continental shelf edges, within eddies and fronts (Johnston et al 2005;Santora et al 2014). Fin whale hot spots in DP have been described in association with aggregations of E. superba (Santora et al 2010(Santora et al , 2014. Santora et al (2010) suggested size-dependent E. superba predation by fin whales, with a preference for swarms of large mature E. superba.…”

Section: Discussionmentioning

confidence: 99%

“…Fin whale hot spots in DP have been described in association with aggregations of E. superba (Santora et al 2010(Santora et al , 2014. Santora et al (2010) suggested size-dependent E. superba predation by fin whales, with a preference for swarms of large mature E. superba. In summer, these predominantly occur around the shelf edge region north of the South Shetland Islands in DP, while smaller juvenile E. superba is found in more coastal areas (Siegel 1988;Siegel and Loeb 1995;Siegel et al 2004).…”

Section: Discussionmentioning

confidence: 99%

“…As mentioned above, it is likely that humpback whales were exploiting krill occurrences beyond a certain density threshold, not driven by highest prey density. Moreover, Santora et al (2010) suggested that humpback whales have a preference for small juvenile krill mainly residing in the shelf waters of the BS, as opposed to large, fast swimming mature krill, mainly found further offshore. Whether size-dependent predation is a driver of humpback whale distribution, or humpback whales feed on krill sizes most available in their preferred habitat cannot be determined on the basis of our study.…”

Section: Discussionmentioning

confidence: 99%

“…This is probably, at least partly, due to local depletion of krill abundance. Santora et al (2010) suggested that baleen whales may be able to deplete the abundance of the local prey at small spatial scales. As mentioned above, it is likely that humpback whales were exploiting krill occurrences beyond a certain density threshold, not driven by highest prey density.…”

Section: Discussionmentioning

confidence: 99%

“…It is possible that whales recorded during our survey were feeding on small, locally restricted krill patches that were not detected by the net sampling survey for krill. Moreover, high densities of whales in an area may have an impact on local krill density due to the feeding activity of the whales (Santora et al 2010).…”

Section: Discussionmentioning

confidence: 99%

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Horizontal niche partitioning of humpback and fin whales around the West Antarctic Peninsula: evidence from a concurrent whale and krill survey

et al. 2016

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A dedicated aerial cetacean survey was conducted concurrently to a standardised net trawl survey for krill in order to investigate distribution patterns of large whales and different krill species and to investigate relationships of these. Distance sampling data were used to produce density surface models for humpback (Megaptera novaeangliae) and fin whales (Balaenoptera physalus) around the West Antarctic Peninsula (WAP). Abundance for both species was estimated over two strata in the Bransfield Strait and Drake Passage. Distinct distribution patterns suggest horizontal niche partitioning of the two whale species around the WAP, with fin whales aggregating at the shelf edge of the South Shetland Islands in the Drake Passage and humpback whales in the Bransfield Strait. Krill biomass estimated from the concurrent krill survey was used along with CTD data from the same expedition, bathymetric parameters and satellite data on chlorophyll-a and ice concentration to model krill distribution. Comparisons of the predicted distributions of both whale species with the predicted distributions of Euphausia superba, Euphausia crystallorophias and Thysanoessa macrura suggest a complex relationship rather than a straightforward correlation between krill and whales. However, results indicate that fin whales were feeding in an area dominated by T. macrura, while humpback whales were found in areas of higher E. superba biomass. Our results provide abundance estimates for humpback whales and, for the first time, fin whales in the WAP and contribute important information on feeding ecology and habitat use of these two species in the Southern Ocean.

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Section: Discussionmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

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Horizontal niche partitioning of humpback and fin whales around the West Antarctic Peninsula: evidence from a concurrent whale and krill survey

et al. 2016

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Historical baleen plates indicate that once abundant Antarctic blue and fin whales demonstrated distinct migratory and foraging strategies

Smith,

Ososky,

Hunt

et al. 2024

Ecology and Evolution

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Southern hemisphere blue (Balaenoptera musculus intermedia) and fin (Balaenoptera physalus) whales are the largest predators in the Southern Ocean, with similarities in morphology and distribution. Yet, understanding of their life history and foraging is limited due to current low abundances and limited ecological data. To address these gaps, historic Antarctic blue (n = 5) and fin (n = 5) whale baleen plates, collected in 1947–1948 and recently rediscovered in the Smithsonian National Museum of Natural History, were analyzed for bulk (δ13C and δ15N) stable isotopes. Regular oscillations in isotopic ratios, interpreted as annual cycles, revealed that baleen plates contain approximately 6 years (14.35 ± 1.20 cm year−1) of life history data in blue whales and 4 years (16.52 ± 1.86 cm year−1) in fin whales. Isotopic results suggest that: (1) while in the Southern Ocean, blue and fin whales likely fed at the same trophic level but demonstrated niche differentiation; (2) fin whales appear to have had more regular annual migrations; and (3) fin whales may have migrated to ecologically distinct sub‐Antarctic waters annually while some blue whales may have resided year‐round in the Southern Ocean. These results reveal differences in ecological niche and life history strategies between Antarctic blue and fin whales during a time period when their populations were more abundant than today, and before major human‐driven climatic changes occurred in the Southern Ocean.

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Resource partitioning facilitates coexistence in sympatric cetaceans in the California Current

Fossette

Abrahms

Hazen

et al. 2017

Ecology and Evolution

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Resource partitioning is an important process driving habitat use and foraging strategies in sympatric species that potentially compete. Differences in foraging behavior are hypothesized to contribute to species coexistence by facilitating resource partitioning, but little is known on the multiple mechanisms for partitioning that may occur simultaneously. Studies are further limited in the marine environment, where the spatial and temporal distribution of resources is highly dynamic and subsequently difficult to quantify. We investigated potential pathways by which foraging behavior may facilitate resource partitioning in two of the largest co‐occurring and closely related species on Earth, blue (Balaenoptera musculus) and humpback (Megaptera novaeangliae) whales. We integrated multiple long‐term datasets (line‐transect surveys, whale‐watching records, net sampling, stable isotope analysis, and remote‐sensing of oceanographic parameters) to compare the diet, phenology, and distribution of the two species during their foraging periods in the highly productive waters of Monterey Bay, California, USA within the California Current Ecosystem. Our long‐term study reveals that blue and humpback whales likely facilitate sympatry by partitioning their foraging along three axes: trophic, temporal, and spatial. Blue whales were specialists foraging on krill, predictably targeting a seasonal peak in krill abundance, were present in the bay for an average of 4.7 months, and were spatially restricted at the continental shelf break. In contrast, humpback whales were generalists apparently feeding on a mixed diet of krill and fishes depending on relative abundances, were present in the bay for a more extended period (average of 6.6 months), and had a broader spatial distribution at the shelf break and inshore. Ultimately, competition for common resources can lead to behavioral, morphological, and physiological character displacement between sympatric species. Understanding the mechanisms for species coexistence is both fundamental to maintaining biodiverse ecosystems, and provides insight into the evolutionary drivers of morphological differences in closely related species.

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Spatial association between hotspots of baleen whales and demographic patterns of Antarctic krill Euphausia superba suggests size-dependent predation

Cited by 115 publications

References 80 publications

Horizontal niche partitioning of humpback and fin whales around the West Antarctic Peninsula: evidence from a concurrent whale and krill survey

Horizontal niche partitioning of humpback and fin whales around the West Antarctic Peninsula: evidence from a concurrent whale and krill survey

Historical baleen plates indicate that once abundant Antarctic blue and fin whales demonstrated distinct migratory and foraging strategies

Resource partitioning facilitates coexistence in sympatric cetaceans in the California Current

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