Intra‐season variations in distribution and abundance of humpback whales in the West Antarctic Peninsula using cruise vessels as opportunistic platforms

Johannessen, John Elling Deehr; Biuw, Martin; Lindstrøm, Ulf; Ollus, Victoria; López, Lucía Martina Martín; Gkikopoulou, Kalliopi C.; Oosthuizen, W. Chris; Lowther, Andrew D.

doi:10.1002/ece3.8571

Cited by 10 publications

(22 citation statements)

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“…showed that humpback whales used the Antarctic Peninsula West (APW), Bransfield Strait West (APBSW), and Drake (APDP) Passage West SSMUs more often than expected, spending more time in a restricted behavioural state in these SSMUs. Similarly, density modelling of humpback whale sightings data likewise identifies the Bransfield Strait and northern Gerlache Strait as areas of high humpback whale abundance, at least during December (Johannessen et al, 2022). In the last decade, krill fishing has shifted spatially into the Bransfield Strait (Santa Cruz et al, 2018), representing the primary krill fishing hotspot in our analysis (Figure 5).…”

Section: Discussionsupporting

confidence: 69%

“…Baleen whale concentrations (Johnston et al, 2012) mirror these supper aggregations of krill and whales consistently distribute in these places and forage in a manner that optimises energy gain (Friedlaender et al, 2013;Friedlaender et al, 2016;Tyson et al, 2016) Johannessen et al (2022 see also Warwick-Evans et al, 2022) estimate peak potential competition (calculated as humpback whales' per capita consumption multiplied by their abundance through the season, and krill catch through the season) in April, which corresponds with the highest values in our monthly spatial overlap index. Based on the assumption that whales spend 120 days in their Southern Ocean foraging areas (Lockyer, 1981), Johannessen et al (2022) calculated very limited humpback whale-fishery competition by May, but tracking data in this study and shows that some individuals remain in the region as late as July. Further, minke whales may remain in the Western Antarctic Peninsula region much longer, and can overwinter in the area (Dominello and Širovi&cacute;.…”

Section: Discussionmentioning

confidence: 66%

“…Sea surface temperature has been found to be an important covariate influencing the habitat selection of humpback whales in the Southern Ocean (e.g., Andrews-Goff et al, 2018;Bestley et al, 2019;Riekkola et al, 2019;Reisinger et al, 2021). Johannessen et al (2022) observed a positive correlation between humpback whale presence and sea surface temperature in the Bransfield Strait region, and interpret this as a preference for the warm, nutrient-rich Circumpolar Deep Water that is delivered onto the continental shelf (Martinson & McKee, 2012;Wang et al, 2022), driving marine productivity (e.g., Ducklow et al, 2012).…”

Section: Discussionmentioning

confidence: 96%

“…However, most work has so far focussed on penguins and seals while baleen whales, despite being major krill consumers (Savoca et al, 2021), have received comparatively little attention (cf. Johannessen et al, 2022;Trathan et al, 2022). Indeed, baleen whales are not explicitly included in CCAMLR's ecosystem approach to fishery management or in the CCAMLR Ecosystem Monitoring Program that monitors other krill consumers (Agnew, 1997).…”

Section: Discussionmentioning

confidence: 99%

“…The humpback whale population that uses waters off the Western Antarctic Peninsula is increasing rapidly (Pallin et al, 2018) and unprecedentedly dense 'super-aggregations' have been observed in this region (Nowacek et al, 2011). Spatial abundance models estimate around 19,000 individuals in this region in early summer (Johannessen et al, 2022; see also Warwick-Evans et al, 2022), a 5.1% per annum increase from the estimated 7,000 individuals in the same region in 2000 (Hedley et al, 2001;Johannessen et al, 2022). Their global IUCN Red List classification is Least Concern (Cooke, 2018).…”

Section: Humpback and Minke Whalesmentioning

confidence: 99%

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Spatiotemporal Overlap of Baleen Whales and Krill Fisheries in the Western Antarctic Peninsula Region

et al. 2022

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In Antarctica, abundant consumers rely on Antarctic krill for food, but krill are also the subject of a commercial fishery. The fishery overlaps in time and space with the foraging areas of these consumers, thus potential competition between krill fisheries and krill consumers is a major management concern. The fishery is managed by the Commission for the Conservation of Antarctic Marine Living Resources with an ecosystem approach, according to which fishing should not interfere with either the population growth of krill, or krill-dependent consumers. Krill catches have become increasingly spatially concentrated in a small number of hotspots, raising concerns about how local depletion of krill impacts consumers. Such concentrated fishing demonstrates that there is a mismatch between the spatial and temporal scale at which krill fisheries are currently managed, and that at which fisheries operate and consumers forage. Information on the seasonal dynamics of predator abundance and their foraging behaviour is fundamental to future precautionary management of the krill fishery. We analysed the spatiotemporal distribution of two major krill consumers – humpback and minke whales – and that of krill fishing, off the Western Antarctic Peninsula. We used whale tracking data (58 humpback whale tracks and 19 minke whale tracks) to develop spatial random forest models predicting the monthly distribution of whale foraging areas from January-July. Using these predictions, we calculated spatiotemporally-explicit geographic overlap between whales and fisheries, the latter represented by krill fishing effort and catch data. Over the krill fishing season, fishing effort and catch hotspots shifted to the southwest, into the Bransfield Strait where effort and catch was highest. Predicted humpback whale foraging areas increased in the Bransfield Strait over the same period, while predicted minke whale foraging areas showed an opposite trend. For both we predicted a whale-fishing interaction hotspot in the Bransfield Strait, strongest in April and May. Our results illustrate the fine spatial scale of likely interactions between baleen whales and the krill fishery, and their concentration over the season, underlining the need for fishery management more closely aligned to the spatiotemporal scale of likely predator-fishery interactions.

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Section: Discussionsupporting

confidence: 69%

Section: Discussionmentioning

confidence: 66%

Section: Discussionmentioning

confidence: 96%

Section: Discussionmentioning

confidence: 99%

Section: Humpback and Minke Whalesmentioning

confidence: 99%

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Spatiotemporal Overlap of Baleen Whales and Krill Fisheries in the Western Antarctic Peninsula Region

et al. 2022

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First evidence for fin whale migration into the Pacific from Antarctic feeding grounds at Elephant Island

et al. 2022

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This study presents the first long-distance tracks of fin whales ( Balaenoptera physalus ) equipped with satellite transmitters off the Antarctic Peninsula. Southern Hemisphere fin whales were severely depleted by twentieth century industrial whaling, yet recently, they have returned to historical feeding grounds off the northern Antarctic Peninsula, forming large aggregations in austral summers. To date, our knowledge only extended to summer behaviour, while information regarding migration routes and the location of breeding and wintering grounds are lacking. During the austral autumn of 2021, we deployed nsatellite transmitters on four fin whales at Elephant Island. Two transmitters stopped working while the animals were still at the feeding grounds, while two continued to transmit during the transition from feeding activity to migration. Both migrating animals left the feeding ground on 15 April 2021, travelling northward into the Pacific and up along the Chilean coast. The most northerly position received before all tags stopped transmitting on 1 May 2021 was at 48°S. These tracks provide initial evidence of seasonal migratory routes and a first indication toward possible locations of winter destinations. This information, even if preliminary, is critical for investigations of population connectivity, population structure and the identification of breeding grounds of Southern Hemisphere fin whales.

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Seasonal acoustic presence of marine mammals at the South Orkney Islands, Scotia Sea

Åsvestad,

Ahonen,

Menze

et al. 2024

R. Soc. open sci.

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Increased knowledge about marine mammal seasonal distribution and species assemblage from the South Orkney Islands waters is needed for the development of management regulations of the commercial fishery for Antarctic krill ( Euphausia superba ) in this region. Passive acoustic monitoring (PAM) data were collected during the autumn and winter seasons in two consecutive years (2016, 2017), which represented highly contrasting environmental conditions due to the 2016 El Niño event. We explored differences in seasonal patterns in marine mammal acoustic presence between the two years in context of environmental cues and climate variability. Acoustic signals from five baleen whale species, two pinniped species and odontocete species were detected and separated into guilds. Although species diversity remained stable over time, the ice-avoiding and ice-affiliated species dominated before and after the onset of winter, respectively, and thus demonstrating a shift in guild composition related to season. Herein, we provide novel information about local marine mammal species diversity, community structure and residency times in a krill hotspot. Our study also demonstrates the utility of PAM data and its usefulness in providing new insights into the marine mammal habitat use and responses to environmental conditions, which are essential knowledge for the future development of a sustainable fishery management in a changing ecosystem.

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Intra‐season variations in distribution and abundance of humpback whales in the West Antarctic Peninsula using cruise vessels as opportunistic platforms

Abstract: This is an open access article under the terms of the Creat ive Commo ns Attri bution License, which permits use, distribution and reproduction in any medium, provided the original work is properly cited.

Cited by 10 publications

References 103 publications

Spatiotemporal Overlap of Baleen Whales and Krill Fisheries in the Western Antarctic Peninsula Region

Spatiotemporal Overlap of Baleen Whales and Krill Fisheries in the Western Antarctic Peninsula Region

First evidence for fin whale migration into the Pacific from Antarctic feeding grounds at Elephant Island

Seasonal acoustic presence of marine mammals at the South Orkney Islands, Scotia Sea

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