Life Histories of Satellite-Tracked Southern Right Whales Through Photo-Identification and Citizen Science in Patagonia, Argentina

Vilches, Florencia Ornela; Sironi, Mariano; Zerbini, Alexandre N.; Fernández, Santiago J.; Uhart, Marcela; Rowntree, Victoria J.

doi:10.1578/am.49.2.2023.167

Cited by 2 publications

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“…Ongoing studies are incorporating new techniques that may provide important information about the life histories of the whales that visit PV. In particular, two new sources of images have recently been developed to photograph individuals for later identification: citizen science photos taken during whale-watching trips and UAV (unmanned aerial vehicle) drone surveys [8,[33][34][35]. By contrast to single annual aerial survey data, these additional sources of data cover most of the whale season and have contributed to expansion of the database.…”

Section: Discussionmentioning

confidence: 99%

“…By contrast to single annual aerial survey data, these additional sources of data cover most of the whale season and have contributed to expansion of the database. The analysis of photos taken by citizen scientists during whale-watching tours throughout the calving season from 2003 to 2007 added 105 new individuals and new sightings of 45 previously known individuals to the reference catalogue [33]. Drone surveys add around 300-400 whales per year to the catalogue.…”

Section: Discussionmentioning

confidence: 99%

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Effect of kelp gull harassment on southern right whale calf survival: a long-term capture–recapture analysis

et al. 2023

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Kelp gulls ( Larus dominicanus ) commonly feed on the skin and blubber of surfacing southern right whales (SRW, Eubalaena australis ) in the near shore waters of Península Valdés (PV), Argentina. Mothers and especially calves respond to gull attacks by changing their swimming speeds, resting postures and overall behaviour. Gull-inflicted wounds per calf have increased markedly since the mid-1990s. Unusually high mortality of young calves occurred locally after 2003, and increasing evidence points to gull harassment as a factor contributing to the excess deaths. After leaving PV, calves undertake a long migration with their mothers to summer feeding areas; their health during this strenuous exertion is likely to affect their probabilities of first-year survival. To explore the effects of gull-inflicted wounds on calf survival, we analysed 44 capture–recapture observations between 1974 and 2017, for 597 whales photo-identified in their years of birth between 1974 and 2011. We found a marked decrease in first-year survival associated with an increase in wound severity over time. Our analysis supports recent studies indicating that gull harassment at PV may impact SRW population dynamics.

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Section: Discussionmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

Effect of kelp gull harassment on southern right whale calf survival: a long-term capture–recapture analysis

et al. 2023

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Seabird attacks contribute to calf mortality in a whale population

Piotto,

Barberá,

Sironi

et al. 2024

Mar. Ecol. Prog. Ser.

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Reports of seabirds attacking marine mammals have become frequent in the 2000s. Southern right whales Eubalaena australis off Península Valdés (PV), Argentina, have suffered the effects of micropredation by kelp gulls Larus dominicanus since at least the 1970s. During 2003-2013, this population experienced 9 yr of unprecedented high calf mortality. Using a 25 yr dataset (1995-2019) of focal follows of gull-whale interactions, we studied long-term changes in gull attack intensity (attacks h-1) and frequency, and explored whether they influenced calf mortality. We also asked whether calf mortality was affected by prey density at maternal feeding grounds during gestation. Applying Bayesian models, we found that the intensity and frequency of attacks increased significantly from 1995 to the 2000s, and that in 2004-2019, calves received 2.85 times as many attacks as did mothers. Moreover, attacks significantly contributed to increase the probability of calves dying, such that a year with average overall harassment had 2.26 times the mortality of a hypothetical year with no attacks. In years of high intensity and frequency of attacks, many older calves died near the end of the season, probably reflecting the cumulative effect of gull harassment on calf health. However, calf mortality was not affected by prey density, and extremely high mortality was not related to extremely high frequency or intensity of attacks, indicating that deaths are also influenced by other unidentified factors. These findings imply that chronic micropredation contributed to the unprecedented high calf mortality observed in PV and that other marine mammal populations experiencing seabird attacks could be threatened.

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Life Histories of Satellite-Tracked Southern Right Whales Through Photo-Identification and Citizen Science in Patagonia, Argentina

Cited by 2 publications

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Effect of kelp gull harassment on southern right whale calf survival: a long-term capture–recapture analysis

Effect of kelp gull harassment on southern right whale calf survival: a long-term capture–recapture analysis

Seabird attacks contribute to calf mortality in a whale population

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