Life History of Risso’s Dolphin (Grampus griseus) (G. Cuvier, 1812) in the Faroe Islands

Bloch, Dorete; Desportes, Geneviève; Harvey, Paul V.; Lockyer, Christina; Mikkelsen, Bjarni

doi:10.1578/am.38.3.2012.250

Cited by 26 publications

(21 citation statements)

References 18 publications

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“…In the eastern Atlantic, records indicate a range throughout European waters, with current northern distributional limits at the Faroe Islands (∼62°N; Bloch et al. ) and central Norway (∼64°N; N. Øien, pers. comm.…”

Section: Resultsmentioning

confidence: 99%

Global distribution ofRisso's dolphinGrampus griseus: a review and critical evaluation

Jefferson

Weir²,

Anderson

et al. 2013

Mammal Review

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The global range of Risso's dolphin Grampus griseus is not well known, and there has been confusion in the literature as to whether the species has a broad, circumglobal range or only occurs along continental margins. To clarify the species' distribution and habitat preferences, we compiled and reviewed all available (published and unpublished) records of sightings and captures of this species for the past 62 years (1950–2012, n = 8068 records). Stranding records were not included. The results showed that the species has a range that extends across ocean basins and spans between at least 64°N and 46°S, and is apparently absent from high‐latitude polar waters. Although Risso's dolphins occur in all habitats from coastal to oceanic, they show a strong range‐wide preference for mid‐temperate waters of the continental shelf and slope between 30° and 45° latitude. Although a number of misconceptions about the distributional ecology of Risso's dolphin have existed, this analysis showed that it is a widespread species. It strongly favours temperate waters and prefers continental shelf and slope waters to oceanic depths. These habitat preferences appear to hold throughout much or all of the species' range.

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Section: Resultsmentioning

confidence: 99%

Global distribution ofRisso's dolphinGrampus griseus: a review and critical evaluation

Jefferson

Weir²,

Anderson

et al. 2013

Mammal Review

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“…Average weaning age for Risso's dolphins in the present study determined from dentinal δ 15 N values was between 1.0 and 2.0 yr, similar to that reported for those caught in Japan (Amano and Miyazaki ) and the Faroe Islands (Bloch et al . ). This demonstrates that changes in dentinal δ 15 N values during the early postnatal period in Risso's dolphins is associated with weaning and can closely reflect the transition in their dietary protein sources to consumption of captured prey.…”

Section: Discussionmentioning

confidence: 97%

“…Growth curves derived from measurements of captured individuals in Japan (Amano and Miyazaki ) and the Faroe Islands (Bloch et al . ) and of those stranded in Taiwan (Chen et al . ) show that Risso's dolphins grow fastest but at a decreasing rate during their first four postnatal years, which coincides with the observed decrease in δ 15 N values in our samples.…”

Section: Discussionmentioning

confidence: 99%

“…, Bloch et al . ). Examination of female reproductive structures of a pod of Risso's dolphins caught in Japan reported gestation periods of 13–14 mo, calving intervals of at least 2–3 yr, and nursing duration of 1–1.5 yr (Amano and Miyazaki ).…”

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confidence: 97%

“…Bloch et al . () also estimated that calves are weaned before 2 yr of age based on examination of individuals caught in an opportunistic drive fishery in the Faroe Islands. Risso's dolphins tend to remain with their natal group after weaning and subsequently leave to form groups of juvenile animals at approximately 5 yr of age (Amano and Miyazaki ).…”

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confidence: 99%

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Annual variability in dentin δ¹⁵N and δ¹³C reveal sex differences in weaning age and feeding habits in Risso's dolphins (Grampus griseus)

Evacitas

Kao

Worthy

et al. 2017

Marine Mammal Science

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Teeth of odontocetes accumulate annual dentinal growth layer groups (GLGs) that record isotope ratios, which reflect the time of their synthesis. Collectively, they provide lifetime records of individual feeding patterns from which life history traits can be inferred. We subsampled the prenatal dentin and postnatal GLGs in Risso's dolphins (Grampus griseus) (n = 65) that stranded or were collected as bycatch in Taiwan (1994–2014) and analyzed them for δ15N and δ13C. Age‐specific δ15N and δ13C values were corrected for effects of calendar year, stranding site, C/N, and sex. δ15N values were higher in prenatal layers (14.94‰ ± 0.74‰) than in adult female GLGs (12.58‰ ± 0.20‰), suggesting fetal enrichment during gestation. Decreasing δ15N values in early GLGs suggested changes in dietary protein sources during transition to complete weaning. Weaning age was earlier in males (1.09 yr) than in females (1.81 yr). Significant differences in δ15N values between weaned males and females suggest potential sexual segregation in feeding habits. δ13C values increased from the prenatal to the 4th GLG by ~1.0‰, indicative of a diet shift from 13C‐depleted milk to prey items. Our results provide novel insights into the sex‐specific ontogenetic changes in feeding patterns and some life history traits of Risso's dolphins.

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First record of Risso's dolphin Grampus griseus (Cuvier, 1812) in Icelandic waters

Chosson,

Randhawa,

Sigurðsson

et al. 2023

Ecology and Evolution

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In July 2022, two Risso's dolphins were reported stranded in Hrútafjörður (N65° 09,503; W21° 05,529), a fjord in northern Iceland. These events represent the first confirmed observations and strandings of Risso's dolphins in Icelandic waters. Given the uniqueness of these events, a decision was made to conduct full necropsies on these individuals. This study reports findings from viral and parasitological investigations, morphological and fitness measurements, as well as stomach and intestine content analysis for each of the Risso's dolphin specimens. The results of the necropsies do not suggest any other cause of death than lack of food and exhaustion. A large plastic fragment in one individual's stomach supports these suggestions. The presence of those specimens in the middle of the subarctic ocean illustrates ongoing changes in spatial distribution expanding northward, impacting not only Risso's dolphins but more generally marine life and biodiversity.

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Life History of Risso’s Dolphin (Grampus griseus) (G. Cuvier, 1812) in the Faroe Islands

Cited by 26 publications

References 18 publications

Global distribution ofRisso's dolphinGrampus griseus: a review and critical evaluation

Global distribution ofRisso's dolphinGrampus griseus: a review and critical evaluation

Annual variability in dentin δ¹⁵N and δ¹³C reveal sex differences in weaning age and feeding habits in Risso's dolphins (Grampus griseus)

First record of Risso's dolphin Grampus griseus (Cuvier, 1812) in Icelandic waters

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Life History of Risso’s Dolphin (Grampus griseus) (G. Cuvier, 1812) in the Faroe Islands

Cited by 26 publications

References 18 publications

Global distribution ofRisso's dolphinGrampus griseus: a review and critical evaluation

Global distribution ofRisso's dolphinGrampus griseus: a review and critical evaluation

Annual variability in dentin δ15N and δ13C reveal sex differences in weaning age and feeding habits in Risso's dolphins (Grampus griseus)

First record of Risso's dolphin Grampus griseus (Cuvier, 1812) in Icelandic waters

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Annual variability in dentin δ¹⁵N and δ¹³C reveal sex differences in weaning age and feeding habits in Risso's dolphins (Grampus griseus)