Preliminary Findings on the Occurrence and Site Fidelity of Photo-Identified Sperm Whales (Physeter macrocephalus) in the Northern Gulf of Mexico

Weller, David W.; Würsig, Bernd; Lynn, Spencer K.; Schiro, A. J.

doi:10.18785/goms.1801.04

Cited by 9 publications

(8 citation statements)

References 7 publications

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“…In agreement with these results, photo-identification surveys indicated site fidelity to the central group of islands over periods up to 7 years (Matthews et al 2001) and use of different groups of islands in different years by some individuals (S. Magalhães, unpublished data). Site fidelity of sperm whales has also been reported based on genetic data in the Galapagos Islands , the archipelago of the Azores (Bond 1999), Gulf of Mexico (Weller et al 2000) and Balearic Islands (Drouot et al 2004). …”

Section: Population Structurementioning

confidence: 84%

Population genetics and social organization of the sperm whale (Physeter macrocephalus) in the Azores inferred by microsatellite analyses

et al. 2009

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(English)In the Northeast Atlantic Ocean, the archipelago of the Azores is frequented by female-offspring groups of sperm whales (Physeter macrocephalus L., 1758), as well as large males. Little is known on their population and group structure, even though the Azores apparently constitute both a feeding ground and a reproduction site. We analysed 151 sloughed skin and biopsy samples by genetic tagging with 11 microsatellite loci and molecular sexing, in order to: determine the population genetic structure, compare relatedness within and between social groups, estimate kinship and the age of males at dispersal. Results suggest that individuals visiting the archipelago of the Azores belong to a single population. High genetic diversity and absence of inbreeding suggest that the population is recovering from whaling. Individuals sampled in close association are highly related, as well as those observed in the same area on the same day, suggesting that secondary social groups (corresponding to the union of primary social units) are composed of relatives. Probable mother-offspring and fullsibling pairs were identified. We obtained an estimated value of 16.6 years for the age of males at dispersal, which was well above previous estimates for this species. Abstract (French)Dans l'Atlantique Nord-Est, l'archipel des Açores est fréquenté par des groupes de cachalots (Physeter macrocephalus L., 1758) femelles avec leurs petits et par des grands mâles. Il semble que les Açores constituent à la fois un site d'alimentation et un site de reproduction, mais la structure des populations et la composition des groupes sociaux sont peu connues pour cette région. Nous avons analysé 151 échantillons de peau de cachalot (peau desquamée et biopsies) par "genetic tagging", en utilisant 11 marqueurs microsatellites, et par sexage moléculaire. Nos objectifs étaient de déterminer la structure génétique des populations, de comparer le degré d'apparentement au sein des groupes et entre groupes, et d'estimer les relations de parenté entre individus. Nous avons aussi estimé l'âge des mâles à la dispersion. La valeur obtenue de 16,6 ans représente un âge très avancé par rapport aux estimations disponibles pour cette espèce. Les résultats suggèrent que les individus fréquentant les Açores appartiennent à une seule et même population. La diversité génétique élevée et l'absence de consanguinité suggèrent que la population est en phase de récupération suite à l'arrêt de la chasse "à la baleine". Les individus échantillonnés ensemble sont fortement apparentés, de même que ceux observés dans une même zone géographique au cours d'une même journée. Les groupes sociaux secondaires regroupant plusieurs unités primaires seraient donc composés d'individus apparentés. Plusieurs paires probables de mères et enfants et de frères et soeurs véritables ont été identifiées. Des preuves indirectes de fidélité au site confortent l'hypothèse que les Açores constituent un site d'alimentation. Par ailleurs, l'observation de mâles adultes étaye l'hypothèse qu...

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Section: Population Structurementioning

confidence: 84%

Population genetics and social organization of the sperm whale (Physeter macrocephalus) in the Azores inferred by microsatellite analyses

et al. 2009

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“…It could be possible that the large difference in length distribution found between the Gulf of Mexico and the Gulf of California was due to the relationship between fluke span and length varying between sperm whale stocks. However, since studies on sperm whales started in the Gulf of Mexico in the early 1990s (Weller et al 2000), it has been suggested that sperm whales were smaller than in other areas contradicting this hypothesis. Furthermore, one first‐year calf (but not newborn) was measured while it floated alongside the research vessel, and was found to be about 3.3 m in total length ( Jaquet and Gordon, unpublished data).…”

Section: Discussionmentioning

confidence: 99%

A Simple Photogrammetric Technique to Measure Sperm Whales at Sea

Jaquet

2006

Marine Mammal Science

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Knowledge of whale length is important to ecological studies. However, photographic techniques to measure sperm whales traditionally require high vantage points or a complicated stereo system. Furthermore, these traditional techniques require an alongside approach that often prevents individual identification. For simple and fast size measurements at sea, I used a laser range finder alongside a digital camera to obtain distance to the fluke at the same time as photo-identification. The camera/lens and laser range finder were calibrated on objects of known lengths. The coefficient of variation (CV) for test objects was low (CV = 0.21%). Forty-seven individually identified sperm whales were measured repetitively on up to 12 different occasions, and the CV was lower (CV = 1.3%) than for other photogrammetric techniques (CV = 4.4%-5.1%). A regression of log fluke span to log total length from whaling and stranding data yielded an r 2 of 0.87 (CV of residuals = 6.7%). Thirty-eight female/immature sperm whales were measured in the Gulf of Mexico (median = 9.3 m, range = 7.1-12.3 m), 167 in the Gulf of California (median = 10.7 m, range = 8.4-13.1 m) and 13 bachelor males off Kaikoura, New Zealand (median = 14.2, range = 11.7-15.8 m). The results were within known sperm whale size and suggested that the population in the Gulf of Mexico was made up of smaller animals than that of the Gulf of California. This technique is easy to implement and allows the measurement of identified individuals.

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“…Commercial landings of adult yellowfin tuna alone exceeded 3.7 million pounds (value >$9 million) in 1998 (National Marine Fisheries Service Annual Commercial Landing Statistics, http:/ /www.st.nmfs.gov I commercial/landings/ annuaLlandings.html). The deepwater GOM is also habitat for substantial populations of marine mammals, sea turtles, and seabirds (Mullin et al, 1994;Davis et al, 1998;Weller et al, 2000). In fact, the same cyclones and the frontal zones of both cyclonic and anticyclonic eeldies shown to support enriched zooplankton and micronekton biomass (Wormuth et al, 2000) have been identified as deepwater concentrating mechanisms for apex predators such as fish and marine mammals (Lamkin, 1997;Biggs et al, 2000;Davis et al, 2000).…”

Section: Deepwater Zooplankton Ichthyoplankton and Micronekton: Meamentioning

confidence: 99%

Distribution and Abundance of Phytoplankton, Zooplankton, Ichthyoplankton, and Micronekton in the Deepwater Gulf of Mexico

Biggs

Ressler

2001

goms

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Preliminary Findings on the Occurrence and Site Fidelity of Photo-Identified Sperm Whales (Physeter macrocephalus) in the Northern Gulf of Mexico

Cited by 9 publications

References 7 publications

Population genetics and social organization of the sperm whale (Physeter macrocephalus) in the Azores inferred by microsatellite analyses

Population genetics and social organization of the sperm whale (Physeter macrocephalus) in the Azores inferred by microsatellite analyses

A Simple Photogrammetric Technique to Measure Sperm Whales at Sea

Distribution and Abundance of Phytoplankton, Zooplankton, Ichthyoplankton, and Micronekton in the Deepwater Gulf of Mexico

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