Group items tagged

Orcas live in stable, structured social groups. And their survival directly depends on it, as a CNRS and University of La Rochelle research team1 has just demonstrated. Between 1996 and 2002, half of the CROZET Islands orca population was killed off by an illegal fishing operation targeting Patagonian toothfish, with the orcas removing the fish from the line during hauling. The orcas' survival rate has yet to return to its former level. Using data from a photo-identification programme begun in 1987, the scientists were able to show that surviving orcas from a decimated family adopted "erratic" social behaviour, moving from group to group. The weaker these social ties, the greater the animals' likelihood of dying. As these orcas are probably not completely accepted by the new groups they join, they are likely to be given less access to food than the regular members of the social unit-and eventually die. These findings-published in the Proceedings of the National Academy of Sciences (20 May 2019)-are the first to reveal the long-term consequences of events affecting the survival and social organization of a mammalian species.

Adult male sperm whales (Physeter macrocephalus) are long distance runners of the marine realm, feeding in high latitudes and mating in tropical and subtropical waters where stable social groups of females and immatures live. Several areas of uncertainty still limit our understanding of their social and breeding behavior, in particular concerning the potential existence of geographical and/or social fidelities. In this study, using underwater observation and sloughed-skin sampling, we looked for male social fidelity to a specific matrilineal sperm whale group near Mauritius. In addition, we captured a wider picture of kin relationships and genetic diversity of male sperm whales in the Indian Ocean thanks to biopsies of eight individuals taken in a feeding ground near the Kerguelen and Crozet Archipelagos (Southern Indian Ocean). Twenty-six adult male sperm whales were identified when socializing with adult females and immatures off Mauritius. Sloughed-skin samples were taken from thirteen of them for genetic analysis. Long-term underwater observation recorded several noteworthy social interactions between adult males and adult females and/or immatures. We identified seven possible male recaptures over different years (three by direct observation, and four at the gametic level), which supports a certain level of male social fidelity. Two probable first- and thirty second-degree kin relationships were highlighted between members of the social unit and adult males, confirming that some of the adult males observed in Mauritian waters are reproductive. Male social philopatry to their natal group can be excluded, as none of the males sampled shared the haplotype characteristic of the matrilineal social group. Mitochondrial DNA control region haplotype and nucleotide diversities calculated over the 21 total male sperm whales sampled were similar to values found by others in the Indian Ocean. Our study strongly supports the existence of some levels of male sperm whale socia

Why did nearly a million king penguins vanish without a trace?

Just a month after the start of the Vendée Globe, on 6th December in the middle of the Indian Ocean to the north of the CROZET Islands, Kito DE PAVANT and his Bastide Otio hit an unidentified floating object. The damage was fatal for the boat and the skipper was forced to abandon the race and his monohull.... Fortunately, the French vessel, the MARION-DUFRESNE, which delivers supplies to the French islands in the Antarctic and Southern Ocean, was sailing close to the area when the incident happened. Kito was rescued and taken aboard the ship, which continued her delivery trip. A few months later, they were able to watch the videos recorded on the hard disk aboard the boat, and discovered that the unidentified object was in fact a sperm whale, which was clearly visible in the wake of the boat. You can watch the video here. Hang on tight!

Barcelona World Race leaders split paths.

Barcelona World Race leaders split paths.

Tech-tagged albatrosses bode ill for rogue trawlers as French Navy battles illegal fishing

Turning Birds into Spies Against Illegal Fishing.