No abstract

No abstract

The abundance and reproductive autonomy of humpback whales from the New Caledonia (South Pacific) wintering grounds were investigated using capture-recapture models and paternity inference based on nuclear microsatellite genotyping, mitochondrial DNA sequencing, molecular sex identification and photographs of natural markings (photo-identification). The analyses included records of 213 individuals (excluding 16 calves used in paternity inference) identified by genotypes (9 loci), and 210 identified by fluke photographs, collected from 1995 to 2001. By comparing records of 175 individuals identified using both genotypes and photographs, a small number of errors were detected (and corrected) in the photo-identification catalogue and in the field and laboratory notes of the genotypes. Using the weighted mean of the Petersen capture-recapture model, the estimate of abundance based on genotyping (N = 533, CV = 0.15) was larger than the estimate based on photo-identification (N = 327, CV = 0.11). Sex-specific estimates of abundance based on genotypes were similar for males and females although the variance of the female estimate was greater than the male (N f = 248, CV = 0.30; N m = 288, CV = 0.18, respectively). The paternity of 5 calves from 16 sampled cow/calf pairs was inferred from the total sample of 133 non-calf males (one offspring each). The 16 sampled cow/calf pairs and the 5 inferred paternities were used for an alternate 'gametic recapture' estimate of male abundance. This gametic recapture estimate (N m = 379, CV = 0.30) was similar to the sex-specific estimate based on the organismal recapture using a 2-sample model (N m = 382, CV = 0.22). The close agreement of the organismal and gametic recapture estimates support the assumption that this humpback whale wintering ground represents an autonomous population unit that is relatively closed to demographic and reproductive interchange. The current low abundance of the New Caledonian breeding unit highlights the slow recovery of this and some other regional populations in the Southern Hemisphere following intensive 20th century commercial and illegal whaling.

Liver, muscle and blubber tissues of two short-finned pilot whales (Globicephala macrorhynchus) and two pygmy sperm whales(Kogia breviceps) stranded on the coast of New Caledonia have been analysed for 12 trace elements (Al, Cd, Co, Cr, Cu. Fe, organic and total Hg, Mn, Ni, Se, V, and Zn). Liver was shown to be the most important accumulating organ for Cd, Cu, Fe, Hg, Se, and Zn in both species, G. macrorhynchus having the highest Cd, Hg, Se and Zn levels. In this species, concentrations of total Hg are particularly elevated, reaching up to 1452 microg g(-1) dry wt. Only a very low percentage of the total Hg was organic. In both species,the levels of Hg are directly related to Se in liver. Thus, a molar ratio of Hg:Se close to 1.0 was found for all specimens, except for the youngest K. breviceps. Our results suggest that G. macrorhynchus have a physiology promoting the accumulation of high levels of naturally occurring toxic elements. Furthermore, concentrations of Ni, Cr and Co are close to or below the detection limit in the liver and muscles of all specimens. This suggests that mining activity in New Caledonia, which typically elevates the levels of these contaminants in the marine environment, does not seem to be a significant source of contamination for these pelagic marine mammals.

Seven Longman's beaked whales (Indopacetus pacificus) stranded together in southern New Caledonia on 16 November 2013 (one adult male, two adult females, two subadult females, one calf, and one unknown). At this time, we have no evidence to suggest that this event was an "atypical" mass stranding associated with active naval sonar or other anthropogenic activities. The adult females were slightly larger (618-640 cm) than the adult male (590 cm). The length of the calf (ca. 300 cm) suggests it was less than a year old. Five of the whales were sampled for mitochondrial (mt) DNA analysis to confirm species identification. All shared the same haplotype over 680 bp of the mtDNA control region. High concentrations of Hg, Fe, Se, Zn (all in the liver), and Cd (in the kidneys) were detected. Necropsies revealed plastic debris in the stomach of two of the whales. One of these same whales had chronic gastritis while the other had acute pleurisy and also tested positive for morbillivirus. This infection may have been a major factor behind this mass stranding event.