Browsing by Author "Reeb, Desray"

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    The abundance of blue whales on the Madagascar Plateau, December 1996
    (International Whaling Commission, 2003) Best, Peter B; Rademeyer, Rebecca A; Burton, Chris; Ljungblad, Don; Sekiguchi, Keiko; Shimada, Hiroyuki; Thiele, Deborah; Reeb, Desray; Butterworth, Doug S
    As part of the International Whaling Commission’s SOWER blue whale research programme, two sighting vessels, the Shonan Maru and the Shonan Maru No.2 , surveyed the Madagascar Plateau between 25° and 35°S, 40° and 45°E, in December 1996. A total of 95 sightings of 110 blue whales (assigned in the field as pygmy blue whales – see discussion), 14 sightings of 21 blue whales (subspecies un determined) and 12 sightings of 13 ‘like blue’ whales was made in 23 days. In the first half of the survey, the whole research area was cov ered in a mainly pre-determined zigzag search pattern, and the associated sightings and effort have been used to derive density estimates for bl ue whales for the area. Sightings in the second half of the survey, where effort was directed at blue whale concentrations, have only bee n used to provide supplementary data for calculation of the effective search half-width and mean school size. The resulting population es timate is 424 (CV = 0.42), or 472 (CV = 0.48) whales when ‘like blue’ sightings are included. Dive times and surfacing behaviour recorded in just over 21h of monitoring suggest that the assumption that all groups on the trackline were seen ( g (0) = 1) is reasonable. As the geographical extent of the survey area was substantially less than that of past catches of blue whales in the region in December, this estim ate must refer to only a portion (possibly about one third) of the total population. Some evidence of feeding on euphausiids in the region was detected, possibly as a consequence of a localised upwelling cell at the southern tip of Madagascar
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    Biopsying Southern right whales: their reactions and effects on reproduction
    (Wiley, 2005) Best, Peter B; Reeb, Desray; Rew, Mary Beth; Palsbøll, Per J; Schaeff, Cathy; Brandão, Anabela
    Collecting skin biopsies from large whales for genetic analysis is often subject to national permit, and in the case of cow-calf pairs, it may be prohibited. We present results of 906 biopsy attempts on southern right whales (Eubalaenaustralis) in South African waters between 1995 and 1997, including 147 cow-calf pairs. Our sampling success was higher for biopsy darts with a bore of 4 mm compared to 4.6 mm. Contact periods averaged 17.7 min for cow-calf pairs and 25.4 min for whales unaccompanied by calves. There were no significant differences in the short-term reactions of males and females to biopsying, but the reaction of single animals of either sex was greater than for larger groups. Cows accompanied by calves had the strongest reactions, which were significantly greater than even single females. We found evidence of sensitization to repeat biopsying (over periods of hours to 65 days) for cows but not calves (n = 20). We compared the subsequent reproductive history of 117 biopsied cows with that of 163 unbiopsied cows from the same years, and we compared the distribution of calving intervals for biopsied animals with 829 intervals recorded from 1985 to 1995. We did not detect any adverse effects on the proportion of successful reproductive cycles, and hence calf survival, or the proportion of longer-than-normal cycles, although the power of all the statistical tests was low. We concluded that any prohibition on the biopsy sampling of cow-calf pairs should be carefully reconsidered in the light of the valuable genetic insights such sampling could achieve.