1/11/2024 0 Comments Richard deliberty phototimeWhen no ice gaps were nearby, the whales were likely to move eastward along highly concentrated ice packs to find a gap. Results show that Antarctic minke whales are likely to search for ice gaps areas and remain there for extended periods until the surrounding ice melts, rather than stay at krill rich shelf breaks or areas with high chlorophyll-a concentration. The tracking data of five animals were fitted to a Bayesian hierarchical switching state-space model assembled from ARGOS data filters to estimate behavioral states. In this study, six minke whales were tracked for an average of 31 days (range 4–77 days) from January to March of 20 between 60° E and 140° E above and off the continental shelf. Condition along the ice edge vary regionally, sometimes forming small ice free areas (ice gaps), and little is known about whale movement patterns associated with these small-scale variations in the physical environment. Because the species frequents the edges of ice packs in summer, the potential impact of long-term physical environmental changes poses serious conservation concerns. The coupled relationship between minke whales, krill, and sea ice suggests that these whales may be sensitive to changes in sea ice concentration, extent, and duration, making them particularly vulnerable to climate change.Īntarctic minke whales Balaenoptera bonaerensis are rorquals that migrate to Antarctic waters to forage during the austral summer. Satellite telemetry from three individuals revealed Antarctic minke whale summer foraging spaces are highly individualized but can generally be associated with pack ice habitat over the continental shelf. Generalized additive model analysis demonstrated environmental variables, particularly sea ice, bathymetry, and sea surface temperature, are the best predictors of presumed foraging areas. Satellite telemetry revealed disparate behavioral patterns between these three individuals. Behavioral states were identified using the Multi-Scale Straightness Index. Individual movement patterns from three Antarctic minke whales fitted with ARGOS-linked transmitters were analyzed with respect to environmental conditions. The primary objectives of this study are (1) to use satellite telemetry to quantify the movement patterns, distribution, and presumed foraging areas of Antarctic minke whales and (2) to assess the environmental conditions that are associated with areas used by minke whales along the western Antarctic Peninsula. Information on their individual movement and distribution patterns is largely unknown due to their association with sea ice habitat where direct observations are limited. The Antarctic minke whale (Balaenoptera bonaerensis) is a relatively small baleen whale species and is well suited to life in the Antarctic pack ice. We speculate on how the minke whale's pagophilic nature (1) could have been encouraged by large-scale industrial whaling and by competition with species more characteristic of open waters and the outer MIZ, and (2) may have protected the population somewhat during industrial whaling resulting in the much greater abundance of this species now compared to other targeted species. The strong relationship to polynyas and the MIZ indicate that sea-ice divergence altered by decadal or longer-term climate change, as described in the recent literature, could well affect any apparent, long-term trends evident in this species' abundance if surveyed only in open or near-to-ice waters. Supporting these findings, the density index was strongly related to ice concentration in an inverse relationship. Probability of detection was higher with distance into the MIZ. Statistical analysis showed that the probability of sighting a minke, as well as killer whale-but not the case for an index to whale density-was related to the proximity of coastal polynyas in early autumn, switching offshore to the MIZ once waters within the pack began to freeze persistently later in the season. Other variables included date and distance to the MIZ and shelfbreak front. Logistic regression and an information-theoretic approach related the occurrence of Antarctic minke whales Balaenoptera bonaerensis (the most abundant species) to whether we were in open- or pack-ice-covered pelagic or neritic waters, in or out of the marginal ice zone (MIZ), and north or south of the Antarctic Circumpolar Current southern boundary. We conducted 239.5 h and 3,494 km of cetacean surveys in the Amundsen and Bellingshausen seas, from 15 February to 31 March 1994 most of the area, the large portion of which was ice covered, had never before nor has it since been surveyed for cetaceans, even to the date when this paper was prepared (2006).
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