Population genetics and behavioural ecology of North Atlantic minke whales (Balaenoptera acutorostrata)
Regional habitat use by a species, dictated by the spatial and temporal availability of resources, influences its distribution patterns and ultimately population genetic structure. Seasonal migrations between geographically separated breeding and feeding areas, as occur in many baleen whales, can co...
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| Format: | Thesis |
| Language: | unknown |
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2009
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| Online Access: | http://etheses.dur.ac.uk/2153/ http://etheses.dur.ac.uk/2153/1/2153_161.PDF |
| Summary: | Regional habitat use by a species, dictated by the spatial and temporal availability of resources, influences its distribution patterns and ultimately population genetic structure. Seasonal migrations between geographically separated breeding and feeding areas, as occur in many baleen whales, can complicate these relationships. Here I try to integrate the population structure of minke whales over the whole North Atlantic with regional habitat use and behavioural adaptations to a particular summer feeding ground, the Hebrides off West Scotland. Whereas no genetic differentiation could be found between separate feeding areas as far apart as Canada, the UK and Svalbard, using microsatellites and mtDNA, the presence of two cryptic breeding populations was detected, which form mixed assemblages on feeding grounds across the North Atlantic. This implies fidelity to at least two breeding grounds irrespective of proximity to feeding areas, i.e. extensive seasonal migrations (over half the North Atlantic or more), which may require a re-assessment of current management stocks. These findings were consistent with the mobility and flexibility in habitat use and behaviour observed within the Hebrides. Results from Generalized Additive Models indicated that minke whale distribution was dependent largely on temporally variable parameters (temperature in spring, chlorophyll concentration in autumn), besides depth and, to a lesser extent, topography. However, fine-scale foraging behaviour was dictated primarily by the strength and direction of tidal currents. Distribution patterns according to environmental parameters changed through the season, but were largely consistent between the entire Hebrides (cell resolution of 4min) and a smaller core study area (2min), and over a time period of 15 years. Significantly higher sighting rates in areas of likely sandeel presence in spring, but not during the rest of the season, combined with prey samples from the core study area consisting almost entirely of sprat in August/September, ... |
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