The distribution and habitat preference of coastally occurring minke whales (Balaenoptera acutorostrata) in the outer southern Moray Firth, northeast Scotland |
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Authors: | Kevin P Robinson Michael J Tetley E Gay Mitchelson-Jacob |
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Institution: | (1) Cetacean Research & Rescue Unit (CRRU), PO Box 11307, Banff, AB45 3WB, Scotland, UK;(2) School of Ocean Sciences, Bangor University, Menai Bridge, Anglesey, LL59 5AB, Wales, UK |
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Abstract: | The coastal waters of the Moray Firth in northeast Scotland (57o41’N 2o40’W) provide rich, inshore feeding grounds for minke
whales (Balaenoptera acutorostrata) during the summer and autumnal months. In order to better understand the habitat selection, movements and feeding ecology
of the animals utilising this North Sea region, distribution data from the southern coastline of the outer Moray Firth were
subsequently examined with respect to the marine physiography of the area, specifically the environmental variables water
depth, slope, aspect and sediment-type. A total of 305 minke whale encounters – collected from dedicated boat surveys conducted
between May and October 2001 to 2006 inclusive – were used in the construction of a Geographic Information System (GIS) for
the 860 square-km study site. The subsequent analysis revealed a strong spatial preference by whales in this location for
water depths between 20 and 50 metres (mean 46.9 m, SD = 30.9), steep slopes (mean 75.7 degrees, SD = 8.9), a northerly-facing
aspect and sandy-gravel sediment type. Kruskal-Wallis tests for variance confirmed that the distribution of B. acutorostrata was significantly different across each of these physiographic features examined (P < 0.05). In particular, water depth and sediment type were shown to be highly correlated with the frequency of whales observed
(Spearman’s Rank Correlation P < 0.05 for depth and sediment respectively). From these results, we conclude that sea bottom characteristics may be used to
predict the fine-scale distribution of minke whales on their feeding grounds; the physiographic features identified providing
valuable proxies for inferring prey distributions in the absence of fisheries data. However, an appreciation of both abiotic
and biotic factors (using a combination of GIS and remote sensing outputs) is clearly desirable for ecosystem-based management
approaches for the coastal conservation of these whales. The application of GIS capacities to ecological studies based largely
on field data of these marine mammals is highly recommended in the present study to cetologists, environmental modellers and
conservation managers alike. |
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Keywords: | Minke whale Habitat Physiography Environmental factors GIS Moray Firth Conservation |
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