4th International Submarine Canyon Symposium (INCISE2018)
5-7 November 2018, Shenzhen, CHINA
This is the detail of Environmental drivers of the foraging distribution of sperm whales in the submarine canyon of Kaikōura, New Zealand
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Tamlyn Somerford, Rob Smith, Steve Dawson, Liz Slooten, Will Rayment
Environmental drivers of the foraging distribution of sperm whales in the submarine canyon of Kaikōura, New Zealand
The submarine canyon of Kaikōura is one of the most productive deep-sea habitats ever recorded and a year-round foraging ground for sperm whales. The number of whales feeding in the area, however, has declined over the last two decades. This trend could reflect a shift in distribution away from the canyon, potentially driven by ecological or oceanographic changes within the whales’ habitat. It is therefore important to understand what environmental factors drive the distribution of sperm whales at Kaikōura. Species-habitat surveys were conducted over three years (2015-2017), and species-distribution models were used to relate the presence of foraging whales to habitat variables, including seafloor topography and water-column oceanographic data. The distribution of sperm whales was correlated with seafloor depth and slope characteristics, as well as with sub-surface chlorophyll maxima and thermal stratification in the water-column. Our results suggested that oceanographic processes play an indirect but important role in attracting prey to the canyon, shaping sperm whale habitat use. An exploratory analysis of climate indices and remotely-sensed SST data suggested inter-annual variability in the oceanographic regime off Kaikōura over the last 30 years, and a possible correlation with whale abundance. The results from this study contribute to our understanding of what habitat features make submarine canyons hotspots for sperm whales, and how climate fluctuations can affect the distribution of wide-ranging marine predators.