Temporal and environmental variables affecting the foraging behaviour of minke whales (Balaenoptera acutorostrata)

• Main Author: Greenhalgh, Holly
• Other Authors: Christiansen, Fredrik, Sprogis, Kate
• Format: Thesis
• Language: English
• Published: 2016
• Subjects: Faxaflói; Balaenoptera acutorostrata; Iceland; minke whale; North Atlantic
• Online Access: https://researchrepository.murdoch.edu.au/id/eprint/35887/

The patterns in the foraging behaviour of predators, both spatially and temporally, can be influenced by environmental variables which affect their prey’s distribution and abundance. For instance, in the marine environment varying water depth and tidal height may contribute to where prey items are distributed, and in turn, to where predators forage. Information on the foraging ecology of predators can be used to identify important areas and time-periods that are critical to the fitness of these predators. This study examined the temporal, spatial and spatiotemporal patterns in the foraging of the North Atlantic minke whale (Balaenoptera acutorostrata) in Faxaflói Bay, Iceland, in order to understand what factors influence the foraging probability of this population. The timing and location of individual minke whale surfacings were recorded with aid of a theodolite from a land-based research platform and any obvious surface feeding events that were observed were also recorded during the focal follows. The effects of temporal variables combined with environmental factors such as depth, tidal height, current bearing and velocity on the foraging probability of minke whales were tested using generalised additive models (GAMs). The full dataset and a refined dataset containing one randomly selected position per focal follow were analysed separately, which affected the results of the GAMs. The results indicate that the probability of minke whales foraging decreased throughout the season, with diurnal and crepuscular peaks and increased with depth. Spatial preferences of foraging minke whales were evident, as the core foraging area of minke whales were mapped using the full and refined datasets. Within the core foraging area day in the season and depth influenced their foraging probability. Therefore, this study is indicative that temporal, spatial and spatiotemporal patterns occur in the foraging behavior of minke whales and highlights variables that affect these patterns.