Fine-scale Prey Aggregations and Foraging Ecology of Humpback Whales (Megaptera Novaeangliae)

• Main Authors: Hazen, Elliott L, Friedlaender, Ari S., Thompson, Michael A, Ware, Colin, Weinrich, Mason, Halpin, Patrick N, Wiley, David N
• Format: Text
• Language: unknown
• Published: University of New Hampshire Scholars' Repository 2009
• Subjects: Whale Tracking; Predator–prey; Foraging ecology; Oceanography; Acoustics; Sand lance; Humpback whale; Telemetry tracking; Digital acoustic recording tag; Oceanography and Atmospheric Sciences and Meteorology; Humpback Whale; Megaptera novaeangliae
• Online Access: https://scholars.unh.edu/ccom/483; http://www.int-res.com/abstracts/meps/v395/p75-89/

Analyses of the foraging behavior of large cetaceans have generally focused on either correlations with environmental conditions at regional scales or observations of surface behavior. We employed a novel approach combining multi-scale analyses of simultaneous environmental conditions, surface and subsurface humpback whaleMegaptera novaeangliae movements, and sand lance Ammodytes spp. prey aggregations in the Gulf of Maine, USA. At the fine scale (<1 >km), digital tags recorded whale movement and behavior in 3 dimensions. Concurrent synoptic prey data were collected using EK60 echosounders with simultaneous surface measurements of temperature and relative fluorescence within 1 km of the tagged whale. A geospatial analysis of environmental features and foraging patterns was conducted at the regional, seascape scale (~10 km). At the seascape scale, we found: (1) a negative relationship between relative fluorescence and sand lance density; (2) a positive relationship between predator surface feeding, presumed sand lance density, and sand bottom types near high-slope edges; (3) a cyclical relationship for predator surface-feeding likelihood and prey density with tidal height; and (4) an observed temporal lag between peak prey density and predator surface-feeding likelihood. At the fine scale, we found that: (1) time of day was the most important factor in predicting whether a whale was feeding when it surfaced; and (2) surface feeding occurred more often around more dense, vertically distributed schools of prey. Multiscale and multi-trophic level studies are an important component in understanding the foraging ecology of top predators in marine systems.