Investigators: Lisa Hildebrand, Dr. Leigh Torres

Linking predator-prey interactions is a favorite topic among ecologists, but can be expensive and challenging to accomplish at fine scales, particularly in shallow waters that limit traditional prey mapping methods. The Pacific Coast Feeding Group (PCFG) of gray whales forages in the Oregon near-shore environment, making them accessible for study with creative, low budget technology. This project aims to link gray whale foraging behavior with fine-scale prey distributions, using inexpensive field methods (e.g., theodolite, Go-Pro cameras and shallow net tows deployed off a research kayak) that have broad applications.

For four consecutive summers we have non-invasively tracked gray whale movements with shore-based theodolites in Port Orford, Oregon, USA. When conditions allow, a research kayak is concurrently navigated to sampling stations in two comparative study areas within the tracking viewshed (Mill Rocks and Tichenor Cove). Go-Pro cameras are used to record zooplankton relative density in the water column and zooplankton net tows are used to assess community structure. Video stills are scored for quality and relative density of zooplankton, and averaged through the water column to provide a daily density estimate for each station. Zooplankton community assemblage structure is derived from zooplankton net tows. Whale behaviors are categorized into search, forage, and transit behaviors using the Residence in Space and Time method.

Despite being only one kilometer apart, we have found significant spatio-temporal differences in the community assemblages of zooplankton between the two study areas, and whales demonstrate fine-scale habitat selection relative to this prey availability. Additionally, we have documented annual variation in prey availability and whale distribution and behavior patterns in the area. As we continue this long-term study we aim to assess the quality of zooplankton prey available to PCFG individuals foraging in the area and whether these individuals display foraging specializations. If individuals display different ecological patterns (i.e. spatial use, prey preferences) then they may be expose to different threats, which can consequently impact populations in variable times, ways, and intensities.

Collaborators:

Dr. Kim Bernard, Bernard Zooplankton Ecology Lab, Oregon State University

Dr. Sarah Henkel and Robyn Norman, Benthic Ecology Lab, Oregon State University 

Dr. Susanne Brander, Brander Lab, Oregon State University

Dr. Aaron Galloway and Dr. Elena Rubio, Oregon Institute of Marine Biology, University of Oregon

Funding:

OSU Marine Studies Initiative

Oregon Coast STEM-Hub

The Wild Rivers Coast Alliance

OSU Port Orford Field Station Development Fund

OSU Marine Mammal Institute

The American Cetacean Society - Oregon Chapter

William and Francis McNeil Graduate Award

Linking predator-prey interactions is a favorite topic among ecologists, but can be expensive and challenging to accomplish at fine scales, particularly in shallow waters that limit traditional prey mapping methods. The Pacific Coast Feeding Group of gray whales forages in the Oregon near-shore environment, making them accessible for study with creative, low budget technology.