Investigators: Florence Sullivan, 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 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 three 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 describe the oceanographic drivers of inter and intra-annual variation in prey and predator ecology in coastal Oregon waters.

Collaborators:

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

Kelli Iddings, Duke University

Dr. Kim Bernard

Dr. John Chapman

 

Funding:

The Wild Rivers Coast Alliance

William and Francis McNeil Graduate Award

The American Cetacean Society-Oregon Chapter

OSU Marine Mammal Institute

OSU Port Orford Field Station

 

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.