Monterey Bay Aquarium Research Institute

Steve Katz, Ph.D.
Northwest Fisheries Science Center

Sevengill sharks (Notorhynchus cepedianus)
in Willapa Bay, a large Pacific Coast estuary

Wednesday – March 14, 2007
Pacific Forum – 3:00 p.m.

Sevengill sharks (Notorhynchus cepedianus) are large predators in estuaries of Washington State. Since 2005, NOAA Fisheries and Washington Department of Fish and Wildlife scientists have been examining habitat use by these fish in Willapa Bay, WA.

Thirty-two sharks have been surgically implanted with uniquely coded acoustic pingers, and 12 data logging hydrophones have been placed at strategic points within the estuary. Significant challenges exist in analysis of this type of data, and this presentation will include some exposition of data management and analysis technique. Data analysis revealed three characteristic scales of movement by the sharks that range from hours to seasons. Seasonal patterns include excursions in excess of a thousand kilometers in the summer months when the fish leave the estuary and travel south. Gender differences in patterns suggest some of the patterns are associated with resource utilization while others are related to reproductive events.