Seattle’s own Sixgill Sharks

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Most Seattle area residents don’t realize that the third largest predatory shark in the world lives in their backyard and sometimes swims right under the Seattle Aquarium! The bluntnose sixgill shark, Hexanchus griseus, which grows up to 15 feet in length, can be found year-round in Puget Sound and has been sighted regularly along Seattle’s waterfront. The sixgill shark is the largest of eleven species of sharks seen in local waters by divers and fishermen.

Sharks attract a lot of attention not only because they are large fish with big mouths full of sharp teeth, but also because there is worldwide concern over the future of these animals. Of the roughly 500 known species of sharks worldwide, the International Union for Conservation of Nature lists the status of 63 percent as near-threatened or worse. Local sharks and conservation came to the forefront in the Seattle area when several sixgill sharks were caught in Elliott Bay. Since little is known about these animals, state regulators responded to requests from the Seattle Aquarium and concerned citizens by placing a permanent sport fishing ban for sixgill sharks in May of 2001.

A joint research team with representatives from the NOAA Fisheries Service, the University of Washington, Seattle Aquarium, Point Defiance Zoo and Aquarium, and Washington Department of Fish and Wildlife is now studying sixgill sharks in local waters. Seattle Aquarium researchers found they could attract the sharks to the Aquarium’s pier, providing a relatively easy and cost effective site to study these sharks. The Aquarium constructed a permanent research station on the seafloor beneath the aquarium’s exhibit spaces, as well as a topside video and communication control station. The sixgill research program uses genetic research, visual markers and acoustic tracking to study the habits, biology and local abundance of sixgills. In addition to research activity, the Seattle Aquarium will be a clearing-house for sixgill shark research and information. Local divers and fishermen are encouraged to be a part of the research effort by reporting any sixgill sighting to the Aquarium using the online reporting form or by calling (206) 386-4379.

When active shark research is not occurring, the topside control station doubles as an exhibit on the sixgill shark research where visitors to the Aquarium can watch a short video that simulates a research session.