POULSBO — A 9-foot shark was discovered on the east shoreline of Liberty Bay Tuesday.

Poulsbo resident Andy Woodford was combing the beach for shells when he made the unusual find. The shark is an immature sixgill female, found with no signs of trauma or obvious cause of death.

Shawn Larson from the Seattle Aquarium took samples from the body Wednesday morning. Department of Fish and Wildlife (DFW) officials will test contaminant levels in the shark to try and determine how the animal died.

It was stranded on shore near the area behind the Asgard Apartments.

Woodford said seeing the shark was initially startling to him. Its presence on the beach was near-missable, its mouth open, bearing rows of teeth.

Debbie Farrer, a scientific technician with the DFW, said sixgill sightings in shallow waters are uncommon, though the Puget Sound is a nesting area for the type of shark. The predators feed on seals, smaller sharks and various types of fish. She said there has only been one reported diver incident with a sixgill shark in which someone was possibly hurt. The unconfirmed incident was not in the area nor was it recent; divers swim with sixgills often without trouble, she said.

The shark’s stomach was empty, meaning all food had been digested and no crab bait boxes had perforated the stomach, which is sometimes found as the cause of death, she said.

Sixgills are most often found in water at least 200 feet deep, but sometimes swim into shallower areas at night to feed, said DFW marine ecosystems manager Greg Bargmann. Between three and five are found stranded on shore each year. Sixgills grow to about 12 feet in length, and usually leave the sound for open waters when they are 6-8 years old, he said.

The DFW is conducting an aging study of sixgill sharks and will be able to put the rare finding to good use, Farrer said. Backbone, muscle, liver and tissue samples were taken to be used to find a technique to measure shark aging, as well as learn more about genetics, obtain stable isotopes and check for contaminants such as mercury and PCPs.

Sixgill sharks are often spotted near Alki Beach and Elliott Bay, she said. The DFW began tagging them in 2003 to see where they travel throughout the area. The washed-up shark was not one of those that was tagged.

Ferrar said the area is closed to sixgill shark fishing. If one is hooked, it is to be released immediately.

The Seattle Aquarium has a working sixgill shark exhibit. For more information, visit www.seattleaquarium.org.