Barb Block from Prince William Sound. The salmon shark team has arrived in Cordova and we're preparing to leave this morning for Gravina Bay.We hope to tag 30 or more salmon sharks with SPOT tags -- satellite position only tags -- and archival tags, which we insert into their abdominal cavity in an operation that takes a couple of minutes. Salmon sharks, which range from 200 to 400 pounds, hang out in Prince William Sound to feed on salmon. If someone catches the shark, they get a reward for returning the tag to us. (Here's a shot of the poster we're spreading around the area.) We've done this successfully with bluefin and yellowfin tuna.

Some sharks will also carry a pop-up satellite tag. We program these tags to stay on the fish for a certain length of time.....one month to nine months. When the tags release from the shark, they float to the surface, where they transmit data to a satellite for a couple of weeks before the battery dies. 

My students and I have been studying salmon sharks since 1999. Kevin Weng, who finished his PhD this year and is now at the University of Hawaii, and Chris Perle, who's finishing up his PhD, have reported on the fascinating migrations of the sharks as they forage here in Prince William Sound and then migrate to the tropics as far south as Mexico.

This year, we're putting archival tags in these sharks (Lamna ditropis) to learn more about their internal temperatures. Of all the sharks in this family -- which includes white sharks and mako sharks -- salmon sharks is the most warm-blooded. Archival tags, because they're inserted into the animal, provide valuable information on body temperature. The food that a salmon shark eats is cold, so the archival tag, which measures the shark's internal temperature, can show us when the shark ate. If we can marry that tag's information with the data from a SPOT tag, we might be able to pinpoint the areas where a shark is eating, and when it's eating.

Scientists from several universities have joined us on this expedition. They'll be sampling the sharks caught by sport fishers and our team to learn more about the blood physiology and cardiac biology of this shark, which lives the furthest north of all warm-bodied fish. Today we're focused on getting the team set up to head out to the fishing grounds and place the first tags on the sharks.