Yellowfin Tuna Expedition, Part 5 - Epilogue

It was, by all accounts and opinions, a phenomenal trip. Because the crew never stopped looking for and the fishermen catching fish, we were able to deploy all our tags.

Clarion Island provided a truly exceptional background while we fished in some of the most productive and legendary waters for giant yellowfin tuna in the world. Besides the fantastic views of the island, we witnessed humpback whales blowing and breeching while their young calves swam in the shallows. Sometimes the adults completely cleared the surface of the water.

Yellowfin Tuna 

On Feb. 25, we dropped off our passengers at Cabo, and began slogging up the coast to San Diego through rough seas. It’s the reason why most people fly out instead of riding back with us!. On Feb. 28, we arrived at Shelter Island, off-loaded our gear, and walked to Point Loma Seafoods for the traditional squid sandwich.

The tally: 537 yellowfin now wear plastic dart tags, of which 160 were 100 to 240 pounds; 65 yellowfin carry archival tags. Of these, 20 fish were 10-50 pounds, 10 fish were 60-90 pounds, and 35 fish were 100-200 pounds. In addition, 12 skipjack (13- 16 pounds) were tagged with archival tags, and 120 wahoo (mostly 20 to 40 pounds) with conventional tags.

We'll be expecting to see some tags from these fish eventually. Based on releases in the islands in 2006, the tag recovery rate is 21 percent, with two of the fish recently recaptured after swimming the seas just over a year.

Of 68 yellowfin caught and released with archival tags off Baja California, Mexico, in October 2002 and October 2003, 36 fish -- 53 percent -- were recaptured. Time at sea ranged from nine to 1,161 days! For the yellowfin that were at liberty for more than 150 days, 95 percent remained within 867 miles of where they were tagged. The fish that went the furthest west traveled 532 miles over 248 days. The fish that traveled the furthest south went 1,572 miles over 560 days. The fish that was free the longest -- 1,161 days -- never swam more than 548 miles from where it was tagged.

These tags have helped us learn some new things about yellowfin. During the day, they "bounce" to depths of 750 to 900 feet, apparently eating squid and fish, and sometimes dive as deep as 3,000 feet! The Baja fish told us that they stay in the same geographical area, probably because there's plenty to eat.

What's next? We hope to retrieve the tags we implanted. They're recording data the entire time they're embedded in the fish, and we can download all of it into our computers. We want to learn more about where these fish go, what they do and how they live. Yellowfin tuna are the tuna in salads, casseroles and sandwiches. Since we humans are depleting our fish stocks, it's a good idea to know more about the yellowfin so that we can manage them sustainably.

Group of anglers
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