Guy Harvey Ocean Foundation Expedition: Bermuda – Part II

The 2010 expedition to Challenger Bank began on July 24, just a couple of weeks earlier in the year than last year’s trip. Much of the crew from the 2009 expedition were on hand again: Neil and Choy – the “local boys” from Bermuda; Mahmood and Brad, our resident scientists; my children, Jessica and Alex; and Capt. James Robinson, whose boat Wound Up once again served the dual role of catch boat and support vessel.

For this year’s trip, the GHRI provided thirteen SPOT (Smart Position or Temperature Transmitting) tags and Neil purchased four three-year SPOTs with assistance from Bermudian sponsors, some of whom rode along with Capt. James on the Wound Up. Neil and Choy were doing a great job in Bermuda in getting local businesses involved in the tagging project and the production of a documentary that was created to educate the public about the success of their work.

The expedition’s plan called for Neil and Choy to take us to Challenger Bank to tag as many tiger sharks as possible over the course of six days. The week started fairly slow, with just one shark caught on each of the first three days. However, things heated up in the second half of the week as we caught and tagged 9 more sharks over the three remaining days.

Chumming was the key to catching the sharks. Luckily, we had ample supplies of fish heads, and we added to the chum mix by catching bonitos, ocean robins (local name for an abundant mackerel scad), blackfins, wahoos and barracudas while we were on the Bank. While the sharks were definitely attracted to all of the fish we served up, they seemed to have a preference for one in particular – fresh barracuda, which proved to be irresistible to the tigers.

We fished for the tigers primarily from the Wound Up. When a shark was hooked, Capt. James would transfer it to the Bones and then return to the mooring to continue fishing. Meanwhile, Neil and crew would safely secure the caught shark, apply a tag to the its dorsal fin, and then release the shark unharmed. Our crew was very experienced at tagging sharks and had gained a lot of knowledge during last year’s expedition, so the entire process – from the initial hook up to the final step of releasing the shark – was well planned and executed, which resulted in all of the sharks being released without harm.

While James was fishing with 130s we put out a quarter inch rope line cable leader and 20/0 circle hook, which was baited with barracuda and suspended from a large buoy. We caught four sharks using this method. One of these was pulled in by Alex, and at 8 feet long, it was the smallest shark we had caught so far.

Brad and Neil decided this shark was small enough to pull into the boat for tagging, so the crew hauled the shark on board, then covered its eyes with a wet towel and ran two deck hoses through its gills for ventilation. With the smaller shark secured in the boat, Neil was able to deploy a 3-year SPOT tag on this young male in just a few minutes.

Interestingly, while on board, this small tiger shark regurgitated several squid beaks, and the horn of the foot from a benthic gastropod (like a conch). This indicates opportunistic bottom feeding and mid-water feeding on pelagic squid (one of the big 12 footers regurgitated the remains of a seabird and lots of feathers).

Unfortunately, we didn’t catch any of the sharks that we tagged last year, nor did we catch any tigers that had been tagged previously by Mahmood and Brad in the U.S.Virgin Islands over the past two years. A somewhat disappointing result, but it suggests that the tiger shark population around Bermuda is comparatively healthy. Of course, we do not know what the population numbers were before the commercial fishing industry exploited this and other species over the last three decades, so it’s difficult to determine just how stable the population has been over time.

Impact of the Guy Harvey Ocean Foundation Expedition: Bermuda

Earlier in July, Brad presented our most up-to-date results at the annual conference of the American Elasmobranch Society, and the results of our comprehensive study amazed the scientific community. The tags applied in 2009 have lasted and stayed attached much longer than expected, and the regular reporting by the sharks (over a year now) is shedding new light on their behavior and migration in the Atlantic. Perhaps the biggest finding so far is that tigers are not the coastal dwellers that they were believed to be. Instead, they appear to make extensive oceanic journeys, and have an oceanic existence for much of the year.

It appears that the majestic tiger shark, which can grow to eighteen feet long, seems just as content in six feet of water chasing stingrays on the Bahamian sand flats as it is lurking near an oceanic bank 2000 miles offshore, hoping to detect and zero in on a dead floating sea bird or loggerhead turtle. This knowledge has serious management implications: since the sharks have been shown to make extensive migrations – passing through the 200 mile Exclusive Economic Zones of several countries in a given year – no country can consider these animals “their resource”.

The GHRI left several SPOT tags in Bermuda with Neil and Choy in the hope that some female tiger sharks would show up later in the year. Oddly, of all the animals tagged so far, only one has been female. This leads us to another question: “Why are there so many males at Challenger Bank at this time of year?” A question perhaps best answered by making another expedition.

Acknowledgements:

I wish to thank Rehanna Palumbo and the staff at the Fairmont Hamilton Princess Hotel in Hamilton, Bermuda for her assistance with accommodation. This is a beautifully appointed 5-star hotel in a wonderful setting on the Hamilton waterfront close to great shopping and restaurants. Well worth the visit.

Thanks to Neil and Choy for getting us together in the collaborative research effort, and for the chance to swim with these magnificent animals. Thanks to James Robinson and his family for his commitment to the project.

It is our collective responsibility to conserve the marine environment and maintain the biodiversity of the planet. Fish responsibly, dive safely.

Cheers….Guy Harvey PhD.

For a complete list of our other featured blog posts and to see the full line of Guy Harvey Sportswear, please visit: www.guyharveysportswear.com

Related posts:

1. Grabbing Tigers By the Tail — A Return to Bermuda —Part I
2. OF SHIPS AND TIGERS
3. Tiger Beach Tagging
4. Tagging Tiger Sharks in Bimini
5. The Misunderstood Tiger Shark Shows Remarkable Migratory Behavior

Tags: Catch & Release, Guy Harvey, Guy Harvey Ocean Foundation, Guy Harvey Research Institute, Shark

This entry was posted on Thursday, August 19th, 2010 at 10:07 am and is filed under Fishing, Our Oceans. You can follow any responses to this entry through the RSS 2.0 feed. You can leave a response, or trackback from your own site.