Satellite yields important data
By SUSAN COCKING - scocking@MiamiHerald.com
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DOLPHIN TAGGING PROJECT |
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DINO BARONE / FOR THE MIAMI HERALD |
| READY FOR DATA: Pembroke Pines captain Rich deLizza releases
a dolphin after it has been satellite-tagged in Bimini, Bahamas, earlier this
month.
On May 10, Pembroke Pines captain Rich deLizza caught a dolphin estimated at 30 pounds off Islamorada, stuck a $4,000 satellite tag in the fish and let it go. Two weeks later, the tag popped out of the mahi and surfaced 130 miles east of Daytona Beach, beaming data on the fish's movements during the time it was at large up to a satellite. The satellite transmitted the information to the computer of Charleston, S.C., fisheries biologist Don Hammond. Hammond says it's the first time satellite pop-up tags have been used to track the movements of one of the most sought-after game and food fish on the U.S. East Coast. ''While it's an expensive proposition, it's justified by how important the information is,'' Hammond said. DeLizza put another satellite tag in a 30-pound dolphin he caught off Bimini in the Bahamas on June 9. That one hasn't popped up yet, but both tagger and scientist are anxiously awaiting the outcome. Hammond is still crunching the data from the Islamorada-to-Daytona fish, which includes location, water temperature, depth and time of day recorded every three to four minutes. The information is much more precise than yielded by external tags, which tell the scientist where the fish started and where it ended up, but not how it got there. Hammond launched the dolphin tagging project in 2002, enlisting the volunteer help of more than 800 captains and anglers throughout the East Coast in putting more than 5,700 tags in dolphin and donating thousands of dollars. Hammond says between 1 and 3 percent of tags have been recovered, yielding some startling information. For example, Don and Justin Brown of Pembroke Pines -- the program's top taggers -- tagged a 20-inch dolphin in July 2005 off Islamorada. The fish was recaptured last March off the southwestern tip of Puerto Rico by commercial fisherman Roberto Rodriguez. In eight months at large, the fish had grown 28 inches and traveled at least 1,036 miles. Hammond believes the fish actually traveled a lot farther than that. He doubts it fought its way against powerful Gulf Stream currents teeming with predatory billfish and sharks to head directly from the Keys to Puerto Rico. Rather, he thinks it's more likely the fish rode the Gulf Stream north for a while, then coasted along on a southerly countercurrent. Only a satellite tag would be able to tell for sure. Hammond said that case and others in his tagging studies throw into doubt the long-held theory that there are separate dolphin stocks in the Atlantic and Caribbean. ''This study has forced me to go to my book of knowledge of dolphin, rip out the pages and start off with white paper,'' Hammond said. Hammond says tracking the movements of dolphin is important on two fronts: to prevent overfishing and to evaluate the health of the marine ecosystem. ''If there is one stock of dolphin in the East Coast, Caribbean and Gulf of Mexico, and if a large commercial fishery were established outside U.S. territorial waters, it would have a huge impact on U.S. domestic fisheries,'' he said. Said deLizza: ``It seems important to me that decisions on dolphin are made based on data. Letting go of one or two 30-pounders isn't that hard. One fish can provide a wealth of information. How can you not do that?'' |
