Pop-up tags help us keep tabs on marlin population

Water Ways
Honolulu Star Bulletin (09/23/00)
By Ray Pendleton

By now, I'm sure just about everyone has an opinion about the recent judicial rulings on longline fishing.

From my very unscientific perspective, based on anecdotal evidence, it would seem that any ruling that limits the commercial take of billfish in nearby waters will have a positive effect on the fishery.

But I also think, at present, there seems to be a lack of solid scientific data to support any position involving the condition of our marlin population.

As a pelagic, or open-ocean, species, billfish range over large areas of the Pacific Ocean, so a decline in numbers in one location may not necessarily mean an overall decline in the population.

During the 1995 Hawaii International Billfish Tournament on the Big Island's Kona Coast, the anglers cooperated with the Pacific Ocean Research Foundation to conduct the first-ever satellite-tagging of Pacific blue marlin.

The object was to get six months of readings that would help PORF learn more about the marlin population and range.

A marlin estimated to weigh about 650 pounds was tagged with a transmitter that some seven hours later "phoned home" to a weather satellite, giving its location as 14 nautical miles southwest of where it had been tagged.

Unfortunately, as I recall, further transmissions were not received.

Now, five years later, another attempt is underway to learn more about Pacific blue marlin by tagging them with satellite-linked transmitters.

Jody Bright, of the Hawaii Conservation Association in Kailua-Kona, has announced the successful retrieval of initial information from a transmitter that had been tagged to a marlin on July 19.

The pop-up archival tag, or PAT, separated from its host fish near Niihau after two months of recording its travel directions and speed, among other data.

Still, until the information is downloaded over the next several weeks, all that is presently known is the fish traveled at least 300 miles in 60 days.

"But, fishermen and scientists know that marlin can sprint at speeds close to 30 mph," Bright said. "So it will be quite interesting to find out just exactly what the marlin did during those two months.

"Did it go on a trip and then come back to the Islands, or did the fish 'go local' and decide it had everything it needed in life right here in Paradise?"

This first PAT is one of six purchased by the HCA as a part of its "Lure an Angler to Research" program which is designed to increase public awareness of high-tech wildlife research, as well as to produce data on Pacific blue marlin.

"Four more deployed PATs are expected to pop up by November 17," Bright said. "And one more will be deployed during the Maui Jim Marlin Tournament, Dec. 6 - 10, off South Point on the Big Island.

"That tournament is a made-for-TV event to be taped for ESPN 2's Xtreme Sports program and should be aired in January, 2001."

Additionally, for those with Internet access, the tracks of all the HCA-tagged marlin will soon be put up on the web. .

With more studies involving PATs, together with other types of data gathered by on-board observers, it may not be long before those involved in managing our pelagic fisheries will have the scientific knowledge necessary to base their decisions, rather than just anecdotal evidence.

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