New implant procedure is on the right track for keeping tabs on bass

April 19, 1992|By Peter Baker | Peter Baker,Staff Writer

HARVE DE GRACE — HAVRE DE GRACE -- The gloved hands work quickly once the anesthetized 4-year-old is placed on the operating table: A small incision is made through heavy muscle, a small electrical device is activated and slid into position, the incision is stitched closed and medicated, and the patient is sent to recovery.

Were the patient human, the implant might pace a heartbeat. But in this case, the 4-year-old is a female largemouth bass, and the implant will neither pace its heart nor impede its ability to spawn.

The implant will, however, allow the surgeon, DNR biologist Carol Richardson, to track its movements during the next 250 days.

On Wednesday, Richardson performed implants of miniature, battery-powered radio transmitters on five bass, which were released near the launch ramp at Tydings Memorial Park. On April 1, she performed six other implant operations, and the fish were released there as well.

In the state hatchery at Unicorn Lake off the Chester River, a separate test group occupies its own pond, where they are monitored daily for complications from surgery.

By all accounts, all the patients are doing splendidly.

The procedure is interesting because it presents an approach different from traditional implant surgery.

Instead of opening virtually the entire belly of a bass to place the transmitter and its long wire antenna, Richardson uses only a small vertical incision through muscle tissue on the side of the fish a few inches ahead of the anus.

A hollow, 12-gauge needle is inserted horizontally at the incision so that it passes between the muscle tissue and the internal organs and exits farther back, anterior of the anus.

The diameter of the hollow needle is large enough to pass the BTC wire antenna through and does away with the need for a long belly incision. The vertical incision is just large enough to allow the transmitter to be placed in the body cavity.

The procedure Richardson uses cuts down the time during surgery, the area of tissue exposed to possible infection and overall trauma for the fish.

Richardson also uses an unusual mixture of a household antibiotic and an adhesive to guard against infection once the small incision has been sutured: a mixture of Neosporin and Krazy Glue.

"After I suture the fish, I will put some Krazy Glue right over top of the stitches and Neosporin over that," Richardson said, "and what it does is form a hard gel, almost an epoxy, as an artificial scab."

On the test group in the lake at Unicorn, the majority of fish netted nine days after surgery still had traces of the artificial scab. One fish retained the covering after 11 days.

"We seined 16 of [20] and saw that maybe two that had slight infections," Richardson said, "and the rest of them were doing great -- no redness, no yellowing."

From previous test groups, Richardson said, there is no evidence of physical harm to the fish that have received implants. Once the incision heals, "the body tissue surrounds the transmitter as if it were a tumor. It is absorbed and kept forever."

Alan Heft, also a biologist with the tidewater bass program, said that one tagged fish was recovered from Liberty Reservoir in good health three years after being similarly tagged.

Bass will live six or seven years around here if they are lucky, Heft said, and most die from natural causes.

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