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By CRAIG CROSBY
Staff Writer Monday, July 2, 2007

Placing the worm on the counter beside the gutted fish, the state's Inland Fisheries and Wildlife pathologist was beginning to see glimmers of the answers to questions he has been asking for years.

"That little fish ate this great big piece of worm," Danner said.

The inch-plus piece of plastic worm filled the nine-inch brook trout's stomach, but later Danner would slice into a similarly sized fish and a nine-inch plastic salamander would pop out.

"The question is, why don't they throw those back up," Danner said.

He hopes an answer to that question, and a host of others, will emerge from the most comprehensive study to date on the effects of consumed plastic lures on brook trout health growth.

"We're just looking to see if it causes any health problems," Danner said.

Danner's study could lead to legislation that would curtail the use of traditional, undigestible plastic lures. Since biodegradable artificial lures are already on the market, "they would be a good choice even now," he said.

The rising popularity of black bass fishing in Maine has meant more fishermen using soft, artificial lures. Scuba divers and fisheries biologists have found these lures, made in a variety of shapes, sizes and colors, littering the bottoms of Maine's ponds.

Ice fishermen are catching brook and lake trout with the undigested worms still in them, Danner said.

"Usually, these baits appear to have been in the fish's gastrointestinal tract for an extended time period, and typically the baits appear to be fusing together to form a single mass," he said.

To study the lures' effects in a controlled environment, Danner split 70 hatchery-raised brook trout into two groups, placed them in tanks at Unity College, and fed them over 90 days.

One group of fish was fed just food, while the fish in the second group ate a mixture soft plastic lures with their food.

The feeding portion of the study ended on Wednesday, when the fish were euthanized and their remains underwent a battery of tests.

Only one fish in the lure-consuming tank died during the 90 days of feeding, but the first signs of trouble came while the fish still swam in their tanks.

Holding a small can of food, Jim Chacko, the college's professor of aquaculture who is assisting with the study, tossed a small handful into the tank with the healthy fish, which swarmed to the top to grab a piece.

When food was tossed into the tank of fish that had consumed the lures, however, the fish slowly made their way to the top to nibble.

"I think it's because their stomach is full so their reaction is very slow," Chacko said.

Danner found an excess amount of green bile inside a number of fish, which is an indication the fish are not eating properly, he said.

"The fact that there's that much bile indicates that fish hasn't eaten that much," Danner said.

Malnutrition is a sign of an unhealthy fish and can lead to a disappointing fishing experience, said Jaime Bray, manager of the Inland Fisheries and Wildlife fish-rearing station in Palermo.

"One of the most important things for us is fish size," Bray said. "It's not very appealing to catch a fish that's all bulging (with undigested plastic lures). Our goal is to produce a nice quality fish for sport enthusiasts."

The fish were measured and weighed and a blood sample was taken to measure glucose levels, the ratio of red blood cells, or hematocrit, and blood protein. All of the fish had a low hematocrit.

"A lot of stressful situations will affect the fish's hermatocrit," Danner said.

The readings, measurements, stomach and liver contents, and the fish themselves, will be compared to those provided by the pure food group to learn how the plastic lures effect the fish overall health.

The fish were fed different colored lures each week during the test, which will allow Danner to learn how long the lures stay with the fish.

"We know what week he ate that particular worm so we'll be able to extrapolate how long it's been in his stomach," Danner said. "I'm pretty certain the worms never leave the belly. No digestive juices are going to break down a plastic worm."

Craig Crosby -- 861-9253

ccrosby@centralmaine.com

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