His Line Is Fishing for Toxic Waste : Environment: Biologist Jack Linn roams the state testing water for contamination. And he hasn’t come up empty in Ventura County.

Knee-deep mud tugging at his boots, Jack Linn makes another slow pass of his net through the murky waters of McGrath Lake.

Bits of tar pop to the surface in his wake, each globule trailed by an oily sheen like a comet’s tail.

Suddenly, Linn and assistant Bobby Villar hoist the net from the water and plop it onto the shore. Dropping to their knees, they pluck two wriggling mosquitofish from a mishmash of algae, bug larvae and pebbles.

“Not much luck,” Linn said.

The real quarry for Linn, a state Fish and Game biologist, is toxic waste. He knows that fish accumulate pesticides, heavy metals and other toxic substances in their flesh. Each year, the state dispatches Linn on a seven-month fishing trip to collect specimens needed to evaluate the environmental health of California’s rivers, lakes and streams.

In his excursions through Ventura County, Linn has stalked the fathead minnow to determine levels of pollution in Calleguas Creek. He’s trapped the black bullhead in the Arroyo Conejo, the gray smoothhound shark in Mugu Lagoon and the longjaw mudsucker in an agricultural drainage ditch.

It was a frustrating morning Friday near Oxnard. Several passes with the seine had netted only two tiny fish from McGrath Lake, which was swamped 18 months ago by a devastating oil spill.

To measure the lingering impacts of the spill, laboratory technicians needed at least a double-cupped handful of the squirming mosquitofish.

Linn’s trips to other sites have yielded plenty of fish and plenty of evidence of contamination. Previous catches in Ventura County have turned up extremely high levels of DDT and other long-outlawed pesticides, in Calleguas Creek and other streams that drain into Mugu Lagoon, state records show.

“Concentrations of chlordane, DDT and toxaphene from Calleguas Creek and Revlon Slough are by far the highest concentrations found in the state,” according to a 10-year report on data compiled by the State Water Resources Control Board.

Another agricultural drainage ditch that feeds Mugu Lagoon has “the highest concentration of DDT found to date statewide,” according to another report. And the lagoon, a sanctuary for migratory birds and other wildlife, showed the highest levels of arsenic, cadmium and other heavy metals in Los Angeles and Ventura counties.

Authorities believe that most of the toxic residues come from farmland on the Oxnard Plain, washed into creeks and streams by storm runoff and excessive irrigation.

“When we find high levels, then we try to find out what the sources might be and ultimately try to control them,” said Michael Lyons, head of surveillance at the regional office of the Water Resources Control Board.

For the past decade, Linn has been assigned to work with state environmental officials on the Toxic Substances Monitoring Program.

His duties inspire the envy of his office-bound colleagues. The usual path to promotion is settling into a desk job. Yet Linn, despite his 38 years with the Department of Fish and Game, has managed to remain in the field.

He is unique: the only Fish and Game biologist who prowls the state on a seemingly endless fishing trip.

“I’m usually in the field about 80% of the time between May and November,” said Lynn, a 60-year-old with a ruddy complexion and shock of white hair. The twinkle in his blue eyes reveals his delight at getting paid to go fishing.

“Before I had this job, I spent a good amount of my spare time hunting and fishing,” he said. “I don’t need to do much of that anymore.”

To be sure, Linn is not always hunting the bigger game fish that anglers find so alluring. His prey tend to be small fish, although most of them are not as tiny as the two mosquitofish nabbed from McGrath Lake on Friday morning.

Linn finally dumped the bucket with the two fish into the water, after repeatedly failing to find any more in the man-made lake amid Berry Petroleum Co.’s oil fields.

“We are wasting our time here,” Linn told his assistants. “Let’s go to the Santa Clara River.”

That next stop on Friday’s tour--and one other at Santa Paula Creek--proved more fruitful.

Linn and his helpers managed to corral a quarter-bucket of Santa Ana suckers after an hour and 15 minutes of dragging a seine along the calf-deep river beneath the Harbor Boulevard Bridge.

Later, carrying electro-fishing equipment to the creek in Santa Paula’s Steckel Park, they stunned and plucked from the water a sufficiently large sample of Santa Ana suckers and arroyo chubs.

The live specimens were then carefully counted, measured and stored in aluminum foil pouches. They joined the catch from the previous six days inside a cooler filled with dry ice on the back of Linn’s well-equipped truck.

Ultimately, Linn will drive his haul back to his office at the Water Pollution Control Laboratory on the outskirts of Sacramento.

There, the fish, depending on their size, will be fileted or thrown whole into a contraption that resembles the “Bass-O-Matic” blender used in a Saturday Night Live skit.

Once they are processed, lab technicians will use sophisticated equipment to pin down specific levels of contaminants.

Linn said he does not get too involved in the fish processing, leaving that to his colleagues in the lab. When he is in the office, he said, he’s more interested in preparing for his next fishing trip.

“Any day in the field is better than a day in the office,” Linn said. “At Fish and Game, I don’t think there would be a better job for me.”