Sparking a fish comeback

[Spiel]

Sparking a fish comeback

Electro-fishing crew sees good variety in lake, a sign conservation efforts are paying off

 

 

Jul 17, 2008

TONY BOCK / TORONTO STAR

Video: Electrofishing

 

The electrical current coursing through the water almost completely immobilized the little silver fish. Now, scooped up out of the water, it lolls on its side in the white plastic tub.

 

Centimetres away in larger containers, its predators thrash, attempting to use their bulk to overturn their temporary plastic prisons.

 

The sun is setting. We're moving slowly across Humber Bay on Lake Ontario. The captured fish were rounded up during an electro-fishing excursion involving members of the Toronto and Region Conservation Authority.

 

Our expedition is captained by senior project manager Rick Portiss. The conservation authority stuns, counts and records data on fish a couple times a year for about two weeks along the waterfront. The point is to determine the health of the city's aquatic ecosystems. Essentially, if they catch lots of different kinds of fish they know things are going well.

 

"If you catch a lot of large predators, you know there are a lot of forage species keeping them alive," said Portiss, as he sorts through the fish, describing where they came from and explaining their various injuries.

 

The conservation authority doesn't track fish populations. Instead, it measures density or the ratio of species, based on what they scoop into the boat. Portiss said the density of just about every species has remained static between 1989 and 2003 – with a new report on numbers coming out this fall.

 

That is with the exception of walleye, which have been making a significant comeback since then, he said. In the past they only caught one or two a year and now the boat hauls in several every night, he said. Walleyes are the strong, sensitive type – they're top predators, but don't react well to changes in the water. The conservation authority helps create and protect habitats, and they take the walleye's comeback as proof that their efforts are paying off.

 

The electro-fishing team works from just before sundown to the early morning hours. That's when little fish come to the water's edge to feed. It also allows the predators to back them up like diners at the edge of an all-you-can-eat buffet, explains Portiss.

 

He likens the water under the boat to a "candy store," stocked with everything from perch, walleye, minnows and trout to carp, bass and pike. If you put them in a food pyramid, the minnows would be close to the bottom, getting snacked on by fish such as perch and walleye. Pikes, with their muscle and razor sharp teeth, eat anything they can catch. Carps are bottom feeders and get their bulk from aquatic vegetation and insects.

 

There are also alewives – the "chocolate bars" of the water, said Portiss. "They don't deal well with stress," he said, releasing a limp little fish off the side. "You wonder why this fish exists."

 

Almost on cue, a gull swooped in and there was one less alewife in the world.

 

It's a seven-hour shift and the conservationists haul in about 200 to 300 fish a night. "In some cases, we need to stop the boat early because there is no room in the livewell," said Portiss.

 

According to the Ontario Federation of Anglers and Hunters, most of the populations around the Toronto area are in good shape.

 

"For a major urban centre, there is a surprising number of great fishing spots," said Jeremy Holden, fisheries biologist.

 

 

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How electro-fishing works

 

A customized steel platform boat – dubbed the Night Heron, in this case – generates an electric current which runs out clusters of slendera nodes suspended at the end of two poles.

 

The metal boat acts as the negative, creating a web of electrical current approximately eight feet around the underside of the boat and eight feet deep. The electrical pulse causes the fish's muscles to contract, pulling them towards the front of the boat.

 

Stunned fish drift limply through the water at varying depths and researchers scoop them up in large nets. The little fish, minnows, pumpkin seeds and alewives, bob close to the surface. With the larger fish, carp, salmon, trout and pike, all you get is a flash of underbelly or a shadow of toothy jaw before it vanishes back into the murky water. (Note to amateur electricians aspiring to become fishing enthusiasts: It is completely illegal to fish this way.)

 

The captured fish are tossed into a livewell and taken back to a second craft to be separated, weighed and measured.

 

By that time, the fish – some weighing more than 14 kilograms – are wide-awake and fighting mad. Once they are weighed and measured and the crew has taken a few photographs, the fish are released back to the water.

 

- Emily Mathieu

[Tarzan's Jane]

That was an interesting read...wouldn't mind that job at all...