Tuesday, November 28, 2000 at 12:59 PM
One of the most important tools state wildlife biologists use to assess fish populations is about to change. The technique called electrofishing has been used since World War II to collect fish, then study them. Scientists use an electric current to stun fish so they can be easily caught and handled, then returned to the water. But for several years, an electrofishing controversy's been hatching between fisheries biologists. Instead of counting fish, some say the dated technique is killing them. 90.3's Janet Babin reports.
Janet Babin- From an early age, children are taught that electricity and water are a deadly mix. Fisheries biologists tap this combination not to kill, only to knock out fish temporarily, so they can survey them. Scientists need to know how many fish are in rivers and streams to determine fish populations to evaluate laws and ascertain the need for new ones.
There are several other ways to do this: visual fish counts, large net collection, surveys of sports anglers. But the electroshocking method is considered the fastest, easiest default method of sampling and studying fish.
On a sunny mild Monday in late September, Ohio division of Wildlife Biologists in Akron are getting a boat ready for an electrofishing expedition on Portage Lakes Reservoir.
Here’s how it works: to capture live fish, scientists string electrodes into the water off the bow of the 18-foot boat. Using a generator, they create a current that travels into the water through the dangling metal pieces. Fish swimming near the electric current are then driven toward the electrodes. They’re shocked by the current and are easily collected into nets. Biologist Vince LaConte has been electrofishing for at least 20 years - he explains where the electricity will come from:
Vince LaConte- The power source is this generator standing behind you. The generator feeds electricity into our control box here and at the control box. I can control the voltage, the amperage, the pulse, pulse width and the timing from here.
JB- LaConte manipulates all those variables, and also must take into account water temperature, and the fish population he’s trying to capture. For this outing, LaConte is using 300 volts, and 4 amps to create an electric field between the metal pieces and the hull of the boat.
VL- That’s enough to kill you, but it will actually only stun the fish momentarily.
JB- With the flip of a switch, the generator on the boat hums and the zapping begins. Almost immediately, two assistants at the front of the boat begin dipping nets into the water to collect the bass, blue gill and other fish that flip upside down and float on the water’s surface, overpowered by the current. About 20 minutes later, the fish deposited in the boat’s holding pen begin to show signs of recovery, with no apparent side effects. But if the shocking is done by an inexperienced scientist, the results could be lots of dead or injured fish. LaConte insists that’s not the case.
VL- In my experience, everyone who does electrofishing in Ohio does it safely and yes, you do need a permit to do it in Ohio.
JB- But the permit isn’t specific to electrofishing. According to the Ohio Natural Resources Administration’s Sherry Zook, about 500 collection permits were issued at $10 each (this past year) - of that number, about 100 of them were used for electroshocking. She says no private company or state agency that requested a permit has been denied one.
Biologist Jennifer Nielsen is well acquainted with electrofishing - she’s used it many times in California and Alaska while working for the United States Geological Survey in the Biological Resources Division.
Jennifer Nielsen- It’s an important component to fisheries science, there really is nothing to replace it. Before it, people would poison rivers or use dynamite to count fish, so it has demonstrated a significant tool in the impacts for surveying fish - but it comes with its own problems.
JB- Nielsen says there are potential negative effects on a portion of fish subject to electroshocking, especially salmon and trout. She also worries that there is no standardization or consensus among the scientific community about when it’s ethical to use it. In 1999, Nielsen published a paper outlining her concerns in a professional journal published by the American Fisheries Society. She says about 10%-30% of fish experience lingering problems or chronic side effects from shocking, that may not be clearly visible.
JN- ...burns on the skin if they get too close to an electrode and spinal column damage that can be so extreme they snap a vertebrae.
JB- While injuring up to a third of the fish subjected to the treatment might not matter for some fish, Nielsen contends that it does matter when studying endangered or compromised fish populations.
JN- My argument to that was that if you’ve only got 16 fish left and you damage a third of them, you certainly are having a population effect.
JB- University of Alaska fisheries biologist James Reynolds is trying to amend how the country’s scientists use the electrofishing technique. He says current guidelines used in Ohio and elsewhere, are not adequate.
James Reynolds- It’s true they have guidelines, but their guidelines only maintain sampling efficiency.
JB- Reynolds says biologists have known about electrofishing’s potential side effects since the 30’s, but the tool was so effective the industry just ignored fish mortality. But in 1988, a study of rainbow trout in the Colorado River showed that one of every two trout subject to electrofishing was injured during the process, a statistic that was hard to ignore.
Reynolds’ electrofishing study was funded by the U.S. Fish and Wildlife Service. It outlines new guidelines that he says will minimize fish injury. The new specifications will be released in January 2001. Reynolds predicts that both private and government fisheries biologists will conform to the new guidelines - eventually. In Cleveland, Janet Babin, 90.3 WCPN, 90.3 FM.
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