New Jersey state wildlife officials were out in the rivers of Warren County this week to take a count of the official state fish – the brook trout.

Brook trout have been in the area for thousands of years, but warmer, cloudier waterways and invading fish have caused the number of brook trout in New Jersey to drop.

Researchers with the New Jersey Department of Environmental Protection and the organization Trout Unlimited were out counting the fish with the use of a fish zapper. The device stuns the fish with a mild electric shock so that they can be rounded up and counted.

“The two locations we sampled today were new locations and the number of brook trout was pretty low. Pretty sparse. But they're hanging in there,” says NJ DEP biologist Pat Hamilton.

The fish are measured, recorded and then released. Surveys like this are done every 10 years in brook trout streams so scientists can see how well the official state fish is doing from stream to stream.

“We'll take this data and extrapolate it over the whole stream and get a rough population estimate,” says Trout Unlimited’s Cole Baldino.

Baldino says that Trout Unlimited is hoping to take some of the fish and move them to streams where they've disappeared.

“You give them a chance, you make the habitat better, you let them do their thing and they'll survive,” he says.

The brook trout are not listed as a threatened species but are being considered for designation as a “species of special concern” which is one rung below threatened status. Fisherman who catch native brook trout must release them unharmed.