DNR studies fluctuations in fish populations

DNR getting samples of local fish populations using a trammel net (John Gaddy/WCIV)

By Sonya

CHARLESTON, S.C. (WCIV) -- Have you ever wondered how the Department of Natural Resources knows about the population of various fish species?

It's a process they have been doing every month since 1991 to provide consistent data.

A trammel net is used to help marine scientists and biologists better understand the ups and downs in inshore fish populations.

"What we are doing now is putting the net again as far in the marsh as possible so we can encircle those fish right against the marsh front," said Steve Arnott, Associate Marine Scientist with DNR.

Once the net is in place, they try to contain as many fish as possible.

"It looks pretty silly but what it does is it scares the fish away from the marsh front and into the nets," said Arnott.

They are then put in a cooler so they can count them, identify them, measure them, and release them.

"This is primarily looking at Red Drum, Spotted Sea Trout, Sheepshead, Flounder, Black Drum and other recreational species such as Spot and Crocker for example,' said Arnott.

Friday's net didn't catch much, but that isn't unusual for February.

"This time of year a lot of fish species have moved out into deeper water or further offshore," said Arnott. "Those spot that we see a lot of are offshore at the moment, flounder have gone out to spawn, so this is fairly typical I would say."

And the whole point is to gather data to better understand the fish below and why their numbers are fluctuating.

"The problem we saw with the natural mortality of the spotted sea trout recently, we are able to see that," said Bill Roumillat, a biologist with DNR. "We are actually able to indicate that by looking at the abundance of the animals prior to the freeze, the lack of the abundance of the animals after the freeze and try and make some sense of their fragility with regard to the water temperature."

Since the environment is such a big factor, another part of the survey is to record things like water temperature and salinity.

Sometimes the declining numbers are because of over-harvesting, too much fishing. If that is the case then DNR would take the data collected and recommend that regulations be changed.

DNR does not set any fishing regulations. All the scientists can do is show their data to the Office of Fisheries Management, NOAA, and the state government and hope that those organizations make good decisions that protect and enhance coastal fish populations.