Gill net surveys not for the squeamish
There are times when science isn't pretty. One of those times is the semiannual gill net survey conducted by the Division of Wildlife Resources at Utah's fisheries.
DWR biologists and volunteer sportsmen were at Scofield Lake State Park Thursday morning, hauling in nets that they had plunked in the lake the afternoon before and tossing the catch into big, galvanized tubs for analysis. What they found was good news for anglers: the fish in the sample looked healthy and well-fed. How they determined that is not a sight for the squeamish.
The three-man survey team was set up as an assembly line. No, better to call it a disassembly line.
Ryan Leonard, a sports fishery technician, was first. He plucked each fish from the bucket and laid it out flat against a measuring rod. He called out the species and length to Justin Hart, the division's Regional Assistant Aquatics Manager. Hart, clipboard in hand, recorded the information.
Leonard then passed the fish to Roy Marchant, Supervisor of the Desert Lake Waterfowl Refuge. Marchant weighed it on a hand-held spring scale and called the poundage over to Hart. Then Marchant got on with the necropsy. A slit up the belly exposed the internal organs and a tug with bare fingers removed them for examination.
Hart explained that the contents and condition of the stomach are of particular interest. Stomach fat is a good indicator of nutrition, and these fish had a good layer of it. Stomach contents indicate what the fish has been eating. An undigested crayfish claw shows up in one, a chub spine in another, a whole chub in another, and - sadly - a little cutthroat trout in another.
By and large, it appeared that the game fish had been doing their job, which is eating chubs. Hart said that the spring survey is not the best time to determine the size of the chub population in a lake. "It is spawning season and they are moving into the shallow water," he explained. In the fall the chub have moved into the deeper parts of the lake where a more representative sample will show up in the nets.
Thursday's survey showed that the game fish population is roughly 50 percent tiger trout, 40 percent rainbows and 10 percent cutthroat. DWR stocked Bear River cutthroat last year to augment the Yellowstone variety already in the reservoir. It looks like the newcomers made it through the winter in good shape. Hart said he thinks it is possible that in a few years Scofield could begin to rival Strawberry Reservoir as a place where anglers could go to catch the big ones.
Whether that happens or not is up to anglers. This year's fishing proclamation continues limits of four trout total. Of those four, only two can be cutthroat or tigers under 15 inches, and only one can be longer than 22 inches. Any cutthroat or tiger between 15 and 22 inches must be immediately released.
Of the fish who gave their lives for science, Hart said only about a hundred or so are sacrificed in a survey. "We have done creel surveys here, and that's not even a day's catch. It's a drop in the bucket," he said.