Biologists Wrap Up Spring With Sampling Of Bear Lake Fisheries

May 10, 2018

It’s 8:00 a.m. on one of the last days of April and two officials from the Division of Wildlife Resources are loading up their boat at the Bear Lake State Park Marina. They are joined by two volunteers for today’s fisheries sampling, the last one scheduled for the Spring.


Once everything is loaded and the crew is on board, the boat starts to move to the first of seven gill-net sites set up throughout the lake. The nets are set at depths ranging from 5 to 50 meters. A GPS unit helps Scott Tolentino, a fisheries biologist for the Division of Wildlife Resources, navigate to the first of the nets.


“We are trying to sample all the species to get a snapshot picture of what the fish populations look like in the lake. Then we’ll be taking some of the fish to do some biological samples on them,” he said.


Tolentino says the sampling helps inform what is happening in and around the lake. Information that is useful for both anglers and researchers.


“Earlier this week, we collected fish for mercury testing for the Department of Environmental Quality and then we also collected some fish for what they call disease testing,” Tolentino said.


Disease testing is important for preventing contamination of hatcheries that make up a portion of the lake’s fish population. Sampling can also help managers monitor the productivity of tributaries and rivers leading into the lake.  


“The Cutthroat Trout are stream spawners and so our natural recruitment for future generations is coming mainly out of the streams,” Tolentino said. “We have one stream in Utah that produces every year and then we have one that if we have a high-water year like last year it will produce some fish. Both streams have had a lot of habitat work done on them.”


Tolentino says the inclusion of screens on irrigation diversions has positively affected the Cutthroat populations.


“When I started here 25 years ago the population of native Cutthroat Trout was about maybe 10-12% native fish and the rest were stocked fish and right now we’re probably at about 70% native fish and only 30% stocked fish," Tolentino said. "So we’ve been able to reduce our stocking numbers out here and still maintain a fishery for the anglers".  


As the crew hauls in the nets, some of the fish seem impossibly tangled, but no one seems too concerned or in a hurry. The sun is out and everyone is working diligently to free the captured fish.


The two volunteers on today’s outing include Brett Kennedy and Brian McBride, both dedicated hunters here in Utah.  


“It’s a three-year enrollment and you have to do so many service hours and you can harvest two deer in three years and so it gets you out a lot more in the field,” Kennedy said.  


While they may not be regulars on this fishery project, the two gentlemen are no stranger to the various service opportunities offered by DWR.


“Yeah, I usually go help on the Logan River, like shocking the fish,” McBride said.


While Kennedy said, “I’ve done sage grouse markers and I’ve done deer fences for captures."


As the morning progresses and the crew works their way back to shore, we start to see more and more fish in the nets. All are being identified by species and measured for length, but only some are being taken back to the office for further biological sampling.


“We’ll work up through all the bags of trout first and if we have any of the small Whitefish that we collected as part of our sample that we don’t know we’ll put those with the net number and net depth off to the side and then we have some bags in the freezer that we’ll add those too,” Tolentino said.


This is because of the likeness between the Bear Lake and Bonneville Whitefish.  


“The only way to separate the two different Whitefish species when they’re below 250mm is to actually count scales along the lateral line and then we count the number of rows of scales above the lateral line from one side down and then back down to the other side.”


With all seven sites completed, the crew heads back to shore. There, Tolentino leads the crew through a data sheet which details characteristics of fish they’ve brought in, including sex, maturity and stomach contents.


They also extract the fish’s ear bones which are called otoliths - small opaque spheres smaller than a ladybug that can be analyzed under a microscope to determine the age of a fish.


 When we get to the Whitefish, Tolentino says:


“It’s important for us to, even though the Bear Lake Whitefish is quite small - it’s maximize size is about 10 inches - it’s important for us to keep a finger on the pulse of that population and make sure we know what it’s doing out there. If the numbers started to decline we’d have to make some changes on the management of the lake.”


Bear Lake is a large and highly-used area in northern Utah. Meaning it has many different stakeholders. The Utah Division of Wildlife Resources works closely with partners including researchers from Utah State University and Idaho’s Department of Fish and Game to learn as much as they can about the lake and its inhabitants.


Seasonal fisheries sampling is one of many studies conducted regularly on Bear Lake.