SWEETWATER COUNTY — Fish stocking crews with the Wyoming Game and Fish Department stocked nearly 35,000 Eagle Lake rainbow trout into Flaming Gorge Reservoir on May 9, and they have only just begun. 453,000 trout and 855,000 kokanee salmon will be stocked into the Gorge though the end of May. Even more, trout and kokanee salmon will be stocked by Utah Division of Wildlife Resources and Jones Hole Federal Fish Hatchery during the same period.
Speas Hatchery personnel Lars Alsager and Pete Starr transported the rainbow trout from the hatchery near Casper to boat ramps along the Gorge the week of May 9 and will continue stocking fish the week of May 16.
“We are very excited and proud to deliver these fish to anglers in southwest Wyoming,” said Alsager. “It’s probably one of the most favorite parts of my job as hatchery superintendent at Speas. We deliver tons of fish in the new, supped-up stocking trucks, nicknamed “Bow” and “Cutty”, and we bring smiles to many anglers. Pete and I get to see lots of new country around the state and meet many new people as an added bonus.”
There are two fish tanks onboard each stocking truck and the water temperature is kept at or below 60 degrees Fahrenheit. The trucks are capable of carrying 4400 pounds per load (2,200 pounds per tank) of fish ranging in size of eight to ten inches. The trucks are equipped with oxygen monitoring equipment that updates oxygen and temperature readings within the tanks every five seconds. There are also fresh flow aerators that turn the water in each of the two tanks every three minutes. The onboard oxygen monitoring system is a new addition to the trucks in an effort to ensure fish arrive in good condition.
Green River Fisheries Supervisor Robert Keith plans for the fish stocking in the region two years in advance. “This gives the culture system a chance to plan the number, species, and strain of fish eggs they need to grow the fish that are requested,” Keith said. “It takes a good deal of planning and coordination between fisheries managers and the culture section to successfully manage Wyoming fisheries for the angling public.”
“In the region, rainbow trout (RBT) and kokanee salmon (KOE) are stocked in May and June to free up space in our hatchery and rearing stations so the facilities can start growing next years’ fish,” Keith said.
“The size at which RBT are stocked can vary greatly depending on what a fisheries manager is trying to achieve. For example, RBT destined for the Gorge are stocked at eight inches during May and early June to overcome predation. We know that an eight inch RBT is too big for many of the predatory fish in FGR to eat. The larger size also means the RBT will escape predation by the largest predators by the end of their first summer of growth. Most KOE and RBT will grow at least an inch per month after being stocked. It takes a RBT nearly 12 months to grow from egg to an eight-inch stocker in our culture facilities. The Eagle Lake rainbow being stocked in the Gorge started as eggs in the Speas hatchery around May 2015.”
“KOE are stocked in the spring at three inches,” Keith said. “Kokanee grow to three inches in our culture facilities from egg in the fall until they are stocked the next spring in May or early June; about eight months. Many fish like trout and kokanee are stocked in the spring to take advantage of the naturally high productivity in most lakes and reservoirs in May and June. There is typically a large bloom in phytoplankton followed by a large zooplankton bloom in spring and early summer. Zooplankton is the primary food for most trout and KOE in Wyoming’s lakes and reservoirs. Zooplankton is a nearly microscopic crustacean.”
“KOE are a pelagic fish – meaning the live in the open water habitats of lakes and reservoirs away from shore and away from the bottom,” Keith added. “As such KOE avoid some of the predation other species like RBT face that live in the littoral zone – the habitat near shore around a lake or reservoir. KOE stocked into in the Gorge serve two primary functions: they help produce the world-class fishery enjoyed by many anglers and they are the primary forage that sustains the trophy lake trout fishery in the reservoir. Stocked KOE also take some of the pressure off the wild spawned KOE that live in the reservoir. Whether it’s anglers or lake trout – the stocked KOE give each additional targets, so fewer wild fish are taken by hook and line or by predators.”