Cutthroat Eggs Project

Bonneville Cutthroat Trout Egg Project

By Markus Schlegel

The Division of Wildlife Resources (DWR) worked in conjunction with the Society to milk, develop, and hatch Bonneville Cutthroat Trout (BCT) from two separate streams during 2003.

Fish were shocked by DWR employees with the aid of Society volunteers. The eggs were fertilized and then incubated in several streamside incubators. The incubators were made from modified Coleman coolers.

The DWR gave the Society a total of 30,200 Bonneville Cutthroat Trout eggs to oversee. The first batch of eggs arrived in March 2003. We were only expecting a couple thousand eggs total. The plan was to stock several lakes and reservoirs in the area with fish hatched from these eggs. However, it was believed that due to the drought situation in Utah that these bodies of water may be too low and result in significant winterkill. Therefore, the Society was given almost all the eggs.

Little Dell Creek had two incubator sites, with a total of three incubators. The lower site on Little Dell produced the first fry 23 days after being fertilized. Three individual fry were wiggling around on top of the eggs. The remaining eyed eggs were extremely active.

The Lambs Creek incubators didn’t eye up until a week or two later. The water temperature there averages 45 degrees, so it took a little longer.

We started with 22,800 eggs in the three incubators at Little Dell. Fungus was a big problem on the lower site at Little Dell due in part to high water temperatures. The upper incubator site had lower water temperature and resulted in a higher hatch rate. We lost approximately 5,500 eggs in all at both Little Dell sites. This resulted in approximately a 72% hatch rate for both sites on Little Dell.

Lamb ’s Creek on the other hand did great and had very little fungus. Only one or two eggs were found with fungus each visit. Almost all the eggs eyed up at the lower site. It was a pleasure to see the upper site spilling over with fry on each visit. Cooler water temperatures are to thank for this. Averaging right around 48-50 degrees in the afternoon and very cold in the morning. We calculated a hatch rate approaching 90% with most of the mortality coming from unfertilized eggs rather than fungus as seen in Little Dell.

Many thanks go out to all the volunteers. This six-week project was made possible because of the numerous volunteers and the DWR. Thanks and congratulations on a job well done.