Current status and trends
The following information is provided to update anglers on the status of the Strawberry Reservoir Fishery. This information may not represent the most current data because of the DWR's inability to frequently update this Web page. Also, the information provided does not represent all of the data collected at Strawberry Reservoir. Caution should be used when interpreting the data as much of it is more complex than it appears. If you have any questions, please contact the Strawberry Project Office of the Utah Division of Wildlife Resources at (435) 649-9368.
For updated fish stocking informaition, visit our current fish stocking report.
Numbers and pounds scheduled to be stocked in calendar year 2006:
- Cutthroat — 761,000 fish totaling 58,489 lbs.
- Rainbow — 557,200 fish totaling 53,768 lbs.
- Kokanee — 380,000 fish totaling 3,826 lbs.
The quotas provided are subject to change in response to water limitations in the hatcheries, egg production, and survival to stocking. It is important to note that pounds are sometimes more informative than numbers when you refer to fish production and stocking. Hatcheries are limited in the number of pounds they can hold and produce. Also, the larger the fish is when stocked, the more likely it is to survive predation by other fish. There is a trade-off in the numbers you can produce and the size they can be stocked at. For instance, we could stock several million one-inch rainbow (provided that our brood stock was geared up to produce the necessary eggs), however, past studies have shown that as many as 95 percent of those fish may be eaten by larger fish during their first year in the reservoir. Therefore, we try to walk the tight rope of how many fish we can stock at what minimum size to provide the most fish for anglers based on limited hatchery space and survival after stocking.
Cutthroat population modeling
The cutthroat population modeling is done to track current trends in the population status of cutthroat trout in Strawberry, and to make predictions for the future. The model is based on our fall gillnetting, and each year class of cutthroat is tracked from one year to the next, with survival estimates derived from relative catch per unit effort from year to year. For instance, if the 2001 year class of cutthroat showed up in the fall of 2002 at a catch rate of four fish per gillnet hour, and then in 2003 they were caught at a rate of two fish per gillnet hour, then 50 percent were lost from 2002 to 2003. All cutthroat that are stocked into Strawberry are marked with either a colored grit that is applied externally on the fish, or with oxytetracycline that puts a mark on the bone. These marks can be seen under a black light, and we can then differentiate among year classes of fish based on the color of grit we used on the external marks.
The other thing the modeling allows us to do is estimate how many fish came from natural reproduction in the tributaries (what proportion were unmarked).
The more restrictive cutthroat harvest regulations imposed in 2003 at Strawberry were largely intended to increase the population of adult cutthroat and to improve their age structure, with older (large) cutthroat to prey on nongame fish. The above graph shows the estimated adult (three years and older) population of cutthroat in Strawberry from 1992 to 2005 and the predicted numbers for 2006 through 2008. There was an immediate positive response to the overall adult population due to the regulations imposed in 2003, and it appears that the population will remain at high levels through the next few years. More importantly, the age structure of the adult population has changed with more of the five- and six-year-old fish than we have ever seen in the past. As is shown in some of the following data, these larger (more predatory) cutthroat are very important in limiting chub population growth in Strawberry. Currently, about 20 percent of the cutthroat in the gillnet catches are over 20 inches, and just over five percent are over 22 inches. We have never had that many large fish in the history of this fishery.
Rainbow numbers have remained relatively low during the last few years. It is likely that many of the rainbow stocks are being eaten by the numerous large cutthroat in Strawberry. As a result, we will be stocking larger rainbows (six-inch minimum) in an effort to avoid some of that predation. We expect rainbow numbers (and catch) will improve in the following years. Regardless of the relatively low numbers of rainbows, several very large rainbows have been caught recently.
The kokanee populations in Strawberry have undergone dramatic fluctuations in recent years. 1999 and 2000 were the two best kokanee runs we have seen, while 2001 and 2002 were some of the poorest. The 2005 kokanee run was the third best we have ever seen in the Strawberry River. The fishing for kokanee has been just as sporadic. We hope that fishing will be relatively good in 2006 for kokanee due to the large number stocked in 2004.
Chub numbers have fluctuated since they were first sampled in our gillnetting in 1992, with their numbers generally increasing from 1998 to 2002. However, chub catches decreased in the fall of 2003 by 25 percent from the previous fall. This immediate response to the regulations protecting cutthroat has continued through the fall of 2005, and overall chub numbers have dropped by 65 percent. The fall catch of one-year-old chubs has decreased by 95 percent. It appears that the cutthroat predators are having a dramatic impact on chub populations in Strawberry.
Cutthroat predators can eat a large number of chubs in a single year. During 2005 we conducted extensive diet surveys to see what the cutthroat were eating. We estimated that the cutthroat ate 856 tons of chubs in 2005, equating to nearly 64 million chubs being eaten.
The trends at Strawberry look very promising for the future of this valuable fishery. The protection offered to the cutthroat by the 2003 regulations are providing a large population of large cutthroat. Chub numbers have declined in response to the increased predation by these numerous large cutthroat. And the bottom line for anglers is that fishing should be great over the next few years for numerous large cutthroat, and rainbow fishing will hopefully improve due to alterations in our stocking practices.