Strawberry Fishing - Trouble With Rainbows
By Roger Wilson, DWR Strawberry Project Leader
Rainbow trout fishing at Strawberry Reservoir during the summer of 1995 has been excellent, due in a large part to adjustments in the rainbow stocking program initiated during 1994. Rainbow stocking quotas were increased to about 1.25 million and all fish were stocked during the spring to enhance survival and growth. A similar stocking program was undertaken during 1995, and we should see similar results during the 1996 fishing season. However, the DWR is currently facing serious problems in producing sterile rainbow trout, which will influence the future rainbow management program at Strawberry.
As most anglers are aware, Strawberry has developed a different character during the 1990s than it exhibited in the past. The reservoir is substantially larger, and surrounding lands now contain a variety of new recreational developments, campgrounds and boat ramps. Fishing pressure has increased dramatically as a result of improvements in the quality of fishing brought about by the 1990 chemical treatment and the tributary rehabilitation program.
To meet the needs of the enlarged reservoir, a
new and innovative management approach was devised during the late 1980s
which incorporated chemical treatment, biological control of re-invading
rough fish populations, new fish species, and tributary stream rehabilitation.
This management plan also emphasizes natural reproduction to supplement
stocking programs. The plan was developed with input from a variety of
state and federal agencies, angler groups, interested publics, etc. It
was recognized at the outset that Utah chubs and Utah suckers would eventually
return to Strawberry
This new management approach focused on three game fish species, including the Bear Lake (Bonneville) cutthroat, sterilized rainbow and kokanee salmon. Although Bear Lake cutthroat trout are not native to Strawberry Valley, this species possesses a number of desirable management traits which are well suited to the "new" Strawberry. This species is long-lived, attains a large size, is a voracious predator, and competes well with high densities of rough fish. It is anticipated that the Bear Lake cutthroat will prey upon Utah chubs and Utah suckers and, at least, subdue populations of these fish in the future. Because it is a "wild fish" Bear Lake cutthroat are more competitive with the aggressive rough fish that have plagued Strawberry Reservoir. Studies in the past have shown that rainbow trout do not compete well with nongame fish, and a fishery dominated by rainbows will eventually fail as it did during the late 1980s.
The DWR is also aggressively pursuing other sterilization techniques through research conducted at the Fisheries Experiment Station, with the hope that sterile rainbows can be retuned to Strawberry at some future time.
Although sterilized rainbow trout are not the primary component of the renovated fishery, they have filled an important role in the recovery of Strawberry, and have become a very popular fish. Sterile rainbow trout provide an alternative fish for anglers to harvest, and have therefore protected the Bear Lake cutthroat from over-exploitation. Rainbow trout are typically found in the weed beds, and provide good opportunities for shallow-water bait fishermen. Overall, sterilized rainbow have exhibited excellent survival, growth and returns to the creel at Strawberry.
Initially, the management plan called for the termination of rainbow trout stocking as soon as the cutthroat trout and kokanee salmon became adequately established in the reservoir. However, it was soon recognized that rainbow trout provided an important component in the developing fishery, and managers had hoped to continue the stocking of this species will into the future.
Rainbow trout are sterilized to prevent hybridization with the Bear Lake cutthroat and to maximize growth rates and condition. If hybridization were allowed to occur, the Bear Lake cutthroat could not maintain its genetic integrity and would lose many of those desirable management attributes so necessary at Strawberry.
In 1987, the DWR initiated a program to sterilize rainbows for Strawberry. The drug used to sterilize these fish was methyltestosterone, a synthetic hormone. Newly hatched fish were administered the drug to change the sex so that only males were produced. Adding the drug to their food for a time further sterilized the fish. Since very few compounds, including this one, were legally registered for use in fish, a special "Investigational New Animal Drug" permit from the Food and Drug Administration was obtained. At that time, the requirements for such a permit were limited and easily met by the DWR. Fish were successfully treated and stocked into the reservoir before and after the rotenone treatment in 1990.
In 1991, the FDA sharply curtailed the legal use of most compounds in fish culture, including methyltestosterone. This was probably due to pressure from Congress and consumer groups who demanded greater assurance of the wholesomeness of aquaculture produces such as fish. DWR was able to obtain a new permit for the drug, under conditions that called for strict withdrawal times, accounting for every gram of the drug, and minimum legal size limits on fish harvested from the reservoir. We also had to provide data to show that the drug was working. Although this was an expensive and time-consuming process, DWR met the challenge and the program continued to the present, even more successfully than before.
The DWR has learned that the FDA is planning to announce that greatly increased amounts of research and data will be needed to continue the use of the drug under the permitting process. This announcement is expected by October 1 of this year. Since no drug company or supplier is willing to fund this research, it would be left up to the users of the drug to perform or fund the research, which could cost millions of dollars. After the research is completed, there is no guarantee that the FDA would approve the drug for continued use. DWR simply does not have the people or money to accomplish this research effort.
As a result of the increased demands from the FDA and the need to maintain the genetic integrity of the Bear Lake cutthroat, the DWR has reached a preliminary decision to terminate rainbow trout stocking until other effective and legal sterilization techniques can be developed. In the interim, the DWR will increase stocking of cutthroat trout and kokanee salmon to compensate for the loss. The total pounds of fish stocked annually in Strawberry Reservoir (about 53,000 pounds) will remain approximately the same.
In addition, the DWR is proposing a regulation change which will allow the legal harvest of more cutthroat trout at Strawberry. We are proposing a four-fish aggregate limit (trout and salmon), only one of which may be a cutthroat or rainbow over 18 inches.
The DWR is also aggressively pursing other sterilization techniques through research conducted at the Fisheries Experiment Station, with the hope that sterile rainbows can be returned to Strawberry at some future time.
Anglers should be reminded that rainbow trout fishing should be excellent for at least the next two years.
Editor's note: Happily, DWR found a reliable source for sterile rainbows and they continue to be a vital part of the fishery.
Copyright Dave Webb, 2005