Lake Stevens kokanee -2015
Posted: Tue May 12, 2015 8:47 am
With the kokanee derby coming up this Saturday and the previous discussions about the alum treatment early this year I thought some would be interested in my observations about the status of Steven's kokanee this year.
Thanks to an exceptional spring biologically the lake is at least a full month ahead of normal. Currently we are seeing water temperatures that would normally be associated with early to mid-June. In addition there seems to be lots of kokanee and between the advance state of the temperature conditions things should be setup for a successful derby.
With the warmer early spring consistent fishing on Stevens start way earlier than normal. Before mid-April the fishery was in full swing and consistent limits (10 fish) were doable for those anglers that took the time to dial the fishery in. Given the lake temperatures I would have expected that consistent fishing to have begun even a week or 10 days earlier. Over the last decade those conditions typically did not occur until 2 to 6 weeks later or on the average about a month later.
Following the alum treatment in March it was not a surprise to find the lake much clearer than normal. It is the phytoplankton (the greenness in the water) that drive the food chain that supports the lake's kokanee. By late April there was phytoplankton and more importantly daphnia (water fleas) in the water column. It is that daphnia that drives both the growth and nice orange flesh of the kokanee. At that time while there were some large kokanee the vast majority were in the 10 inch range with another group of obviously smaller fish. At this time the kokanee (especially the smaller fish) stomachs were stuffed with daphnia. Though those daphnia were much smaller than normal (it took looking under a scope to be sure that food was indeed daphnia). This small size is important factor for several reasons; 1) it takes a lot more of them to fill the fish's stomach, 2) the larger fish are less effective in filtering them from the water, and 3) the smaller/slower growing daphnia take longer to mature and reproduce. That long time period to reach maturity means that the next generation of daphnia is delayed and over the course of the spring there will be fewer daphnia.
That clearer than normal water conditions (lack of phytoplankton) continues to date. Though to be far the lake is finally "greening-up". As recent as the 4th of May I could still see my release (a yellow seps) at a depth of 20 feet. That distance decreased over the week until yesterday (May 11) the release disappeared at 10 feet. At the same time the daphnia was getting slightly larger. For the kokanee in spite of that month or more jump on the growing season they remain on the average at least 1.5 inches smaller than what we have seen the past several years for similar water temperatures (currently the lake is in the lower 60s).
I expect that the size of this years kokanee to remain below what we have seen the last few years. Generally I saw rapid growth of the kokanee during May and early June after which the fish to move from a growing mode to a more maturing condition. As that transition occurs and growth rates slow I see a physical change in the fish. That change is that the fish's scale become set and are no longer easily shed. This past week I have started seeing some of that transition.
The good news is that there is good numbers of kokanee and within the normal day to day variability that is the major part of the kokanee game things are lining up for a good derby and hopefully and continued good fishing for the rest of the season. Though experience has shown as the fish switch into a more of a maturing mode they become more temperamental; while still very catchable it at times will take significant experimentation to dial them in.
Good luck
Curt
Thanks to an exceptional spring biologically the lake is at least a full month ahead of normal. Currently we are seeing water temperatures that would normally be associated with early to mid-June. In addition there seems to be lots of kokanee and between the advance state of the temperature conditions things should be setup for a successful derby.
With the warmer early spring consistent fishing on Stevens start way earlier than normal. Before mid-April the fishery was in full swing and consistent limits (10 fish) were doable for those anglers that took the time to dial the fishery in. Given the lake temperatures I would have expected that consistent fishing to have begun even a week or 10 days earlier. Over the last decade those conditions typically did not occur until 2 to 6 weeks later or on the average about a month later.
Following the alum treatment in March it was not a surprise to find the lake much clearer than normal. It is the phytoplankton (the greenness in the water) that drive the food chain that supports the lake's kokanee. By late April there was phytoplankton and more importantly daphnia (water fleas) in the water column. It is that daphnia that drives both the growth and nice orange flesh of the kokanee. At that time while there were some large kokanee the vast majority were in the 10 inch range with another group of obviously smaller fish. At this time the kokanee (especially the smaller fish) stomachs were stuffed with daphnia. Though those daphnia were much smaller than normal (it took looking under a scope to be sure that food was indeed daphnia). This small size is important factor for several reasons; 1) it takes a lot more of them to fill the fish's stomach, 2) the larger fish are less effective in filtering them from the water, and 3) the smaller/slower growing daphnia take longer to mature and reproduce. That long time period to reach maturity means that the next generation of daphnia is delayed and over the course of the spring there will be fewer daphnia.
That clearer than normal water conditions (lack of phytoplankton) continues to date. Though to be far the lake is finally "greening-up". As recent as the 4th of May I could still see my release (a yellow seps) at a depth of 20 feet. That distance decreased over the week until yesterday (May 11) the release disappeared at 10 feet. At the same time the daphnia was getting slightly larger. For the kokanee in spite of that month or more jump on the growing season they remain on the average at least 1.5 inches smaller than what we have seen the past several years for similar water temperatures (currently the lake is in the lower 60s).
I expect that the size of this years kokanee to remain below what we have seen the last few years. Generally I saw rapid growth of the kokanee during May and early June after which the fish to move from a growing mode to a more maturing condition. As that transition occurs and growth rates slow I see a physical change in the fish. That change is that the fish's scale become set and are no longer easily shed. This past week I have started seeing some of that transition.
The good news is that there is good numbers of kokanee and within the normal day to day variability that is the major part of the kokanee game things are lining up for a good derby and hopefully and continued good fishing for the rest of the season. Though experience has shown as the fish switch into a more of a maturing mode they become more temperamental; while still very catchable it at times will take significant experimentation to dial them in.
Good luck
Curt