Menacing pike continue to plague the trout in Davis
The Davis Lake Steering Committee has been meeting regularly this past month and has had a number of northern pike experts come from all over the country to decide whether these fish can be eradicated by some means other than by poisoning.
There has been quite a bit of dialogue, but there certainly seems to be no “silver bullet.”
Experts from the Alaska Department of Fish and Game, Idaho Department of Fish and Game, Wisconsin Department of Natural Resources and the Minnesota Department of Natural Resources have attended meetings this past month. There has been a lot of discussion regarding getting rid of the pike, but there is still no definitive plan on how to proceed. It should be noted that these people are all considered experts on the northern pike within their jurisdictions.
What has been learned is that each lake presents its own problems and the physical configuration of the lake is key to how the pike will do in a particular body of water.
Davis is a relatively shallow lake with a mean depth of about 20 feet. The experts all seem to be in agreement that systems in their jurisdictions that have various species co-existing in them have an average depth of 40 to 50 feet.
Why is this important? Most lakes in the midwest that have pike in them are deep cold lakes with steep shorelines. The trout in them are mostly lake trout that co-exist with them. The reason for this co-existence appears two fold. First, pike spawning areas are extremely limited because there are few shallows and is virtually no weed bed formation. This leads to very limited natural reproduction. Secondly, the lake trout spawn well in such an environment and are at peak production. Therefore, the numbers appear to stay in balance.
When asked about areas specific to rainbow and pike co-existence, the Alaska representative indicated that there was co-existence in much of western Alaska. According to him, “Pike have been there forever, but those are real large lake systems with moderate pike habitat. The streams are clear water streams, good spawning areas.. .the trout don’t have to fight their way through weed-choked areas to get to their spawning grounds.”
He went on to say that they also have a situation on some of their moderate river systems, where we have some pike habitat in the side sloughs and channels.
“That unfortunately is where most of the Coho (silver) salmon rear. They are really impacted in those systems. However, our Chinook (king) salmon rear in the mainstream, in quicker water, and are almost unaffected at all. I find very few Chinook salmon in pike stomachs. Same with the rainbows in those systems.”
What about lake comparisons? With each body of water being so different it is difficult to say what the level of the problem could be, but the experts seem to be in agreement that conditions are right at Davis for a substantial pike problem to exist. This is based upon their own work and the fact that the population prior to the chemical treatment had exploded.
The pike expert from Minnesota had probably the best examples of rainbow trout and pike interaction in lake environments.
“In Minnesota, rainbow trout are not native and they are stocked,” he said. “So, our experience has been limited to lakes that typically are very small, that have been poisoned. These usually have a good ground water source, so they’re getting cold water. Trout have been stocked back into those lakes. In some cases, pike have illegally or somehow gotten back into those lakes. We’ve had very bad experience trying to manage trout in those lakes. In fact, a couple of the area managers up there … the one in Ely says it’s the worst of all possible fish to get into a trout lake.
They once said that pike wipe out the rainbows as fast as they can put them in. He was talking about fingerling rainbows, and they had also tried yearlings, which were about three fish to the pound, so fairly good size trout”.
Discussed in these sessions were also various methods to control or eliminate the pike populations. Discussions included; salting the shallows, introducing fish that would eat the pike, trapping the pike, fishing them out through sportfishing, altering water levels, draining the lake, chemical treatment, and retrofit of the dam and dam site to create a temperature curtain such as that exists at Shasta.
Reviewing the dialogue of the experts, it certainly appears that no option is likely to be 100-percent effective. There seems to be a consensus that sportfishing has been totally ineffective in reducing any overpopulation problem in other jurisdictions.
The other more critical item appears to be an agreement that the pike could and would most likely create a huge problem in the Delta. They can and do move, even in salt water according to the Alaska expert. Certainly not good news for our fisheries below.
The threat is real and not perceived.
There are more meetings and more experts that are being contacted, but it appears that Davis Lake has a good potential to be overrun by the northern pike.
If it is, this would pose a real threat to any fishery below. Can they be managed? If eradicated, how do you insure that they won’t be reintroduced? These are the challenges that the steering committee must answer in a very short time frame.
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