A couple weeks ago I was merrily hauling perch through the ice at Bulwagga Bay when a peculiar thing occurred. I set the hook on what I thought was a small perch, but when it came through the hole I caught a glint of silver. Initially I thought smelt. Not uncommon to hookup a few when fishing perch with flies, I thought. But it wasnt a smelt. It was an alewife. I tossed it on the ice in disgust. While the presence of these big-eyed, shad-looking bait fish may seem harmless enough, it could be the single largest setback to the sport fishing industry here ever. Thats right a bigger problem than the sea lamprey. Bigger than any fish disease past or present. And there is absolutely nothing that can be done to stop it. The history of the alewife in Lake Champlain
It was the summer of 2004 when biologists of the Vermont Fish & Wildlife Department first discovered what appeared to be an alewife captured during a routine fisheries sampling. The find did indeed turn out to be one of the small, non-native fish, and biologists were quick to warn the public about what might occur should the fish take hold in the lake. Because of their ability to reproduce at an incredible rate, they can quickly take over a lake as the dominate forage species, driving out native fish species, wrote Vermont fisheries biologists Bernie Pientka and Shawn Good in 2004. Alewife thrive because they out compete other fish for food sources, Pientka wrote. If alewives establish themselves in Lake Champlain, they could foreseeably replace smelt and perch as the dominant forage in the lake. To make matters worse, the nuisance fish, which has no commercial value, also eat eggs and fry of important sport fish like lake trout and landlocked salmon, thereby reducing their populations in a waterbody. It now appears thats exactly whats occurring. Just three short years after the Alewife was first discovered in Lake Champlain, it looks as if the nuisance fish has established itself and is here to stay. In fact, the lake just recently experienced its first die-off a situation in which huge groups of the nasty little bait fish die and wash up onshore, creating a stinky mess. This occurrence usually transpires only after the fish have grown in numbers to the point where they actually out-compete one another for food, and die-off in large numbers. However, biologists are pointing to the inability of the species to handle drastic changes in water temperature as the reason behind this die-off in Lake Champlain. Residents of other lakes with alewife populations spend thousands annually raking beaches to cleanup the piles of rotting fish, Pientka said. How the alewife has altered other ecosystems
Alewife first appeared in Lake Michigan around 1949, and by the 1960s, they made up 75 percent of fish populations in the lake, severely depleting other natives like perch and smelt, said Jim Francis, Lake Michigan fishery biologist. These fish filter feed, meaning they open their mouths and swim, feeding on sport fish while they are in the larvae stage, Pientka said. And, once theyve established themselves, there is no way to remove them. You have to live with them, he said. Because the species reproduce in open water, there numbers cannot be reduced by traditional treatment programs, such as those used on sea lamprey, Pientka said. The origin of the alewife
Originally a salt water fish, alewives were accidentally introduced into the Great Lakes in the 1870s. They have since been introduced into all the Great Lakes and some Finger Lakes, and have fundamentally altered the ecosystem of every water body they inhabit, Francis said. Although alewives often drive away other small fish used as forage by larger sport fish, their presence in a lake has some benefits. The alewife does provide an excellent food source for trout and salmon, and, because they feed on zooplankton so extensively, they have increased water clarity in some lakes, Francis said. But because of its overwhelming ability to reproduce and out compete similar species, alewives often explode in numbers, negatively effecting sport fish, he said. Alevies are also intolerant of severe temperature change, meaning their numbers will likely fluctuate dramatically as they die off during the cold winter months experienced here in the North Country, Good said. Lake Champlains future
Because of its inability to handle temperature changes, Good said residents will likely see many more die-offs of alewives in Lake Champlain. There is a lesson to be learned here, said Good. This is exactly why its not a good idea to move fish from one water to another or introduce new species to Vermont lakes. While some anglers think alewives are a good food source for game fish, the reality is alewives provide an unstable and uncertain forage base -- a here today, gone tomorrow type of scenario. One month our game fish have an over-abundance of alewives to feed on, and the next month they are starving. Such alewife collapses in the Great Lakes historically have had huge negative impacts to the sport fishing there. Good said anglers should be aware of the risks involved with introducing new species to new waters. The great fishing we enjoy today could be gone tomorrow if aquatic nuisance fish species are allowed to spread, he cautioned. We all need to work together to slow or prevent the spread of exotic species and protect Vermonts native fish and the fishing opportunities they provide.