Spinal Fire Scientia Est Potentia

The Woes of Lake Superior
By John Kedrowski

Lake Superior is a big lake. It spans not only multiple states, but also two countries. Management of Lake Superior is obviously going to be complicated and nearly impossible with five governments dealing with it. People in the ground drive all of these systems, though. It would be interesting to see what people in Canada want from their fishery. People in WI, MI, and MN. People from across the US. I know that is asking a lot, but all of those places have an effect on what is going to happen here. What the people want there and what they stock in those locations WILL make it to our side of the lake. Let me explain why.

There are three classifications of lakes. Oligotrophic, Mesotrophic, and Eutrophic. In a process known as Eutrophication, a cold and infertile lake with fill in with sediment, its water temps will rise, and its O^2 levels will fall. This process requires time, though. Hundreds of years for ponds, thousands of years for small lakes, tens thousands years for medium lakes and hundreds of thousands of years for very large lakes.

The environment also has an effect on Eutrophication. Warmer regions, typically, have increase levels of eutrophication, because water temps can get high and stay high throughout the year. Increased amounts of sediment can increase Eutrophication because they fill in the lake basin. The addition of N and P will increase Eutrophication because they cause the nutrient level of the lake to fly off the charts. Lake Superior, because it is so big, will be around for a long time, but its death will be a swamp, most likely a million years from now.

Oligotrophic lakes are typically classified as Lake Trout/Cisco systems. There are aquatic and terrestrial insects that come into play, but it is not a huge, vastly supportive, niche compared to the pelagic baitfish. Also, calling the pelagic baitfish, "vastly supportive" is a mischaracterization. Comparatively, the bait can support more fish, but this is a candle next to a fire when compared to mesotrophic and eutrophic lake, literally! The older lakes contain more energy! And that is the root of this debate. Lake Superior is considered by the scientists to be an Ultra-Oligotrophic lake.

We have two basic niches. There are other, smaller niches, but these are not niches that are going to spread through the entire lake. Shoreline insects and pelagic baitfish support species of fish that will spread throughout the entire lake. The shoreline insect niche is competition saturated because not only to species of fish exclusively target the insects; the young of the pelagic species are in on the game as well.

In Lake Superior, the pelagic baitfish are the wildcard. It’s easy to understand. The more bait out there, the more fish we can have. Herring and ciscoes have been in the lake for a long time. They were, traditionally, the forage bases. The addition of smelt changed this. Smelt out competed the other baitfish and ate their eggs, so levels of natural bait have fallen dramatically. Smelt levels started to rise. When lamprey hit, predators across the lake were nearly wiped out and this caused the explosion of smelt that people remember in the 70s and 80s because there was nothing left to eat the little buggers.

This when the DNRs across the region started to step up their exotic species programs. Lake Trout populations were in shambles and the fishery was a mess. People though they could change the nature of the fishery with the addition of more Steelhead, salmon, and Kamloops Rainbow Trout and whatever. The only problem was the lamprey. The agnathans killed big fish no matter what their species, suppressing the numbers of any predators.

When that pressure was removed, populations of predators exploded. I remember coming up here with my dad in the late 80s and early 90s and we caught so many of every kind of fish compared to what we catch now. I'm only 27, but the fishing I saw back then, when compared to stories I've heard, was probably the best it’s ever been. Meanwhile, smelt runs dwindled to nothing until we have come to the point where stocked fish are a major food source.

This is where we are today, a big empty lake. It has always been big an empty, but comparatively to other population lows; there are literally few fish. For example, when the lamprey hit, there were still baitfish. When the lamprey left, there were predators. Now all species are at population lows and its time, in my opinion, to seriously discuss some long-term management plans for the lake. Not all groups are going to win this contest. Lake Trout and Coasters are the indigenous species and are the ones that evolved for this lake. Salmon and Steelhead are the invaders, but they could hold stable populations if manages correctly. We can't have both though. The fish have to travel long distances for food. They are going to cross imaginary lines and push into other areas of the lake. The energy in the ecosystem can't support even with the addition of more prey species. Lake Superior is ultimately limited by its producers (algae and zooplanktons) and zebra mussels have taken a chunk out of those populations. What do we want for this lake? I will post my answer later.