Here is What I Learned at the DNR Large Lake Conference
Mille Lacs:
Walleye season effectively ends there in mid-july because the perch that they feed on become big enough to eat around then and they are focused on eating perch and not on your lousy fake lures.
Tullibee populations have taken a huge dip lately. Tullibee are not regarded as prime fishing targets, even though everyone attests to how tasty they are. This is important because tullibee are prime forage species for walleye. Because they are not "valued" as much as other species, you have been allowed, until now, to fish for tullibee with nets. The Asian community liked to come to Mille Lacs and bring home trailers full of tullibee. In response to the tullibee decline, you can no longer fish with nets (sport netting), there is a bag limit of 10 fish, and they stopped aggresively stocking Muskies because muskies hammer on the tullibees. I guess these new regulations mean the tullibee has graduated from junk fish to valued managed fish.
Lake of the woods:
Lake of the woods is split by the pre-cambrian shield as well as the border with Canada. The canadian side has tons of islands that are the remnants of ancient mountains and US side is scraped clean of all that and is flat and open.
Suprisingly, ice fishing has made up more of the angling pressure on this lake than summer fishing. This is because of the warm winters in which Lake of the Woods was about the only place to go for ice fishing.
When we were out on Lake of the Woods, our guide pointed out islands that had shrunk because of rising water levels. One long skinny island (map) had rows of dead pine trees lying by the water.
Pepin:
Why is Pepin even considered a lake? Because of water retention. Water that flows into Pepin stays there a while. There are high algae and zooplankton levels that you wouldn't find in a river. Biologically, it looks like a lake. However, there is not a seasonal water turnover as cold surface water sinks and warmer bottom water rises.
How is Pepin different from a regular lake? One big difference is that walleye spawning habitat is created by flooding land vegetation instead of using clean gravel substrates. If it is a dry year and water levels are low during spawning season, "recruitment" suffers (recruitment is the number of individuals that make it into the fish population in a given year). In high water, they swim past the submerged park benches and picnic tables and lay their eggs in submerged vegetation like reed canary grass. In 1999, fisheries biologists set out to prove this was the primary spawning method on Pepin and tracked 20 walleyes to see that they did, in fact, all spawn on reed canary grass. They published their study in Investigational Report No. 481 . The question comes up about how the fish learned to do this. It is not a localized adaptation; the Lake Pepin walleyes are 'mutts' and get genes from up river mixed in all the time. It could also be that young spawners follow older fish to the spawning areas when the time comes.
Invasive species. The biggest threat lately seems to be carp (black, asian, silver). The aquaculture industry and their friends in congress down in the grit eatin' part of the world resisted attempts to ban these critters because they are helpful in eating pond scum in rearing enclosures. In spite of promises, they escaped from the ponds and now migrate further north each season. These carp are planktivorous and eat all the food that tiny walleyes and other native species would eat. Some of these carp also leap out of the water at the sound of an approaching motor and have caused injuries and deaths to boaters. Fish biologists in Missouri are required to wear motorcycle helmets when working on a boat. Note to jet skiiers: being struck simple by a 20 pound flying carp doesn't give you an excuse to blame the conservationists for this one. Your friends in the aquaculture industry pushed this one through. You can thank them when you get knocked off your $5000 jet ski. Exotic Daphnia found in lower pools in 2002.
Zebra mussels, a nasty invasive species that cement themselves in large numbers to substrates, intake pipes, and even slow moving animals ( ;-D ), have threatened Pepin and other waters. In 2001, Lake Pepin trawling samples had to be cancled because massive numbers of zebra mussles made the nets too heavy to lift. Zebra mussles experienced a huge die off lately. (There were mounds of mussle shells on the shore of Pepin last year and only three muscles were found in the nets). This looks really positive because there was a huge die off in Illinios and the mussels have not yet come back. No one knows why. It could be warmer water. It could be sediment.
Vermillion
Rusty Crayfish are still a big problem on Vermillion. Rusty crayfish mow down aquatic vegetation and outcompete less aggressive crayfish that fish like to eat. When they do surveys, they find that their nets are full of crayfish that have skeletonized the fish they are trying to weigh and measure. There is talk of using a formula to calculate the actual poundage of the catch from the weight of the crayfish found in the net.
The two basins of Vermillion are quite different. The east basin is more productive
Concern over Bass tournament:
- Hundreds of boats over several days can impact the fishery. This upsets resort owners who see the tournaments driving away regular customers.
- Fish caught from all over the lake are all released in the same place.
Red
Upper and Lower Red lakes are at the center of what was once the glacial lake Agassiz. In the area around them, you can see sand berms that once formed the shores of Lake Agassiz. The lower red lake is 100% inside the Red Lake Indian Reservation and Upper Red Lake is about 3/4 reservation lands. The walleye population crashed in the early 1990s due to overfishing. Commercial netting and sport fishing for walleye has been banned on Upper Red Lake since 1999. The DNR is stocking fry into the lake with a goal of restoring the spawning population. The survey numbers are going up slowly. As one fish biologist put it, if you wanted to design perfect walleye habitat, you would make a lake just like Red Lake. It is shallow and windswept with a long fetch (distance of unbroken open water). That means that the wind can clean off the gravel substrate. Clean gravel is important for walleye spawning because the eggs fall down into spaces between the gravel and are thus protected from predators. If the gravel wasn't clean, then biological activity in the spring could starve the eggs of oxygen.
Superior
Lamprey is an invading species that has declined due to lamprey control efforts (i.e. poison). Historic lamprey wound rates on lake trout was about 40%, meaning that 40% of fish had marks that showed they were attacked by lampreys. That is now down to 5%.
Stocked fish do not have the survival rate that wild fish do. Stocking has been ceased in one huge area of Lake Superior and continues at a slower rate in the two other regions of the lake managed by Minnesota. 80% of lake trout are there due to natural reproduction as opposed to stocking.
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