Nature out of balance
By George Rowe
Published April 19, 2006
We all know in the water the little fish are eaten by bigger fish which are eaten by still bigger fish and so on.
This is nature's way.
We also know that things get out of balance, occasionally, usually because man has messed with nature in some way. The current situation in the Great Lakes illustrates this very well.
The alewife was imported quite by accident, and when they became super-abundant and a smelly nuisance on the beaches, Pacific salmon were then imported to eat them. Fine, the salmon thrived, until they ran up against a shortage of alewives and then they developed a stress-related problem called BKD or bacterial kidney disease. The stress was finally identified as hunger. The fish were not getting enough food to sustain them properly.
The alewife population is now so depressed in Lake Huron that the salmon there are in big trouble - fishing has taken a nosedive and salmon are now so scarce that anglers have turned to lake trout as their target.
Lake Michigan is better off, but there is still a problem. King salmon that should have matured, spawned and died at age 3-4 are still out there in the lake and competing with year classes that have been planted more recently. As a result, there are more salmon in the lake than planned and they are eating themselves into trouble. The fish are smaller, of course, and not maturing on schedule.
There are other, more subtle situations tied to the alewife population. The alewives dine largely on small fish and a tiny shrimp-like organism that is also an important food item for really small perch and walleye. When the alewife population is up, the perch population is impacted adversely, and, in those shallow bays that they frequent, the walleyes may be affected as well.
Now, the various Great Lakes states have agreed to cut back on salmon plantings this year by about 25 percent, trying to balance the forage fish to the predators. We still expect Lake Michigan to produce fair to good Chinook salmon fishing this summer, even though the fish will be smaller and perhaps thinner.
A check with Dave Clapp, manager of the Department of Natural Resources's Great Lakes Fisheries Station in Charlevoix, indicates there is some hope for alewife populations in Lake Michigan. Last fall, a good-looking year class of young alewives was spotted and these fish could save the situation and the salmon.
Other good news, of course, is related to Great Lakes and especially Lake Michigan stocks of perch. With the alewives down, the perch will recover somewhat and we can look forward to improved perch fishing on the big water.
There is already some evidence of a perch recovery. Walleye fishing is also expected to improve with some really robust year-classes resulting from better survival of young walleyes. This will mean some banner years in prime walleye waters such as the Bays de Noc in the Upper Peninsula and in Saginaw Bay, another outstanding walleye fishery.
The Lake Charlevoix situation is another problem area. When I checked with DNR Fisheries biologist Tom Rozich a couple of years ago, inquiring about the apparent problem with the brown trout in the lake, he stated, rather bluntly, that there had to be a decision made at some point on whether Lake Charlevoix was going to be a brown trout fishery or a walleye lake.
Many of us can remember when, at this time of the year, we could troll long-lines on Lake Charlevoix and catch a few football-shaped browns on every outing. One year, during the Trout Tournament, our boat landed 24 browns in two days, putting two of them on the leader board. That fishing is now history, despite the fact that the DNR has continued to plant some browns in the lake and it is now clear that the lake has indeed become a walleye fishery and a good one. The browns apparently could just not find enough to eat but the more flexible walleyes can.
The DNR has also learned some new techniques for planting fish, to avoid predation, with some fish planted in deep water, so the fish can disappear into the depths before being eaten by gulls or cormorants and planting fish at night or even through the ice to avoid predation.
Handling the situations imposed by the various alien species in the Great Lakes will continue to be a substantial challenge for our natural resources people and especially those charged with scientific research at the grass roots level. We will have to learn how to cope with and probably live with the round goby and the zebra mussel and hope that some day we can control the alien species that would invade our pristine waters.
George Rowe may be contacted at 547-4138, or email@example.com.