After a very dry winter and early spring, it appeared we would be in for a very dangerous fire season. Recent rainfall has reduced the fire hazards, but we will continue to remind everyone to be careful of your use of fire … save our watershed.

As promised in our last newsletter, we will try to provide more details on the major “happenings” going on, realizing that, for some of you, this may be your only source of ”... the rest of the story”.

Without question, the most frequent recent questions have been directed at the Custer Weir; it’s even overshadowed the work going on with our Big South project.

Custer Weir

Up until the opening in 1935 of the Welland Canal, Niagara Falls had served as a very effective barrier to keeping ocean-going organisms from entering the Great Lakes (I know, four out of five … Lake Ontario has always been downstream of Niagara). And until that time, the (upper) Great Lakes were known worldwide for their outstanding whitefish and Lake Trout fishery. However, although man’s efforts to improve this world by allowing ships to passage the falls via the ship canal were well intended, probably never thinking that the sea lamprey was also likely to be able to bypass the falls. Undoubtedly delighted to find the magnificent food supply, the lamprey found the Lake Trout to be its easiest prey, then the whitefish. In less than twenty years, both the Lake Trout and whitefish populations had been decimated. Numerous agencies and organizations began to study means of controlling the predator, and many alternatives were proposed and tested. Some unsuccessful ideas included a wire screen which had to be manned twenty-fours a day to keep it clean, and an A.C. electric fence with drop lines which resulted in heavy fish mortality, and serious danger to people, but finally constraint was focussed on four methods:

• Electrical barriers (using wing pulsed D.C.) – lamprey are more sensitive due to length-to-girth ratio;
• Mechanical barriers – low-head dams and fish ladders work as lamprey cannot climb more than twelve inches;
• Sterile males – expensive but effective as “neutered” males do not produce offspring;
• Selective poison TFM, while more toxic to lamprey, is expensive, requires treatment every four years, can harm other organisms, and is not ecologically correct in a time when we strive to keep all foreign chemicals from our environment. The P.M. has received TFM treatment ten times from 1964 to 1999; the cost has risen from $2.98/lb. to $30/lb. and the last treatment cost $500,000.

March 2000

Sixty-five years after the first arrival of the sea lamprey, we are today beginning to see the first attempts to a perennial inexpensive method of controlling this predator. The D.C. grid was first activated on March 21st, however not all the steelhead that would climb the ladder would find the PVC pipe which would return them to the river … for some reason, many would turn around and go back down the ladder. After operating only ten days, it was decided to shut down the electrical field from 10:00 AM to 4:00 PM daily; this would allow further modifications to the system, allow new larger footings for the large pump to cure, and was felt to be a safe time to work since 75% of steelhead migrate during daylight, and nearly all lamprey migrate at night during the early part of the run. The DNR’s statewide expert on fish passage ways also recommended nine other adjustments to fine-tune the apparatus, and most of these were accomplished during the daytime shutdowns. The system was reactivated April 8th. The one remaining construction item, the installation of the viewing window and camera, will be in place by June.

The evaluation study by MSU to quantify fish passage has been passed from Doug Workman (who did most of the baseline data) to grad student Aaron Snell. He began netting and tagging fish just above P.M. Lake, near the Dow Chemical factory. Fifty-seven steelhead and fifty-eight longnose suckers were trapped and implanted with radio transmitters, allowing Aaron to precisely locate those fish and know which fish is which. Of the fifty-seven steelhead, twenty-one were males, thirty-six females and twenty fin-clipped from hatcheries. Thirty-nine were identified by the radio receiver at Custer. You might wonder why the suckers? … MSU has considerable prior data on them, they are native to our river, and they too are anadromous. Aaron reports that most fish that approach the electric grid will attack it trying to get through, then drop back, then attempt to find a way around it. The flow velocity from the pumps is the real attraction; the larger pump is rated at 25 cubic feet per second; the smaller at 16. A tagged fish, even after the significant implant procedure, can travel from P.M. Lake to Custer in one day, and from Custer to Bowman Bridge in one day. As an aside, Aaron reports trapping rock bass, a few smallmouth bass, numerous bowfins (dogfish), and several Northern Pike, in the 38-39” range! Not all the tagged fish proceed up or stay in the P.M., as Aaron says one was caught in the Sable River below Hamlin Dam, and one was captured in the fish weir on the Little Manistee after climbing the ladder at that site.

So it appears we have a successful working electrical barrier for our river. U.S. Fish & Wildlife will run a lamprey census after two years to determine whether or not a final TFM treatment might be necessary in 2003. The weir will continue to run through July 15, and may be turned on and tested for fine-tuning during the fall salmon run. Aaron will continue to follow the fish and we will report his findings as we receive them. We hope we have finally found the solution to keeping the sea lamprey from spawning in the Pere Marquette.

Don’t forget to mark your calendars for our Annual Banquet and Cast for Conservation™ Fish Tournament, July 15th this year. We’ll have Bob Garner of the Natural Resources Commission as Guest Speaker, and will give you the latest news on the Big South Project, and, of course, on the Custer Weir.