GREAT LAKES weekly FISH NEWS
Week of June 28, 1999

STUDY: WATER-FLOW MANAGEMENT IN MICHIGAN AIDS IN SALMONID RECOVERY

ANN ARBOR, Mich. - For 80 years, water flow in western Michigan's Manistee River fluctuated dramatically each day, ranging from 10-year floods to drought conditions. The variation was caused by hydropower dam operations known as peak-flow management, a practice that permits the periodic release of large amounts of water. Studies have shown that such erratic flows can cause aquatic organisms to alternately become stranded or swept downstream, negatively impacting the fish that rely on them for food.

On the Manistee, a major Lake Michigan tributary, relief came in 1989. Peak-flow management was abandoned in favor of a less disruptive practice known as run-of-river flow management. Water was allowed to flow naturally through the Tippy and Hodenpyl dams as a result of terms specified in new hydropower licenses. Today, a decade later, the change is beginning to pay off. Researchers at the University of Michigan and Michigan State University, funded in part by NOAA's Michigan Sea Grant Program, have found that survival of young chinook salmon in the Manistee has increased dramatically since the late 1980s in response to a stable water flow.

"Natural reproduction is incredible now," said Sea Grant and UM fisheries biologist Ed Rutherford. "It's gone from virtually nothing to approximately 700,000 smolts annually."

Still, the switch to run-of-river flows hasn't solved everything. The researchers found that although steelhead reproduction has also increased, the fish had a lower survival rate than that of young chinook. Rutherford suspects warm water temperatures may be the reason. Using electroshocking sampling techniques, Rutherford and colleagues measured the abundance and diversity of fish in the Manistee over a two-year period. They also used smolt traps to monitor the smolt run and examined the scales and vertebra of adult fish to distinguish wild salmon from those reared in hatcheries. They estimate that the greater numbers of chinook and steelhead wild smolts surviving in the Manistee represent an 8.6 and 6.4 percent increase, respectively, in potential harvest available to recreational anglers, as compared to the harvest during peak-flow regimes in the late 1980s.

The increase in chinook and steelhead is crucial information for the next phase of the project to be completed this year. UM economist Michael Moore, and colleagues MSU agricultural economists Frank Lupi and John Hoehn, will use a state-of-the-art economic model of Michigan recreational fishing to translate the improved ecological changes into the dollars and cents of economic benefits.

They already know that sportfishing is big business. Chinook and steelhead are two of five species that make up the salmonids group. Spending associated with fishing for salmonids in the Great Lakes is estimated to contribute $1 billion per year to the economy, according to a Great Lakes Fisheries Commission Special Economic Report. However, estimating the economic benefit of improvements can be tricky, but incorporating detailed data on costs and benefits can have tangible effects.

In the coming years, the economic approach may be relevant to more than just the Manistee River as numerous dams in the Great Lakes basin come up for relicensing. Over the next two years, the re-searchers will continue their work on the Au Sable and Muskegon rivers in order to create a scientific evaluation framework that is generally applicable to Great Lakes tributaries. From that work may just come a model case study for other regions struggling with the conflicting goals behind sustainable ecosystem management.
 
 

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go to last week's news STATUS OF LAKE MICHIGAN PREY FISH POPULATIONS

GOPHER ANGLERS SET SIX BIG FISH RECORDS

MICHIGAN AGENCIES ASK U.S. FOR DELAY ON METHYLMERCURY ISSUE

On April 1, members of two Michigan agencies sent a letter to Dr. Donna Shalala, secretary of the U.S. Department of Health and Human Services, on the proposed Chronic Minimal Risk Level for oral exposure to methylmercury. They are: Dennis M. Drake, chief, Air Quality Division, Dept. of Environmental Quality, and David Wade, acting administrator, Environmental Epidemiology Division, Department of Community Health. Their letter follows:

"We are writing to you to express our concern about the proposed Chronic Minimal Risk Level for oral exposure to methylmercury which the Agency for Toxic Substances and Disease Registry is apparently going to adopt very shortly.

Our agencies previously sent a letter to the Administrator of the ATSDR regarding the draft Toxicology Profile for Mercury (see attached letter). The primary issue that concerns Michigan is the development of a Chronic Oral MR. The proposed draft Chronic Oral MRL. for methylmercury, at 0.5 micrograms per kilograms per day (ug/kg/day), is four times higher than the previous Acute/Intermediate MRL, and is four times higher than the reference dose for methylmercury developed by the U.S. EPA and included in their final Mercury Study report to Congress submitted December 1997.

seal of the state of Michigan

We continue to be concerned that these differing numbers will cause confusion at the state level when developing policies and procedures related to determining the safe exposure level of methylmercury for the citizens of Michigan. It is essential that federal government agencies involved in establishing mercury health benchmark values speak with one voice on this important issue.

"We are also still concerned that the ATSDR did not use all of the published literature in developing this MRL. Important data on the effects of prenatal exposure to methylmercury and associated effects on child development have been published in the Journal of Neurotoxicology and Teratology (Grandjean et al., 1997). This data should also be reviewed and evaluated when considering a methylmercury health benchmark. We believe ATSDR should delay the release of the Toxicological Profile for Mercury until additional results from ongoing studies and the National Academy of Science review can be incorporated in the mercury MRL assessment.

"Mercury continues to be a high priority pollutant for Michigan. We hope the ATSDR will use the best available data in developing a MRL that is protective of all citizens, including sensitive populations."

LAKE ERIE FISH KILL STIRS CALL FOR NET BAN

SANDUSKY, Ohio -

After an accidental fish kill ( * see accompanying story at right), a number of Ohio sport anglers called for an end to commercial fishing in the state, according to a column written by D'Arcy Egan in The (Cleveland) Plain Dealer.

"The deadly Ohio gill nets were banned 15 years ago," said Toledo fishing guide Jim Fofrich, longtime spokesman for Lake Erie angling groups and an advocate of a netting ban. "Now it's time to do away with the seine and trap nets," Fofrich said. "The days of the freelance fishery must end. Kills like this in spring are not uncommon. It's only common that the (ODW) becomes aware. Since walleye were granted protection in 1970, this problem pops up every spring," Fofrich added.

   

* Fish kill benefits Lake Erie-area needy

SANDUSKY, Ohio - An accidental fish kill at a seining ground east of Port Clinton is providing about 2 tons of walleye to soup kitchens and food banks in the Lake Erie region.

A seine is a large net that hangs vertically in the water and encloses fish when it is pulled together and drawn to shore. At the seining ground, the fish that can legally be caught with the seine are put on a conveyor, and fish that are not legal are returned to the bay.

This procedure was followed, but when the walleye were released, they began to die and wash back up on shore. The kill was attributed to excessive stress on the fish. Division of Wildlife officials iced down the fish and contacted various agencies where they could donate them. Port Clinton Fisheries cleaned the fish.

LAKE MICHIGAN BOATERS TRY TO COPE WITH LOW WATER LEVELS

Boaters and others around Lake Michigan and parts of other Great Lakes are trying to cope with lower water levels this season. Lake Michigan, for example, is 26 inches below where it was a year ago this time, according to Scott Thieme, chief of the hydraulic engineering section of the Army Corps of Engineers, which has kept records on lake fluctuations since 1860. As of mid-April, the lake was 27 inches above its record low.

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SUMMERY OF LAKE TROUT REHABILITATION

Lake trout spawning assessments in the Southern Refuge were conducted on the Sheboygan and East reefs in Wisconsin waters.

The buildup of a large population of spawning-age fish on the Sheboygan Reef is the direct result of stocking efforts. Continuous stocking on an annual basis was first initiated on the reef in 1982. This population was first apparent in fall assessments in 1994. Over the last four annual assessments, the 1982 and 1984 year-classes have been increasing in abundance. Also in 1998, the large abundance of the age 7 and 8 year-classes can be attributed in large part to fish stocked at other Southern Refuge sites.

It appears the development of an increasingly abundant and older spawning population on the Sheboygan Reef is serving as an attractant for fish of spawning age maturity originally stocked throughout the Southern Refuge. The Michigan DNR and USGS conducted assessments on three stocked spawning reefs in the Northern Refuge area of Lake Michigan: Boulder Reef, Gull Island Reef, and Richard's Reef. The Little Traverse Band of Odawa Chippewa Indians and COTFMA biologists conducted nearshore sampling at the six nearshore sites: Fisherman's Island, 9-Mile Point, Menonaqua Bay, Good Hart, Sturgeon Bay, and Il Aux Galet.

Lake Trout

During the spawning season, offshore planted fish are frequently moving to nearshore sites in spawning condition. The northern nearshore sites had the lowest returns and catch rates, while the southern sites produced some of the highest catch rates observed during northern Lake Michigan fall spawning surveys.

The mid-lake refuge area contains healthy spawning populations of adult lake trout with age distributions that are increasing. The Northern Refuge area, on the other hand, is showing mediocre returns at two of the offshore stocked sites and poor returns at a third, Richard's Reef. Many fish planted at offshore sites are moving to nearshore locations. The age distribution is relatively low with few fish returning beyond the ages of 7 and 8.


 
 
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