Multimillion dollar Wisconsin salmon fishery benefits from dynamic management.
Wisconsin-stocked chinook salmon appear to be a hearty lot. That's the implication of a recent study from U.S. Fish and Wildlife and the Wisconsin Department of Natural Resources. Of the salmon stocked by the four states surrounding Lake Michigan, those with a Wisconsin pedigree are more likely to survive the three to five years it takes to attain the size most anglers look for. Wisconsin salmon also make up a substantial percentage of the chinook caught in the lake, regardless of location.
Of course anglers may catch fish that were stocked by any of the four participating states (Illinois, Indiana, Michigan, Wisconsin) during the summer months. Anglers are also catching significant numbers of naturally reproduced fish, especially those that were spawned in Michigan streams.
Natural reproduction has become an important factor in the salmon fishery, with estimates of over 50% of the total chinook population coming via natural means. The impact of natural reproduction on the fishery is, however, also somewhat dependent on environmental conditions such as lake levels and extended severe weather conditions.
The research reveals that of the stocked fish caught by anglers throughout the lake, almost 50% of those are Wisconsin stockings. Of the stocked fish taken from the Wisconsin side of the lake that number jumps to almost 60%. Last year the total number of stocked chinook, from all states, was close to three million. Wisconsin DNR officials indicate that 824,000 of that total came from the Wisconsin hatcheries Wild Rose and Kettle Moraine Springs.
Data concerning the interstate stocking program is collected a number of ways, with the collection and analysis of coded wire tags (CWT) being perhaps the most intriguing. CWT are tiny wire tags - about the size of the number '1' of the year date on a penny - embedded with stocking information. The tags are implanted into the snouts of the salmon when small, and the fish's adipose fins are clipped to identify them as tagged fish. The heads or snouts of tagged fish are collected, the data analyzed and the information used to help define succeeding decisions concerning the stocking program.
DNR fisheries supervisor for southern Lake Michigan, Brad Eggold, indicated that the fisheries program is a cooperative effort involving many people and several agencies, saying;
"We greatly appreciate the opportunity to work with the U.S. Fish and Wildlife team to collect this data, which will inform our management efforts going forward. We also want to thank the many thousands of anglers and other partners who aided this effort by collecting the tens of thousands of fish heads needed for the analysis."
Charles Bronte, senior fisheries biologist with the U.S. Fish and Wildlife Service, pointed out that the management of the stocking program is a fluid and sometimes fickle undertaking, as there is still much to learn about salmon behavior and adaptability in the Great Lakes.
The lakes themselves are also dynamic entities, with continually fluctuating influences such as water levels, changing baitfish population levels, the impact of invasive species, and so on. Collecting and analyzing multiple streams of data in order to enhance and maintain a strong fishery in an ever-changing environmental situation can be a challenge.
"If we're going to find the answers, we need this kind of coordinated research among all the states in the region that stock chinook because the fish don't stay in one place," Bronte said. "What we learn from this work will help guide best practices for producing healthy fish throughout the region, maximize returns and provide further insight into the conditions essential for these fish to thrive."
DNR Secretary Cathy Stepp concluded, "Wisconsin offers a world class recreational fishery and DNR's Lake Michigan stocking efforts continue to play a key role in sustaining this resource and its multimillion dollar economic impact. This study reinforces the importance of our high quality hatchery efforts while supporting the value of ongoing investments in our fisheries operations."