I will be the first to admit that I am not a huge fan of stocked fish. As I have heard it put best, if stocking were the answer, don't you think we would have solved the problem by now? Stocking does not solve many problems and I would argue it creates plenty of problems of its own, but there is also a place for stocked fish.
I think there is little question that Wisconsin's inland trout fishing has improved greatly as the state put less effort and money into stocking and more of that effort and money went into habitat improvement. Wisconsin has largely - but not entirely - gone to the "Montana model" where they do not stock trout over wild trout. Stocking is costly and is a long-term problem because you are rarely solving problems with stocking (though, there are some exceptions that we will talk about). Once you start stocking fish, the expectations seem to be that it will continue more or less forever. That is part of why Montana, way back in 1974, really shook things up and I am sure there were no shortage of upset anglers that were quite vocal in their opposition to the plan. After all, stocking has to mean more fish, right? Stocking is popular, in no small part, I think, because the public feels like "something is being done to help us!". Never mind that "something" might really be nothing or next to nothing or stocking may actually be hindering the goals of the project. People like to see "something" done!
I will mostly focus on inland streams but I think the Great Lakes stocking is a little more interesting so I will certainly venture there a bit too. And the Wisconsin Walleye Initiative, essentially a stocking program, has been in the news a fair bit recently and is worth exploring here.
Below is from the Wisconsin Department of Natural Resources page on fish stocking:
Why are fish stocked into some lakes and streams? Stocking is used as part of an integrated management approach:
Rehabilitation: To restore self-sustaining fish populations.
Research or Evaluation: To determine the cost-effectiveness of stocking, evaluate alternate propagation techniques, or other management actions.
Remediation: To maintain an existing fishery that has been reduced due to external impacts, such as habitat losses or winter kills.
Recreation: To create or maintain a recreational fishery that did not previously exist and is not self-sustaining.
Introductions: To introduce a species into a waterbody where not previously present, ideally resulting in the establishment of a self-sustaining fishery with minimal impacts on existing fisheries.
Quite obviously, there is some overlap between some of these reasons to stock fish. Most stocking is probably done with recreation as a primary reason. Historically, there are a number of examples of successful introductions. At times, we look back at these and wish they had not been so successful and other times, we enjoy that Brown Trout, Walleye, Muskellunge, and a good number of Great Lakes fishes provide a valuable resource for us outside of their native ranges.
There is no question that stocking has expanded opportunities for anglers. You might be surprised to learn that the Potomac River and Susquehana River - both known for the great Smallmouth Bass fisheries - are introduced fisheries (USGS NAS fact sheet). Smallmouth Bass are not native east of the Appalachians. A species like the Muskellunge is now found in many more states and have wider ranges in their native states than ever before (USGS NAS fact sheet). Same with Walleye which have a larger native range than Muskellunge but have also been introduced over much of the country where they are not native (USGS NAS fact sheet). And for us trout anglers, Brown Trout provide much of our trout fishing in the United States (USGS NAS fact sheet) and they are of course not even native to the continent. (Are they invasive?).
There is, of course, a bit of hypocrisy in lauding the spread of fishes outside of their range that have resulted in wild populations and then decry stocking now but we know more know about the issues with stocking fish.
Great Lakes Example
How to put this nicely, the Great Lakes are an odd mix of native and non-indigenous species and the management of fisheries in the lakes is rather schizophrenic. They are a biological mess - a near random assemblage of native and non-native species. The fishery probably most associated with the lakes are the Pacific salmon (Coho and Chinook) and steelhead (rainbow trout) which are only there because we put them there to control the non-native Alewives (Alosa pseudoharengus). Alewives reached the Great Lakes after the opening of the Welland Canal and from Lake Ontario, they spread throughout the lakes. From Miller (1957):
A chronological record of the appearance of alewives in the upper Great Lakes shows the first specimen reported from Lake Erie was taken in 1931, Lake Huron 1933, Lake Michigan 1949, and Lake Superior 1954.
Salmon were established into lakes in the late 1960's with the goal of reducing the Alewives that were comprising around 95% of the biomass in Lake Michigan. The idea that Pacific salmon could be brought in to control Alewives (note, Alewives are not a species of the Pacific but of the Atlantic Ocean) was - as Howard Tanner the man most responsible for the salmon introduction - a S.W.A.G., which stands for “scientific wild-ass guess” (source). Tanner's S.W.A.G. hit the mark and Great Lakes beaches no longer had millions of dead Alewives washing ashore. No longer were front end loaders needed to clear beaches of dead alewives which meant that the beaches were usable again. Of course today those dead fishes have been replaced by Zebra and Quagga mussel shells. In-between these events, a multi-billion dollar fishing industry developed around the non-indigenous salmon.
Today, the lakes are still filled with a host of non-indigenous species that have greatly altered the lake's food webs. Zebra and Quagga mussels have altered the clarity and the bottom of the food web. Round Goby (Neogobius melanostomus), another unintentional introduction to the lakes, is a native of the Black and Caspian seas are a predator of Zebra and Quagga mussels both in their native and now Great Lakes ranges. This means that nutrients held by the non-indigenous mussels are moved back into the food web by gobies. The gobies are now a favorite food of some of the benthic fishes like the native Smallmouth Bass, Walleye, and Lake Trout and the non-indigenous Brown Trout. A former World record Brown Trout is evidence that the smallmouth record is in jeopardy.
And the Pacific salmon that have been stocked into the lakes are still stocked but today, most of the Chinook Salmon in Lake Michigan - the fish anglers and charter captains most prize - are born in Michigan streams, not hatcheries. But holy Hell do anglers and charter captains scream bloody murder if you propose to stop stocking "their fish".
The Great Lakes are in a state of flux but then again, that is nothing new for the Great Lakes. Lake Huron's Chinook Salmon fishery's collapse is more than a decade old (source) and there is not much hope of a recovery (source). Maybe Coho and Atlantic Salmon are the new hope for Lake Huron (source). Native Lake Trout, whose populations had crashed due to invasive Sea Lamprey and the fact that eating the abundant Alewives lead to a decrease in reproductive success linked to thiamine deficiency in their eggs (source). Today, the Lake Trout are thriving - much to the chagrin of charter boat anglers that much prefer catching and eating the non-native salmon to the native "greasers" (Lake Trout).
The irony of the whole situation is that the goal of Pacific salmon stocking has been achieved - the control of Alewives. Now get this, because Alewive populations have crashed, some peoples' answer is to, wait for it...stock Alewives! You can't make this stuff up. The Pacific salmon are pelagic (water column) feeders but with the other non-indigenous species (zooplankton, mussels, and gobies) in the lakes, the food web has shifted to benthic-dominated (bottom) system due to non-native mussels tying up so many of the nutrients in the lake (source). Round Gobies, another non-native fish, has moved the nutrients sunk in mussels back into the lakes' food webs. Fishes that are able to take advantage of the abundant Round Gobies have increased in numbers - and sizes - and the pelagic salmon have seen better days.
I know I did not paint the rosiest of pictures but the Great Lakes are a mess. A hodgepodge of native and non-natives species - some of which got to the lakes by accident, others because we put them there, in some cases to control accidental non-indigenous introductions. It illustrates both the place for stocked fish and the problems with stocking fish. Alewives are no longer washing up on Great Lakes beaches and needing to be removed by front-end loaders as they once were (source). But the "need" to stock fish remains because once you start stocking, it is really difficult to convince anglers that it is no longer needed (even though most Lake Michigan Chinook are born in Michigan streams). If I were a betting man, I would bet that Lake Michigan does what Lake Huron did - which is to see the salmon fishery collapse.
Wisconsin Walleye Initiative
Wisconsin politicians response to walleye declines is pretty much textbook politics. Let's do something that probably is not going to really do much...but the people are going to love it! Maybe I will be wrong and the increased numbers of "advanced" Walleye fingerlings will be the savior that Walleye needed but rarely is the answer to a region-wide phenomena going to be localized stocking. It seems like a tiny little band-aid trying to cover a gaping wound. That wound is that Walleye are declining over much of their range. The causes are complex but begin with climate change and the changes to our environment are exacerbated by the fact that too many Walleye are harvested. I had written in the mortality post about this issue for a more detailed treatment of the issue.
The WDNR's Walleye plan is being updated but it will be more holistic than the Walleye Initiative. Stocking may be part of the puzzle but until the factors that have lead to the Walleye decline are addressed - climate change, changing lake clarity, overharvest, and others - stocking is what we have to fall back on. And it may work. The issue seems to be with the survival of first year Walleye and stocking larger fingerlings may move them past that hurdle. Of course, it is not much of a long-term solution unless you call putting $1.3 million dollars a year into hatching Walleyes a long-term solution. To be sure, we are good at raising more fish. The science behind it is pretty simple and money is generally the biggest limiting factor. In 2013, Wisconsin was raising about 450,000 large fingerlings and by last year (2020), that number was over 800,000 fish. Will it work to make Walleye fishing better? That is the grand experiment we are witnessing.
One important thing to understand is that Walleye fisheries that rely upon natural reproduction are almost always better fisheries. Biomass, production, and production/biomass ratios were higher in natural recruitment lakes than supplemented lakes which were better than lakes that were only stocked in Wisconsin (Rypel et al. 2018). The story is much the same in Minnesota where a number of lakes have seen changes to regulations prevent overharvest and, like in Wisconsin, clearer water and climate change are partially to blame - along with overharvest. The problem is that the simplest answer is to reduce harvest to where harvest can be sustainable, and that is not a popular solution (source). The story is the same here in Wisconsin. In both states, reducing harvest any further is not an option that the tourist industry is behind.
What I think is interesting is that the place for stocking might be taking some of the pressure off of naturally reproducing populations. If anglers have more options, they may be less likely to flock to and overfish the natural reproducing populations.
Genetic Issues Associated with Stocking
The Walleye discussion leads me to think about the potential genetic issues associated with widespread stocking. Why hatcheries work so well is that survival is off the charts. In nature, a tiny fraction of fertilized eggs ever become adults; in hatcheries, most survive to be stocked. While it is certainly a feature, it is also means that not just the strong survive. In naturally reproducing populations, natural selection has shaped the genetic makeup of the population over time to fit a particular environment. Those adaptations can get drowned out by hatchery fishes and worse, replaced by non-indigenous strains. More on this for another day.
A Place for Stocked Trout
To move this back to inland trout as most of the posts on this page focus on trout; let's talk about a place for stocking trout in inland waters. The urban and community fishing program in Wisconsin is one of the better things we do to get young people interested in outdoor activities. We can not all live in places with abundant outdoor opportunities so stocking trout and other fishes in urban areas provides an opportunity for a great number of people.
A number of streams now have wild, self-sustaining trout populations due to stocking, particularly the wild (feral) trout stocking program created by Wisconsin DNR. Raising trout of wild parentage in a mostly human free setting gives them a much better chance of surviving in the wild and producing a wild, self-sustaining population. It might be a great way to restore some of the streams in northern Wisconsin that seemed to have lost Brook Trout after the late-1980's drought.
Image source: Wisconsin DNR Stocking Data
There are significant biological, economic, and social issues associated with stocking fish. It is expensive and the return on that investment is not always there. However, stocking is not inherently bad. It is effective in providing a resource where opportunity does not otherwise exist (urban fisheries, 2-story lakes/ponds) and it has provided us with a number of wild, naturalized, and self-sustaining populations - such as Brown Trout in Wisconsin. We know more about the genetic issues associated with stocking native fishes now and can better deal with those potential issues. Stocking is not without its issues but it has its place today as it has for decades. I like to think we have learned from some of the past issues associated with stocking and can avoid them in the future.
More next week as this is running a little long...