What about the report from DNR about hatchery walleye populations being mostly female?
Jon of Trego asked about DNR’s discovery that extended growth walleye raised in state hatcheries had a highly skewed sex ratio favoring females. Isn’t stocking mostly females advantageous? Why waste money researching something that isn’t a problem?
There certainly are sport fishing advantages to stocking females. They grow faster so they reach legal size sooner and they have longer life expectancy than males. It’s almost always the females that reach quality or trophy size in any walleye fishery. For a stocking-dependent fishery, females could be the way to go. Historically research was done to find ways to treat milt (fish sperm) specifically to promote production of females.
On the other hand, the Governor’s Walleye Initiative was intended to raise large fingerlings as a tool to restore natural reproduction in lakes that once were self sustaining. General tax dollars not just license fees went into this effort. The appropriate genetic diversity is very important to sustain natural reproduction over time. If there is something about the hatchery operations that screen out the male chromosomes what other genetic material might also be lost?
This sex ratio issue was only noticed the last couple of years and may be related to a host of factors. The reason for science is to find out why something happens. Then that knowledge can be applied to help reach whatever the goals might be.
How long do fish live in the wild?
Maryanne S. asks: I mostly fish walleye and musky. How long do each of these fish live in the wild?
Answer: It is possible for walleyes to live 30 years and muskie might reach 40. Of course those are the exceptional cases like humans that reach 100. Individual genetics and local environment and fishing pressure determine what the maximum age might be on the waters you fish. Female walleyes and musky live longer than the males.
Since wild fish don’t come with a birth certificate, the exact age of fish can be difficult to determine. Biologists have to estimate age by looking at fish bones like scales and ear bones. A layer of bone is added each year of growth like the rings on a tree stump. A fish grows the fastest when it is young which creates wide easy to see rings. Older fish grow slowly so the rings pile together tightly and it becomes harder to distinguish the individual rings even under a microscope. The size of a fish is not a good indicator of its age. A 50 inch musky could be anywhere from 12 to 35 years old. Estimating fish ages in a waterbody is important for management purposes. For instance, you need to know the average length of fish at various ages to determine what size limit would be best.
~ Larry Damman, FISH Board, Retired DNR Fish Manager
Can I stock my own private lake?
Stan S. asks: I live an a small private lake, because there is no public access the DNR says they are unable to stock. I would like to see if I can do that myself.
Answer: A permit is required to stock fish into Wisconsin waters. Getting approval is pretty routine as long as you aren’t introducing something exotic or potentially detrimental. You can get a stocking permit application from your local DNR Fish Manager. Permits are free but you have to buy your fish from a private fish hatchery that is current with its health inspections. You may not transfer wild fish from one water to stock another.
Stan, your fish manager is Craig Roberts at the Spooner DNR office 715-416-0351
~ Larry Damman, FISH Board, Retired DNR Fish Manager
Why do we have hatcheries? Can’t fish reproduce naturally?
Andy T asked: Why are there hatcheries? Don’t fish reproduce naturally?
Answer: Yes Andy, in a perfect world fish reproduce naturally and we wouldn’t need hatcheries. In the world we live in there are many reasons to stock.
The environment may not always support robust reproduction. Pollution, habitat loss, introduction of exotic plants and animals and climate change can hinder or eliminate reproduction. The early life stages of fish like eggs and fry are the most vulnerable. Often planting larger fingerlings allows the species to continue to play its role in the environment which can include sport harvest. Walleye stocking often falls into that category.
Stocking also has a long history of introducing new species into suitable habitat. When the white man came to northern Wisconsin, they found many lakes had no fish at all. After the glaciers receded, fish could only find their way into lakes that had outlet streams. Loggers and early settlers transferred fish from nearby streams to fish-less lakes. Suckers and bullheads were popular in the early days because they could be smoked or canned. Later people put more value on game fish so the state provided milk cans of fry transported by train for settlers to establish fisheries in their local waters.
Today species are often introduced to try to establish better ecological balance in disrupted systems like the great lakes. Invasive species pretty much made it impossible for many native species to survive so new species that could survive and help create a more functional ecosystem and useful fisheries are stocked.
Of course, the whole thing really hinges on whether you are a fisherman or not. If you don’t fish it doesn’t matter what fish are out there or even if there are any fish at all. On the other hand, fishing is a big part of our way of life and our tourism industry. Stocking is one tool that fish managers use to assure that public waters provide useful fisheries for recreation and food. Wisconsin anglers feel it is important enough to pay for it all through license fees and taxes on fishing and boating equipment, not general tax dollars.
People will say you have to stock to replace what anglers harvest. This is not totally true. Each water can only produce so much. If anglers are harvesting fish faster than fingerlings (natural or stocked) can grow up, the problem is overharvest not reproduction.The solution to overharvest is more restrictive regulations, not more stocking.
~ Larry Damman, FISH Board, Retired DNR Fish Manager