True Walleye Resource Management

The wisdom that comes with age can be lost even if one writes it down … as someone not only has to read what he has to say but believe in it … and act upon it to makes this a better world. This is an attempt.

Wisconsin has been my home my whole life. Understanding nature in an ecological sense has been both my passion and driving force in my career. The aquatic world has been the focus of my career … and the focus of this world began with fish and their ecology. In my present community of the Northwoods the walleye is king. And the king is dying… or is it its kingdom?

Nothing living survives without the habitat that allows it to reproduce, provides food, and allows its growth until the time it can reproduce again. This is what resource management of any species, including humans, is all about. The proposed Wisconsin 2021-22 Walleye Management Plan suggests a shotgun pattern that government and all stake holders may never pull the trigger on or even approach to meet the needs of the first sentence in this paragraph.

We have through scientific research, observation, and propagation come to understand the life history and much of the ecology of walleye. We also are now understanding the functioning of aquatic systems and how humans and politics are disrupting them. Yet, we have not focused on truly functioning of aquatic systems … only concentrating on a single species, or fauna (e.g., fish) or only one aspect of an aquatic system. The basic functioning of an aquatic ecosystems must be applied to solve the collapsing of walleye populations that fishery managers and scientist recognizes as a failure of recruitment to an adult population to sustain the species for a plethora of human needs.

So, in my suspected gained lifetime knowledge, experience, and yet to be proved wisdom I suggest the following through the principals of Strong Inference. Strong inference is the process of solving a problem through the process of elimination of tested theories, practices, and tried solutions without forgetting the original problem.

We now are approaching a century of walleye resource management and by now, if we collectively look at what we have done and learned, the Strong Inference principle should be applied. The problem, and the expected solution we seek, is why are walleye populations collapsing … as recognized and analyzed as a recruitment problem … and to correct it.

We must assume natural selection and evolution has created an environment for walleye to thrive and survive … we need to give them a chance. Recruitment is defined as their survival in the first year. This is key to a sustainable population and any management objective now or in the future is also dependent upon this … any government conservation management shotgun pattern needs to be choked down to this focus.

This is my proposal. Through the process of Strong Inference elimination, one might label as “intelligent speculation vs precise knowledge” plan. We must first assume and accept that the walleye is like many other fish (e.g., salmonid) species, in that they imprint and return to spawn where they

originated. This imprinting causes reproducing age walleye to migration to spawn at the site of original conception and birth. The genetic imprinting is tied to the location where the eggs are laid, and the sac fry emerges from.

This site of spawning and imprinting is a place where cold oxygenated water flows into an aquatic system through a hydrogeological source. Each aquatic system will have varying hydrogeological sources, but walleye must connect to these sites to have the genetic “code” for them to return to this site to spawn. This is the key to changing our resource management of the past and future in helping them to succeed. If we review and follow the walleye management history of our hatchery development and stocking practices one will see how we have disrupted these processes. Better yet, to move forward, we can use these same tools and walleye management to correct them. Including using this inference in spawning practices and restocking.

The second hurdle in the recruitment is based on the life histories of walleyes we have learned through the management tools of both research and propagation. Emerging walleye sac fry takes time to fully develop to become mobile and feed. The timing, just like spawning and egg incubation, is tied to the water temperature. Eventually, the egg sac is absorbed, and the sac fry become post larval and begin the actions of seeking food. This is an aggressive action, the right size and abundance of food must be there or the individual dies, or often with lack of suitable food they cannibalize each other, and both perish. To get over this initial hurdle in hatchery husbandry the success is tied to producing the right size and plentiful zooplankton which carry them into the fingerling stage where their diet needs shift to bigger prey. Again, when this happens at two to three inches, if suitable prey food items are not available, they again cannibalize and the loss of both predator and prey can occur.

This is the lesson of walleye life history we have learned from propagation observations, but also applies to what occurs in their natural aquatic systems of lakes, reservoirs, and river systems. So as fish biologist looking for recruitment success in an open aquatic ecosystem, we need management tools and actions to increase the survival through these two critical developmental feeding periods added to recognizing hydro-geological spawning sites and patterns.

We do have one tool in lake management that can go along way in matching zooplankton to the emerging feeding by walleye post larva and 2-3” walleye. It is the Secchi Disc. It is a black and white disc that is lowered over the side of a boat used in lake research and management to describe water quality conditions attached to clarity and nutrient content … or to describe lake health. It is has been historically used for the last twenty years for monthly sampling by lake volunteers and whose observations and data was eventually used to develop satellite imagery to document changes in lake health and even temperature changes… and more. There are hundreds of waterbodies in Wisconsin where this practice has a long history.

But in this case, if Secchi disc observations are done weekly, especially from May to early July, it can identify the natural processes of phytoplankton/ zooplankton successions that are key to walleye post larval fry and fingerling, as well as other fish predator/prey food sources, for survival and growth. Post larval walleye stocking can be timed to match the first zooplankton bloom of a lake or water body which can pre-warn stocking walleye stakeholders (by the prior phytoplankton bloom) recognized with the Secchi disc and/or satellite technology if it exists.

Using the same Secchi disc observation system, the stocking of 2-to-3-inch fingerlings can match the second later phytoplankton/zooplankton lake and aquatic ecosystem pulse. This pulse is also used by later spawning/ hatching/ post sac fry warmer water fish species. Walleye food prey would be available to smaller stocked fingerlings to include the yellow perch post larval fingerlings that emerged from earlier hatches with other early spawning fish species such as suckers.

This simple improved proposal for walleye management in Wisconsin can go along way into getting stakeholders, lake, and waterway communities into addressing other concerns that involve water quality, fish, and other biotic species. The sensible possibilities that can come from this are not limited … and doable on a practical local level. As with any biotic ecosystem, especially now, we need to start immediately with an action such as this that stops the path of progress effecting natural ecosystems as well as individual species as the walleye.