This winter the South Dakota Game, Fish and Parks (GFP) held public fisheries meetings in Pierre, Mobridge, and the first ever virtual fisheries meeting. These meetings covered Lake Oahe, Lake Sharpe, Lake Francis Case, and Lewis and Clark Lake. If you weren’t able to make these meetings, the full recordings are available on the GFP YouTube page.
As you’ve listened in on these meetings you’ve probably learned a few new phrases along the way. Wr anyone? There’s plenty of technical terms that have come out at these meetings, but the moral of the story is that fisheries management comes down to three elements: recruitment, growth, and mortality.
Recruitment
Recruitment is the first step of the cycle. This is fish literally entering the system and becoming available for anglers to catch. Recruitment can occur naturally or by stocking, the extent of which depends on the specific fishery.
First let’s talk a bit more about stocking. Every spring, fisheries biologists across the state take to the water to collect female walleyes that are going through their spawning ritual. This process collects eggs and allows fisheries staff to spawn these eggs and raise them in our hatcheries.
It’s easy to ask why fisheries staff collect these eggs instead of letting fish go through their natural spawning process. To start, spawning activities take place on fisheries that have excellent populations of walleye and strong natural recruitment. Beyond that, collecting these eggs and raising them in a hatchery setting results in more fish ultimately making it to catchable sizes for anglers.
The truth is, the wild is a difficult place for a young fish. A good rule of thumb is to think in 10s. Approximately 10% of eggs in the wild will survive, with 10% of those fish making it through their juvenile stages. Hatching these eggs and raising these fish in a hatchery setting increases the survival rates and thus the total number of fish that will make it to sizes for anglers to catch.
These stockings also support fish populations in fisheries where natural reproduction is not as strong. Stocking plays a key role in our fisheries across South Dakota, in 2024 there were a total of 710 stockings that occurred across 206 waters. Walleye in particular saw 150 stockings across 94 lakes. Overall 50,805,550 walleye fry were released with an additional 6 million juveniles stocked as well.
The difference between a fry and a juvenile is the size. Fry are the size of fish immediately after hatching. These fish are very small, where juvenile fish are essentially 1 inch or larger. The larger the fish stocked, the more likely it is to survive. This also takes time, and depending on each individual fishery the number and size of fish stocked relates to the overall elements and goals of the specific fishery.
Growth
Whether it’s through natural recruitment or stocking, the next important element is growth. Generally speaking, the target for strong growth rates is an age-3 walleye reaching about 15 inches in length. This is the traditional “eater class” fish, and when these fish reach maturity and do their part to continue the recruitment cycle.
While length at age-3 is a good indicator of growth within a fishery, another component of growth is the relative weight of fish, or Wr. Simply speaking this is the plumpness of a fish. The lower the value, the skinnier the fish. The higher the value, well those fish can be considered chunky! A Wr value between 80-90 is generally an indicator of a healthy fishery.
This is generally tied to the forage available within a fishery. On the Missouri River reservoirs like Lake Sharpe, Lake Francis Case, and Lewis and Clark Lake gizzard shad play a critical role in walleye growth. On smaller natural lakes, yellow perch and white bass can be excellent food sources. Other small fish species, aquatic insects, and even frogs can all be walleye forage as well.
While it’s good to see fish fat and happy, this can sometimes mean tough fishing for anglers. The more forage in the system, and well fed the fish are, the less they need to eat. Additionally, this means the more options your bait is competing with when enticing a fish to bite. That said, you don’t want skinny starving fish in a system either!
Mortality
A healthy fishery sees fish constantly recruiting to the population and growing to quality sizes in terms of both length and weight. This means there’s fish to be caught, and that factors into the final element, mortality. Fish being caught by anglers is the ultimate goal, and every fish harvested really is a success story in terms of fisheries management.
Mortality is a natural element of every population. When a fish is harvested by an angler, that’s a success. Fish succumbing to natural mortality is a part of life too. Angler harvest plays a role in mortality, and depending on the size of the waterbody and total population can have either major or minor impacts.
Now, while it may seem that a fish being taken out of the system is a negative on the total population that’s not necessarily true. In fact, harvest and mortality is critical to ensure adequate forage remains in the system for other fish working their way through the recruitment and growth stages of the fishery. We all want more fish to catch, but taking some fresh fish home to enjoy a fish fry is an important part of fisheries management too!
Fisheries staff play a critical role in all of these elements. In the spring, they are spawning fish and growing them to stockable sizes in our hatcheries. In the summer, they’re collecting harvest information and other lake sampling efforts. Fall is lake surveys, as they determine growth and population dynamics within a fishery.
There’s plenty of ways to get involved with fisheries management, and tuning in to these meetings and these recordings is a great way to educate yourself on the dynamics of these fisheries. The most important way to get involved is to purchase your license, introduce someone new to the sport, and invite them to a fish fry at the end of the day!
Your license purchase directly supports these management efforts, and recruiting someone new is just as important for us as it is the fish. Get involved in fisheries management this year, it’s as easy as wetting a line with some friends!
Lake Oahe and Lake Sharpe Public Meeting
Lake Francis Case and Lewis and Clark Lake Public Meeting
