One of the most common concerns anglers express is waterbodies being “fished out”, which would be all or a significant amount of the fish in a population being caught by anglers or otherwise experiencing mortality. In this article, we’ll fish out the facts on how harvest is studied on game fish populations.
To begin, there are three main components of fisheries management: recruitment, growth, and mortality. Recruitment is new fish entering the population, growth is how they move throughout the size classes, and mortality is when a fish exits the population.
There are multiple ways biologists monitor fisheries including gill net surveys, electrofishing, creel surveys, and tagging studies. While gill net surveys and electrofishing provide indicators for all three aspects, particularly recruitment and growth, creel surveys and jaw tagging studies provide valuable information on mortality.
Creel surveys provide information on angling pressure, catch rates, and the fish being harvested by anglers. These surveys are conducted at boat ramps throughout the primary fishing season, and also provide a way to gauge angler opinions on social topics. Learn more about these studies, and the information they provide, in Fishing Out Facts – Angling Pressure, Catch Rates, and Harvest.
Jaw Tagging Studies
Jaw tagging studies provide fisheries biologists a way to determine the percent of fish in a population that are being harvested by anglers. The fancy definition for this is “exploitation.” Percent exploitation is determined by placing metal tags in the jaws of a certain species, and then seeing how many of these tagged fish are reported by anglers.
In the spring, specifically the beginning of the primary fishing season, fisheries biologists will capture a certain number of fish, place metal jaw tags with a unique identifying number in them, and release them back into the reservoir. Number and location can vary by reservoir.
For example, in 2026 a jaw tagging study is set to take place on Lake Francis Case. In this study, 1,500 walleyes will be tagged in total. Because of the size of the fishery, the reservoir will be split into three separate zones, and 500 tags will be placed in each. Of these 500 tags, 100 will be worth $100.
The $100 incentive, which is marked “REWARD” directly on the tag, provides biologists a glimpse into how many tags may not be reported. Because anglers will likely make an effort to both report this tag and claim their prize, it can be gauged how many anglers may catch a tagged fish and not report their tag.
For this study to be successful, anglers must report when they catch fish with these tags and the tag number. This process is simple, and can be completed at tags.sd.gov. If an angler catches a tagged fish, treat it as they would any other fish, and report the applicable information on the form. This information will then automatically be shared with fisheries biologists.
After one year, the total number of tags returned will be used to determine the percent of the population that experiences exploitation. Overall, healthy fisheries can maintain 20-35% harvest exploitation without negative impacts. Should exploitation be elevated, particularly for multiple years in a row, this is when management activities such as reducing daily limits or placing a minimum length limit could be enacted.
The Missouri River reservoirs are some of South Dakota’s most popular fisheries, so let’s take a deep dive into the information from these jaw tagging studies.
Lake Oahe Walleye Exploitation
Lake Oahe is the largest and most popular fishery in South Dakota, and notably also has a “boom and bust” walleye fishery. Two major flooding events, 1997 and 2011, have played a significant role in the dynamics of the fishery and coincidently jaw tagging studies took place in the years following these events.
Beginning in 1999 and through the early 2000s, walleye exploitation was 17-22%. This is below, or at the very minimum threshold, of acceptable harvest exploitation rates for the fishery.
Lake Oahe Walleye Exploitation: 1999-2003
- 1999-2000: 17%
- 2001-2003: 22%
A decade later, another jaw tagging study took place following the major flooding event in 2011. At this time, there was significantly reduced forage available in the reservoir, and angling catch rates and exploitation rates reflected this.
Contrary to the 1999-2003 study, which studied the entire reservoir, the 2013-2016 study split the reservoir into the two management zones – Upper and Lower Lake Oahe. This division takes place at the Hwy 212 bridge in Gettysburg.
As can be expected, the upper end of the fishery was less impacted by the flooding event than the lower end. Similarly to the previous study, Upper Oahe saw 15-27% exploitation rates, just below or on the lower threshold of acceptable exploitation.
Upper Oahe Walleye Exploitation: 2013-2016
- 2013: 24%
- 2014: 18%
- 2015: 27%
- 2016: 15%
The lower end of the reservoir was significantly more impacted by the flooding event, and this was reflected by the exploitation rates. Lower Oahe saw 19-39% exploitation rates. Two of these years, 2013 and 2015, saw exploitation rates on the upper end or above the threshold for acceptable exploitation.
Lower Oahe Walleye Exploitation: 2013-2016
- 2013: 32%
- 2014: 19%
- 2015: 39%
- 2016: 27%
This is an excellent example of how harvest exploitation rates can increase when a fish population is in trouble. While this was due to the natural occurrence of the flood event in 2011, and less a “fished out” or overfishing situation, it shows the types of information these exploitation studies can showcase. Fortunately, things are looking much better on Lake Oahe now.
The most recent walleye exploitation study on Lake Oahe took place in a non-flooding year, specifically when forage was abundant, growth rates were spectacular, and walleye abundance was increasing. These harvest exploitation rates, while current as of January 2026, show a fraction of the exploitation seen in previous studies.
Lake Oahe Walleye Exploitation: 2025*
- Upper Oahe: 9.4%
- Lower Oahe: 6.6%
*Numbers current as of January 2026 Lake Oahe Public Fisheries Meeting
Lake Oahe is one of the most popular fisheries in the state, and these tagging studies indicate there are plenty more walleyes for anglers to harvest within the fishery.
Lake Sharpe Walleye Exploitation
Lake Sharpe provides a much different fishery, referred to as a walleye factory, the reservoir offers an abundance of 15-20 inch fish to be caught by anglers. This action fishery is known for producing limits, which means that walleye harvest is a critical component of the fishery.
A jaw tagging study from 2017-2022, although without data for the 2020 covid year, indicates the fishery has been successful maintaining this level of harvest as the exploitation rate is between 8-25%.
Lake Sharpe Walleye Exploitation: 2017-2022
- 2017: 15%
- 2018: 8%
- 2019: 15%
- 2020: No Data/Covid Year
- 2021: 25%
Both Lake Oahe and Lake Sharpe are incredibly popular fisheries, see a great deal of anglers on the water, and fish at the cleaning station. Despite this, walleye exploitation rates are well within acceptable for the fisheries. There’s plenty more walleyes to be caught, and anglers should get out and enjoy!
Learn More: Hot Bite Sees More Anglers Fishing Lake Oahe
Lake Sharpe Smallmouth Bass Exploitation
While walleye on Lake Sharpe are well within acceptable harvest rates, smallmouth bass offer a slightly different story. While exploitation in 2023 was within range, the 2024 exploitation rate was significantly higher, and overall these exploitation rates are higher than anticipated for smallmouth bass within the fishery.
Lake Sharpe Smallmouth Bass Exploitation: 2023-2024
- 2023: 19.9%
- 2024: 37%
Overall smallmouth bass exploitation is 20-37%, which indicates this population may be a candidate for a 15 inch minimum length limit. The combination of this jaw tagging study, population modeling, and angler opinion surveys point toward a possible regulation change that could improve the overall size structure of the population.
This is an excellent example of how these surveys can prompt discussions for regulations changes, and the importance of anglers reporting the tagged fish they catch. This is also a very good example of the type of information that goes into a potential regulation change, which is still an ongoing process. Complete information regarding this can be found in Lake Sharpe Smallmouth Bass Harvest Study Results.
Do Your Part, Report Tagged Fish
Walleye tagging studies will take place on both Lake Sharpe and Lake Francis Case in the spring of 2026. This means that anglers should report any tagged fish they catch, which can be easily done at tags.sd.gov. It’s an important way to get involved in fisheries management, and provide accurate data for fisheries biologists.
While the term “fished out” is thrown around on social media and the local bait shop, the fact of the matter is anglers play only a small role in the mortality of fish. Mortality is inevitable in all populations, and anglers should feel confident that enjoying a fish fry after a fun day on the water is one of the more rewarding components of fisheries management.
If you enjoyed this article, or would like to learn more about our fisheries, check out the South Dakota Fisheries Focus page. This highlights all current fisheries status reports and forecasts, recruitment, growth, and other components of fisheries management in the state!
