This past winter, there’s been a lot of information shared regarding our Missouri River fisheries. This has included status reports on Lake Oahe, Lake Sharpe, Lake Francis Case, and Lewis and Clark Lake as well as other more detailed articles on recruitment, growth, and mortality within these fisheries.
One article in particular, Angler Harvest Thoroughly Evaluated on Lake Francis Case, drew many questions and comments on the Lip Ripper Fishing Facebook page and text inbox. These questions and comments, some more professionally written than others, focused predominantly on how these numbers are calculated. There are many ways to evaluate a fishery, specifically in terms of angler usage, and today we’re going to fish out the facts regarding this data.
Lake Surveys and Sampling
The first way to sample a fishery, specifically in regards to the fish populations within it, is through gill net surveys. These gill net surveys are conducted in September, which is after the primary angling and harvest season, and provide information on walleye numbers, sizes, growth, and condition.
It is important to point out the timing of these surveys, because the bulk of the fishing pressure and harvest occurs between April-July. While there will be fishing, and harvest, throughout the rest of September, October, and potentially into November and through the winter months the story of the season will be pretty well written by the time the calendar flips to September.
One last note in terms of timing, anglers will make comments about the July and August months on Lake Sharpe and Lake Francis Case, when the 15 inch minimum on walleye is removed. Similarly to the primary fishing season, this period would have passed by the time lake surveys are conducted in September.
Every walleye sampled within these surveys is measured, weighed, and aged. This is used to develop length frequency graphs, which show exactly the number and size of fish within the system. This can be compared to the 15 inch minimum bench mark, and used to determine the number of legally harvestable sized fish within the system.
The three most important factors in fisheries management are recruitment, growth, and mortality. These lake surveys indicate the number of fish that are recruiting to the system, how they are growing through the size classes, and when they are experiencing mortality. Now, let’s dive specifically into mortality and angling pressure.
Creel Surveys
While lake surveys focus specifically on the fish within the system, creel surveys are geared towards anglers using the fishery. Creel surveys are conducted by creel clerks, which are South Dakota Game, Fish and Parks fisheries staff, that ask a series of questions to anglers as they get off the water.
The timing of these creel surveys is not random, in fact, creel clerks work incredibly specific schedules to ensure the times and locations they are surveying provide an accurate sample of the fishing pressure. These are defined by creel routes, which feature both morning and evening shifts, and are conducted in various orders to provide the most randomized and accurate sample.
When a creel clerk arrives at a boat ramp, they first start by counting the number of boat trailers that are currently in the parking ramp and the number of shore anglers in the area. Through the time period at that boat ramp, they will then mark the number of boats that get off the water, the number of boats that launch, and the time all of them do.
When a boat is getting off the water, creel clerks will then conduct an interview with these anglers. The interview questions will focus on the time they got on the water, time they got off, how much time they spent not fishing (such as running to their spots), the number of fish they released, and the number of fish they kept.
“How do you figure out how many walleyes are released lol?“
These interviews are exactly how to figure out how many walleyes are released. Assuming the anglers are being honest, which when you complete a creel survey please do, this will tell the total amount of fish caught. Whether these are fish that were too short to legally harvest, they had already filled their limit, or simply just didn’t want to clean them, this all is valuable data for angler catches rates.
“I released 1,263 14 and ¾-in fish myself”
This is exactly the type of information to share in these creel surveys. Anglers report the number of fish they released and are not included in their daily limit they harvested. Thanks for providing that feedback and be sure to share those specifics for your day on the water in your next creel survey.
“There is no way possible to come up with those numbers”
Thanks for that lead in, let’s dive a bit deeper into the way possible to come up with these numbers. After the total time on the water, along with time spent actively fishing, and those released fish are reported, it’s then time to count and measure the fish that the boat has harvested.
“We’re they releasing them into bacon grease?”
These are the fish that are released into the bacon grease, or canola oil, whatever your personal preference may be. Check out Fast and Easy Fresh Fried Walleye Tips to learn more about preparing your catch.
Each walleye or sauger harvested will be identified by species and measured in millimeters, which is significantly more precise than inches. This provides both the exact number and size of fish that are harvested. This data can then be compared to the lake survey reports, providing even more in-depth information on the fish sizes within the system.
Once the fish are counted, species are determined, and exact size is recorded there is one final component of the interview and this is social questions. These questions are often a yes or no type question, and used to determine specific information. Recent examples of these questions would be “did you use live imaging” and “is this a guided fishing trip.”
The final questions in the interview would be the demographic for where these anglers are from. This includes the zip code of the angler, and approximately how many miles they drove to fish that day. This provides a glimpse into where these anglers are coming from, their residency, and how far they were willing to travel to enjoy the fishery.
Creel surveys are conducted April-July, and occur throughout the entire fishery. This results in literally hundreds of surveys that are combined and calculated into a full report. The information from the interviews combine with the information from the total trailers at the ramp, breakdown of angler compared to recreational boats (if the boat coming in was not fishing it is marked as a recreational boat, which is used for this information), how many hours the anglers spent fishing, the reported number of fish released, and harvested fish lengths.
It’s a lot of data, and even more time spent at the boat ramp, but it’s important to understand angling usage of popular fisheries. Creel surveys are an important management tool, and when anglers have the opportunity to visit with a creel clerk at the ramp this is a special opportunity for them to engage in fisheries management.
We’re fortunate to have some incredible fisheries here in South Dakota, and fishing on the Missouri River is truly a special opportunity. While the passion regarding these fisheries is appreciated, let’s please keep it civil and kind on social media. At the end of the day, we all just want to get out on the water and have some fun, and we’re pretty dang lucky we get to do that.
If you’re looking to learn more, check out the South Dakota Fisheries Focus page. This has all of the fisheries forecasts and status reports, as well as highlights on all components of these fisheries. If you have questions, please don’t hesitate to ask them, but please ask them kindly. The idea of “mail bag” type articles is fun, but let’s keep the comments and questions constructive towards what we all like to do!
Lastly, thank you to everyone that has shared kind words and support. These fisheries highlights have been very well received, and the data shared is very important for anglers to understand. Hopefully these have done a good job articulating that and they’ve been both beneficial and informative. Thank you again for those that have expressed support, you’re the reason behind all of these articles and videos. Thank you, and good fishing this season!
