Posted 8/10/2022 3:01 PM (#1010653 - in reply to #1010417) Subject: RE: Hot Water Musky Fishing - Study Results
Location: Twin Cities Metro
The Stonewall Jackson reservoir study has a p value of 0.64. P values below 0.05 indicate a statistically significant result. In other words, the result of that study is that the hypothesis that water temperature affects mortality is NOT supported by the data. This is the study where 28 muskies were caught during the warm water period.
In the James River study, 12 muskies were caught during the warm water period. The p value for this study was a much more significant 0.03. One way to summarize this result is “high water temperature appears to have some effect on muskie mortality due to angling in the James River.” And yet, the sample size in this study is less than half that of the Stonewall Jackson Reservoir study.
The data don’t support a broad conclusion on the effect of water temperature on muskellunge mortality (i.e. if you combine the data, the statistical significance vanishes). However, the disparity in the data suggests that mortality could be linked to the availability of a cool water refuge in a water body. In other words, in shallow environments with relatively uniform water temperatures in excess of 78F, muskellunge have an elevated risk of post-angling mortality. But in deeper impoundments that have sections that stratify, there appears to be little risk of post-angling mortality in muskellunge even when surface temperatures exceed 78F.
Posted 10/19/2022 12:29 PM (#1013920 - in reply to #1010417) Subject: Re: Hot Water Musky Fishing - Study Results
Location: Twin Cities Metro
Let's say I caught 23 muskies in the cool water period and 1 died. Then I went fishing in the warm water period and caught 8 fish, and 0 died. Does angling in warm water kill muskies?
Here's the thing. I just ran a quick simulation to generate the above scenario by rolling dice for each fish. For the cool water period, I said there was a 5% chance of each fishing dying, and for the warm water period, I said that the chance of each fishing dying was 15%. That should be a noticeable difference, right? Not for this sample.
Let's try again. Same number of fish. Cool water: 23 caught, 2 dead. Warm water: 8 caught, 4 dead. Seriously, I just ran this using dice. Now is there an effect? Oh yeah! Fishing in warm water is CLEARLY death to all things esox masquinongy. But it's the SAME MORTALITY CHANCE as before.
Okay, let's put them all together (ie. let's aggregate the data). Cool water: 46 caught, 3 dead (3/46=6.5%). Warm water: 16 caught, 4 dead (4/16=25%)). Even when aggregating the samples, the mortality rate is significantly higher than the actual mortality chance (the cool water rate is actually off by 30%, and the warm water rate is off by 67%!). Beware inferring too much from small sample sizes.