Just wanted to follow up as I spoke to Tom Jones, Tom Heinrich (Mille Lacs Area Fisheries Supervisor), and Phil Talmage (Lake of the Woods Area Fisheries Supervisor). A few key points summarized from the studies, and I’ll link the summaries of the studies they directed me to (if you want the hard data and full write up, you should be able to contact each fisheries department for a copy).
First of all, the 12% Circle Hook and 27% J-Hook estimates were an independent study unrelated to Hooking Mortality or the management of Mille Lacs. This study hasn’t been published yet, but should be soon and was designed to look at hook type only without any solid correlation or connection to management practices. Basically a case of poor journalism by the ML Messenger that portrayed the study incorrectly.
The 5% number is based off of their seasonal Hooking Mortality Rates with their Creel survey factored in, which was the first link Bruesewitz and Reeves study. For example next to no hooking mortality early in the season when water temps are low, and pressure is high, but up to 16% Mortality during the water temperature peak (See Pic in next post) and fishing pressure varies seasonally as well.
There are two studies, one from P4 (Hoxmeier and Meerbeek) and one from Rainy Lake (Talmage and Staples), that show basically no hooking mortality from fish caught under 30 FOW, once you get beyond that the number goes up drastically. Also, the Talmage study was done in 60-70 degree water temps, so the correlation to water temp seemingly is more dependent on depth of capture rather than water temp.
IMO there are a few significant issues with these studies and the application of them for management. First of all they are done by catching fish and then putting them in holding nets for 3-5 days, and there is no way to get a true baseline of mortality from that process, i.e. they can’t put fish in a holding cage for 3-5 days without catching them first. So since there is little mortality from this method in the spring when water temps are low, they assume there’s a statistically insignificant amount of mortality from fish being held for 3-5 days when the temps are high. That may be true, but it may not be as well, unless there’s a new way of measuring the baseline, we will never know that important variable. The other significant issue is the Creel factor, which again is an inexact science that is used as a primary factor in ML Management. The HM ratios are factored against fishing pressure which is determined by the Creel surveys. Creel surveys don’t accurately factor in target species (how many of those boats are fishing musky, northern, panfish, bass or just out for a cruise?), nor depth they were fishing. With the increased popularity of other species along with recreational boating this is significant, and even walleye fisherman that fish shallow is as well imo. I think it’s important to note that all of the DNR guys I talked to were very receptive to my questions, openly discussed these studies and potential flaws, and imo are doing their best to be accurate and well intentioned.
ML: https://afspubs.onlinelibrary.wiley.com/doi/10.1577/M05-209.1
P4: https://afspubs.onlinelibrary.wiley.com/doi/10.1080/02755947.2011.571490
Rainy: https://afspubs.onlinelibrary.wiley.com/doi/10.1080/02755947.2011.623759
