The DNR has been conducting a study of catch and release mortality on Mille Lacs as part of their “Treaty Managment” program. Some interesting things have been learned in the last 2 years. First, they found that the mortality was not as high as they had originally figured. If you remember correctly, when we started the harvest quotas, and the DNR reduced the slot mid season a couple years ago, they were thinking there was a 10% mortality rate. The study has shown them they were a bit high in their estamates, and that actually it was closer to about 5-6%. They have also determained that the 2 biggest factors in a walleye’s survival, was 1.) Proper handling and quick release of the fish if they were not keepable (protected) so it could quickly return to the same depth and water presure/temp. that it came from, and hopefully without any, or much of its slime wiped off, and 2.) Soluable oxygen levels in the livewell water. Most common livewell pumping systems just don’t supply ample water/disolved oxygen, to the fish in such a small enviroment as a livewell. The temperature of that water is also a factor. Think about it! You catch a fish out of say 20 feet of water. The temperature at the bottom of the lake is usually much colder, in the summer, than the surface water you are pumping into your livewell. That warmer surface water does not contain the same saturation of oxygen that is found in the deeper cooler water. The fish has been severly stressed from the fight once it was hooked, and you are now putting it into a smaller enviroment with other fish, and its trying to suck air out of used water that is maybe as much as 15-20 degrees warmer. The fish goes into shock, maybe suffocates, either way, thats the end of it.
It also does not help the fish at all to have the boat slamming up and down throwing the fish back and forth bouncing off the walls because the fisherman has to run a long distance over rough water in order to make weigh in either.
There are several things we can do to improve the mortality of our tournament fish.
1. When possible, make the ride in to shore as smooth as possible, and use a survivor system to constantly supply fresh water to the fish while running.
2. Turn off the timers on your aeriator systems. Have them run non-stop, full force all the time while there are fish in your livewells.
3. Handle the fish as little as possible, and get them back into water as fast as you can. Be carefull not to lay the fish on the carpeting of the boat and flop around wiping the slime off it. Don’t keep the fish out of water an extra 2-3 minutes while everyone pooses with the fish for a picture either.
4. Fill your livewells to the lid. If there is no air space between the lid, and the water, there will be much less sloshing back and forth, and less beat up fish at weigh in.
Every year there are more and more guys fishing tournaments. Thats more and more pressure on what is now becoming an increasingly smaller resource. Its all of our responsibility to do as much as we can to protect those resources.
I believe it was Teddy Rosevelt who once said,”any sportsman who is not a conservationist, is nothing more than a fool”.