Muskies and High Water Temps

[RK]

Hiya -

With numerous discussions about water temps going on in various forums, I thought I'd post an excerpt from a piece on the subject I did for the Outdoor News in 2011. Among other things, it goes into some detail on they physics and physiology at play when releasing fish in hot water.

***begin except***

With water temperatures already high due to an early July period of hot, calm weather, the latest descent into the furnace is sending water temperatures soaring. Even lakes in northern and central Minnesota had surface temperatures in the high 70s to low 80s, well before the current hot streak.

Sustained high water temperature and the effects it has on muskies when they’re caught and released leads to a simple and straight-forward conclusion: if you care about the survival of the fish you catch and release, it’s time to leave muskies alone until water temps subside.

Why? The answer is part fish physiology, and part physics.

Even in a resting, unstressed state, mobility, circulation, respiration – all the physiological functions fish perform require an adequate supply of oxygen.

And recently-caught fish are far from un-stressed. Fish – especially fish like muskies built for short bursts of speed and not sustained exertion – quickly reach oxygen deficit in their circulatory system forcing the muscles to function anaerobically (without oxygen). In place of oxygen, body systems build up lactic acid in muscle tissues as lactic acid is burned to provide energy. After exertion, lactic acid dissolves into the fish’s blood stream, causing dramatic changes in blood chemistry, specifically blood PH.

Given adequate oxygen in the critical early stages of recovery time, this imbalance can be restored with minimal long term harm. But adequate oxygen is the key.

In extremely warm water, oxygen – the one critical component to a fish’s recovery – simply isn’t there.

As temperature increases, water’s ability to carry dissolved oxygen decreases in direct proportion. The higher the temp, the less oxygen is available. As temperatures approach 80 degrees, oxygen levels drop below what’s required to sustain a muskie’s metabolism even for un-stressed fish, much less one recovering from an anaerobic state. PH imbalances have dramatic effects on a fish’s metabolic system, and can cause death up to three days after the catch.

A stressed fish in an anaerobic metabolic state, sitting in high temperature, low oxygen content water at boatside while it’s unhooked and released is a fish at high risk of serious difficulty after its release. The end result is, to me, an unacceptably high chance of delayed mortality.

So, don’t fish. Leave muskies alone.

I realize that more than a few of you are saying to yourself “It’s just a fish.” True, but to me, a sportsman’s ethics requires this kind of decision, dramatic as it might seem.

I won’t belabor this, but to me the ethics here are fairly straight-forward: if conditions are such that a released fish is unlikely to survive, releasing it at all is a farce. It may “take right off” but if chances are good it will die later, out of sight and out of mind, releasing it under those conditions is no more ethical than throwing it up on the bank and hoping it squirms back into the water eventually. Dead is dead.

I realize too that this will earn me a few labels. I’m a catch and release radical. A Muskie Zealot. I’ve been called that and worse often enough. In cases like this (and frankly, most others as well) I take it as a compliment.

So what, then, in practical terms, is too warm? For me, based on a lot of conversations with fisheries biologists and physiologists, once you get close to 80 degrees, things start getting dicey. As hot weather lingers and temps rise even deeper in the water column, things get serious indeed. Personally, if I see anything above 78 degrees, I’m done with muskies until conditions change. Even prior to the 80 degree mark, I’m taking steps to minimize the chances of fish dying after I release them. I try to use single hook lures as much as possible, and often use barbless hooks besides. I release fish in the water without ever picking them up (skip the out of water photo session, and get a release shot instead). I’ll fish early in the morning, or on windy days rather than on still days when surface water super heats and stagnates…

It’s difficult to lose a chunk of a fishing season that’s already painfully short. But high water temps are already a reality on many of Minnesota’s muskie waters. In the last couple days, I’ve heard several independent reports of dead muskies found floating that showed evidence of being recently caught and released. And this was before things really heated up.

For anglers that like muskies as much as so many of them profess to, it’s time to do the right thing, and leave them alone.

***end excerpt***

[Nick Kuhn]

This is getting a bit ridiculous though, I haven't tossed a muskie lure since June 2nd... Can we get about 3 inches of graupel?

[Tommy1990]

Thanks for the info. I have been curious of how hot is too hot. Hopefully we get a lot more days like today with some cool nights and hopefully some rain to get the temps down.

[Muskiefool]

Thanks RK good article

[john skarie]

Good, solid factual information that should give anglers reason to pause when fishing muskies.

Unfortunately the masses of today's muskie anglers have never chucked baits back in the days when seeing a 50"er in a season was a big deal, not to mention actually catching one.

I don't think people realize what we have now, and how little it would really take to put as back to where we once were.

JS

[JPenny]

Thanks for posting this RK. It'a a great lesson for those who don't know, and a good reminder for those who do. Please spare those muskies folks (and the big pike too!).

[Apex]

Please post this on all forums you know of.................

[Stringerless!]

Forest was 68 this morning at sunrise and 74 by the time we left.