| As Muskie fishermen, we have a great deal of control over many of the factors affecting delayed mortality, simply by limiting the amount of time we keep a fish out of the water. While the incidence of delayed mortality has been estimated to be in the range of 5-30% the exact figure can never be known, as there are many determining factors. Therefore we recommend that every effort be made to keep delayed mortality deaths to a minimum.
There are many other situations that also require taking precautions to help minimize the risk of delayed mortality, such as targeting deep-water fish. To achieve neutral buoyancy and have the ability to stay at any depth it may want to, a Muskie has to be able to take gas into the bladder and let gas out of it. When fish are rapidly brought to the surface from deep water, they may experience a rupture of the swim bladder, possibly allowing a gas bubble to enter the bloodstream. This gas bubble could then find its way to the gills, brain, (or other vital organ) and thus block vital blood flow from the downstream tissue. This type of injury is similar to that seen in humans who rapidly ascend from deep water. In addition, if the fish is caught from water deeper than about 40 feet, it may experience decompression sickness, (the bends), just like humans do. Due to these concerns, it has been suggested that Muskie fishermen avoid pursuing deep-water fish if they intend to release them.
Certain care should also be taken to ensure the release of healthy fish when fishing at night. In many instances the water temperature will be more beneficial to the well being of the fish in the cooler evening hours, but there are other issues that come up. You’ll want to make sure you’re aware of the location of your release tools and also minimize the amount of time the fish is in the net.
Cold air temperatures may also have a slight effect on the Muskie. When taken from the water in very cold air temperatures, there is a risk of freezing to the fish’s eyes and/or gills. Some consider it to be a concern, but at this point it doesn’t seem to be a big issue.
As much as we enjoy fishing for Muskies, there are times throughout the year when it can prove detrimental to their survival for us to fish for them without first considering the scenarios we’re faced with that particular day. If certain steps are taken, we can ensure that Muskies will survive and prosper for the next generation of fishermen.
References
Thomas Betka, MD, BS (Aquatic Biology)
Medical Director, Hyperbaric Medicine & Wound Care, Aurora Baycare Medical Center, Green Bay, Wisconsin
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