Lake Ontario Catch And Release is a topic often discussed dockside among my fellow charter captains. In this post, I will present my feelings on the matter, as well as some others. More specifically, on why and when it’s beneficial or detrimental to the concerned species to keep or let them go. My premise is that if you keep your first legal catch, more fish will survive in the Lake Ontario aquatic ecosystem to be had for later opportunity.

Species Matter
The primary species sought after by most charters on Lake Ontario are brown trout and king salmon. These will be the main focus in this post, today! Time of the year is important. Age class also has a huge bearing on catch and release success and, or mortality, of the aformentioned species.
Water Temperature
Perhaps the most influencial factor for success or failure of Lake Ontario catch and release is water temperature. More specifically, the surface water temperature plays a huge part in this matter! If the Lake’s temperature is homogenous, i.e. little to no change in temperature numbers from top to bottom, released fish have a much better chance of survival. Conditions like these are indicative of spring fishing or when the Lake gets iced out.
Warm Water On The Surface
During the summer, warm surface water temperatures are prevalent on the eastern end of Lake Ontario. Water temps can be as high as upper 70’s and approaching 80 degrees or more. Being predominently cold water species, salmon and to a lesser extent brown trout, live in cold water. When their preferred water temperatures are deep in the water column, bringing them to the warm surface temperature produces catostrophic stress. Perhaps more so in salmon, but it does occur with brown trout, as well.
Mortality Factors
Mortality factors include stress, disease brought on by scale loss, depth of catch, length of fish battle, and age class. This list is just some, but not all, of fish mortality causes. An interesting article can be found here , written by Aaron Bartholomew & James A. Bohnsack. Their findings are pertinent to Lake Ontario catch and release. The report discusses mortality factors such as some of the ones mentioned above. It mentions mortality rates as high as 30% in certain conditions. I believe it’s even higher on Lake Ontario due to the more extreme conditions the Lake posseses. Here is a link to another interesting read on catch and release shedding more light on the subject. https://hikingandfishing.com/catch-and-release-fishing/ I disagree with their premise that even if released fish die, some will survive to be caught again, as all kept fish are dead! Mathematically it doesn’t add up, especially when at least 30% die after you release them. If you keep catching and releasing them at a 30% mortality rate, you are killing one out of every three fish. All this mortality just to catch bigger fish!
Scale Loss Among King Salmon
Besides stress due to bringing king salmon up from the depths into warm water, an often overlooked cause of future mortality is scale loss, especially among certain age classes of king salmon. One and two year old king salmon are prone to scale loss due to their inherrent loose scale structure. In fact, one method used to tell the difference between a two year old and adult salmon is the scale loss that occurs during netting of the two year olds. Fish need their scales intact to survive. Once they are disrupted, disease and future death can occur!
Killing Fish For No Reason
With some history in fisheries biology via U Mass Amherst class of 1979, and some use of common sense, releasing juvenal fish that have been pulled up from the depths is a death sentence. Think about it. Being pulled up out of 44-48 degree water into warm water and fighting all the way, how can these fish not be stressed to the max. Add to it, loss of fish scales due to netting, and you have the recipe for disaster. Why put them back just to swim off and die, if in fact, they swim off at all!
Released Fish Show No Signs
Even though two year old salmon swim away more times than not, the loss of scales and their stressed out condition on top of it, limit their future chances for survival. Fish scales do grow back but slowly if at all! Without any antibiotics available for treatment in the wild, infection is almost a certainty. Emperical evidence shows over half of the caught and released one year old salmon end up floating after release, just to become sea gull food. What a waste!
Keep Your First Legal Catch
Whether its lack of education or just egotistical disregard for the species, releasing stressed out salmon in hopes of catching a bigger one in my opinion, is just plain wrong! I do believe in utilization of the resource. Catching and keeping fish from a put and take fishery paid for by fishermen is there by design to be used. Even promoting fishing tournaments is ok too, providing the resource is utilized and put to good use at the end. I’m in favor of tournaments that promote keeping your first legal catch but would like to see the minimum size coincide with state regulations on the species. Cull tournaments on the other hand, promote releasing smaller fish to keep bigger ones with no regard to exisiting Lake conditions. Conditions that enhance stress and unsuccessful survival of released fish are not taken into consideration.
Some Final Thoughts
Stress kills fish ,especially when brought up from the depths from cold water to warm. Once fish scales are lost, they grow back slowly if at all and leave fish prone to disease. If you think about it, when was the last time you ever caught a two year old salmon with half its scales missing! There are times that catch and release on Lake Ontario is ok to do as long as certain precautions are taken. If Lake temperatures are homogenously cold, top to bottom, the fish are less stressed out due to warm water temperature shock. Care must be taken not to dislodge scales through proper handling. Rubber nets along with keeping the fish in the water when dehooking is preferred. Also, allow the fish time to catch their breath before releasing them.
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