Winter Catch and Release mortality

[Haris122]

I recently went to the meramec red ribbon trout section and to my surprise I came across more action with warm water fish than the trout. One spot in particular, I was getting a lot of cooperation from, and after fishing it for a bit, it got me wondering, how much stress does a fight put on those kinds of fish during the winter when they need the energy reserves to get through it? In particular how does survival relate to size and species? Cause I was catching a decent range of species, of various smaller sizes with regularity.

I used a rubber net, a single hook roostertail to release quicker, continued to wet my hand that I held the fish with, kept the net underwater as much as I could once they got caught, and tried to bring them in as quick as I could without losing them (albeit using a light action rod). But at the same time I was wondering how much I was lowering their chances of survival by catching them at a time that they're probably having a net loss in calories and energy anyways, especially when it came to the smaller fish. Eventually I decided it's best to spread the pressure out over a larger area, so I started moving more but it just got me wondering since people say not to stress the trout once it gets above a certain temperature, how does the opposite apply to Crappie, Largemouth, Rock Bass, Smallmouth and etc.

[Al Agnew]

I don't know for sure, but here are a few thoughts...I think fish actually need fewer energy reserves in the winter.  They aren't warm-blooded, so they don't need to use up energy to keep their body temperature up.  Since their metabolism is lower (unlike warm blooded animals which, unless they hibernate, need a higher metabolism in the cold to maintain body temp, so must stay quite active and hunting or feeding in order to keep it up) they are using less energy.  They are slower and somewhat weaker when fighting in the winter, so automatically use less energy once hooked.

I know that when I keep fish to eat, including spotted bass, largemouth, and walleye, that I've caught in the winter, they stay alive far longer and under worse conditions than warm weather fish.  I've crammed them into a minnow bucket so tightly that there was more fish than water and driven more than an hour and found them still alive and reasonably active when I got home...I once carried two big spotted bass home that way, and when I got home they still seemed pretty healthy.  I didn't want to clean them, so decided to turn them loose in the pond by the house.  They both survived because I caught them several times in the next year or so.

So bottom line is, right or wrong I worry less about mortality in the winter than I do in the summer.

[Haris122]

I didn't really think of looking at it that way. For some reason even with them being cold blooded I still pictured them as loosing energy, especially after a hookup and the fight, since they just spent even more energy and yet likely don't get much opportunity to eat much to make up for the energy expenditure to begin with. If that's more likely the case, that would be pretty nice. So in your experience Al do you think fish loose any weight over the winter then?

[Al Agnew]

I doubt that they lose much weight, if any, for much the same reason...except for maybe years like this one when they had to expend some energy fighting flood waters.  For fish in normal wintering pools, I'd guess it depends upon the food available.  It wouldn't take much food to maintain their weight since they aren't usually expending that much energy.  

I REALLY question the whole "fall fish feed heavily to fatten up for winter" thing.  They shouldn't need a lot of extra fat reserves to winter over, since, again, they are cold-blooded and the only way they use fat or energy is in swimming and feeding (and in females, developing eggs), not in maintaining a body temperature.  Fall fish may or may not feed heavily, but it's probably just because of the water temps, availability of food, and perhaps, for those who migrate long distances, to stockpile or regain the reserves used in migration.

I do know that if you fish all winter, the fish you catch in February are no skinnier than the fish you catch in November.

[Al Agnew]

Another thought...they obviously don't keep growing much over the winter, because otherwise you wouldn't have rings on the scales by which you can age them.  However, I've had the biologists tell me that the rings are often less pronounced and even impossible to read on some of the bigger fish.  Does that mean those fish DID actually grow a bit over the winter?  I would think that those who go to thermal refuges like the big springs might actually keep growing over the winter, since they are in water temps that never get much below 50 degrees and there is usually plenty of minnow type food around those areas.

[mjk86]

10 hours ago, Al Agnew said:

I don't know for sure, but here are a few thoughts...I think fish actually need fewer energy reserves in the winter.  They aren't warm-blooded, so they don't need to use up energy to keep their body temperature up.  Since their metabolism is lower (unlike warm blooded animals which, unless they hibernate, need a higher metabolism in the cold to maintain body temp, so must stay quite active and hunting or feeding in order to keep it up) they are using less energy.  They are slower and somewhat weaker when fighting in the winter, so automatically use less energy once hooked.

I know that when I keep fish to eat, including spotted bass, largemouth, and walleye, that I've caught in the winter, they stay alive far longer and under worse conditions than warm weather fish.  I've crammed them into a minnow bucket so tightly that there was more fish than water and driven more than an hour and found them still alive and reasonably active when I got home...I once carried two big spotted bass home that way, and when I got home they still seemed pretty healthy.  I didn't want to clean them, so decided to turn them loose in the pond by the house.  They both survived because I caught them several times in the next year or so.

So bottom line is, right or wrong I worry less about mortality in the winter than I do in the summer.

Agreed....cold water fish are much more durable.....I caught some crappie about a month ago...tossed em on ice and took em home.   Later that evening i went to clean them and they were all still alive and surprisingly lively, never seen anything like it!  They dont need much energy, or oxygen or food when their metabolism drops and all the biochemistry in their bodies slows down significantly.  Most chemistry (metabolism) slows down tremendously as temperature drops...cold blooded animals have no ability to keep the temp up...thus keeping the chemical reactions moving at the same pace.  The cold blooded bodies simply adjust to the slower chemistry, by shutting down unnecessary functions (less blood to the extremeties and muscles for movement, less blood to digestive system for feeding).  People have long said that fish caught from cold water taste better than fish from warm water, the reason is because blood vessels have contracted to force more to the brain, and vital organs.  Less need for movement...so less blood to the muscles. 

[Mitch f]

On January 17, 2016 at 10:48 PM, Haris122 said:

I recently went to the meramec red ribbon trout section and to my surprise I came across more action with warm water fish than the trout. One spot in particular, I was getting a lot of cooperation from, and after fishing it for a bit, it got me wondering, how much stress does a fight put on those kinds of fish during the winter when they need the energy reserves to get through it? In particular how does survival relate to size and species? Cause I was catching a decent range of species, of various smaller sizes with regularity.

I used a rubber net, a single hook roostertail to release quicker, continued to wet my hand that I held the fish with, kept the net underwater as much as I could once they got caught, and tried to bring them in as quick as I could without losing them (albeit using a light action rod). But at the same time I was wondering how much I was lowering their chances of survival by catching them at a time that they're probably having a net loss in calories and energy anyways, especially when it came to the smaller fish. Eventually I decided it's best to spread the pressure out over a larger area, so I started moving more but it just got me wondering since people say not to stress the trout once it gets above a certain temperature, how does the opposite apply to Crappie, Largemouth, Rock Bass, Smallmouth and etc.

I really wouldn't call these fish winter fish anyway, they stay in that same water temp virtually year round.

[mjk86]

Just now, Al Agnew said:

Another thought...they obviously don't keep growing much over the winter, because otherwise you wouldn't have rings on the scales by which you can age them.  However, I've had the biologists tell me that the rings are often less pronounced and even impossible to read on some of the bigger fish.  Does that mean those fish DID actually grow a bit over the winter?  I would think that those who go to thermal refuges like the big springs might actually keep growing over the winter, since they are in water temps that never get much below 50 degrees and there is usually plenty of minnow type food around those areas.

Some probably do...its a balancing act for energy reserves/requirements....summer, more food in, more energy out...winter, less food in less energy out.  If there is abundant forage, warmer than average temperature, or even just a fatter hungrier induvidual fish (after all...just like people they are induviduals) then one or more than one may grow over the course of the winter.   In the early spring...fish gain lots of weight as they are beginning to feed heavily, but temps are still cold.

[Haris122]

Now that you guys mention it, I helped last spring a day with some pallid sturgeon survey, and I wondered how many of the fish in the nets at the bottom end up dying from taking a while untangling them out of the nets while out of the water, since I thought it was taking me a long time to get most of them out, and the people researching said its not much of a problem because it's winter and their metabolism is much slower, so they don't seem to lose many of them.

Mitch, I figured the water might still be colder than what they're used to most of the year. Maybe that's not the case, but I expected them mainly to be from further downstream what with the mention of the springs being used as wintering spots by some of those fish.

[Al Agnew]

I would bet that a lot of the fish at Maramec Spring in the winter come from upstream, though probably some also come from downstream a few miles.  The smallmouth population above the spring in the summer is probably a lot denser than in the first few miles below the spring, though.  At any rate, however, Mitch is right that fish that winter around the spring are not exactly typical winter fish, which spend much of the winter in water from 35 to 45 degrees.  The spring water fish are living in water that is seldom below 50 degrees all winter.