Fish Mortality in Warm Water

[K1500]

I know that post-release trout mortality skyrockets when water temps reach 70 something, to the point they advise don’t fish unless you plan on keeping them. Does the same thing occur to bass (at higher temps)?  

 

I caught a white bass yesterday, brought it in quickly and released it quickly. Surface temps were 87 or so and it would up dying. It got me thinking about the effect water temps have on bass mortality when released. 

[Bluebasser86]

Yes, warmer water will increase fish mortality. That's why some states don't allow summer time tournaments and some tournament circuits reduce limits during summer months to help with fish mortality.

 

Don't fight them to exhaustion, don't handle them too long or keep them out of the water a long time, don't haul them around in the livewell, and release them as quickly as possible to give them the best chance. You may still lose one occasionally, but that's going to happen regardless of what you do.

[Captain Phil]

Fish mortality is a big problem in Florida during the summer months.  Surface water temps are in the nineties and the mid day sun is relentless.  Live wells cook more bass than anglers.  After a tournament, our marinas were full of floating dead fish upsetting anglers and shoreline observers.  As stated, most summer bass tournaments in Florida have had their hours cut back.

 

My personal opinion is all bass tournaments should go to a three fish 15" limit. There would be less fish riding around in live wells.  It would also concentrate more effort on catching big fish rather than numbers. To me, it's more significant to catch one 4 pounder than 5 dinks.  So far, the best option I have seen is to go to a weigh, photo and release format. 

 

 

[BrianMDTX]

7 hours ago, Captain Phil said:

So far, the best option I have seen is to go to a weigh, photo and release format. 

I think it’s time has come. 

 

Yeah, everyone wants to see fish at the weigh-in. It's exciting. But it’s bad for the bass. It’s 2020. We can do better. 

[RoLo]

 

Pure and simple, the higher the temperature of water, the lower its capacity to hold dissolved oxygen.

Florida-strain bass is mother nature’s answer to waterbodies in the deep south

that sustain high temperatures. The water temperature in a livewell can quickly exceed the thermal

tolerance of even Florida-strain bass. It’s like leaving a dog in a car parked in full sun.

 

There was once was an upscale lakeside restaurant situated alongside a ramp used for tournaments.

The restaurant eventually went belly-up, mainly because the sight of dead bass

bobbing in the lakeview window, was not conducive to customer appetites.

 

Throw a few ice cubes in the livewell every hour, and you’ll perform a service equivalent to most

chemical additives. Better yet, I’d love to see an MLF-style format abolish the ego trips we refer to

as ‘weigh-ins’. Many years ago, my wife & I were at the ramp when Gerald Swindle won on Lake Toho.

When Gerald told me he was on his way to the Orlando weigh-in, it blew me totally away.

 

Roger

[WRB]

Black bass (largemouth, smallmouth, spotted) all have about the DO (dissolved oxygen) needs, about 3 to 12 mg/L. Lower DO the fish suffocate, higher the blood does brain damage. Florida strain LMB have a higher warm water temperature tolerance but lower cold water temperature range, about 45 to 90 degrees.

The basics Black bass are most comfortable in 70 degree water with about 9 to 10 mg/L and seek out the cooler water during hot water months.

As Roger noted the warmer the water is the less DO it can contain. For this reason bass like green aquatic plant cover that is producing DO in hot water or move to cooler deeper water if availble.

The problem is livewells. Livewells take water from the hot water surface with low DO levels during the summer. The water must be cooled and aerated for bass to survive.

If the water is more then 10 degrees different then water the bass is acclaimated to it suffers thermo shock and DO changes that can kill the fish in a short time.

The most notable TV event was Ike's melt down during the MS Delta Classic when all his bass died. The other was the Falcon big bass event when a high % of the bass found floating dead after the event.

Sure-Life has a good video on how to maintain proper livewell DO and temps.

Tom

PS, post tournament mortality rate average about 3% for weight in events.

[K1500]

Thanks for the replies, it jibes with what I have experienced. 

[TnRiver46]

I prefer my fish mortality with fried potatoes ........

[frogflogger]

I used frozen bottles of water and salt in my livewell tournament fishing in FL had good results but I never felt good or confident hauling fish around in hot weather - I like the mlf format and wish it was the norm for all tournaments.

Weigh ins never excited me that much. I still cringe when I see the big ones haul fish for miles in their live wells and then hang them out for everyone to see. We need to be good handlers of this precious resource if we want this sport to thrive and grow.