Has anyone had this happen?

[croppiedude]

I was fishing in Tennessee on my local lake this weekend. It was hot and humid but the crappie were responding beautifully to jigs in 15-17' of water. I noticed, however, the non-keepers I put back in the water were floating belly up and dying so I stopped fishing immediately. I didn't want to kill any more fish I wasn't going to keep. Anyone else had this problem? What causes it? Any way to keep it from happening? I didn't think it was deep enough for them to get the bends.

[Shellback]

Probably hot water temps and stress on the fish. Just like a bucket of minnows in the summer, they won't last long unless you keep them cool. You did the right thing stopping fishing.

[Barnacle Bill]

That is a new one on me. I wonder what was causing it?

[J White]

Yes, I have noticed this before, I would say this time of year where I
fish, it would be expected. It seems to help if you hold them by the tail
and let them drop about 3-4 feet head first into the water, in my experience.
It seems like they go into shock or something, but if you drop them and
they get below the surface good and fast, they don't come back up.
Just a thought, but the fish you were catching may have just moved up
from deeper water, so even though you were only pulling them up 15 feet,
they might still be "adjusted" to deeper water they just left.

[DENNIS BOWERS]

I too have had this happen.I figure it was due to water temps,and the depth they came from.Seems like the mortality rate was high regardless of what we tried.Guess I"ll try Jeff"s method the next time as I usually quite fishing when this starts happening.

[Bruce Carp]

Play the small fish a bit, the sudden rise may injure the smaller fish during the hot summer months. Similiar to decompression of a diver, rising to quickly. Don't have this problem with bigger fish as they fight more and rise slower, so I play with smaller fish, seldom have this happening. But did in the past quite often. The deeper the fish the more likely you will have problems with smaller crappie. my two cents

[Fishnbuddy]

Crappiedud, the same thing happened to me last summer. It seems like I don't have that problem other times of the year. Good for you for stopping fishing. I did the same. Since then, in hot weather like this, I've gotten them back in the water quickly. So far this year I've not lost a one except the big one that always gets away before I can boat it every time I go fishing. If I've got to measure 'em they are out of the water longer, but my eye has gotten pretty good so I don't have to measure too many. I'm not sure what causes it, but it's got to be shock related.

[Moose1am]

It's caused by the bends. The Bends occurs when gases get disolved into a solution (Blood) under high pressure. At 17ft the pressure of the water combined with the sky above (80,000ft of air above the water level) caused the gases that are taken into the fish's body though the gills to dissolve into solution. A sudden decrease in this pressure will cause the gases inside the fish's air bladder and blood and all the fish's organs to suddely expland and to form bubbles. This dissolved gas comes out of the solution and can damage the fish and kill the fish. The air bladder is surrounded by many tiny blood vessels and gases can diffuse between though the air bladders membrane (cell walls) and into the blood vessels and vise versa. The exchange of gases takes some time. Normally a fish can change depth over time and thus the gases don't come out of solution.

Now I know that a scuba diver and Dive down into deeper water (higher Pressure area) easily without problems other than having to equalize the pressure inside the head to keep the ear drums membranes from popping. A diver will squeeze air inside his ear cannel to the inner ear and that air pressure will help keep the ear drum membrane from being pushed inward by the increase water pressure on the other side of the membrane. This is easily accomplished unless one has blocked sinus cause by a cold or something similar. If you have a head cold and blocked sinus then you are not suppose to go diving. The same thing can happen when you take off in a jet and climb fast to a higher altitude. You must yawn to expell air out of the inner ear space so that the lower air pressure out side the ear drump does not cause the ear drum membrane to pop. This is the opposite effect of diving deep and is the same thing as coming up from a deep dive too fast.

Air molecules will become further apart when under less pressure and the volume occupied by these air molecules will be greater. Conversely when the pressure on those same air molecules is increased the air molecules will be squeezed closer together and occupy less volume.

These principles are well established in science. Charles's Law and Boyles Laws explain how air behaves under different temperatures and pressures.

We have discussed this many times in here. Some guys believe that a fish can be saved by just popping the air bladder and releasing some air molecules from the air bladder so that the fish can more easily return to the depths. It like trying to dive down with a live jacket on you. You can't go below the water's surface until you remove the life jacket or deflat the boyancy compensator vest. But I am not aware of any studies where they tagged these fish and followed them for the next week to see if they survived or not. They may sink and die from complications. And it's hard to pop the air bladder without doing other damage to the fish's internal organs. Also the danger of introducing bacteria or fungi into the fish's body cavity can't be overlooked. But at least with this method you think that the fish has a better chance of making it than just floating on top of the hot water and dying.

One thing that might help is the put the fish in very cold water which may cause the gases to go back into solution. Cold liquids can hold much more air in solution than warm gases. So by cooling the fish's water and therefore cooling the fish's blood you might save the fish over time. Also cold water will hold more oxygen. One of the first things a EMT or paramedic will do to a paitient is give them pure oxygen to help the patient. Increasing the oxgyen levels in the patient can work miracles. It works this way with fish also.

So if you catch a fish in deep water where he is under higher pressure and acclimated to cooler water temps and higher levels of dissolved oxygen and you bring him up to the surface suddenly you can do serious damage to that fish's body.

A diver can be cured of the "bends" by putting the diver back in the water and taking the diver back down to the depths where the pressure of the water forces the gas in his blood stream back into the blood. Back into solution. This releaves the diver of bubbles in his blood stream that can block the proper flow of blood in the small blood vessels and capilaries. Over time the increased pressure will cure the bends. Then the diver can be decompess by coming up in stages. There is a huge increase in water pressure in the first ten feet. ie if you go from the surface down to 10ft the increase in pressure is greater than when you go from 10ft down to 15ft. At a depth of 33ft you are under 2 atm of pressure. 1 atm from the air pressure above you and 1 atm of water pressure from the water above you. Normal air pressure of 29" of water or 760 mm of Hg is equal to 1 atm of air pressure. And normal temp is approx 25 deg C or 77 deg F. I did a temperature profile on my fishing lake the other day and found that the surface water temp was around 31 deg C. At 19ft the water temp was around 20 deg C or less. That is a huge difference in water temp. This is equivalent to a change in temp from 87.8 deg F to 68. Water at 88 deg F will not hold very much oxygen but water at 68 deg will hold a lot of oxygen. Blood holds more dissolved oxygen at 68 deg F than at 88 deg F.

Another way to save these fish is to take them back down to 19ft asap. But how would we do that? Someone posted a link to one of the State's DNR web sites where they discussed this. They suggested somehow attaching a weight to the fish via a hook though the thin skin of the fish. Then dropping the fish back into a water that is 19ft deep. The weight would take the fish back down to the bottom and start the decompression process. This should almost immediately cause the expanded air inside the fish's swim bladder to decrease in volume. By compressing the air inside the air bladder the fish will then be able to obtain neutral boyancy at that depth. But then how does the fish get off the weight? If the fish is attached to the weight via a fish hook that is attached to the soft part of the fish's fins the fish maybe able to free itself by tearing the hook out of the fin. Even this may harm the fish as any tear in the skin can become infected. Fish normally have a protective slime coat over their scales and this helps to prevent bacteria from entering into the fish's body in any great numbers. Any small number's of bacteria that get into the fish can be killed by the fish's immune system's white blood cells or antibiodies. But if a great number of bacteria enter the fish at one time they may overwhelm the fish's immune system and this could result in a systemic bacterial infection that causes the fish to die.

The only way to really save fish that have been pulled up out of deep water is to put them back under high pressure and then slowly decrease the pressure over time so that the fish can adjust to the lower water pressure.

I guess we could attach the fish to a long line with a weight and then drop them back down to the depths. Then slowly over the day raise the line with the fish back up towards the surface 5ft at a time with pauses inbetween. Sort of decompressing the fish as we would do with a scuba diver.

I was fishing in Tennessee on my local lake this weekend. It was hot and humid but the crappie were responding beautifully to jigs in 15-17' of water. I noticed, however, the non-keepers I put back in the water were floating belly up and dying so I stopped fishing immediately. I didn't want to kill any more fish I wasn't going to keep. Anyone else had this problem? What causes it? Any way to keep it from happening? I didn't think it was deep enough for them to get the bends.

[KARL]

..should be able to rig up clothespin on line with weight to return fish to depth and then quick release...clip pin to tail or dorsal fin....just thinking out loud here...worth a try maybe..

[croppiedude]

Thanks guys! Everyone was a help. Good fishing!!!!!!!!!!!