?Biology question?

We all know that all living organisms in the water are susceptable to depth changes, fish especially. I know that the amount of oxygen in a fish’s swim bladder (or air bladder) lets it suspended at different depths. So a fish that dwells nearer to the surface will have more O2 in its bladder than a fish that dwells down deep. So here’s my question.. Why does a fish, such as a lake trout that dwells in deeper, colder, more oxygen rich water “burp” when you bring it to the surface from the depths? Is that air entering the swim bladder or what? I asked one of my profs who gave me some bs answer so if anyone can explain it, that’d be sweet.

Heres another one if you’ve got time on your hands (if you’re a quick one you’ll get it right away)….
A 40 acre pond has lilly pad growth that doubles in area every day. It will take 40 days for the pond to be completly covered in lilly pads. On what day will the pond be exactly half covered?

Well the answer to the second question is on day 39 as for the first one I believe the fish is releasing oxygen as it rises to the surface.Just like humans the deeper you are in the water the more pressure there is and oxygen is compressed.As you rise to the surface oxygen expands and needs to be released.A diver for instance that is at a depth of 100 feet has to release exspanding oxygen as you rise slowly to the surface or he will get what they call the benz.This is when oxygen exspands to fast in the lungs and is released into the blood stream.This also happens to fish that are pulled up to fast.If you look down a fishes throat that has been pulled up to fast the air sack will be sticking out of his throat and although it might swim away probably wont survive.

RIght on the nutz Castaway!

An easy way to visualize what is happening with the air bladder of a fish can be demonstrated with an upside down glass in water that is filled with air. When this upside down glass is just below the water surface, the glass will be completely full of air. When this glass is lowered to 10 feet deep, the water pushes on the air in the glass so the glass is only about 90% filled with air. When this glass is lowered to 50 feet deep, the water pushes on the air in the glass so the glass is only about 20% filled with air.

Imagine that you had an air tank under water and filled the glass full of air at 100 feet deep. You bring the glass toward the surface and with each few feet upward some air would escape from the glass.

Imagine taking the same glass back to 100 feet deep and filling it full of air. Then stretch a balloon over the end of the glass. As you bring the glass toward the surface the balloon will continue to get bigger. This is what happens to the air bladder on a fish that is pulled up from deep water.

The fishes body acts like a minature air pump and can slowly adjust to depth changes. However, it the fish is pulled from deep water to the surface before it can adjust to the pressure, just like the balloon would get bigger and burst; the fish’s air bladder would get bigger and burst unless enough air bubbles could escape.

If I could sleep till noon I would have probably known that.
I always thought lake trout just liked beer.

Lake Trout are also a memeber of the Char family. This family of fish has the ability to vent the air in the air bladder out their mouth. Other fish, like walleyes, do not have this ability. They must pass their air through their body which takes a fair amount of time. They do not adapt to depth changes as quickly as the Char family does.

There are some good explanations above about how air changes the volume it occuppies based on the amount of pressure. Anyone who has taken SCUBA lessons has learned about Boyles Law and Charles Law and why this occurs. The one thing I took from this that is most telling is that for every 30 feet you descend you increase the pressure 1 atmosphere (15 lbs/sq. inch). At sea level we would have 1 atmoshpere of pressure on us. Descend 30 feet and your have 2. Descend to 60 feet and you have 3. Hopefully you can see how pulling fish out of 30 feet of water causes their air bladder to expand to twice the size it was at 30 feet. Not many fish can handle this change.

Hope that helps.

Garrison.

Good stuff, thanks. Hooking mortality studies on Mille Lacs walleye are taking place currently i think.. big issue in population analysis’ especially on high demand fisheries like ML, cass, leech, ect.

Have a good one