polo-dog - 5/27/2008 10:56 AM
craazysmom - 5/26/2008 9:45 PM
Ok Billy, What exactly does fizzing the swim bladder do for the fish and why does it not harm it?
Don't know why I'm asking that, 'cause you know I will be fishing with a toad
Deb
Fizzing a bass or other fish releases the pressure that builds up in an organ inside the fish called the "swim bladder". A fish uses it's swim bladder like SCUBA divers use a BC (bouancy compensator). To easily stay at a certain depth a fish must be neutrally bouant, in other words he/she doesn't want to use energy to swim down if it's too bouant or to swim up if it's not bouant enough. The volume of gas that is in a bass's swim bladder cannot be changed quickly because it does not have an opening to the outside of the fish. Some fish such as tarpon and gar can "gulp" air into their swim bladders because they have a connection from the swim bladder to the digestive tract and therefore can change their bouancy much quicker than a bass or other less "primative" fishes. The gar and the tarpon and others also can use their gas bladders as lungs as there is a rich blood supply to the gas bladder in those species. That's one reason that both of those species can survive in water that has very low dissolved oxygen content as they don't have to rely solely on their gills for oxygen.
The gas in the gas bladder of fishes that do not have a connection between the gas bladder and the digestive tract is affected to a large extent by the pressure exerted on it and the temperature of the water. If the pressure on the outside of the fish increases the volume of the gas decreases and/or the pressure in the bladder decreases. If the pressure on the gas decreases, as in when you pull a fish up from deep in the water, the volume of the gas increases and/or the pressure in the bladder increases. When the volume of the gas in the bladder increases it puts pressure on the internal organs and makes the fish more bouant. The pressure on the organs can damage them and the bouancy can make it impossible for the fish to swim back down to the depths to deflate the swim bladder. The gas in the bladder as are all gasses influenced by a law called Boyle's law:
Boyle's law (sometimes referred to as the Boyle-Mariotte law) is one of the gas laws and basis of derivation for the ideal gas law, which describes the relationship between the product pressure and volume within a closed system as constant when temperature and moles remain at a fixed measure; both entities remain inversely proportional.[1][2] The law was named after chemist and physicist, Robert Boyle who published the original law in 1662. The law itself can be defined succinctly as follows:
“ For a fixed amount of gas kept at a fixed temperature, P and V are inversely proportional (while one increases, the other decreases).[2] ”
At sea level we experience 1 atmosphere of pressure on our bodies but a fish that is 33.9 feet below the water experiences 2 atmospheres of pressure on it's body. When the fish is caught and brought to the surface the gas in it's gas bladder increases in volume because the pressure being exerted on it is decreased. So, if a fish is caught at 33.9 feet and brought to the surface (at sea level) the gas in it's bladder would potentially occupy two times the volume that it would when it was 33.9 feet down. Just think if you had swallowed a small balloon and suddenly it became twice as large inside of you as you came up from a depth. That would put pressure on your internal organs and that's what happens to fish. The bladder may not double in size, depending on how pliable the gas bladder was but you could understand how getting the air let out of the gas bladder by "fizzing" with a needle would decrease the force on the internal organs and make it so that the fish could dive back down without the bouancy of all of that gas in it's bladder.
If any of you are SCUBA divers you might understand the principle as changing the amount of gas in your BC needs to change depending on the depth of water you are in. It's an interesting way fish have been made to compensate for moving up or down in the water column. It might also help us understand why the change in barrometric pressure in the atmosphere might change a fish's " mood" in that when there is a big change in the barrometric pressure the fish has to change it's depth to compensate for the change in the volume of it's air bladder and therefore it's bouancy. Fish that have a gas bladder that doesn't have the connection with the digestive tract can slowly change the volume in it's bladder but cannot change it quickly in response to large changes in external pressure. I have seen lots of pics of fish that have been caught deep in the ocean with the gas bladder so full that it sticks out of the mouth of the fish but I can't find a pic thus far on the web to post to show how bad it can be.
I hope that I have cleared up some of the whys involved with "fizzing".
DK, the needle has to be sharp becuase it has to pierce through the tissue of the fish, not merely go through an opening.