fish age

[lonehunter]

how is a fishes age determined ?
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[basstracker29]

I heard that fish age can be determined by its weight and length.Basstracker29
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[ruger]

It really depends on the location and type of fish. Generally fish in warmer waters are very difficult to age due to the lack of scale rings. Yet in colder waters, most of the trout species don't even have scale rings and therefore cannot be reliably aged. Perhaps the best info for a specific species or body of water will come from your State's department of wildlife. Get in contact with a fisheries biologist and they are more than likely to get you the information you would like.

[JapanRon]

Hi there lonehunter,

Fun Question. As another poster said, your state's fish and game department will probably have the info on their website. In California, the DFG has a pamphlet titled 'How to tell a Fishes Age' or something like that.

For some fish, they use the scales to tell age as it's something like a tree with the tree rings. The white sea bass here can be checked by the size of a calicium deposit in there heads.(They use it for equalibrium and maybe navigation)

The calico bass may live to be 35 years but can be smaller than a much younger fish if that fish has eaten better thru greater forage, etc.

Don't know how they do catfish and other fishes without scales. Maybe just the old fashioned length, girth, and weight routine we all know.

Some fishes here in California change color, patterns or sex with age. Hey no California jokes!

tsurikichi
JapanRon
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[lonehunter]

LOL !!!!!!!!!!!, THANKS RON, THAT LAST PART WAS A REAL GRIN !
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[davetclown]

I herd that old cat fisherman can be judged by how grey their wiskers are.

just kiddin[]

in all my research I have not found any thing to help show the age of a fish. other than if it is floating upside down it has past its living age.

but I
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[gvanzant]

JapanRon: Yes you are correct. Although fish age can be determined by fins, scales and internal organs, the best way is investigation of the "Otolith" that bone in the fish skull that is an earbone in the human. I have a fishing buddy who has a sack of sea bass otoliths, collected from all the sea bass he has caught over the years. I actually knew this fact but looked it up in Google under "Fish age determination".
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[lou]

thought i heard or see somewhere a trout will grow three inches a year
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[JapanRon]

Hi lonehunter and all,

lou's got a point. I guess we know how old a lot of salmon and steelhead are on the west coast at least! Kinda neat how some of the guys spawn on staggered years in the same stream (man that's traffic control), how some spawn, don't die and go back out to sea, how some come back to the stream but are still too young to spawn. Kinda confusing. One salmonoid in Hokaido, Japan lives in freshwater and swims out and spawns in the ocean.

Did anyone just ask 'em politely how old they are?

JapanRon
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[lonehunter]

CAN YOU SEE CONGRESS DEBATEING THIS SUBGECT ! lol
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[Flagmanonice]

[shocked] Im not sure how to tell how old they are, but they (the state of Minn ) are doing a study on pike on Lake Of The Woods here !, By tagging them and fisherman turning in the tags when caught, they determined a 20 # pike is around 25 yrs old !( In this lake ). But to tell a fish by length, girth, etc, will not work up here anyway !. The fish here could be 2 # in one lake, and a same age fish in another lake could be 4 # . It all depends on the feed , the depth of a lake, if its in any water system that flows . All of these depends on the growth of a fish. For example, a walleye that has smelt for forage, will be larger than a fish in the same year class, of fish that has suckers for its forage. A walleye in a warmer state will grow faster than one thats froze over 5 months of the year ! . The growth will be slower in colder water. Just my 2 cents worth!

Flagmanonice----------- remember, keep the eaters, not the breeders !!!!!!
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[davetclown]

one of my buddies is raising trout in his back yard, he buys a fresh shock every year.

in the first year his trout grow to about 12+14 in lenth the first year from 3 inch fry.

he feeds them every day.

as you said it all depends on the conditions and available food.
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[katfish]

There are several ways that biologists can age fish. Judging size of fish cannot give an accurate age of fish.



Scaled fish often replenish scales as they wear out or are scraped off much the same as human skin is constantly replaced. This would mean that scales could not produce accurate annulus rings since it is unknown if a particular scale has been replaced or not.


A fishes ear is under the skin and the bone that transfers sound is called an otolith. The otolith has annulus rings(circuli) and accurate age can be determined by counting the rings under a microscope.

http://www.aquariums.state.nc.us/ata/fishage.htm



Since annual growth can vary widely an even more accurate aging of the otolith can be done by using radiocarbon dating.

A cross section of a fin can also be sliced and viewed under a microscope making it possible for a non lethal method of agin fish.
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