Do fish shrink after they die?
Nov 6, 2019 15:21:09 #
the troller
Loc: Downers Grove, il.
I did not write this article, but I Thought it might be of interest:
New research suggests anglers should think twice about keeping fish that are close to the minimum size limit.
Knowing minimum size limits for the fish species you target is only half of the story. What happens to that fish after it dies in your cooler? If it’s right at the minimum size for harvest when you land it, be forewarned. How many times do you think fisheries law enforcement officers have heard “Honest, it was the minimum size when I caught it”?
Research Need
Fisheries managers frequently use minimum size limits and slot limits to prevent over-exploitation of different species. In North Carolina, for example, we have a 14” recreational minimum limit on total length for spotted sea trout and an 18-to-27” slot limit on total length for red drum. This requires anglers to be aware of the species-specific size limits and to accurately measure the length of their retained catch upon harvest.
But what if the fish you caught changes in length while in your possession after it dies?
Scientists have long known that fish can shrink after death. The problem is that how much fish shrink depends on the species — and researchers have examined relatively few species in a controlled setting.
As an angler, knowing how much — and how fast — a fish may shrink after harvest may be the difference between a good fishing trip and an expensive citation from a fisheries law enforcement officer.
What did they study?
A review of the latest science revealed that few studies have examined changes in length after death in commonly targeted recreational fishes in southeastern U.S. waters. Researchers, working with Florida state management officials, captured multiple, legal-sized popular saltwater sport fish in the state: lane snapper, common snook, bluefish, Spanish mackerel, Florida pompano and spotted sea trout. All but lane snapper and common snook are abundant in North Carolina waters, too.
They euthanized the fish after capture and laid them on ice in 70-quart or 120-quart coolers. They also took total, fork, and standard length measurements at the time of death and then at 30-minute intervals for six hours. They measured total length with the fish’s tail fin relaxed, not pinched.
What did they find?
In general, all species but common snook gradually shrunk. Lane snapper decreased in average length the most, by 3%, whereas bluefish, Spanish mackerel, Florida pompano and spotted sea trout all decreased in length by less than 1%. Interestingly, the common snook increased in mean length by 1.2% over the course of the study.
Anything else?
Desiccation — the removal of moisture — may have played a role in fish shrinkage after death, but researchers did not measure weight or water loss as part of this study. Over the course of the six-hour period of measurement, the tail fins on most fish became drier, stiffer and more splayed.
At the time of this study’s data collection, from 2004 to 2006, the state of Florida transitioned from using the relaxed tail fin to the pinched tail fin method to measure total length, in part because the latter was less prone to measurement error. Most states, including North Carolina, now measure total length by pinching the tail fin.
So what?
The amount of shrinkage for these species does not seem like much, but any reduction in length from a fish harvested and retained at the exact minimum size would result in the angler being in possession of smaller fish — which might be illegal, depending on the law and the body of water.
www.fishingfacts.net
Thanks for looking.....Good Luck!
New research suggests anglers should think twice about keeping fish that are close to the minimum size limit.
Knowing minimum size limits for the fish species you target is only half of the story. What happens to that fish after it dies in your cooler? If it’s right at the minimum size for harvest when you land it, be forewarned. How many times do you think fisheries law enforcement officers have heard “Honest, it was the minimum size when I caught it”?
Research Need
Fisheries managers frequently use minimum size limits and slot limits to prevent over-exploitation of different species. In North Carolina, for example, we have a 14” recreational minimum limit on total length for spotted sea trout and an 18-to-27” slot limit on total length for red drum. This requires anglers to be aware of the species-specific size limits and to accurately measure the length of their retained catch upon harvest.
But what if the fish you caught changes in length while in your possession after it dies?
Scientists have long known that fish can shrink after death. The problem is that how much fish shrink depends on the species — and researchers have examined relatively few species in a controlled setting.
As an angler, knowing how much — and how fast — a fish may shrink after harvest may be the difference between a good fishing trip and an expensive citation from a fisheries law enforcement officer.
What did they study?
A review of the latest science revealed that few studies have examined changes in length after death in commonly targeted recreational fishes in southeastern U.S. waters. Researchers, working with Florida state management officials, captured multiple, legal-sized popular saltwater sport fish in the state: lane snapper, common snook, bluefish, Spanish mackerel, Florida pompano and spotted sea trout. All but lane snapper and common snook are abundant in North Carolina waters, too.
They euthanized the fish after capture and laid them on ice in 70-quart or 120-quart coolers. They also took total, fork, and standard length measurements at the time of death and then at 30-minute intervals for six hours. They measured total length with the fish’s tail fin relaxed, not pinched.
What did they find?
In general, all species but common snook gradually shrunk. Lane snapper decreased in average length the most, by 3%, whereas bluefish, Spanish mackerel, Florida pompano and spotted sea trout all decreased in length by less than 1%. Interestingly, the common snook increased in mean length by 1.2% over the course of the study.
Anything else?
Desiccation — the removal of moisture — may have played a role in fish shrinkage after death, but researchers did not measure weight or water loss as part of this study. Over the course of the six-hour period of measurement, the tail fins on most fish became drier, stiffer and more splayed.
At the time of this study’s data collection, from 2004 to 2006, the state of Florida transitioned from using the relaxed tail fin to the pinched tail fin method to measure total length, in part because the latter was less prone to measurement error. Most states, including North Carolina, now measure total length by pinching the tail fin.
So what?
The amount of shrinkage for these species does not seem like much, but any reduction in length from a fish harvested and retained at the exact minimum size would result in the angler being in possession of smaller fish — which might be illegal, depending on the law and the body of water.
www.fishingfacts.net
Thanks for looking.....Good Luck!
Nov 6, 2019 15:30:11 #
Well that clears up my way of thinking. Precisely why my standard keeper limit is 1" over legal.
Nov 6, 2019 15:51:48 #
A very good read troller, thank you for posting it. I have often thought about that but I had never done any research on it. I very seldom keep anything over the slot because they usually don't taste as good as the smaller ones, especially walleye or reds. Pb's rule to add 1" to the minimum is a good one. Thank you, pb.
Nov 6, 2019 15:56:25 #
Sometimes its 3 to 6 hours which doesn't seem very long especially the 3 hours before I get back in the kayak and I swear that 15" was just over my mark on the cooler top. Put him on the cutting board and he is just over legal. Thanks to troller and the scientist I haven't loss it, totally anyway.
Nov 6, 2019 17:01:24 #
Great post.
Almost need to print and laminate and keep with ya, not likely to prevent you getting a ticket.
Almost need to print and laminate and keep with ya, not likely to prevent you getting a ticket.
Nov 7, 2019 12:00:28 #
Raw Dawg Ron
Loc: St. Petersburg, FL
Need to keep in mind with cooler fish, pull the plug out and drain water off, iced fish last longer too. Beside`s a one inch longer fish has thicker filet`s too!
Nov 7, 2019 12:21:52 #
Obviously being a charter boat captain if we showed up at a dock and our fish keep shrinking it would be a problem.
If you keep a fish wet on ice it should not shrink. Studies do show fish shrink but again these were done without measuring then placing back into water.
I was told by experts in the field that if you catch a 15 inch fish keep it wet it shouldn’t shrink.
If you keep a fish wet on ice it should not shrink. Studies do show fish shrink but again these were done without measuring then placing back into water.
I was told by experts in the field that if you catch a 15 inch fish keep it wet it shouldn’t shrink.
Nov 7, 2019 19:43:32 #
I struggle with all of this. If I catch a legal fish and keep it but it shrinks and I get a ticket then I’ll see you in court. I don’t make the laws but I do follow them. The law should understand shrinkage.
Nov 7, 2019 20:40:52 #
First time I saw this was in Tampa Bay while I was working with the FWC. A Charterboat was caught and charged with a short fish. The FWC officer took the fish and froze it for evidence. It was a red grouper that measured 20" on the boat. When the officer measured the fish at the dock was 19 3/4 when it was measured in the courtroom after it had been frozen measured only 19 1/2. I know the Fl FWC officers ate a little more relaxed on the measuring of fish now since they have learn fish do start shrinking as soon as they are killed
Nov 7, 2019 21:04:07 #
I think it also depends on who caught it. I have known several "gentlemen" whose fish grow exponentially after they have caught them. Just saying.....
If you want to reply, then register here. Registration is free and your account is created instantly, so you can post right away.