You'd spotted it, stalked it and laid the trap that hooked it. You
played it to the net, laid it gently on an unhooking mat, and
removed the barbless hook carefully. You then quickly took a couple of pictures
because it was a fine specimen and then nursed it in the water's edge
as it recovered its strength and its bearings, and then released
it.
It was a proud and satisfying moment for you as you watched it
swim away, apparently strongly.
Maybe not. Studies across the United States have shown that a
certain percentage of released fish die after they swim away. In
scientific circles, it's called 'hooking mortality'.
Although hooking mortality rates vary according to species and
fishing conditions, it's accepted that an average of 10 percent of
all released fish die from being hooked, the study concluded.
"There have been numerous studies done around the country on
different species, and it's surprising how often we come down to 10
percent hooking mortality," said Tim Goeman, Department of Natural
Resources regional fisheries manager based in Brainerd, Minn. "The
fact is, we know hooking mortality occurs."
"Delayed mortality is the most common type of death we see,"
Goeman said. "As a rule, most of the fish that succumb to hooking
mortality will die two to five days later. If (such a fish) floats to
the surface, it will be gone in a day or two because there are so
many predators out there."
Experience counts
Hooking mortality can increase, too, if fish are caught in deep
water or released on warm days, when less oxygen is in the water.
More experienced anglers may be able to release 99 percent of their
fish successfully, but less-experienced anglers might see that number
drop to 85 percent, Goeman said.
"Let's say I'm the guy who caught 100 fish and released them and
I'm feeling smug, but the fact is I've done more damage than the guy
who caught and kept six fish and went home," Goeman said.
The 10 percent hooking mortality figure is so well-accepted, DNR
biologists figure it into their models used to compute harvest on
certain lakes. When the agency figures the walleye harvest quota,
biologists assume 10 percent of the released fish will die. That's
added to the anglers' final quota.
Anglers who play big fish on light tackle may be endangering the
fish, experts say. Prolonged struggles increase the amount of lactic
acids in a fish's body, which can increase the chance of the fish
dying in the days after it has been released.
Barbed or barbless?
Anglers also assume that barbless hooks increase the survival of
released fish. Not true, Goeman said.
"There's been a lot of research done on this, said Goeman. "It
started to come out 10 or 15 years ago that barbless hooks didn't
decrease mortality, and it was a shock to the scientific community.
It makes sense to the layman that barbless hooks would be the answer,
and it even makes sense to scientists, but the science doesn't bear
it out."
Barbless hooks accomplish one thing - they help the angler remove
the hook and perhaps reduce the time he spends holding the fish. But
it still doesn't alter the fact that the fish still fights.
"Barbless hooks do not reduce hooking mortality, period," Goeman
said.
Nevertheless, most released fish survive to fight another day.
There are many tales of fish that got away that end up being caught
by another angler the same day.
Graham Marsden
