by fly addict » January 26th, 2010, 9:15 pm
I read this article in another newsletter and thought it was interesting.
Mark
One of the joys of living in California is that we can
and do fish throughout the year. But this benefit
includes a burden. For the last few years, I have
been reminding people on our winter fishing trips,
especially the January and February trips to the Lower
Owens for the new anglers, that removing fish from
the water to remove the hook or to take photographs
can be hazardous to fish. The reason I gave is that
the water is often warmer than the air temperature
and sometimes the gill filaments will freeze instantly
when the fish is lifted from its native environment. A
frozen gill filament is irreparably destroyed.
I’ve often heard anglers say when photographing
their trophy to hold your breath while you have the
fish out of water to appreciate its predicament. The
problem, as I see it anyway, is that when you tell some
one to hold his breath, he will inhale to be sure he has
an ample supply. But I know that when I fell out of
the boat on the Bighorn, I did not have the presence
of mind to inhale on the way into the water. Rather
I was in a state of shock that the boat was no longer
underneath me.
I would imagine a fish that is rapidly changing
from water to air is similarly challenged. Besides, he
can’t store oxygen with a big gulp of water.
I don’t recall where I read about the frozen gill
problem but it made sense to me. Recently, an article
appeared in the winter 2010 edition of Flyfishing
& Tying Journal entitled “Fish Out of Water”. The
author is an angler, photographer and biologist. The
genesis of the article was his observation that the
number of states is growing which now require that
fish to be released, must remain in the water.
We practice Catch and Release Fishing as a method
of preserving the fishing enjoyment for others and
for future generations. But the author was driven by
the question “What science is available to support the
new regulations?” While he notes there is a paucity of
scientific literature, initial studies are quite revealing
and of deep concern.
In one study, Brook trout were chased by hand for 30
seconds in 50 degree water. Then they were subjected
to swimming stress tests to measure their ability to
swim after being removed from the water for 0, 30,
60 and 120seconds. While the fish that was kept out
of the water for 30 and 60 seconds performed about
as well as the control fish (which were not subjected
to air), the fish that were kept out of water for 120
seconds failed to swim at all. Since this was not a
mortality study, the researchers did not determine
how well the 30 and 60 seconds fish swam or whether
they could have escaped their natural predators.
A mortality study performed on Rainbow trout
provided some insight. All fish exposed to the air
experienced a drop in oxygen levels to 20% of the
control group. The results changed with vigorous
exercise (read “playing the fish”). The survival rate
of fish not exposed to air after exercise dropped to
88%.
But fish out of water for 30 or 60 seconds (after exercise)
survived 62% and 28% of the time, respectively. And
all the fish exposed to air experienced some adhesion
of the gill filaments and inhibited gas exchange. Not
just frozen gill filaments!
Another study that was performed on Rainbows
exposed the trout to exercise and then electroshock
after which the researchers would keep the trout out
of water from 0 to 4 minutes. The bottom line of this
study is that the decreased swimming function lasted
from one to six hours. Enter the fish hawks!
While lamenting the absence of a significant body
of empirical experimentation and data, the author
clearly is concerned that a fish out of water will
be stressed both biochemically and in its future
performance regardless of the time involved. These
studies were all performed at 50 degree water.
Water higher in temperature loses its ability to hold
dissolved oxygen. So these limited results are not
transferable there. Similarly, larger fish have a greater
need for oxygen; the suggestion is made not to
remove the head from water at all. And maybe there
is a difference between the survivability of hatchery
trout and wild natives. Since even a small exposure to air (especially in Los
Angeles) is detrimental, it behooves us to keep our
finned friends in the water as much as possible.
For the novices, this means that your fly rod must
be suitable for your target fish because you must
get your trophy under control and spend the least
amount of time playing or fighting your fish. The use
of barbless hooks will make easy work of removing
the fly while the fish is still in the water.
But keep your forceps handy. You want your fish to
have good memories of being caught so that it will
readily take a fly in the future!.
Make Fly Fishing Great Again!