With
the growth in catch-and-release angling, it is a common belief
that fish that are released will “live to fight again
another day.” It can also be heard in tournament angling
circles that “bass are too valuable to keep.”
All of this is based on the assumption that released fish
survive. However, a high release mortality (death rate) can
limit the effectiveness of largemouth bass harvest regulations,
especially in areas with high catch rates.
In the
month of August, Texas Parks and Wildlife (TPW) biologists
conducted a release mortality study on largemouth bass in
Lake Umphrey, a small private lake in east Texas. Two trips
were made by four teams, with two anglers per team. Each team
used a different bait type: treble hook lures, plastic worms
fished “Carolina rigged,” live carp under a cork,
and live carp on the bottom. Each team fished until it had
30 bass over 14 inches long.
The hooking
location was recorded for all fish before they were tagged
and placed in the boats’ aerated live wells. If the
fish was bleeding, it was also noted. For deep-hooked fish,
the anglers were given the option of cutting the line and
leaving the hook in place, instead of removing the hook. No
fish were held in boat live wells longer than 15 minutes before
being transferred to a 20-foot deep floating nylon mesh cage.
There, the fish were held for 72 hours before release.
At the
end of the 72 hours, 22% of the bass had died. The death rate
was no higher for fish caught on live bait than for those
caught on artificial baits. On the first trip, mortality was
13% for live bait-caught fish, compared to 23% for artificial
baits. On the second trip, it was 28% and 23%. The mortality
rate was related to where the fish were hooked, however. It
was 48% for fish hooked in the throat, 17% for fish hooked
in the gill, and 20% for mouth-hooked fish. The percentage
of throat-hooked fish was highest with plastic worms.
Bleeding
was also important. Of the 240 fish captured, 19 were observed
to be bleeding and nine (47%) of these died. Bleeding was
observed more often for fish hooked in the throat (48%) and
gill (50%) than for fish hooked in the mouth (1%). Anglers
cut off and left hooks in 16 of 21 throat-hooked largemouth
bass. Eight (50%) of these fish and two of the five (40%)
throat-hooked fish from which the hook had been removed were
dead by 72 hours. For all fish, the larger the fish, the lower
the mortality was.
The biologists
concluded that the type of bait used had little effect on
release mortality, so banning live bait use would not improve
release survival. Also, since mortality occurred in mouth-hooked
fish, the least severe hooking location, just the action of
hooking, playing, landing, and hook removal adds substantially
to release mortality.
TPW also
conducted a monitoring study of a bass tournament at Lake
Fork, Texas. During this tournament, each two-person fishing
team was allowed to keep five bass measuring 14 inches and
longer and was allowed to cull their catches throughout the
day.
The biologists
monitored immediate and delayed mortality of several test
groups of bass—fish caught and immediately released;
fish which were caught, held in live wells and released (culled)
later in the day when larger fish were caught; and fish brought
to weigh-in at the end of the fishing day. These mortality
rates were compared to bass that the biologists collected
by electrofishing (shocking). All the bass were marked and
held in four large holding nets for 6 days following the tournament.
The bass
taken by electrofishing and held for comparison with hook-caught
fish suffered a 3.7% mortality rate. Those caught and released
immediately had 1.3% mortality, bass caught, held and culled
had 14.9% mortality, and fish brought to weigh-in had 39.1%
mortality. The researcher in charge stated that bass mortality
due to tournaments can be much higher than many fishermen
believe.
Download:
catch&release.pdf
(99KB)
