Wednesday, February 8th, 2023
Wednesday, February 8th, 2023

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Louisiana doctoral student tracking fish

Lake Charles, La. (AP) – Who wouldn’t like to know where the
specks are on Calcasieu Lake, especially when you can have the
scoop almost a year in advance?

According to Jody Callihan, a doctoral student in LSU’s coastal
sciences department, some fish – about a third of all tagged ones –
spent December and January in Turner’s Bay.

“The highest number of fish always occurred at high tide, and
they may be moving in to feed,” said Callihan, who is heading a
speckled trout telemetry study on the lake as part of his
dissertation. “We see this pattern again and again and again. It
shows that fish behavior is very clearly linked to tide.”

In the spring and fall of 2007 and 2008, Callihan and volunteers
implanted acoustic tags in 172 specks. Fifty-nine receivers, placed
throughout the estuary from Lake Charles to the jetties, have
picked up more than 500,000 hits. program will conclude in
October.

Close to home

Callihan said scientists don’t know much about the movement
patterns of the fish or about their use of different estuary
habitats.

He presented preliminary results from his first full year of
data at a recent Coastal Conservation Association meeting in Lake
Charles. Many of the study’s volunteer anglers are CCA members.

“Most of these 65 fish were caught at the southern end of the
lake and released in the ship channel or at Nine Mile Cut,”
Callihan said. “We’ve had 210,000 hits from these fish, who range
in size from 12 to 27 inches.”

In addition to the action at Turner’s Bay, other hopping fishing
holes included Commissary Point, Long Point, West Cove and the cuts
near West Cove – areas that may be favorite feeding spots, Callihan
said.

“In the cuts at West Cove, the incoming tide may have water
pummeling through these narrow cuts, where trout like to hang out
and ambush shrimp,” he said. “Most hot spots were in the main body
of the lake and the upper estuary and are generally areas of higher
current velocities -higher than we would expect in the middle
portion of the lake.”

The study, which also monitors how sex affects fish movement,
has found that males and females regularly appear in the southern
zone of Big Lake and in West Cove the entire year _ though that may
just be because that’s where they were released, Callihan said. The
fish in the study, he said, stayed within 10 miles of the area.

Not so hot spots

“Artificial reefs are not utilized as heavily as preexisting
natural oyster reefs,” Callihan said. “Even though these fish did
not use artificial reefs extensively, bear in mind that these reefs
are pretty new. It may take time for a community to develop before
fish really use these for breeding habitats.”

Also low on the hit list was the ship channel, which Callihan
said was more of a migratory route for fish. He said fish of either
sex were detected along the lake’s southeast bank less than 5
percent of the time from May through August. Sex accounts for some
of the pattern, Callihan said.

“Salinity has a strong effect on fish distribution. Only males
use the Calcasieu River zone,” he said. “Males are more tolerant of
low salinities than females. Larger fish are also more sensitive to
changes in water quality and salinity.”

Callihan said a salinity of less than six caused females to seek
areas with higher salinities.

Change of seasons

“We saw the steepest decline in the number of fish that are
alive in the summer each year,” Callihan said. “Part of the reason
for this was that some fish moved offshore during the summer.

“We had 12 total fish – 23 percent of our tagged fish – move
offshore from these release groups during the summer. None of them
returned to the estuary.”

There was no size or sex trend with the offshore movement – both
small and large males and females headed out – but Callihan said
the movement coincided with the peek spawning season for
specks.

“Habitat use by spotted sea trout is not random,” Callihan said.
“There were certain areas of the lake they liked at certain times
of the year.”

He played an animated movie of movement for eight trophy specks
let go during spring of 2008; they were 24-27 inches and 5-7 pounds
at the time of their release. The movie moved at a rate of
one-second per day.

“Overall, I think that our telemetry method was successful, but
we still have lots of data analysis to do,” Callihan said. “The
information is challenging to look at, and tools like the animated
movie provide a new way to look at the data.”

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