On any
good summer weekend, many in coastal Louisiana are out chasing
speckled trout. Of course, fishing for Louisiana’s most
popular estuarine fish isn’t limited to the summer.
Probably only in February do they get a slight break. With
all of that fishing pressure, how can they reproduce enough
to keep their population healthy?
One way
is by beginning to spawn while quite young and by spawning
often. Research indicates that in the Gulf of Mexico, more
females begin spawning by age 1, and some are mature at age
09 (before their first birthday). Such fish are 10 to 13 inches
long. Studies have shown that by age 1, 96% of trout females
in Louisiana are mature, 80% are mature in Mississippi, 78-100%
in northern Florida and 68% in Texas.
During
the April to September spawning period, female speckled trout
can spawn once every 4-5 days or 40 to 50 times per year.
Spawning activity seems to have two peaks, one in May and
another in August. Older fish and those spawned early in the
spawning season of the previous year produce the first peak.
The theory is that the August peak is partly due to fish spawned
late in the previous year coming into maturity. Speckled trout
seem to spawn more frequently at the beginning and end of
the season and less often during June or July. Older trout
spawn more frequently than young fish.
Spawning
is done at water temperatures of 71-93° F. About 4-6 hours
before spawning, the eggs to be spawned begin to swell with
water (hydration), roughly doubling in size, and then spawning
begins at dusk. Salinity of 20 parts per thousand (seawater
is 32-35 ppt) is ideal. At salinities below 10 ppt or over
45 ppt, the stress on speckled trout is so high that they
have little energy left for reproduction.
The advantage
of spawning at an early age is limited by the trout’s
size. Egg production for each spawn is from 8,400 to 11,200
eggs per ounce of body weight (minus the weight of the eggs).
Estimates on total annual egg production range from a low
28,000 for age 1 fish in Louisiana to 52 million for age 5
fish in Florida. (The low number for Louisiana fish may be
an underestimation when compared to other states.)
Download:
trout_romance.pdf
(44KB)
