Sr. Craig et al., Seasonal changes in the reproductive condition and body composition of free-ranging red drum, Sciaenops ocellatus, AQUACULTURE, 190(1-2), 2000, pp. 89-102
Adult red drum (Sciaenops ocellatus) from a wild, autumn (fall) spawning po
pulation were studied over a 1-year period to evaluate seasonal changes in
body composition in comparison with cultured red drum. Each month, female a
nd male fish were captured and blood sampled. Standard length and weight we
re measured, and gonads, liver, intraperitoneal fat (IPF), and a sample of
muscle tissue were collected from each fish. Gonadosomatic index (GSI), hep
atosomatic index (HSI), IPF ratio, protein and lipid composition of muscle
and liver tissues, and lipid class composition of liver samples were determ
ined for each fish. All tissue indices exhibited a similar seasonal cycle i
n both sexes, with highest HSI in spring (March-April) and maximal IPF rati
o in May, followed in September and October by minimal values for HSI and I
PF ratio. Whereas GSI was low, gonadal histology demonstrated activation of
spermatogenesis and oocyte development in July and August. Liver compositi
on varied dramatically throughout the year. Liver lipid content ranged from
7.4% of wet weight in November to 30.2% in August, with triglycerides (TG)
being the most abundant component at all times. Liver protein was more sta
ble, ranging from 11.5% in August to 16.3% in September. Muscle composition
was relatively constant, with muscle crude protein ranging from 20.5% to 2
5.6% of wet weight and muscle lipid ranging from 0.4% to 2.2% of wet weight
. These data indicate that red drum utilize the liver as a major depot for
lipid. Depletion of maximal lipid reserves from liver and IPF in late summe
r indicates that lipid stored during active spring and summer feeding suppl
ies energy for reproduction which is mobilized rapidly (within 1 month) in
this fall-spawning species. Body composition of wild fish is similar to tha
t of laboratory cultured red drum. (C) 2000 Elsevier Science B.V. All right
s reserved.