Dt. Brewer et al., ASPECTS OF THE BIOLOGY OF CARANX-BUCCULENTUS (TELEOSTEI, CARANGIDAE) FROM THE GULF OF CARPENTARIA, AUSTRALIA, Australian Journal of Marine and Freshwater Research, 45(3), 1994, pp. 413-427
Caranx bucculentus is the most abundant secondary consumer and the mos
t important predator of commercially important penaeids in the Gulf of
Carpentaria. More than 18 000 individuals of this species were collec
ted from 406 trawls during 13 cruises in the Gulf of Carpentaria from
1986 to 1991. The species was most abundant in coastal waters, with a
maximum biomass at a depth of 28.1 m. Catches were higher in prawn-tra
wling grounds than elsewhere in the gulf, and prawns comprised a great
er proportion of the diet than is the case for other predatory fishes.
Interannual variations in biomass occurred, but there were no differe
nces between cruises or seasons. The decreased catches at night may ha
ve resulted from vertical diel migration of C. bucculentus. Sexual mat
urity is reached at 110 mm standard length and about one year of age,
which is much younger than in congeners. Back-calculated birth dates o
f C. bucculentus show year-round recruitment that peaks in the pre-wet
season months of spring, and gonadosomatic index values are generally
higher in the pre-wet season than in the wet season. Gonadosomatic in
dex values remain relatively high (> 1.0), which indicates continuous
spawning by C. bucculentus in the gulf. Other large tropical species o
f Caranx spawn annually, in summer. C. bucculentus fecundities range f
rom 18 000 eggs for a 120-mm fish to about 650 000 eggs for a 460-mm f
ish. A possible switch is seen in the sex ratio - males seem to predom
inate at smaller sizes, whereas females seem to predominate among bigg
er fish. MULTIFAN length-frequency analysis gave values of L(infinity)
= 538.8 mm (8 years old) and K = 0.305 year-1. A growth rate of 82.2
mm year-1 at L(infinity)/2 is comparable to the growth rates of other
tropical carangids. The diet of C. bucculentus throughout the gulf is
dominated by epibenthic crustaceans and teleosts.