Reproductive Biology of Three Commercially Important Hemiramphid Species in South-eastern Australia |
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Authors: | Julian M Hughes John Stewart |
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Institution: | (1) New South Wales Department of Primary Industries, Cronulla Fisheries Research Centre, PO Box 21, 2230 Cronulla, NSW, Australia |
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Abstract: | Synopsis The reproductive biology of eastern sea garfish Hyporhamphus australis, eastern river garfish H. regularis ardelio, and snub-nosed garfish Arrhamphus sclerolepis were described throughout their respective ranges in the coastal waters of New South Wales (NSW), Australia. Peaks in gonadosomatic
indices indicated that spawning of eastern sea garfish occurred in late spring and early summer (November–December) on the
south coast of NSW, and in winter and early spring (June–September) on the north coast. Eastern river garfish spawned between
July and December in NSW estuaries and snub-nosed garfish spawned between October and January in the Clarence River. The sex
ratios in commercial catches of eastern sea garfish from the north coast of NSW were biased toward male fish, but approached
equality for fish caught from the south coast. Sex ratios were significantly biased toward female snub-nosed garfish, and
female eastern river garfish from all estuaries sampled. Mean (±SE) batch fecundity was 1498 ± 110 (range: 98 – 3449) ripe
oocytes per female for eastern sea garfish, 917 ± 36 (range: 102 – 2268) ripe oocytes per female for eastern river garfish,
and 716 ± 104 (range: 20 – 2956) ripe oocytes per female for snub-nosed garfish across the range of mature sizes examined.
There was a linear relationship between batch fecundity and fish size for all three species of garfish. Eastern sea garfish
approached 50% maturity at a larger size than snub-nosed, or eastern river garfish. Size at 50% maturity was similar for male
and female eastern river and snub-nosed garfish, but male eastern sea garfish matured at a significantly smaller size than
females. All three species appear capable of spawning in the spawning season immediately following the one in which they were
born. Mature female fish of all three species had distributions of oocyte diameters consisting of three or four modes, which
strongly suggests asynchronous oocyte development and a multiple spawning strategy during the spawning season. Implications
for the management of garfish fisheries in NSW are also discussed. |
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Keywords: | hemiramphidae Hyporhamphus Arrhamphus gonadosomatic index size-at-maturity sex ratio batch fecundity asynchronous oocyte development |
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