Reproductive biology of blue marlin (Makaira nigricans) in the western Pacific Ocean
The reproductive biologyof blue marlin (Makaira nigricans)was assessed from 1001 fish (rangingfrom 121 to 275 cm in eye-to-forklength; EFL) caught by Taiwaneseoffshore longliners in the westernPacific Ocean from September 2000to December 2001 and from 843 gonadsamples from these fish, The overallsex ratio of the catch was approximately1:1 dur ing the samplingperiod, but blue marlin are sexuallydimorphic; females are larger thanmales. Reproductive activity (assessedby histology), a gonadosomatic index,and the distribution of oocyte diameters,indicated that spawning occurredpredominantly from May to September.The estimated sizes-at-maturity(EFL50) were 179.76 ±1.01 cm (mean±standard error) for females and 130±1 cm EFL for males. Blue marlin aremultiple spawners and oocytes developasynchronously. The proportion ofmature females with ovaries containingpostovulatory follicles (0.41) andhydrated oocytes (0.34) indicated thatthe blue marlin spawned once every2–3 days on average. Batch fecundity(BF) for 26 females with themost advanced oocytes (≥1000 μm),but without postovulatory follicles,ranged from 2.11 to 13.50 millioneggs (6.94 ± 0.54 million eggs). Therelationships between batch fecundity(BF, in millions of eggs) andEFL and round weight (RW, kg) wereBF = 3.29 × 10 –12 EFL5.31 (r2 = 0.70)and BF = 1.59 × 10–3 RW 1.73 (r2= 0.67),respectively. The parameters estimatedin this study are key informationfor stock assessments of bluemarlin in the western Pacific Oceanand will contribute to the conservationand sustainable yield of
| Main Authors: | , , , |
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| Format: | article biblioteca |
| Language: | English |
| Published: |
2009
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| Subjects: | Biology, Ecology, Fisheries, |
| Online Access: | http://hdl.handle.net/1834/25423 |
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