Spawn habitat suitability for albacore(Thunnus alalunga) in South-central Indian Ocean

Based on the data collected by Chinese tuna longliner operating in South-central Indian Ocean during Mar.to Apr.2009,the spawning habitat suitability(sHSI) of albacore(Thunnus alalunga) in the South-central Indian Ocean using an important indices that represent fish's reproduction ability,gonadsomatic index(GSI) and the habitat factors,Sea Surface Temperature(SST),Sea surface salinity(SSS),water temperature at 100 m depth(TEMP) and Dissolved Oxygen at 200 m depth(DO) were studied.The results showed that the optimum upper boundary quantile curves for SST-pGSI,SSS-pGSI,TEMP-pGSI and DO-pGSI were as follow: pGSISST0.55=159.47-12.20SST0.55+0.24SST20.55,pGSISSS0.70=527.22-28.51 SSS0.70 +0.39SSS20.70,pGSITEMP0.55=2.25-0.23TEMP0.55-0.01TEMP20.55 and pGSIDO0.70=53.71-17.66DO0.70+1.49DO20.70.The sHSI of albacore ranged 0.52 to 0.97 in the survey area.The sHSI was increased significantyly from north to south,and below 0.65 in the south of 25 S.The present study presented a newly methodology for further understanding the spatial distribution of spawning for bigeye tuna in the Indian Ocean.