SCIENTIFIC COMMITTEE FOURTH REGULAR SESSION 11-22 August 2008 Port Moresby, Papua New Guinea REPRODUCTIVE ACTIVITY OF SWORDFISH (Xiphias gladius) IN THE PACIFIC OCEAN ON THE BASIS OF DIFFERENT MACROSCOPIC INDICATORS

A total of 23,639 swordfish females were analysed. The percentage of females larger that 145 cm shows important differences among areas. Maximum percentages were obtained in temperate waters South of 25º S and the lowest values in warm areas where small females were observed. The overall sex-ratio obtained was 51%. The sex-ratios at size suggest that females are predominant as of 170 cm although different patterns of sex-ratio at size were obtained between zones. The gonad index detects areas as producing the most intense maturation activity in females, ranging from the central Pacific between 10ºN and 10ºS to the West of 120ºW where the greatest gonad development was observed. The results would indicate that reproductive activity is mostly carried out in certain areas of the central-western Pacific but that there may also be sporadic-seasonal or moderate reproductive events in some of the other areas adjacent to these. At the same time, the SE Pacific show resting females with active feeding behaviour. The most active areas with maturity events are linked to warm waters where the characteristic spawning patters of sex-ratio at size are caused by the higher abundance/catchability of males over females within particular size ranges. The results match well with similar indicators observed for the Atlantic swordfish. However, the Pacific shows somewhat broader warm areas than the Atlantic, suggesting that the potential spawning areas for the Pacific swordfish could be relatively broader and eastern than those reported for the Atlantic.