SIZE SEGREGATION, SEX RATIOS PATTERNS OF THE SWORDFISH (Xiphias gladius) CAUGHT BY THE SPANISH SURFACE LONGLINE FLEET IN AREAS OUT OF THE ATLANTIC OCEAN AND METHODOLOGICAL DISCUSSION ON GONADAL INDICES.

This paper presents a description of the overall sex ratio at size for the swordfish (Xiphias gladius) caught by the Spanish surface longline fleet in some areas outside of the Atlantic (Pacific Ocean) which could be very useful for comparison with some Atlantic patterns described in previous papers. The results obtained from the sampling of 9693 swordfish specimens point to differences in sex ratio values, both overall and by size class as in the case of the Atlantic areas, between the areas of the NE Pacific (warm waters) and the SE Pacific (temperate waters). In addition, an analysis of the gonad weight of 3150 female swordfish specimens, resulted in gonad indices (GI), using different definitions, which are inter-related and preliminary equivalences were obtained. As in the case of the East Atlantic areas, the results suggest that swordfish females from the areas under study were not generally found to be in an advanced stage of reproduction, barring a few possible cases, which would imply that they were about to spawn. This result agrees with the situation observed in the eastern areas of the Atlantic where spawning females were not detected until now, suggesting that the spawning of the female swordfish is more rare or sporadic in eastern areas of the Oceans probably because of the more favourable thermal surface layer structure in westerns areas. RESUME