Email this article (Login required)
Email the author (Login required) Species catch composition, length structure and reproductive indices of swordfish (Xiphias gladius) at Easter Island zone
DOI: https://doi.org/10.3856/vol37-issue1-fulltext-7
Abstract
The species composition, size distribution, and gonadal index (GI) of swordfish (Xiphias gladius) are reported from catches obtained by longliners in the zone of Easter Island in the southeastern Pacific. Five cruises were made during the summer season between 2001 and 2006 completing a total of 150 fishing sets. A total of 3,781 fish belonging to 24 species were registered, of which 17 were commercial and 6 were bycatch. Of the total, 44.1% were swordfish, 28.3% sharks, 12.1% marlins, 8.4% tunas and 7.1% other teleosts. Amongst the sharks the most important species was the blue shark (Prionace glauca, 16.5%) followed by the brown shark (Carcharhinus spp., 6.9%). Amongst the tunas and istiophorids, striped marlin (Tetrapturus audax, 8.0%) and yellowfin tuna (Thunnus albacares, 4.9%) were also important (≥ 4% in number). The number of units by species, the nominal yield in number and weight and the gutted average weight are reported in addition to size statistics. The population structure of swordfish was dominated by males and differences in the average length between sexes were not found. Individuals with high values of GI were observed during every survey, mainly during December-February which suggests a reproductive area for this species. The blue shark showed a predominance of males, and differences in the average length between sexes were observed, possibly due to a spatial and temporal segregation.
