Standardized yields of the sailfish (istiophorus platypterus) caught as bycatch of the spanish surface longline fishery targeting swordfish (xiphias gladius) in the indian ocean

Standardized yields of sailfish were obtained from 1,914 recorded trips (65.1*106 hooks) by the surface longline fleet targeting swordfish in the fishing areas of the Indian Ocean during the period 2003-2017. The observations represent about 90% of the total fishing effort of this fleet during this combined period. Roughly 50% of the trips recorded during this period showed a positive catch of these species (at least one fish). Because of the relatively low prevalence of this species in this fishery, the standardized yields were calculated using a Generalized Linear Mixed Model, assuming a delta-lognormal error distribution. An overall flat trend was predicted for the whole period considered, with some annual fluctuations. Some other considerations are also discussed