Spatial segregation by size of billfishes bycaught by the tuna purse-seine fishery in the Eastern Pacific Ocean

Osman Crespo Neto

Billfishes are large highly migratory fish species found in all the world’s oceans. Several studies have been developed to understand how oceanographic environmental variables influence marine species distribution. The main goal of this research was to describe the environmental conditions driving segregation by size of six billfish species on the eastern Pacific Ocean (EPO). For this, Generalized Additive Models (GAMs) were used. Best-fitted models were used to describe spatiotemporal distribution of billfishes’ size in the EPO. Results showed marked spatial segregation by size for striped marlin, black marlin and blue marlin, with larger individuals to be present at south of 5°N, where colder and highly productive waters are present. Larger swordfish were predicted to occur in cold and offshore waters. Larger shortbill spearfish were found to be present close to the coast. Smaller sailfish were present in warmer and highly productive areas located at north of 5°N.