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

Billfishes are large highly migratory fish species found in all the world's oceans. Several studies have been developed to understand how oceanographic and environmental variables influence marine species distribution, but little information exists about the size distribution of these important species. 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). Generalized Additive Models (GAMs) were used to describe the effect of environmental factors on the size of billfish species bycaught by the tuna purse-seine fishery in the EPO. Results suggest some or high degree of segregation of the billfishes related to its size and driven by environmental preferences. For striped marlin, black marlin, and blue marlin larger individuals are present at the south of 5 degrees N, where colder and highly productive waters are present while, smaller sailfish were present in warmer and productive areas located at north of 5 degrees N. These results may be useful to conduct further studies to detect nursery, reproduction or feeding areas of billfishes in both coastal and oceanic waters.

Automated summary

The research highlights the influence of environmental conditions on the size distribution of billfish species, indicating a clear segregation driven by size and environmental preferences in the eastern Pacific Ocean.