Effects of environmental factors on the spatio-temporal distribution of striped marlin catch rates off Cabo San Lucas, Baja California Sur, Mexico

The striped marlin is the primary target of the sport fishery operating out of Cabo San Lucas, Baja California Sur, Mexico. Recreational fishery log books indicated that striped marlin constitute approximately 80% of annual billfish catches by the local sport fishing fleet. Generalized additive models were used to identify major environmental factors that affect the distribution of striped marlin where the recreational fishery operates. For statistical modeling, the nominal catch rate (number of fish per trip) was used as the response variable and environmental, spatial, and temporal variables were used as the predictor variables. Exceptionally high catch rates were recorded in late 2008 and early 2009 (>5 striped marlin per trip), which followed observations of high concentrations of chlorophyll-a during the previous six months. Seasonal variations with greater catch rates during the late fall and winter were found. The best model showed that high catch rate of striped marlin occurs when warm temperatures (26-28°C), high chlorophyll-a concentration (>1mgm^-3), and negative values of PDO index (<-1) are present, mainly during late autumn and early winter (December-February). Physical factors such as geographical position and depth of seafloor, showed that highest catch rates are present in western coast of Los Cabos (centered at 23°N, 110°W: Golden Gate bank). Bathymetry data with higher spatial resolution (~4×4km) showed the presence of seamounts in this hot spot area for striped marlin.