Standardized catch rates of shortfin mako (Isurus oxyrinchus) caught by the Spanish surface longline fishery targeting swordfish in the Atlantic ocean during the period 1990-2010

Standardized catches per unit of effort (in number and weight) were obtained for the Atlantic shortfin mako (Isurus oxyrinchus) using General Linear Modeling (GLM) procedures based on trip data from the Spanish surface longline fleet targeting swordfish in the North and South Atlantic Ocean over the period 1990-2010. In all cases area was considered to be the most relevant factor in explaining CPUE variability. Area, area* quarter and ratio were the most important factors in the North Atlantic, and area, year and quarter or area* quarter in the South Atlantic. Other factors were also identified as significant but with a minor effect on CPUE variability. Part of the CPUE variability was explained by the targeting criteria or ratio between the two most prevalent species in the catches, especially in the North Atlantic case. The significant models explained between 35% and 44% of CPUE variability. The mean variability of the predicted standardized CPUE between pairs of consecutive years was between 14% and 16% or around +2% when their absolute increments or both positive and negative increments were considered, respectively.