For fish categories that showed significant catch changes between the periods, trends over time with monthly LPUE values were estimated through time series analysis.
Of these, only whitemouth croaker, largehead hairtail, Jamaica weakfish, flounders and catfishes showed no significant difference in the LPUE values among the years, with P-values of 0.
Figure 3 shows monthly values of LPUE for fish categories that presented significant differences between the BEPA and AEPA periods.
The grey triggerfish LPUE values increased significantly between the two periods.
Mann-Whitney test of landings (kg) per unit effort (days at sea) between the periods for those categories that showed significant difference of LPUE over the years.
Either scenario, 1 or 2, allows for a comparison of the relative values of estimated effort and LPUE within a time series.
Squid abundance, measured as LPUE, also showed a pronounced drop and rapid increase in response to the El Nino.
Indeed, the high LPUE in the present study in late 1999 and early 2000 points to increased squid abundance in response to a more productive environment.
We were concerned that an underestimation of effort along the mainland coast would explain this study's post-El Nino increase in LPUE.