Comparing Electronic Monitoring and human observer collected fishery data in the tropical purse seine operating in the Western and Central Pacific Ocean
Electronic Monitory (EM) systems have been proven a valid tool for collecting fishery
dependent data. They are being widely used in many fisheries as a complement or
alternative to human observers to increase the monitoring coverage of fisheries.
However, considering its wide application, following agreed minimum standard, it is
important to compare the congruence between the information collected by EM and
observers. We compared EM and two sets of different observer data collected on 6 trips
of tuna purse seiners in the Eastern and Western and Central Pacific Ocean to analyze
the similarity of fishing set type identification, estimation of tuna and bycatch catches
between both monitoring systems. Overall EM was a valid tool to estimate the type of
fishing set. Retained total catch of tunas by set was estimated by EM as reliable as that
by both observer programs and logbook. When comparing the information by set, EM
estimation of the main species, such as skipjack and bigeye and the combination of
bigeye/yellowfin, was proven to be less accurate but statistically similar to the estimates
made by both observers’ programs. EM tended to underestimate the retained catch of
skipjack in comparison to both observers estimates and slightly overestimate bigeye and
yellowfin, the overestimation being less pronounced for bigeye than for yellowfin. For
bycatch species, EM is able to identify main bycatch species as observers do. However,
the capability of EM to estimate the same number of bycatch items in comparison to
IATTC and WCPFC observers varies greatly by species group. For sharks, which are
the main bycatch issue in the FAD purse seine fishery, the overall congruence between
EM and observers was high. EM and IATTC observer identified a similar overall
number of individual sharks, however, WCPFC observers estimated lower number of
shark individuals than the other two monitoring systems when considering all trips
together.Versión del edito