Changes in the purse-seine fleet fishing on floating objects and the need to monitor small vessels

There has been an increasing trend in the number of floating-object sets by both small (Classes 1-51) and large (Class-6) purse-seine vessels since about 2005 (Figure 1a), which correlates with a decreasing trend in purse-seine catch-per-set, to some degree, for all three major tropical tuna species (yellowfin, skipjack, and bigeye) in floating-object sets (Figure 1b). This change in the dynamics of the purse-seine fishery on floating objects has prompted the need for a review of the data available for Class 1-5 vessels for the purpose of fisheries management. Vessel logbooks, cannery records, and port-sampling data are collected from purse-seine vessels of all size classes. However, while large vessels have nearly 100% on-board observer coverage, trips by small vessels are rarely sampled by observer programs. Observer data provide important details about fishing activities and floating-object characteristics. A lack of detailed information on the fishing activities of small purse-seine vessels, particularly as regards sets on floating objects, may compromise the management of the purse-seine fishery.
This document presents a brief review of the catch and effort data available for small purse-seine vessels. In addition, data deficiencies with respect to bycatch information and floating-object characteristics are discussed.