Report of ecosystem studies conducted during the 1988 eastern tropical Pacific dolphin survey on the research vessel McArthur.

The National Marine Fisheries Service (NMFS) has the responsibility of assessing the status of dolphin stocks affected by the tuna purse-seine fishery in the eastern tropical Pacific (ETP) . In 1988, the Southwest Fisheries Center (SWFC) conducted the third survey of a six-year program to monitor population trends in ETP dolphin stocks (Jackson and Holt, 1989). Two NOAA research vessels were used, the McArthur and the David Starr Jordan (hereafter referred to as Jordan) . The vessels operated concurrently in the ETP from July 28 through December 6, 1988. Approximately the same area and time period are surveyed during each year of the program. As part of this monitoring program, the SWFC is also studying the physical and biological environment inhabited by the dolphins. This ecosystem approach will facilitate the interpretation of dolphin population trends detected by these surveys, and will provide information necessary for understanding the biological basis of ETP dolphin distribution and abundance. The physical oceanographic research of the program is being carried out jointly with NOAAIs Atlantic Oceanographic and Meteorological Laboratory (AOML), as part of their contribution to the long-term Eastern Pacific Ocean Climate Study (EPOCS) and Tropical Ocean Global Atmosphere (TOGA) programs. This report describes the types of data collected and sampling techniques used, and summarizes data collected (including disposition of the data) for the environmental studies conducted aboard the McArthur. Results from the Jordan are available in a separate report (Lierheimer et al., 1989).