EASTERN AREA CRUISE NUMBER FOUR This report is a summary of observations and collections made by P.O.B.S.P. personnel in the eastern Pacific Ocean from 21 February until 02 March, 1967. Participating personnel included Brian Harrington (biologist-in-charge), David Burckhalter, and James Lewis. Superior cooperation was again received from the officers and crew of the U.S.N.S. SHEARWATER (T-AG 177). The grid track (see map 1) was followed accurately. Hourly LORAN or sun-line fixes insured that all diurnal positions were reliable within five miles, and dead reckon- ing of positions during nocturnal hours are probably accurate within ten miles. This report is divided into two sections: the first deals with the eastern grid survey while the second summarizes the non-grid portion of the cruise. Eastern Pacific Grid Survey No.3 The eastern grid survey was conducted from 0745 hours 22 February until 0310 hours 02 March, 1967. A total of 89.0 hours of diurnal observations was conducted over 849 linear miles. Diurnal grid observations are summarized in table 1. In addition 14.4 hours of nocturnal observations were conducted and are summarized in table 5. Weather data during this survey were recorded on appropriate forms and ADP sheets. In general, light winds and seas predominated. This probably favors a larger number of bird and mammal sightings than would have been record- ed were conditions similar to that of the last two cruises. However, no allowance has been made in any of the tables or species discussions as the effect of varying conditions was not determined. Flocking activity was again low, but a few instances are worth mention. First, an area of concentrations of Fulmar mentioned in the last two reports was crossed again during this cruise. This time, however, the birds were much more spread out. While the total for the day is about the same as on the las t two cruises, the birds were noted over three times as large an area. As before,