Atlas of July Oceanographic Conditions in the 

 Northeast Pacific Ocean, 1961-64 



BY 



R. W. OWEN, JR., Oceanographer 



Bureau of Commercial Fisheries Tuna Resources Laboratory 

 La Jolla, Calif. 92037 



ABSTRACT 



An atlas of July oceanographic conditions in 1961-64 is presented for the 

 region bounded by the coast of Oregon-Washington and long. 132° W. The atlas 

 consists of charts that show distributions of temperature, salinity, density, oxygen 

 concentration, thickness of mixed layer, dynamic height, chlorophyll _a_ concentra- 

 tion, and catch of albacore, Thunnus alalunga (Bonnaterre), at the time of year 

 when albacore first become available to the commercialfishery of the region. Some 

 remarks on the albacore catch and the environment are included. 



INTRODUCTION 



Marked variation of the annual commercial 

 catch of albacore, Thunnus alalunga (Bonna- 

 terre), characterizes the fishery off the coast 

 of Washington and Oregon. This variation, 

 due in part to changes in fishing effort, ap- 

 pears to be related to the nature of the environ- 

 ment as well (Alverson, 1961; Johnson, 1962). 

 Adverse economic effects of catch variation 

 and the desire for efficient use of the albacore 

 resource have prompted a series of cruises 

 to characterize the environment that albacore 

 encounter annually off the west coast of North 

 America, and to examine relations between 

 albacore and measurable characteristics of 

 this environment. The series was a coopera- 

 tive venture of the Bureau of Commercial 

 Fisheries Tuna Resources Laboratory, La 

 Jolla, Calif., with the Bureau's Exploratory 

 Fishing and Gear Research Base, Seattle, 

 Wash. The survey vessel, M/V John N. Cobb , 

 was operated by the latter agency. 



Albacore usually first become available to 

 the commercial fishery off Oregon and Wash- 

 ington in mid- July. The present work is an 

 atlas of oceanographic conditions in the region 

 off the coast of Oregon and Washington during 

 July in 1961-64. The atlas contains charts of 

 horizontal distributions of temperature, sa- 

 linity, density, and oxygen concentration in 

 the surface layer (figs. 1-16), at 100 m. depth 

 (figs. 17-32), and at 500 m. depth (figs. 33-48), 

 as well as some vertical sections of these 

 properties (figs. 49-61). Corresponding dis- 



tribution charts are given that depict mixed- 

 layer depth (figs. 62-65), geopotential topog- 

 raphy of the sea surface (figs. 66-69), chloro- 

 phyll a_ at the sea surface (figs. 70-73), and 

 vertical profiles of chlorophyll _a_ in July 1964 

 (fig. 74), For comparison, July distributions 

 of albacore catch by research vessels are 

 depicted (figs. 75-78). 



These presentations are intended for use by 

 oceanographers and fishery scientists, as 

 well as for use as a supplement to a descrip- 

 tion of oceanographic processes that produce 

 and modify the distribution of variables and 

 their relation to the albacore fishery (Owen, 

 manuscript). 1 



Exploratory fishing and albacore-oceanog- 

 raphy cruises off Washington and Oregon 

 previous to 1961 have been listed by Owen 

 (1963). Since 1961, no other reports have 

 been published, although albacore trolling has 

 been conducted on oceanographic cruises by 

 R/V Brown Bear of the Department of Oceanog- 

 raphy, University of Washington, and by R/V 

 Acona , of the Department of Oceanography, 

 Oregon State University, as well as on M/V 

 Cobb cruises. In addition, the Fish Commis- 

 sion of Oregon made exploratory fishing 

 cruises early in the albacore season in July 

 1962 and July 1964. 2 



1 Owen, Robert W. Manuscript. Oceanographic condi- 

 tions off the American Pacific Northwest and their rela- 

 tion to the albacore fishery. 



2 Unpublished reports of the Fish Commission of Oregon, 

 dated July 27, 1962, and August 20, 1964. 



