PROGRESS IN BIOLOGICAL INQUIRIES, 1939 5S 
period of another season, will cause overrepresentation, of the small 
size in the one season as compared with the other. During 1938-39 
a method of weighting the samples to eliminate part of the distortion 
has been devised. Unfortunately, that method results in each run 
being given equal weight, and, though it is perhaps an improve- 
ment over an unweighted series, it still does not represent the 
relative abundance of the various sizes because the relative abun- 
dance of the fish in the various runs is not taken into account. 
A method of treatment which will accomplish the desired results 
remains to be discovered. Until then, our information on the rela- 
tive strength of year-classes in the commercial fishery, the rate at 
which they have been consumed by natural and fishing mortality, 
in short, the condition of the resource, can only be understood 
imperfectly. 
EARLY LIFE HISTORY 
It has been reported * that there is some relationship between tem- 
perature and successful survival. As yet it is unknown whether it 
is the temperature alone that governs survival, or whether it is other 
things associated with temperature, for example, ocean circulation. 
To investigate further the factors related to survival, a preliminary 
oceanographic survey of the waters off California, Oregon, and Lower 
California was carried on during the spring and early summer, when 
90 stations were occupied; some of them as much as 320 miles off- 
shore. The Scripps Institution of Oceanography cooperated by 
taking serial temperatures, making salinity and oxygen determina- 
tions, and phytoplankton and zooplankton hauls at all stations 
visited. The Institution is now studying the hydrographic data to 
elucidate the system of currents. 
The Bureau’s collections of fish eggs and larvae at the same stations 
will afford knowledge of the relationship between the distribution of 
young stages of pilchard and the various water masses in the cireula- 
tion pattern. Off central, southern, and Lower California, substan- 
tial numbers of young stages of the pilchard were found well offshore 
in a band lying 125-175 miles off Monterey, 75-125 miles off San 
Pedro, and 75 miles off Ensefiada. Thus the bulk of the planktonic 
stages were taken well outside the range in which most of the com- 
mercial fish are caught prior to the spawning season, indicating that 
the fish largely go offshore to spawn. No stations were occupied oft 
northern California, owing to rough weather. A few eggs were 
taken at widely scattered stations off the Oregon coast, although not 
enough of them were obtained to define their zone of distribution. 
The survey off Oregon was made rather early in the season, possibly 
before the climax of pilchard spawning had been reached, and con- 
versely in southern and Lower California rather late in the season, 
undoubtedly after the climax of spawning had passed. It was impos- 
sible to reach all parts of the area in the limited amount of time with 
only one boat. It is probable that the stations visited off central 
California were occupied near the time of the spawning peak in that 
locality. If so, the amount of spawning there was substantially less 
than in southern California. 
5 Progress in Biological Inquiries, 1938. 
