PROGRESS IN BIOLOGICAL INQUIRIES, 1931 



461 



Table 1. — Sutmnary of offshore oceanographical work done in conjunction with cod, 

 haddock, mackerel, and shore-fish investigations, 1931 



• Albatross series. 



» Includes 9 horizontal zooplankton hauls at the surface, 



' 60-foot otter trawl. 



< 35-foot otter trawl, 



' Temperatures onlj*. 



EXPERIMENTAL REARING OF FISH LARV-S: 



As discussed in previous sections, many of the fluctuations in 

 yield of our food fishes are due to variations in the success of various 

 year classes pointing to critical stages in the early life history of the 

 species. Studies on oceanic conditions may reveal the causes for 

 excessive mortality in some years and nominal losses in others; but 

 the probability of ascertaining them might be enhanced greatly if 

 it were known what conditions of temperature, salinity, light, and 

 other physical and chemical properties are favorable to survival of 

 the newly hatched young of fishes, and what food materials must be 

 provided. 



Generally speaking, it has been impossible to rear the newly 

 hatched young of marine species of fish under laboratory conditions. 

 However, in the summer of 1929 and 1930 Louella E. Cable suc- 

 ceeded in rearing several fish through the larval stages in the Beau- 

 fort (N. C.) laboratory and in 1931 conducted experiments at the 



