PROGRESS IN BIOLOGICAL INQUIRIES, 1938 QY 
of river flow. For example, in 1938 most of the eggs taken in the 
plankton were dead. This may merely represent oversampling of 
the surface levels, for all plankton collections were made by surface 
nets. Further observations will be made in 1939 using bottom nets. 
Such observations are expected to be of great value in estimating 
the optimum spawning escapement and also as a basis for estimating 
the most suitable size for releasing young shad produced in hatcheries, 
Mr. Pearson conducted experiments im rearing shad fry in bass 
ponds at the Edenton, N. C.,and the Orangeburg, S.C. , Hatcheries, At 
the former station 6, 500 young shad grew “to a mean length of 35 mm. 
(18% inches) in 35 days in April and early May. The pond was 
drained and an attempt made to rear a second lot in the same pond. 
Only 500 fish survived. It is not known whether this was the result 
of diminished food production during the summer or to the activities 
of predators accidentally introduced, 
As a working hypothesis for the shad investigation, it has been 
assumed that the majority of the shad return to the river in which 
they were spawned. The correctness of this assumption is being 
tested from several angles. The tagging experiments which were 
intended primarily to measure fishing intensity will also indicate 
whether adult shad seek the same river each time they spawn. (Five 
shad have been recaptured, after a lapse of a year, in the same river 
or 1n estuaries en route.) Vertebral counts of adult shad are being 
compared with those of juveniles taken in connection with the early 
life history studies. The scales of adult shad from each of several 
rivers are being compared with those of young shad. Marked differ- 
ences have been noted in the size and appearance of the stream- 
growth portion of the scales from different rivers, but until data 
from other years are available it cannot be determined whether these 
differences are characteristic of each year’s brood in the individual 
streams. Attempts to tag juveniles have been unsuccessful thus far, 
but further experiments are planned. 
SHRIMP INVESTIGATIONS 
Minton J. LInpNER, 77 charge 
With an annual catch averaging well over 100,000,000 pounds, the 
shrimp fishery is the most important marine food resource of the 
South Atlantic and Gulf States. The Shrimp Investigations are 
designed to provide a thorough knowledge of the life history, migra- 
tions, ecological relationships, and abundance of this first- ranking 
marine organism of the Southern States as a basis for its intelligent 
conservation. 
All the members of the scientific staff which, in addition to Mr. 
Lindner, includes William W. Anderson and C. Howard Baltzo, 
have been associated at different times during the year with each of 
the various field investigations undertaken. In’ addition to the 
Bureau employees, Albert Collier, Marine Biologist of the Texas 
Game, Fish, and Oyster Commission, has been activ ely engaged in 
conducting a cooperative research program in Texas under “the gen- 
eral direction of Mr. Lindner. The Louisiana Dey partment of Con- 
servation has continued to furnish office and laboratory s space In 
New Orleans for the headquarters of the investigation. In October, 
