22 
BULLETIN OF THE BUREAU OF FISHERIES 
same species), small mollusks, and plant debris are all eaten. Often it appears to eat 
the mud or sand for the organic matter which it contains. The presence of consider- 
able amounts of mud or sand in the intestine appears to be the rule. In aquaria, fish 
or other shrimp are readily and successfully attacked and eaten. 
Convincing evidence is at hand that the behavior of the shrimp is influenced by 
temperature and salinity, but as yet no observations have been made on its reac- 
tions to these stimuli or to others such as light, hydrogen-ion concentration, and 
oxygen tension. Early work on these important features of the shrimp’s behavior 
occupies a prominent place in the program of the cooperative investigation. 
DEPLETION AND PROTECTION 
The shrimp investigation was initiated by the Federal and State Governments 
to supply the biological information necessary to guide analysis of the state of the 
fishery and to permit the framing of effective protective legislation when such is needed. 
It is not possible here to discuss in detail the bearing of the facts presented in this 
report upon the questions of depletion and protection; the intention is to do this in a 
subsequent publication. Here we may only indicate the lines which such a discussion 
must take. 
First, it should be emphasized that depletion can only be detected by a careful 
analysis of the abundance of shrimp and that knowledge of abundance requires ade- 
quate statistical data. Existing catch statistics are inadequate, since they do not 
show the effort by which the indicated total catches were obtained. In addition we 
must know the amount of gear and number of men, or the individual boat catches must 
be recorded for analysis. Improvements in the method of gathering statistics have 
recently been made by Louisiana, and it is to be hoped that all of the eight South 
Atlantic and Gulf States will so modify their regulations covering the reporting of fish 
taken as to make possible the future analysis of abundance. 
Fortunately it is not necessary to take an alarmist attitude, as we have obtained 
no evidence of serious depletion. At the same time common prudence should make 
impossible a complacent inaction until depletion is easy to see and hard to remedy. 
While there is yet time a concentrated effort should be made to institute the collection 
of statistics which may be used effectively in the immediate future. 
In the absence of evidence of serious depletion at the present time we are unwill- 
ing to urge increased stringency of existing regulatory measures. We shall therefore 
merely suggest the bearing of the facts of the life history of the shrimp on the prob- 
lems of protection and indicate the types of restriction which may be employed 
when analysis of the catch statistics indicates that additional protection is needed. 
The outstanding features of the life history of the shrimp which may affect the 
question of its resistance to overfishing are: (1) Its short life span of 1 year, (2) its 
extended breeding season of about 5 months, (3) the very large number of eggs pro- 
duced, and (4) its extensive habitat in the littoral waters of the South Atlantic and 
Gulf. 
The shrimp’s life span of 1 year, shorter than that of any other important eco- 
nomic animal, is clearly an unfavorable factor. The shrimp fishery must obviously 
lack the stability shown, for example, by the halibut fishery, where animals from 7 
to 20 years of age appear in the catch and the entire failure of the young of any 
particular year would not seriously reduce the total. When the pressure of over- 
