LIFE HISTORY OF THE COMMON SHRIMP 
23 
fishing begins to be felt the shrimp will show sudden and violent fluctuations probably 
disastrous to the fishery. 
Its extended breeding season of at least 4 % months, longer than that of the 
majority of animals of economic importance, and the large number of eggs produced 
are factors very favorable to the shrimp, since they render almost impossible the 
failure of an entire breeding season. 
The South Atlantic and Gulf coasts, cut by a multitude of tidal rivers and 
bayous, furnish an unequaled extent of shallow, littoral waters of all degrees of salinity 
in which the shrimp flourishes. This extensive favorable habitat and the wide range 
extending from Massachusetts south to Brazil is an obviously advantageous condition. 
Without it, the multitude of shrimp would not have developed in this region. But 
while it may furnish a breeding reserve in places not readily fished, it affords no com- 
plete protection. The shrimp seems to be confined wholly to a narrow coastal strip 
favorable for fishing, since, as we have seen, Penaeus setiferus appears to be absent from 
deeper water. Certain of the creeks and bayous in which the young are found are 
unsuitable for fishing; but since these young all move to the larger bays or to outside 
waters during the winter, at some time all shrimp on our coast must run the gauntlet 
of trawls and seines. The number that escape depends wholly on the intensity of the 
fishery. 
It is clear that under natural conditions the favorable factors were so far in the 
ascendancy as to produce an amazing abundance of shrimp. Even the great numbers 
taken by man have not sufficed to produce an alarming depletion. We must look 
forward, however, to a time when the increasingly intense fishery will turn the balance 
against the shrimp. Then the catch, maintained by constantly increasing effort, 
will begin to show great variations from year to year, some of them ruinous to fisher- 
men and canners. 
When additional protection becomes necessary it may take one or more of four 
lines- — limitation of sizes taken, closure of certain seasons, closure of certain areas, 
and regulation of gear. All of these have been tried; the regulation of gear and the 
closure of certain areas, as, for example, nursery grounds and inside waters furnishing 
a preponderance of young, and certain seasons promise the most satisfactory results. 
Experiments now in progress will, it is hoped, indicate how gear may advantageously 
be modified. 
SUMMARY 
The present paper contains the results so far attained in certain phases of a 
cooperative program of study of the shrimp initiated by the United States Bureau of 
Fisheries and participated in by the States of Louisiana, Georgia, and Texas. 
The shrimp supports the most valuable fishery in the South. Little has been 
known of its abundance, life history, and habits, consequently it warrants an investi- 
gation of some magnitude. 
The importance of the shrimp fishery may be seen from the fact that in the 
United States in 1929, 113,263,000 pounds were caught, the value of which to the 
fishermen was $4,575,000. Of this, 95 percent was produced by the eight South 
Atlantic and Gulf States, Louisiana alone contributing 43 percent. In the South the 
shrimp exceeds the combined value of the two fisheries next below it. 
Otter trawls operated from gas-driven boats take about 90 percent of the shrimp, 
the remaining 10 percent being caught by seines and cast nets. 
