202 MARINE FISHERIES OF NORTH CAROLINA 



Ocean off North Carolina. The absence of shrimp from North Carolina 

 during a part of the spawning season suggests the possibility that spawning 

 does not occur in this state's offshore waters. Preliminary examination of 

 specimens from offshore has failed to yield evidence of mating activity. 

 The possibility must therefore be admitted that our shrimp population may 

 be a migrant one, the young being supplied from breeding areas to the south 

 and this young population being augmented by the spring and summer 

 migration of larger individuals from southern waters. At the same time, the 

 presence of a spring run suggests the possibility that spawning activity may 

 occur in the southern waters of this state or in the waters of South Carolina. 

 Information fixing the northern or southern limit of spawning areas is not 

 available; yet the data on migration suggest that such limits may exist. 

 If this be so, the fall migration may then end in an almost complete disap- 

 pearance of shrimp (P. setiferus and P. aztecus) from these waters until the 

 spring run. While this hypothesis is suggested by the available literature, 

 contradictory evidence is lacking insofar as P. setiferus is concerned. 



P. aztecus is a species of considerable value in North Carolina, possibly 

 more so here than in any other state. Weymouth, Lindner, and Anderson's 

 1933 figures represent the only available estimate of the percentage of P. 

 aztecus in the total catch of the United States. This species has become 

 more abundant in the catches of recent years, but percentage estimates are 

 not available. In North Carolina, however, this species has been shown to 

 be of considerable economic importance. The season starts and ends before 

 the season for P. setiferus, large individuals being common in Pamlico 

 Sound as early as July. Since no growth rate data for this species exist, it 

 is impossible to designate the age or source of these individuals. 



The large specimens of P. duorarum taken frequently by fishing trawlers 

 in all depths up to 30 fathoms in the vicinity of Cape Hatteras suggest a 

 resident population of this species. The absence of these large individuals 

 from the inshore waters concurs with Burkenroad's observations (see 

 above). Small individuals of this species are taken in the spring inshore. 

 There is evidence indicating a winter residency of these forms in the Sound 

 waters. Except in the early spring runs, the percentage of P. duorarum 

 taken is low. In the offshore waters, however, P. duorarum has been taken 

 almost to the exclusion of other species during the winter of 1949- This fact 

 not only indicates the permanent residency of P. duorarum in North Caro- 

 lina, but also strengthens the hypothesis regarding the migratory nature of 

 the other species. 



The data on fecundity, growth rate, and duration of life of shrimp 

 indicate considerable ability to withstand exploitation. A single female may 

 lay as many as a million eggs in a season. Within six months, these eggs 

 will have produced marketable shrimp and spawning shrimp within a year, 



