338 U.S. BUKEAU OF FISHERIES 



south; (3) instead of wintering near Cape Canaveral as in recent 

 seasons the shrimp moved further south along the Florida coast and 

 out of the customary fishing grounds ; (4) the shrimp migrated south 

 to Cape Canaveral, but because of colder waters along the coast 

 moved offshore to warmer waters nearer the Gulf Stream. 



Because of the lack of data over a sufficient number of months, it 

 is impossible to state at this time which of these hypotheses repre- 

 sents the true situation. It is extremely important that the present 

 studies, with some modifications, be continued in order to arrive at a 

 correct solution of the problems involved as they are of vital 

 importance economically and biologically. 



In addition to the above, the South Atlantic operations have 

 yielded sufficient information to allow the projection, for the first 

 time, of what appears to be a normal growth curve. The constant 

 influx of young shrimp into the fishery and the continual movements 

 of the shrimp from place to place have made this impossible in the 

 past. Application of this curve to data gathered along the South 

 Atlantic and Gulf coasts indicates that there may be a longer spawn- 

 ing season than at first suggested and also that there may be two 

 peaks of spawning, one in winter and the other in late spring and 

 summer. 



In Texas, Kenneth H, Mosher has continued the sampling of the 

 commercial catch of shrimp at Aransas Pass. In addition, the Texas 

 progi-am has been extended along the coast to cover the major 

 shrimping ports monthly. In each locality a random sample of 

 shrimp is taken from a number of fishing boats. The shrimp are. 

 sexed, measured, and the degree of maturity noted. 



An analysis of the Texas lighthouse temperature records inclucf-^ 

 ing Sabine Pass Light, Galveston Jetties Light, Half Moon Reef 

 Light, Aransas Pass Light, and Brazos Santiago Light, indicates 

 an inshore cold water barrier near Point Isabel, Tex., that averages 

 20° F. colder during the summer and 10° F. colder during the winter 

 than any of the more northern Texas points. Because of the lack 

 of sufficient offshore water temperatures adjacent to Point Isabel, 

 it is difficult at this time to state how representative the water tem- 

 peratures at Brazos Santiago Light are of the conditions in the 

 Gulf near Point Isabel. The occurrence of a cold water barrier in 

 this locality would have considerable influence on the coastwise 

 movement of shrimp, fishes, and other marine life in southern Texas 

 and northern Mexico. 



In Louisiana, owing to decreased funds, the collecting trips of the 

 Bureau's research vessel Black Mallard., which is maintained by the 

 Louisiana Department of Conservation, were reduced to 1 a month 

 but of slightly longer duration, instead of the customary 2. John 

 C. Pearson has examined the entire plankton collections secured 

 since the inauguration of the study in Louisiana and has found 

 that young postlarval Penaeus hrasiUensis occur in the surface 

 offshore tows throughout the winter, spring, and summer, which 

 indicates an extended spawning season for this species. Although 

 P. setiferus is much more abundant than P. brasilensis, no post- 

 larval young of this species have been secured in the surface tows. 

 From this evidence it is believed that the young stages of P. setiferus 

 are demersal. The recent addition of new hoisting equipment 



