Trachypeneus similis; and Solenocera atlantidis had not progressed as far 

 toward the completion of their reproductive cycles and were more prevalent 

 in 7-2 and 15 fathoms. 



2. There seemed to be little correlation between size of shrimp 

 and degree of maturation. 



3. Determination of the degree of ovarian development employing 

 visual criteria proved to have dubious utility. Compared with determinations 

 based on cytological examination of the same ovaries, 40 to 70 percent of vis- 

 ual determinations constituted misclassification. 



4. The average catch of larval penaeids was approximately five per 

 tow from, midwjanuary to early March. During the fourth cruise (March 21-23) 

 it rose to 31 as a result of the increasing abundance of S. brevirostris larvae. 



5. Penaeus larvae were not taken at those stations located in depths 

 less than 15 fathoms during the first two cruises, but were found at the 72- 

 fathom stations in late February and March. Of special interest was the oc- 

 currence of five Penaeus postlarvae at stations more than 70 miles offshore. 



6. Larvae of S. brevirostris were found at the 15-, 25-, and 45- 

 fathom stations. Trachypeneus, Solenocera, and Parapenaeus larvae oc- 

 curred sporadically in samples taken throughout the study area. 



Distribution and abundance of larvae The last half of I960 was devoted to 



processing and examining 3, 111 plankton samples taken systematically from 

 passes connecting Galveston Bay with the Gulf of Mexico, and from the Gulf 

 itself. These samples, obtained with a Gulf V sampler from March 1959 

 through March I960, form the basis for a study designed to determine the fea- 

 sibility of assessing relative seasonal and areal abundance of penaeid larvae. 

 Larvae were sorted from each sample, catalogued and enumerated according 

 to their stage of development and probable identity, and stored in small vials. 

 A system of coding facilitated tabulation. For exanaple, the code 2NI refer- 

 red to a Nauplius I which was most likely the brown shrimp, Penaeus aztecus; 

 3MII referred to a Mysis II of the white shrimp, Penaeus setiferus; etc. Fifty- 

 seven such code designations have been employed, but as morphological re- 

 lationships between and within species become better understood, this number 

 will gradually be reduced through consolidation of material on a genus or spe- 

 cies basis. 



An important aspect of this project is the accuracy and compara- 

 bility of the abundance indices determined for each species. Volumes of water 



12 



