Spawning Populations 

 William C. Renfro and Harold A. Brusher 



During 1961, 17 cruises were made in the area between Galveston, 

 Tex. , and Gameron, La. , to as far as 100 miles offshore. At each of the 

 11 stations in the area, a 45-foot shrimp trawl was towed for 1 hour. Penaeid 

 shrimps taken were counted, sexed, and measured, and predetermined num- 

 bers of females of each species were dissected to obtain samples of ovary 

 tissue. Ovary samples were fixed in Bouin's solution and returned to the lab- 

 oratory where they were prepared as stained slide mounts. Cytological exam- 

 ination of all brown shrimp (Penaeus aztecus) ovary sections to determine 

 stage of ovary development was recently completed. 



Of 1, 374 brown shrimp ovary sections examined, 262 are from small 

 females less than 140 mm. total length. The ovaries of most (73%) of these 

 smaller specimens are either undeveloped or in very early stages of develop- 

 ment. Less than 10 percent are in the "yellow" or more advanced stages of 

 development. 



"Developing" and "yelloAv" stage ovaries are most prevalent (79%) 

 in females 140 mm. or larger, indicating that these two stages consume most 

 of the time in the process of ova maturation. Less than 3 percent of the larger 

 females sampled were undeveloped or in early developmental stages. This sug- 

 gests that there is no "resting" or "dormant" stage in this species. Apparently 

 in this area, once a brown shrimp female reaches sexual maturity, ova gener- 

 ation and maturation continue unabated throughout the remainder of her life. 



Very few brown 

 shrimp were found at 

 the 7 2 -fathom stations 

 during the first 5 months 

 of 1961. In June, small 

 shrimp began to naove 

 offshore from the estu- 

 arine nursery grounds. 

 Almost all females taken 

 in 72 fathoms from June 

 through December were 

 small with "undeveloped" 

 or "early developing" 

 ovaries. There was little 

 evidence for spawning of 

 bro\vn shrimp in 72 fath- 

 oms. 

 The spawning condition of brown shrimp 

 collected during 1961 betw^een Gcdveston, 

 Tex. , and Cameron, La. 



(~1 -D««eiop'na 



13 



