sonal communication), however, observed in the 

 laboratory that mature females that did not bear 

 a spermatophore spawned eggs that developed nor- 

 mally ; the eggs were reared to subadult stages. 

 OVARY DEVELOPMENT 



The female reproductive system consists, as m 

 other Pemcus, of two partly fused ovaries, which 

 in mature animals extend for much of the length 

 of the body. Each ovary has a long, slender an- 

 terior lobe that extends to the level of the an- 

 terior portion of the gastric mill and bears lateral 

 projections (usually 6-8) in the cephalothorax, 

 and a posterior lobe running the length of the 

 abdomen dorsolateral to the midgut. 



The five ovary stages recognized by King ( 1948) 

 and now generally accepted are : 



1. Undeveloped. Found in young shrimp; 

 ovaries are small and translucent. 



•2. Developing. Ovaries larger, opaque, and yel- 

 lowish, with scattered melaTiophores over surface. 



3. Nearly ripe or yellow. Ovaries are still larger 

 than in previous stage and are yellow to yellowish- 

 orange. 



4. Eipe. Ovaries reach maximum size, occupy 

 practically all space among other organs, and are 

 drab olive-brown. Diameters of ova range from 

 0.192 to 0.300 mm. (Gutsell MS."). According to 

 Pearson (1939), eggs measure 0.28 mm. 



5. Spent. Eecently si^awned ovaries are flaccid, 

 muddy greeii, not so deeply colored as in the ripe 

 stage. As they regress the ovaries become yellowish 

 or milky and resemble the "developing"' stage. 

 Only through microscopical examination can the 

 stage of the opaque ovary be accurately deter- 

 mined, although the length and weight of the 

 gland often permit a distinction between the two 

 stages. 



The eggs are spherical and opaque, and possess 

 a chorion with purplish-blue coloration in reflected 

 light under a microscope (Pearson, 1939). The 

 spermatozoa have a large, subspherical head, a 

 short and narrow middle piece, and a relatively 

 thick, short tail (King, 19-18). 



The number of eggs produced by a female is not 

 known with certainty. Burkenroad (1934) indi- 

 cated that a female white shrimp produces an 

 average of about 500,000 eggs, whereas Anderson, 

 King, and Lindner (1949) stated that the ovary of 



■' Outsell, James S. A -study of the ovaries of the comniun 

 shrimp Petiaeus setiferus with reference to the life history. In the 

 files of the Gulf Investigations, U.S. Fish and Wildlife Service. 

 New Orleans. La. (rnpublishe<l manuscript, 1936). 



a l72-mm. female contained about 860,000 eggs and 

 that a female could be expected to lay between 

 500,000 and a million eggs at a single spawning. 

 For the present, this range of fecundity of one-half 

 to almost a million eggs in a single spawning must 

 be accepted. 



SPAWNING 



Spawning is in oceanic waters. On the basis of 

 the presence of ripe and recently sjDcnt females, 

 Lindner and Anderson (1956) concluded that in 

 Louisiana waters most spawning takes place in 

 depths of 4.5 to 17 fm. Their finding has been con- 

 firmed by a number of authors for the entire 

 northern Gulf of Mexico. Pearson (1939) and 

 Lindner and Anderson (1956) indicated that in 

 some areas of the Atlantic Coast spawning may 

 occur near shore. 



The beginning of spawning varies slightly in 

 different areas, but even within an area it seems 

 to vary from year to year and with depth. Lindner 

 and Anderson (1956) stated that spawning prob- 

 ably begins late in March or early in April and 

 may extend into November, though probably it 

 is completed by the end of September. Eenfro and 

 Brusher (1964) concluded that in the northern 

 Gulf of Mexico the onset of spawning is in mid- 

 April or early in May at 7i/2 fm., but takes place 

 several weeks earlier at 15 fm. Recently, Temple 

 and Fischer (1967), as a result of their studies in 

 the Gulf of Mexico, near Galveston, Tex., stated 

 that "The occurrence of larvae at 14 m. (about 

 734 fm.) stations in April to August reflects, we 

 believe, the spawning of white shrimp in shallow 

 waters." Li northeast Florida spawning seems to 

 begin at about the same time as in Texas; Joyce 

 (1965) suggested that spawning probably begins 

 in April and lasts until October. In South Caro- 

 lina and North Carolina it apparently starts later. 

 Lindner and Anderson (1956) stated that in South 

 Carolina they found spawning to start in May and 

 extend into September; they believed that no more 

 than 2 weeks separated the onset of spawning in 

 South Carolina and Texas. Williams (1955a) 

 gathered evidence that spawning starts in May 

 in North Carolina. 



Lindner and Anderson (1956) concluded that in 

 the northern Gulf of Mexico, spawning appears 

 to increase to a single peak in June or July, but 

 the number of shrimp in inshoi'e waters did not 

 follow this trend. On the basis of frequency dis- 

 tribution of the catches, two main broods appeared 

 annually in cei-tain localities and three in others. 



WESTERN ATLANTIC SHRIMPS OF GENUS PENAEVS 



481 



