LIFE HISTORY OF THE COMMON SHRIMP 
13 
Xiphopenaeus kroyeri. In fact, only 20 such females have been obtained from the 
thousands of shrimp examined. Considering only females handled during those 
months in which spermatophores have been found, we have the relations shown 
in table 4. 
Table 4. — Penaeus setiferus spermatophore records April to August 1981 and April to July 1932 
State 
Females 
examined 
Sperma- 
tophores 
found 
Percent 
Georgia 
11,015 
3 
0. 027 
Louisiana - 
3, 561 
7 
.20 
Texas - 
3,911 
10 
.26 
All these 20 spermatophore-bearing females were in the ripest of the stages dis- 
tinguished by examination of the ovary. Their lengths, which range from 141 to 
186 mm with a mean at 166.3, agree well with the lengths of females showing the last 
stages of maturity. 
The period in which these females are found is from April to August, inclusive, 
which covers almost the entire season during which the ovaries appear ripe. All 
were taken in fairly deep water, either in open sounds or the sea or Gulf, in localities 
where the salinity is the highest found in the range of the shrimp for this season of 
the year. 
The next question is as to the time during which the male is capable of furnishing 
spermatophores. The spermatophores when formed are easily recognized in, or 
expressed from, the lower end of the vasa deferentia of the male, and records of their 
presence or absence are at hand for part of our series of length-frequency data. In 
1932 in Louisiana maturing males were first present in the latter part of March, thus 
appearing slightly in advance of maturing females. They usually appear slightly 
earlier and last as late in the season as mature females. We may conclude, therefore, 
that during the period that females are capable of spawning, breeding males are also 
present. 
To summarize: Ripe females are common during April, May, June, July, and 
present but scarce in August and September (Georgia, 1931). Spermatophore- 
bearing females have been obtained from April to August (these must be within a few 
hours of spawning). Mature males are present throughout this period. Young in 
the first post-larval stages are found from at least late April to August. We feel 
justified in assuming, on the basis of these data, that in 1931 spawning occurred during 
April, May, June, July, and to a reduced extent in August and September, even with- 
out having as yet observed spawning or having obtained fertilized eggs. Of course, 
the dates of spawning will vary from season to season. 
It may next be inquired, Where are the shrimp spawning grounds? On this 
important question our evidence is again indirect, consisting of four types of data — 
the relative distribution of males and females, the relative distribution of the various 
stages of maturity, the distribution of that stage of maturity represented by the sper- 
matophore-bearing females, and the distribution of larvae. 
The plankton material containing penaeid larvae has not yet been analyzed and 
therefore cannot throw light on the location of the spawning grounds. 
As stated, all spermatophore-bearing females have been obtained in fairly deep 
water of high salinity. Since we have good reason to think that the spermatophores 
