ANDERSON and LINDNER: BIOLOGY OF ROYAL RED SHRIMP 



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-J I I i_ 



3 133 143 153 163 173 183 



TOTAL LENGTH [fA.ff,) 



Figure 10. — Regression of carapace length on total 

 length for males. 



For female H. robustiis (Figure 11) the break 

 occurs at the midpoint of the 151- to 155-mm 

 class interval and the new slope is not reached 

 until the midpoint of the 161- to 165-mm class 

 interval. Here again this morphometric change 

 is associated with maturity. 



These regressions were made from data gath- 

 ered in July 1957. Possibly the lengths at which 

 the slopes change would be different at other 

 times of the year. 



SPAWNING 



It was possible to separate several stages of 

 ovarian development in the field without micro- 

 scopic examination, because maturation is ac- 

 companied by changes in size of the ovaries 

 and by very distinct color changes. In the field, 

 however, we were unable to distinguish with 

 certainty the spent females. These were in- 

 cluded in the "undeveloped" and "developing" 

 categories. We usually recorded ovary develop- 

 ment in the following stages: 



1. UN = undeveloped. In this stage the tiny 

 ovaries are almost threadlike and trans- 

 parent. 



2. D = developing. The ovaries have in- 

 creased markedly in size and are opaque 

 but have not developed a distinctive color. 



3. P = pink. The ovaries continue to in- 

 crease in size and first take on a light yel- 

 low color which rapidly becomes light pink. 



4. R = ripe. Now swollen to full size, the 

 ovaries are a dark red or maroon color. 

 At this stage the male attaches the sper- 

 matophore to the female. 



The length distribution of shrimp with pink 

 ovaries difl^ered little from the length distribu- 

 tion of those with ripe ovaries. Because we 

 have no conception of the time required for 

 the pink stage to develop to the ripe stage, and 

 because the sizes were similar, we grouped these 

 two ovarian stages and called them ripe. We 

 also grouped females with undeveloped and de- 

 veloping ovaries, mainly to avoid discarding the 

 data collected during the first two cruises in 

 1957, when these two stages were not difl'erenti- 

 ated. 



We have presented this material in Figure 12 

 by seasonal periods. The periods chosen were 

 November; January and February ; April, May, 

 and June; and July, August, and September. 



BB 99 108 118 UB I3> 148 ISB 



Figure 11. — Regression of carapace length on total 

 length for females. 



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