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penaeid shrimps Pakistan
|Abstract:||The spawning seasons of four species of penaeid shrimp, Penaeus penicillatus (Alcock), P. merguiensis (de Man), Metapenaeus affinis (Milne Edwards) and Parapenaeopsis stylifera (Milne Edwards) from Pakistan’s inshore waters were studied on the basis of ovarian colour and ovarian histology. During maturation shrimp ovaries pass through a series of colour changes. Females with green ovaries (green yellow, green white, light green and dark green) were considered as spawning females while those with other than green ovaries (translucent, white, cream and yellow) were considered as non-spawning. The maturation stages of the ovaries recognized histologically in these shrimps are: undeveloped, developing, nearly-ripe, fully-ripe, resorbing and resorbing/developing. Presence of nearly-ripe or fully-ripe ovaries in these species throughout the year suggests that these shrimps have the potential for spawning throughout the year. However, P. penicillatus, P. merguiensis and M. affinis showed two spawning peaks, the first one in winter-spring (February-May) and second one in July, September and/or October. In P. stylifera the spawning was more frequent from November to February. The present study indicated that the spawning seasons based on the colouration of the ovaries and on ovarian histology are more or less similar.|
|Appears in Collections:||IJMS Vol.31(2) [June 2002]|
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