Males were defined as those whelk with a penis, and females were defined as those whelk with a nidamental gland.
This finding could be due to the presence of the nidamental gland, which takes up a large portion of shell volume in mature females.
Specimens were measured for mantle length (ML) distribution, and some of them were measured for total weight (in grams) and nidamental gland length (in millimeters).
These stages were correlated strongly to the nidamental glands more than 40% of the mantle length in females.
Two conspicuous white nidamental
glands, one on each side, measuring 30 x 42 mm each.
After recording the total body weight (TW), each specimen was dissected to separate different organs and the following measurements of weight were recorded in grams: mantle weight (MW); head weight, including arms and tentacles (HW); viscera weight, including gills, stomach, cecum, hepatopancreas, and ink sac (VW); ovary weight, including oviduct and oviducal gland (OW); testis weight (TW); and nidamental gland weight (NGW).
The indices, the gonadosomatic index (GSI) for both sexes and the nidamental gland-somatic index (NSI) for the females, were calculated as follows:
Female organs Character Grade Nidamental
gland length millimeters Accessory nida- color 0=clear, 1=whitish, 2=pink, mental gland 3=peach, 4=reddish-orange Oviduct number of large 1=none, 2=1-20, 3=21-200, clear eggs 4=>200 Ovary number of large 1=none, 2=1-20, 3=21-200, clear oocytes 4=>200 Ovary number of opaque 1=none, 2=1-20, 3=21-200, or white oocytes 4=>200 Table 2 Percentage of spawning female market squid classed by the number of eggs in their oviducts and by the number of ages (stages of degeneration) of postovulatory follicles (POFs) in their ovaries.
Also, total weight was registered using a digital scale (Mettler PC440) and dimensions of different reproductive organs were recorded, including weights of the nidamental
glands (NiW), ovary (OvW), and oviducts (OdW) in females and weights of the testes (TeW) and spermatophoric complex (ECoW) in males.
Females were considered mature if they were gravid, had oocytes larger than 26 mm in diameter, or if nidamental
gland width was greater than 20 mm.
There was a negative correlation between Gonado Somatic Index and Nidamental gland Somatic Index and each of total protein and lipids in different sexes (P = 0.
The presence of a spermatophoric sac in males and the orange or pink color of the accessory nidamental gland in females indicated the mature stage (Richard 1967; Riad 1993).