What sizes are mature males and females?
Size at maturity is not fixed in fish or crustacea and usually varies between individuals and under different growth conditions. Spawning females in the stunted stock we’ve been studying at Pingelly are predominantly in the 20-40 gram weight range, with very few (just) below 20 grams. Females just below 20 grams examined in late winter-early spring have well developed eggs in their ovaries, but can’t spawn until they undergo a moult that widens their tail shell (see previous answer on external body parts). Many measurements have shown that tail broadening occurs in females in this dam at 20 grams or so; mating trials at our Waterman laboratory have confirmed that mature females can be reliably identified by this easily seen external characteristic. Males appear to mature at a larger size than females. But which sizes of males actually mate with females may be more a question of behavioural size dominance, like bulls and rams, than potential ability. Since females spend most of the grow
