Sampling of commercial fisheries bycatch in south-western Australia has yielded a second and different form of hermaphrodite of the Port Jackson shark Heterodontus portusjacksoni. Its total length (706 mm) and weight (2740 g) fall within the range of those of mature males, but below those of mature females. The left clasper was similar to that of normal mature males, whereas the right clasper was far smaller, had a poorly-developed rhipidion groove and lacked a spur. The body cavity possessed a testis on the left, an ovotestis on the right, and contained sperm ducts, oviducal glands and uteri on both sides. As with normal mature males, the testis and the testicular component of the ovotestis contained germ cells in various stages of spermatogenesis, including late stage spermatids. The ovarian component of the ovotestis contained 14 follicles that were larger (5–9 mm diameter) than those of normal females of similar size, which were immature, but far smaller than those of normal mature females. Six of those follicles were atretic. The widths of the left and right oviducal glands and uteri were far greater than those of normal females of similar size, but similar to those of normal mature females. Thus, although gonadal maturation had progressed further in the testis and the testicular component of the ovotestis than in the ovarian component of the ovotestis, the oviducal glands and the uteri of the hermaphrodite were of similar size to those of normal mature females and were far better developed than those of normal females of similar length, which are immature.

Heterodontus portusjacksoni was obtained from the catches of commercial trawl, gillnet and longline fisheries operating in south-western Australian waters, in which this shark is an abundant bycatch species. Ninety per cent of the H. portusjacksoni caught by commercial trawling in a marine embayment were <400 mm in total length, whereas 99 and 100%, respectively, of the individuals taken by commercial gillnet and longline outside that embayment were >400 mm. Although the differences between the size compositions in the catches obtained by trawling vs both gillnetting and longlining, which were similar, are partly attributable to gear selectivity, they also reflect a use by juvenile H. portusjacksoni of protected nearshore waters as nursery areas and a tendency for larger juveniles and adults to occupy reef/rock habitats in a range of water depths. The fact that all but one of the numerous H. portusjacksoni >800 mm were females is reflected in the ratio of females to males differing significantly from parity in the gillnet and longline samples. Yolked oocytes usually take one year to develop to ovulatory size. Ovulation occurs in late winter to early summer and hatching takes place a year later when the embryo is 180–220 mm. The claspers of males commence rapid growth at a total length of ~450 mm, coincident with the onset of clasper calcification and gonadal maturation. The rate of clasper growth relative to total length reached a maximum at ~570 mm and then declined precipitously as the claspers approached full calcification. Based on gonadal criteria, the L50 at maturity for females (805 mm) was nearly 40% greater than that for males (593 mm). Values of the deviance information criterion and marked overlap in their 95% confidence intervals demonstrate that the L50 of 581 mm derived for males using full clasper calcification as the index of maturity was equally valid as the above L50 derived for males at maturity using gonadal criteria. The capture of substantial numbers of juveniles by trawling and of females <L50 at maturity by gillnetting and longlining may be having localized effects on the population structure of H. portusjacksoni in south-western Australian waters.