July and October. During reproduction, the females typically incubate 200-400 eggs inside of them for almost 6 months, although larger females have been known to produce up to 800 eggs. The female then lays the eggs on her swimmerets, and reproduction takes place when a male passes a sperm packet to the female, which the female then uses to fertilize the eggs in a process nearly identical to that used by the smooth marron. The eggs are then held under the female's tail for several weeks, hatching at or just after the end of the mating season, and the juveniles remain on the mother's swimmerets until they have finished consuming their yolk sacs and are mature enough to feed on their own, which is usually by November or December. The smooth marron is known to follow a similar reproductive pattern, but there is some evidence that their breeding season occurs earlier in the year than that of the hairy marron. This difference in timing is theorized to result in the juvenile smooth marron reaching larger sizes before juvenile hairy marron, granting the smooth marron a competitive advantage. Invasion by smooth marron One of the greatest threats to wild populations of hairy marron is invasion by the closely related smooth marron, which was introduced into the Margaret River in the 1980s, and which progressively replaced the hairy marron in the lower regions of the Margaret River from 1980 to 1992. Although the replacement of the hairy marron by the smooth marron in the middle portion of the river is not very well documented, the hairy marron was observed to be completely gone from the middle of the river in 2000. Beginning in the same year, smooth marron have always been observed living alongside all hairy marron populations in the upper portion of the Margaret River. Marron populations in the Margaret River follow the general trend of increasing in hairy marron and decreasing in smooth marron for regions further up the river. This trend has led scientists to conclude that smooth marron were most likely introduced in the lower portions of the river and spread to the middle and upper regions over time, replacing hairy marron through several processes including competition and hybridization. Hybridization The hairy marron and the smooth marron have been classified as two separate species in past studies based on their morphology and genetics. However, further research has found