The first moult, from red to white, occurs just before migration, with anecdotal evidence indicating that “white” lobsters are observed on reefs around the same time as they begin being caught in pots as they migrate offshore. This migration usually occurs in November each year, and research has indicated that the exact timing of this migration is correlated with water temperature. Modelling of commercial fishers’ behaviour has indicated a strong correlation between the average water temperature in August/September, and the day in November that fishers move their gear offshore as they “chase the whites” (Figure 1). Because the timing of fishers moving offshore is indicative of the timing of the white’s migration, we can conclude that in warmer years the white’s moult and migration occur earlier, while in cooler years, they occur later (Figure 1).
There is also some evidence that the white to red moult which occurs after the migration, is also impacted by water temperature. The peak in catches at this time of the year is thought to relate to this moult as well as the synchronised adult female moult that occurs around the same time. In warmer years, this peak occurs earlier than in cooler years, as indicated by the ratio of March to April catches in Figure 2. Therefore, it is believed that these moults occur earlier in warmer years compared with cooler years.
