ANSWER 1

The fishers’ observation of lower than average recruitment of abalone over time is strongly supported by the data, particularly over the last 25 years or so.

However, it is almost impossible to determine how much climate change may or may not have impacted these changes.

It is important to note that the declines in abalone recruitment have not only affected blacklip abalone in South Eastern Australia, it has impacted almost all abalone species in all Australian jurisdictions. Many of these fisheries have suffered stock declines at a very similar time. This suggests that some external factor such as impacts from climate change could be a key driver of the change. However, abalone populations are very difficult to monitor and there are no reliable population models that have been developed to study factors that may be impacted by climate change.

In Victoria, all three zones have declined in abalone abundance since the year 2000. The Eastern Zone has been impacted by various environmental changes including an increase in sea urchin abundance, and suspected impacts at the southern end of the zone from Snowy River water outflow in the last decade. The Western Zone was severely impacted by abalone disease, as was the western end of the Central Zone. While all three zones have had different impactors, all three showed strong declines in abundance around 2005 to 2010, suggesting that the impacts on recruitment were felt across the state.

The final point to make regards what is “less recruitment”. Recruitment patterns in abalone remain poorly understood because it is very difficult to monitor recruitment of juveniles at scales that are representative of the fishery. There is evidence to suggest that abalone stocks generally received a “standard” level of recruitment in most years, and then every 7-10 years or so, when the conditions were ideal, there would be a “very high” level of recruitment occur that was many times the standard level. These types of recruitment patterns are seen for other marine invertebrates such as WA pearl oysters. The data would suggest that he last time a very high recruitment was observed was prior to the year 2000, and this sustained large catches for the first half of that decade. Finally, it is also difficult to know now whether or not the “average” recruitment year in 2026 is the same as the average recruitment year around the year 2000. One thing for certain is that the area of the fishery accessed by fishers has reduced dramatically over that time.

Apologies there is no clear answer but hopefully this provides additional insights.