Christmas Island (CI) is an Australian external territory in the Indian Ocean, approximately 2600km northwest of Perth. The community has a strong connection to the sea, and fishing plays a vital role in food security, culture, and recreation. Being geographically isolated, island stocks may be vulnerable to overfishing and environmental change, however, until this program, no formal stock assessments had been conducted.
In 2022, CI fisheries transitioned to a co-management model by the community (via the Shire of Christmas Island) in partnership with the Australian Government, with support from independent experts. To support science-based management, we initiated a stock assessment program applying a participatory approach (Barefoot Ecologist’s Toolbox), which estimates spawning potential based on the size composition of the catch (length-based spawning potential ratio, or LBSPR).
The Fisheries Ranger and local fishers were trained to collect length and maturity data for eight priority species. The approach helps fishers to compare the size of fish they catch with the size of maturity, building an understanding of how fishing pressure affects future productivity. It not only generates critical data but enhances local stewardship and understanding.
Data collection has progressed more slowly than anticipated, reflecting low landings, limited fishing opportunities (poor weather), and low reporting. In response, we have partnered with a commercial fisher to obtain additional samples and introduced new tools, such as 3D-video, to reduce participation fatigue.
To date only 386 fish have been measured. The sample includes 298 tengiri/wahoo, which has enabled an initial assessment of this species. While further sampling is needed to reduce uncertainty, preliminary results suggest the stock (SPR=0.24) is below generally accepted target levels (SPR=0.3 – 0.5); however, given the low local catches (<10 t per year) and prevalence of lost fishing gear (hooks) from tuna long lines found in locally-caught wahoo, it is likely that CI fishing is not the main pressure on this resource.
This work establishes the first scientific baseline for CI fish stocks and provides an adaptive model for monitoring recreational fisheries in remote island contexts, providing a foundation for long-term management of locally-important species.
Funding provided by the Australian Government.