Characterizing the marine recreational fishery of Hong Kong using data compiled from a social media platform

Intensive marine recreational fishing can lead to deleterious effects on fish stocks and marine ecosystems similar to large-scale commercial fishing. Nonetheless, recreational fishing is seldom included in fisheries management owing to a scarcity of reliable data in many regions, especially in Asia, which currently accounts for the bulk of total marine recreational catches and exhibits the strongest upward trend globally. In this study, we used photographic records of fish landings collated from a social media platform (Facebook) to characterize Hong Kong’s marine rod-and-line recreational fishery for the year 2019. We recorded 122 species from 49 families and estimated that recreational fishing contributed to a substantial proportion (>10–15 %) of total marine catches from Hong Kong’s waters. We found that recreational catches, with an economic value of nearly 32 million USD, exhibited a disproportionate dominance of large predators (e.g., groupers, seabreams, jacks and pompanos, snappers, croakers, Asian seabasses), although the vast majority (93.4 %) of targeted species lack conservation assessments at the regional level. Most notably, we observed that most commonly-exploited species exhibited truncated size distributions strongly indicative of overfished stocks. Our results serve as a baseline for the sustainable management of Hong Kong’s recreational fishery and suggest that focused strategies targeted at large predators are urgently needed. Moreover, our study highlights the potential for iEcology datasets (e.g., from social media platforms) to be a cheap and convenient but largely untapped means of monitoring recreational fisheries in lieu of traditional manpower-intensive surveys, particularly in regions that, to date, remain data-sparse.