Understanding the biological foundations of culturally important fisheries is essential for their sustainable management, particularly in data-limited regions. Siganus spinus (Little spinefoot, also known as Scribbled rabbitfish) is a fast-growing, short-lived, and highly fecund reef fish that supports a centuries-old seasonal fishery in the Mariana Islands. This study characterizes the life history and reproductive ecology of S. spinus in the southern Mariana Islands using otolith-based aging, histological examinations of gonadal tissue, gonadosomatic index (GSI) analysis, and traditional ecological knowledge of Chamorro fishers. Results reveal a highly truncated, fast-paced life-history strategy, with most individuals maturing within six months of recruitment and rarely living beyond one year. Biannual spawning peaks in March–April and August–September were followed by recruitment events ~ 30 days later, demonstrating tight spawning--recruitment synchrony. These biological patterns align with the traditional mañåhak harvests in Guam and the Commonwealth of the Northern Mariana Islands, represented by mass collection of juvenile rabbitfish timed to lunar cues and environmental signals. Siganus spinus exhibits traits associated with high resilience, yet also strong stochasticity in population dynamics. This dynamic is accentuated by very high natural mortality and punctuated by annual recruitment pulses of widely varying magnitude. Interannual variability in recruitment is likely driven by oceanographic conditions, fluctuations in resource availability, and associated changes in fecundity. The species is genetically distinct in the Mariana Islands, suggesting a self-recruiting population where recruitment failure could have significant local impacts. These findings underscore the importance of integrating place-based ecological knowledge with empirical life-history data to inform sustainable, culturally-grounded management of reef fisheries.
Taylor et al. (Mon,) studied this question.