Participatory fishery monitoring is successful for understanding the reproductive biology needed for local fisheries management

Abstract

Tropical fisheries management should rely on reproductive biology to inform management regulations; however, this information is often lacking and can be highly variable over in space and time. It is unfeasible for many fisheries, especially data-poor ones that are typical of tropical reefs to collect the necessary information on reproductive biology. One solution is a participatory approach where local fishers, scientists, and regulating agencies gather the necessary information to assess population variability for important management metrics such as size at maturity, reproductive output, and spawning seasons. Through collaborations with local fishers, we developed a monitoring program to gather population-level information on the reproductive characteristics of the convict tang, Acanthurus triostegus sandvicensis. We examined four locations across the main Hawaiian Islands and found size at maturity [size at which 50% of individuals are mature (L50)] to vary among locations, with interpopulation differences in maturity ~ 20% of the fish’s total length. Larger individuals produced more eggs and spawned more often than smaller individuals. A semilunar spawning pattern was observed, with group spawning occurring near the new and full moons. However this pattern was variable by year and location, likely resulting from different seasonal peaks in spawning by location. Gonadosomatic index (t = 2.41, p-value = 0.02) and spawning fraction (z = 2.92, p-value < 0.01) were both significantly higher in 2014 compared to 2013, suggesting annual variability in reproductive output. Participatory fishery monitoring proved successful in collecting biological needed for management and improved understanding of population reproductive variability.