CRABBING AND CONNECTIVITY: FISHERIES ASSESSMENT IN A TRADITIONALLY MANAGED HAWAIIAN FISHPOND

Hawaiian fishponds, or loko iʻa, are ancient aquaculture systems that are models of sustainable aquatic resource management based on long-term experience from traditional Native Hawaiian har vest practices.  An estimated 350+ fishponds provided food security for ancient Hawaiʻi, but by 1901 only 99 remained in production, and most of those were abandoned by mid- century. Reclamation efforts, beginning in the 1970s, have resulted in the rejuvenation of 38 actively managed fishponds across the State.  Building on indigenous local knowledge, f ishponds  are  being adapted to modern human population needs, because functional fishponds contribute to  perpetuation  of culture, improved food security and enhanced ecosystem services .  In this study, we examine culturally and economically important crab fishery species to illustrate that  traditional management practices are currently effective even with introduced species. This study was conducted in collaboration with Paepae o Heʻeia, a private non-provit organization that cares for the ancient Hawaiian Heʻeia fishpond (fig.1).

The state of Hawai ʻi  only has size limits (6 in) for the introduced mud crab,  Scylla serrata, but no bag limits for catch. However, with traditional management practices,  limits are set and enforced in response to fluctuations in catch. During the assessment period of 2017-2019, the average number of crabs per harvest was 24 individuals, with an average keep of 7 individuals and average release of 17 individuals. Average crab size is larger during the winter months but catch is lower than during summer months. Over 95% of catch over the study period was above the size of sexual maturity of mud crab males (CW >90 mm). In order to address merging traditional and modern management practices, we investigated traditional fishing and combined it with modern collection data (assessments and abundance estimates) to propose a sustainable crab fishery model that may be tailored to fit manager preferences.