Presentation on theme: "Topics Roi (C. argus) in Hawaii Roi removal study design Study objectives o Approach o Progress Next steps."— Presentation transcript:
Topics Roi (C. argus) in Hawaii Roi removal study design Study objectives o Approach o Progress Next steps
Roi (Cephalopholis argus) in Hawaii Estimated population 7.8 km 2 reef = 56,290 roi consume 8.3 mil. fish/year Surpass biomass of all other reef fish predators Increasing with prey populations (DAR) Dierking, 2007
Managers: Science is equivocal Community members: Roi are a big part of why there are so few native fish What do roi ACTUALLY do to Hawaiis reefs???
Experimental roi removal design
Experimental roi removal goals Address the following questions: Can we reduce roi populations with removal efforts? How do nearby roi populations respond? Do we know how many roi are out there? Does reducing roi populations change the native reef assemblage? Can we work with the fishing community on this project in a collaborative spirit that builds relationships and trust?
Objective) Begin to experimentally assess the actual affect that roi have on native reef communities Approach: Collect baseline data on the structure and composition of benthic and reef fish communities Continue monitoring quarterly (for multiple years)
Average fish abundance by feeding guild at three study sites F=10.4, p<0.001
Objective) Create an independent estimate of roi populations via a depletion experiment Approach: Calculate the original population density of roi in the removal area Track catch per unit effort (CPUE) of fishers
Objective) Quantify immigration into cleared areas Approach: Externally tag roi around removal site Recapture tagged individuals o Inside removal area o Via visual surveys o Via tag returns from community members
Objective) Evaluate the efficacy of roi removal as a management tool Approach: Quantify the level of effort (time and money) required to fish roi down to <10% of original population.
Spearfishing! Caught roi are used for: o Ciguatera research o Age/growth studies o Organic fertilizer Next steps:
Objective) Build stronger ties between coral reef managers, researchers, and the fishing community through an open collaborative approach Approach: Contract two fisherman to help with experimental removal Present project broadly within the community before, during, and after implementation
Mahalo nui loa We are truly grateful for the opportunity to do this work, and especially want to thank: HCRI, NOAA, DAR Kona, Russell Amimoto, Kydd Pollock and all of TNC, Kosta Stamulous, Paolo Usseglio and UH manoa, Jim Beets, Bill Mautz, Cam Muir and UH Hilo, TCBES ohana, Kawika, Mike, Rob White and the Roi Rally, Mike Kawamoto and the Hilo Dive Club, Darrell Tanaka and the Roi Round-up gang, The Puakō Community Association, Liz and Michael Morris family and friends and all of the community volunteers and supporters of marine conservation in Hawaii.