Marine Fish Monitoring Protocol: Pacific Islands Network (Version 1.0)

Brown, Eric; Beets, James; Brown, Paul; Craig, Peter; Friedlander, Alan; Jones, Tahzay; Kozar, Kelly; Capone, Mark; Kramer, L; Basch, Lawrence

Fish are a major component of the coral reef ecosystem, potentially numbering 500 – 1,100 species in Pacific Islands Network (PACN) parks depending on geographic location (Allen et al. 2003, Randall 2005, Randall 2007). This highly diverse assemblage of carnivores, planktivores, herbivores and detritivores serve a variety of ecological functions that affect ecosystem structure, productivity, and sustainability (e.g., Sale 1991, Hixon 1997). Fish assemblages or selected species can also act as indicators of general reef health and provide a warning of environmental stress and potential ecosystem change (e.g., Friedlander and DeMartini 2002). Additionally, fish within the parks are harvested in traditional, subsistence, artisanal, and recreational fisheries (e.g., Craig et al. 2008) which may affect the species composition, abundance and size of targeted species. Fishing is increasingly being recognized as the principal threat to Pacific coral reefs and other marine ecosystems worldwide (e.g., Dayton 1998, Friedlander and DeMartini 2002, Birkeland 2004, Hutchings and Reynolds 2004). In this respect, it is highly probable that most of the Pacific Islands parks can be categorized as “impaired” to “seriously impaired” in terms of their fish communities. Marine Fish ranked 11th in priority as a network Vital Sign. While the harvest of fish is addressed in a separate complementary (fisheries-dependent) protocol, data collected through the Marine Fish Protocol will contribute to the overall understanding by providing an in-water (fisheries-independent) assessment of the size and numerical density of daytime, non-cryptic species within park waters. Monitoring efforts will be conducted concurrently with Water Quality and Benthic Marine Community Vital Signs to maximize data interpretation value. Long-term changes in the numerical density and biomass of fish assemblages can often be correlated with specific stressors or drivers. For example, a decline in size and numerical density of target species is often associated with overfishing. Reef fish diversity and biomass also correlate with the structural complexity of reef habitats so changes in habitat topography can alter the fish assemblage at various spatial scales. Moreover, many reef fishes are either large apex predators or major herbivores whose trends in numerical density can have ecologically and statistically significant impacts on coral reef ecosystems and the dynamics of major system components; e.g., declines in herbivorous fishes could result in increased growth and benthic cover of native or invasive algae which can out-compete and overgrow corals, leading to associated declines in coral health, reef structure, and ecosystem resiliency. The Marine Fish Monitoring Protocol will be implemented initially in four parks: Kaloko-Honokohau National Historical Park (KAHO), Kalaupapa National Historical Park (KALA), National Park of American Samoa (NPSA), and War in the Pacific National Historical Park (WAPA), and will address one primary monitoring question: What are long-term trends in the numerical density, biomass, and size of reef fishes? The primary objective is to annually determine the density, biomass, and size of daytime, non-cryptic reef fishes at sites randomly selected on hard substrata in an isobath between the 10 and 20 meter depths (selected for ecologic and safety reasons). The complete Marine Fish Protocol consists of this narrative with appendices and Standard Operating Procedures (SOPs). A complete list of SOPs is found in Appendix J. Any changes in this narrative will be logged in the Revision Log found in Appendix A.

Marine Fish Monitoring Protocol: Pacific Islands Network (Version 1.0)

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