title: Comparison of Reef Fish Survey Data Gathered by Open and Closed Circuit SCUBA Divers Reveals Differences in Areas With Higher Fishing Pressure.
abstract: Visual survey by divers using open-circuit (OC) SCUBA is the most widely used approach to survey coral reef fishes. Therefore, it is important to quantify sources of bias in OC surveys, such as the possibility that avoidance of OC divers by fishes can lead to undercounting in areas where targeted species have come to associate divers with a risk of being speared. One potential way to reduce diver avoidance is to utilize closed circuit rebreathers (CCRs), which do not produce the noise and bubbles that are a major source of disturbance associated with OC diving. For this study, we conducted 66 paired OC and CCR fish surveys in the Main Hawaiian Islands at locations with relatively high, moderate, and light fishing pressure. We found no significant differences in biomass estimates between OC and CCR surveys when data were pooled across all sites, however there were differences at the most heavily fished location, Oahu. There, biomass estimates from OC divers were significantly lower for several targeted fish groups, including surgeonfishes, targeted wrasses, and snappers, as well as for all targeted fishes combined, with mean OC biomass between 32 and 68% of mean CCR biomass. There were no clear differences between OC and CCR biomass estimates for these groups at sites with moderate or low fishing pressure, or at any location for other targeted fish groups, including groupers, parrotfishes, and goatfishes. Bias associated with avoidance of OC divers at heavily fished locations could be substantially reduced, or at least calibrated for, by utilization of CCR. In addition to being affected by fishing pressure, the extent to which avoidance of OC divers is problematic for visual surveys varies greatly among taxa, and is likely to be highly influenced by the survey methodology and dimensions used.
authors.affiliation: Coral Reef Ecosystem Program, Ecosystem Sciences Division, Pacific Islands Fisheries Science Center, National Oceanic and Atmospheric Administration, Honolulu, Hawaii, United States of America.|Joint Institute for Marine and Atmospheric Research, University of Hawaii at Manoa, Honolulu, Hawaii, United States of America.
authors.forename: Andrew E
authors.identifier: http://orcid.org/0000-0001-6261-8824
authors.initials: AE
authors.lastname: Gray
authors.affiliation: Coral Reef Ecosystem Program, Ecosystem Sciences Division, Pacific Islands Fisheries Science Center, National Oceanic and Atmospheric Administration, Honolulu, Hawaii, United States of America.
authors.forename: Ivor D
authors.initials: ID
authors.lastname: Williams
authors.affiliation: Department of Environment and Agriculture, Curtin University, Perth, Australia.|Fisheries Ecology Research Lab, Department of Biology, University of Hawaii at Manoa, Honolulu, Hawaii, United States of America.
authors.forename: Kostantinos A
authors.initials: KA
authors.lastname: Stamoulis
authors.affiliation: Ecosystem Sciences Division, Pacific Islands Fisheries Science Center, National Oceanic and Atmospheric Administration, Honolulu, Hawaii, United States of America.
authors.forename: Raymond C
authors.initials: RC
authors.lastname: Boland
authors.affiliation: Coral Reef Ecosystem Program, Ecosystem Sciences Division, Pacific Islands Fisheries Science Center, National Oceanic and Atmospheric Administration, Honolulu, Hawaii, United States of America.|Joint Institute for Marine and Atmospheric Research, University of Hawaii at Manoa, Honolulu, Hawaii, United States of America.
authors.forename: Kevin C
authors.initials: KC
authors.lastname: Lino
authors.affiliation: Papahānaumokuākea Marine National Monument, National Oceanic and Atmospheric Administration, Honolulu, Hawaii, United States of America.
authors.forename: Brian B
authors.initials: BB
authors.lastname: Hauk
authors.affiliation: Papahānaumokuākea Marine National Monument, National Oceanic and Atmospheric Administration, Honolulu, Hawaii, United States of America.
authors.forename: Jason C
authors.initials: JC
authors.lastname: Leonard
authors.affiliation: Coral Reef Ecosystem Program, Ecosystem Sciences Division, Pacific Islands Fisheries Science Center, National Oceanic and Atmospheric Administration, Honolulu, Hawaii, United States of America.|Joint Institute for Marine and Atmospheric Research, University of Hawaii at Manoa, Honolulu, Hawaii, United States of America.
authors.forename: John J
authors.initials: JJ
authors.lastname: Rooney
authors.affiliation: Coral Reef Ecosystem Program, Ecosystem Sciences Division, Pacific Islands Fisheries Science Center, National Oceanic and Atmospheric Administration, Honolulu, Hawaii, United States of America.|Joint Institute for Marine and Atmospheric Research, University of Hawaii at Manoa, Honolulu, Hawaii, United States of America.|Department of Environment and Agriculture, Curtin University, Perth, Australia.
authors.forename: Jacob M
authors.initials: JM
authors.lastname: Asher
authors.affiliation: Tropical Conservation Biology and Environmental Science, University of Hawaii at Hilo, Hilo, Hawaii, United States of America.
authors.forename: Keolohilani H
authors.initials: KH
authors.lastname: Lopes
authors.affiliation: Papahānaumokuākea Marine National Monument, National Oceanic and Atmospheric Administration, Honolulu, Hawaii, United States of America.
authors.forename: Randall K
authors.initials: RK
authors.lastname: Kosaki
mesh_terms: D000818:Animals; D018533:Biomass; D003247:Conservation of Natural Resources; D057894:Coral Reefs; D004242:Diving; D005398:Fisheries; D005399:Fishes / Q000145:classification*; D006254:Hawaii; D011795:Surveys and Questionnaires