Comparison of Reef Fish Survey Data Gathered by Open and Closed Circuit SCUBA Divers Reveals Differences in Areas With Higher Fishing Pressure

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.

[1]  J. García-Sais,et al.  Reef habitats and associated sessile-benthic and fish assemblages across a euphotic–mesophotic depth gradient in Isla Desecheo, Puerto Rico , 2010, Coral Reefs.

[2]  Benjamin L. Richards,et al.  Assessing the importance of fishing impacts on Hawaiian coral reef fish assemblages along regional-scale human population gradients , 2008, Environmental Conservation.

[3]  Euan S. Harvey,et al.  A comparison of visual‐ and stereo‐video based fish community assessment methods in tropical and temperate marine waters of Western Australia , 2013 .

[4]  C. Meyer.  The impacts of spear and other recreational fishers on a small permanent Marine Protected Area and adjacent pulse fished area , 2007 .

[5]  J. Báez,et al.  First record of intersexuality in Euthynnus alletteratus in the Mediterranean Sea: histological description , 2014 .

[6]  L. Rocha,et al.  Ecology and Zoogeography of Deepreef Fishes in Northeastern Brazil , 2005 .

[7]  John C. Montgomery,et al.  Bubbled waters: The noise generated by underwater breathing apparatus , 2005 .

[8]  K. Nash,et al.  Influence of spear guns, dive gear and observers on estimating fish flight initiation distance on coral reefs , 2012 .

[9]  A. Heenan,et al.  Coral Reef Ecosystem Division standard operating procedures data collection for rapid ecological assessment fish surveys , 2011 .

[10]  Alan M. Friedlander,et al.  Contrasts in density, size, and biomass of reef fishes between the northwestern and the main Hawaiian islands: the effects of fishing down apex predators , 2002 .

[11]  J. Baum,et al.  Human, Oceanographic and Habitat Drivers of Central and Western Pacific Coral Reef Fish Assemblages , 2015, PloS one.

[12]  D. Stanley,et al.  Effect of Scuba Divers on Fish Density and Target Strength Estimates from Stationary Dual-Beam Hydroacoustics , 1995 .

[13]  Arne Sieber,et al.  A review of the use of closed-circuit rebreathers for scientific diving , 2010 .

[14]  R. Appeldoorn,et al.  Fishes associated with mesophotic coral ecosystems in La Parguera, Puerto Rico , 2014, Coral Reefs.

[15]  M. Kulbicki,et al.  Comparison of density estimates derived from strip transect and distance sampling for underwater visual censuses: a case study of Chaetodontidae and Pomacanthidae , 1999 .

[16]  Benjamin L. Richards,et al.  Re-Creating Missing Population Baselines for Pacific Reef Sharks , 2012, Conservation biology : the journal of the Society for Conservation Biology.

[17]  M. Schmidt,et al.  Influence of scuba divers on the avoidance reaction of a dense vendace (Coregonus albula L.) population monitored by hydroacoustics , 2006 .

[18]  C. Roberts,et al.  Effects of fishing on sex-changing Caribbean parrotfishes , 2004 .

[19]  N. Graham,et al.  Fear of Fishers: Human Predation Explains Behavioral Changes in Coral Reef Fishes , 2011, PloS one.

[20]  A. Friedlander,et al.  Effects of habitat, wave exposure, and marine protected area status on coral reef fish assemblages in the Hawaiian archipelago , 2003, Coral Reefs.

[21]  D. Wagner,et al.  Mesophotic surveys of the flora and fauna at Johnston Atoll, Central Pacific Ocean , 2014 .

[22]  Panagiotis Dendrinos,et al.  The Structure of Mediterranean Rocky Reef Ecosystems across Environmental and Human Gradients, and Conservation Implications , 2012, PloS one.

[23]  William J. Walsh,et al.  Impact of observers experience level on counts of fishes in underwater visual surveys , 2006 .

[24]  R. Pyle.  Assessing undiscovered fish biodiversity on deep coral reefs using advanced self-contained diving technology , 2000 .

[25]  E. Sala,et al.  Differences in fish-assemblage structure between fished and unfished atolls in the northern Line Islands, central Pacific , 2008 .

[26]  B. Wilson,et al.  Bubble use during prey capture by a lone bottlenose dolphin (Tursiops truncatus) , 1997 .

[27]  K. Bjorndal,et al.  Historical Overfishing and the Recent Collapse of Coastal Ecosystems , 2001, Science.

[28]  Rainer Froese,et al.  FishBase. World Wide Web electronic publication. , 2014 .

[29]  M. Kulbicki.  How the acquired behaviour of commercial reef fishes may influence the results obtained from visual censuses , 1998 .

[30]  S. Jennings,et al.  Biased underwater visual census biomass estimates for target‐species in tropical reef fisheries , 1995 .

[31]  D. J. Creasey,et al.  Reactions of fish to sound generated by divers' open-circuit underwater breathing apparatus , 1974 .

[32]  Oceanic winds estimated from underwater ambient noise observations in SWADE , 1996, OCEANS 96 MTS/IEEE Conference Proceedings. The Coastal Ocean - Prospects for the 21st Century.

[33]  A. Acosta,et al.  A large-scale field comparison of strip transect and stationary point count methods for conducting length-based underwater visual surveys of reef fish populations , 2007 .

[34]  N. Graham,et al.  Spillover of fish naïveté from marine reserves. , 2013, Ecology letters.

[35]  M. Kulbicki,et al.  Factors affecting the detection distances of reef fish: implications for visual counts , 2011 .

[36]  Alan M. Friedlander,et al.  From Reef to Table: Social and Ecological Factors Affecting Coral Reef Fisheries, Artisanal Seafood Supply Chains, and Seafood Security , 2015, PloS one.

[37]  Queensland Townsville.  Observer effects and training in underwater visual surveys of reef fishes , 1997 .

[38]  Nicholas K. Dulvy,et al.  Coral reef cascades and the indirect effects of predator removal by exploitation , 2004 .

[39]  S. Jennings,et al.  Impacts of predator depletion by fishing on the biomass and diversity of non-target reef fish communities , 1997, Coral Reefs.

[40]  David R. Bellwood,et al.  Quantifying Relative Diver Effects in Underwater Visual Censuses , 2011, PloS one.

[41]  Does breathing apparatus affect fish counts and observations? A comparison at three New Zealand fished and protected areas , 2007 .

[42]  Aileen C. Mill,et al.  Size structural change in lightly exploited coral reef fish communities: Evidence for weak indirect effects , 2004 .

[43]  Benjamin L. Richards,et al.  A towed-diver survey method for mesoscale fishery-independent assessment of large-bodied reef fishes , 2011 .

[44]  D. Kramer,et al.  Body size and reserve protection affect flight initiation distance in parrotfishes , 2009, Behavioral Ecology and Sociobiology.

[45]  Euan S. Harvey,et al.  Calibration stability of an underwater stereo-video system : Implications for measurement accuracy and precision , 1998 .

[46]  Frank A. Parrish,et al.  Field comparison of open-circuit scuba to closed-circuit rebreathers for deep mixed-gas diving operations , 2002 .

[47]  Euan S. Harvey,et al.  Silent fish surveys: bubble‐free diving highlights inaccuracies associated with SCUBA‐based surveys in heavily fished areas , 2014 .

[48]  N. Graham,et al.  Effects of Customary Marine Closures on Fish Behavior, Spear‐Fishing Success, and Underwater Visual Surveys , 2010, Conservation biology : the journal of the Society for Conservation Biology.

[49]  M. Kulbicki,et al.  A general approach to length-weight relationships for New Caledonian lagoon fishes , 2005 .