Asher, Jacob; Ivor D. Williams; Euan S. Harvey

An Assessment of Mobile Predator Populations along Shallow and Mesophotic Depth Gradients in the Hawaiian Archipelago

2017

Scientific Reports

7

3905

"Large-bodied coral reef roving predators (sharks, jacks, snappers) are largely considered to be depleted around human population centers. In the Hawaiian Archipelago, supporting evidence is primarily derived from underwater visual censuses in shallow waters (less than or equal to 30 m). However, while many roving predators are present or potentially more abundant in deeper strata (30 - 100m and deeper), distributional information remains sparse. To partially fill that knowledge gap, we conducted surveys in the remote Northwestern Hawaiian Islands (NWHI) and populated Main Hawaiian Islands (MHI) from 2012-2014 using baited remote underwater stereo-video. Surveys between 0-100m "found considerable roving predator community dissimilarities between regions, marked conspicuous changes in species abundances with increasing depth, and largely corroborated patterns documented during shallow water underwater visual censuses, with up to an order of magnitude more jacks and five times more sharks sampled in the NWHI compared to the MHI. Additionall, several species were significantly more abundant and larger in mesophotic versus shallow depths, which remains particularly suggestive of deep-water refugia effects in the MHI. Stereo-video extends the depth range of current roving predator surveys in a more robust manner than was previously available, and appears to be well-suited for large-scale roving predator work in the Hawaiian Archipelago."

10.1038/s41598-017-03568-1

FY2017; CRCP Project ID 743; Project Title: National Coral Reef Monitoring Program (NCRMP) Implementation (Biological monitoring); Principal Investigator: Justine Kimball FY2015; CRCP Project ID 381; Project Title: Improving assessments of Hawaii priority reef fish species and apex predators using remote video-survey imagery; Principal Investigator: Jacob Asher