Echosounder derived metrics from small-scale coastal surveys

Echosounder surveys are appealing for monitoring benthic rocky reef fishes like rockfish (Sebastes spp.) as they cover large areas quickly and are non-destructive, but they are rarely used due to difficulties ensonifying benthic fish in rocky habitats.  We conducted echosounder and remote operated vehicle (ROV) surveys at 39 sites in Mowachaht/Muchalaht territory (Nootka Sound, BC, Canada) in August 2023.  We examined correlations between an echosounder biomass proxy (nautical area scattering coefficient (NASC)) and ROV benthic fish density using generalized linear models. Increases in the fish biomass proxy (NASC) within 10m of the bottom was correlated with increasing benthic fish density (deviance explained 52%), suggesting NASC helps predict benthic fish hotspot locations.  We compared echosounder and ROV habitat metrics using Spearman’s rank correlation tests and found rugosity and slope were comparable across methods with reduced analyst variability in echosounder m..., , # Echosounder derived metrics from small-scale coastal surveys

Dataset DOI: [10.5061/dryad.1rn8pk167](10.5061/dryad.1rn8pk167)

## Description of the data and file structure

The purpose of this research project was to develop an efficient method of identifying rocky reef fish hotspots in coastal regions using echosounder surveys. We focused on developing simple echosounder techniques that would be accessible to active acoustic novices to make echosounder surveys more feasible and understandable to a wider audience. A general understanding of active acoustic theory is still recommended before undertaking any echosounder surveys. We recommend the comprehensive active acoustic text by Simmonds et al. (2007) as a go to resource for gaining a basic understanding of active acoustic principles:

Simmonds, E. John, and David N. MacLennan. *Fisheries Acoustics: Theory and Practice*. 2. ed., Fish and Aquatic Resources Series 10. Oxford: Blackwell, 2007.

In this study we utilized nautical area ...,