Comparing video and visual survey techniques for Barred Sand Bass in rocky reef ecotone habitats

Abstract

Fishery-independent data contribute estimates of the distribution and abundance of marine species that are valuable to fishery management. Here, we compared two fishery-independent survey methods: Underwater visual census (UVC) and baited remote underwater videos (BRUVs) to determine the best design for a long term monitoring study of Barred Sand Bass (Paralabrax nebulifer) at the edges (ecotone) of inshore natural and artificial reefs in southern California. Both methods were effective at detecting Barred Sand Bass, which were significantly more abundant at artificial compared to natural reefs. Seasonal effects on Barred Sand Bass abundance were observed on UVC but not on BRUV. BRUVs detected Barred Sand Bass more frequently than UVC surveys (83% vs 46%, respectively), and a power analysis estimated that BRUVs required substantially fewer samples than UVC to detect a 100% change in the relative abundance of Barred Sand Bass over time (19 vs 52 samples, respectively). However, Barred Sand Bass exhibited territorial behavior around the bait and BRUV data were quite conservative, suggesting that UVC will perform better at generating estimates of total abundance. UVC only detected three unique species, while BRUVs detected 23, many of which were cryptic or transient and predatory. So a combination of UVC and BRUV surveys may be ideal, depending on the monitoring objective and available resources.