Diel behavioral rhythms in sablefish (Anoplopoma fimbria) and other benthic species, as recorded by the Deep-sea cabled observatories in Barkley canyon (NEPTUNE-Canada)

Recent advances in cabled observatory video-imaging now enable faunal monitoring over extended periods of time. These platforms can be used to avoid biases in population and biodiversity assessments due to behavioral rhythms (i.e. massive population displacements). In this study we used video monitoring to examine the interplay between day-night and internal tidal cycles in regulating the behavior of sablefish (also referred to as black cod; Anoplopoma fimbria), hagfish (Eptatretus spp.) and crabs. We counted the number of animals in 50 s video-recordings taken at 30 min intervals with 3 NEPTUNE-Canada cameras located in Barkley canyon at approximately 1000 m depth (one in the axis and two on the wall of the canyon). Current data just above the seafloor was recorded as an indicator of the local internal tidal regime. Chi-Square periodogram analysis did not show significant (p < 0.05) day-night or tidal-based rhythms for the three species. The same analysis conducted for the sablefish (i.e. the most abundant) at each camera separately revealed different and significant (p < 0.05) 12- and 24-h based periods. Waveform analysis for these time series showed a temporal phase shift among cameras, suggesting diel displacements within the canyon axis. Our results highlight how some Deep-sea fish may present diel rhythmic displacements along canyons according to the day-night and internal tidal temporization. In this context, bathymetric networks of cabled video-stations can be an effective sampling tool to monitor this kind of behavior.