Site fidelity, movements and habitat use of gray smooth-hound sharks, Mustelus californicus (Gill, 1863), in a newly restored estuarine habitat

It is thought that some elasmobranchs use shallow temperate embayments during warmer months because they may provide a thermal physiological advantage. Abundance surveys and acoustic telemetry were employed to examine the influence of water temperature on site fidelity and habitat use of gray smooth-hound sharks (GSH) in the Full Tidal Basin (FTB) of Bolsa Chica. GSH were more abundant inside the FTB during summer months (May-September), and moved out during the winter (December-February) when this shallow embayment becomes colder than coastal waters. Sharks fitted with acoustic transmitters ( n = 22) were continuously detected for 5-153 d (March-December). Long-term, fine-scale acoustic data revealed that GSH only used a small core area (<5% of FTB area); however, they exhibited consistent diel movements in the FTB. GSH selected soft mud-substrates with eelgrass more intensively at night. Behavioral and abundance data suggest that GSH are mainly using this newly restored habitat during warmer months, presumably for feeding on potential prey available.