Abyssopelagic grenadiers: the probable cause of low frequency sound scattering at great depths off the Oregon and California coasts

Volume reverberation measurements from the slope base and abyssal plain along the coasts of Oregon and northern California show an unexpected scattering layer peaking around 2000 Hz at depths greater than 1000 m. A model of swimbladder resonance applied to published records of bottom-dwelling grenadier size and abundance provided a good fit to the data, suggesting the widespread pelagic occurrence of grenadiers, Coryphaenoides spp., of 20–68 cm length at densities near 0.004 ind. m−2 over the slope base and abyssal plain.