Effects of Sounds from a Geophysical Survey Device on Catch-per-Unit-Effort in a Hook-and-Line Fishery for Rockfish (Sebastes spp.)

We examined the concern of commercial fishermen that the sounds generated by acoustic geophysical survey devices result in decreased commercial catches. In blind experimental trials, a test of effects was performed on the rockfish (Sebastes spp.) hook-and-line fishery located along the central California coast. A single 1639-cm3 air gun with a source level of 223 dB re 1 μPa was used to produce peak pressures above 186 dB re 1 μPa at the base of rockfish aggregations. There was an average decline in catch-per-unit-effort of −52.4% (90% confidence interval −27.9%, −76.9%) under emission conditions relative to control trials. This overall decline was also reflected in the individual catches of chilipepper (S. goodei (α = 0.046)), bocaccio (S. paucispinis (α = 0.007)), and greenspotted rockfish (S. chlorostictus (α = 0.021)). The overall reduction in catch translated to an average economic loss of 49.8% (90% confidence interval −21.7%, −77.9%) under the test conditions of this experiment. Fathometer recordings during the study showed no significant change in an index of aggregation size as the result of air-gun emissions (α = 0.374). However, aggregation height appeared to change as the result of emission (α = 0.094) after adjustment for species composition of the catch.