Results of initial trials to determine if laser light can prevent seabird bycatch in North Pacific fisheries
Here we report results of the first field trials of a laser-based seabird deterrent in North Pacific fisheries. We tested a commercially available product and a prototype device, each operating in the visible region at 532 nm (green). The optical power output measured in the laboratory was similar for both (1.26 and 1.01 W, respectively) placing them well within the class-4 laser classification. The calculated Nominal Optical Hazard Distance (NOHD) for each was also similar (102 m and 192 m, respectively). Field trials were carried out on a trawl catcher-processor off the Oregon-Washington coast in October 2015. Trawl was selected over longline because it represents a worst-case challenge for seabird deterrence: large aggregations of birds feeding on an abundant food source (continuous offal discharge from the factory) 24/7. Attending seabirds (all species) showed little detectable response to the laser beam during daylight hours. At night however, Northern fulmars (Fulmarus glacialis) showed a transient and localized response at lower vessel speeds (3.5 kts) while feeding in the offal plume. In contrast, gulls in flight at nighttime in pursuit of the vessel showed a strong aversion at higher vessels speeds (11 kts). These results suggest that laser beam detection by birds may be more challenging at high light levels. The implication is that lasers might be modified to increase its visual contrast during the day. From these field trials, lasers appear more likely to scare birds from an abundant food source at low light levels and success may be species and condition specific.