Estimation of the incidental capture of seabird species in commercial fisheries in New Zealand waters, 2000/01

Ministry of Fisheries observers reported 1236 seabird captures from fishing operations in 2000–01: 701 from observed trawl fishing operations (87% landed dead); 53 from tuna (Thunnus spp.) longlining operations (87% landed dead); 452 from ling (Genypterus blacodes) longline operations (99% dead); 26 seabirds from snapper (Pagrus auratus) longlines (100% dead); and 4 from bluenose (Hyperoglyphe antarctica) longline operations (75% landed dead). Observed squid (Nototodarus spp.) and hoki (Macruronus novaezelandiae) trawl fisheries accounted for 94% of the 701 seabird captures in observed trawl fisheries.
Observed incident rates in longline fisheries were highest in the ling longline fishery: 24% of observed ling autoline sets caught seabirds, compared with 6% of observed chartered tuna longline sets caught seabirds, 15% of domestic tuna longlines, and 16% of snapper longlines. Lower incident rates were observed in the trawl fisheries: 8% of observed tows in the squid fishery, 4% in hoki, barracouta (Thyrsites atun), and scampi (Metanephrops challengeri) fisheries, and < 2% in jack mackerel (Trachurus spp.), southern blue whiting (Micromesistius australis), and orange roughy (Hoplostethus atlanticus) tows.
Mean seabird catch rates were estimated for the main fisheries with observed seabird captures: for ling longline fisheries, mean catch rates varied from 0.218 seabirds per 1000 hooks (s.e. = 0.033) in LIN 6 to 0.004 (s.e. = 0.004) in LIN 2; for chartered tuna fishery off the southern west coast of the South Island, 0.026 seabirds per 1000 hooks (s.e. = 0.008); for hoki fisheries, between 0.014 seabirds per tow (s.e. = 0.004) in the west coast South Island fishery and 0.037 (s.e. = 0.030) in the Puysegur fishery; and for squid trawl fisheries, 0.095 seabirds per tow (s.e. = 0.009) at the Stewart-Snares shelf fishery and 0.073 seabirds per tow in SQU 6T.
Total estimates are provided for the main fisheries: 16 seabirds (c.v. = 6%) were caught during chartered tuna longline sets, primarily off the southern west coast of the South Island; 757 seabirds (c.v. = 11%) were estimated caught by four autoline vessels when stratified by area and season compared with an estimated 2 367 seabirds (c.v. = 12%) for the six autoline vessels by area; 1065 seabirds (c.v. = 9%) were estimated caught during hoki targeted trawls; and 586 seabirds (c.v. = 11%) were estimated caught during squid trawls. Numbers are given for seabirds in total, rather than individual taxa, because of problems in extrapolating by seabird species over a fishery.
In fisheries for which the observer coverage was < 10% of the total effort in a season or fishing year, the number of observed seabirds are reported: 68 seabirds from domestic tuna, bluenose, and snapper longline sets and 44 seabirds from trawls targeting at least 10 species other than hoki and squid.
Apart from one black-backed gull (Larus dominicanus), the remaining 1045 seabirds observed caught and returned for identification represented nine albatross and thirteen petrel taxa. These taxa included three previously unrecorded as caught during observed fishing operations: Buller’s shearwater (Puffinus bulleri), fluttering shearwater (Puffinus gavia), and short-tailed shearwater (Puffinus tenuirostris). White-chinned petrels (Procellaria aequinoctialis), sooty shearwaters (Puffinus griseus), grey petrels (Procellaria cinerea), white-capped albatrosses (Thalassarche steadi), and Salvin's albatrosses (T. salvini) accounted for 92% of the seabirds landed dead and returned for autopsy.