Summary of the capture of seabirds, marine mammals and turtles in New Zealand commercial fisheries, 1998–99 to 2007–08

Citation

Abraham, E. R., Thompson, F. N., & Oliver, M. D. (2010). Summary of the capture of seabirds, marine mammals and turtles in New Zealand commercial fisheries, 1998–99 to 2007–08. New Zealand Aquatic Environment and Biodiversity Report No. 45. 148 p.

Summary

A summary is presented of all captures of seabirds, marine mammals, and turtles during trawl and longline fishing within the outer boundary of the New Zealand Exclusive Economic Zone (EEZ) between 1 October 1998 and 30 September 2008. Ministry of Fisheries observers record captures of seabirds, marine mammals, and turtles, and these data, along with information on fishing effort, are used for estimating total captures.

Within this report, captures are divided into the following groups: sooty shearwater (Puffinus griseus), white-chinned petrel (Procellaria aequinoctialis), white-capped albatross (Thalassarche steadi), other albatrosses, other birds, New Zealand sea lion (Phocarctos hookeri), New Zealand fur seal (Arctocephalus forsteri), dolphins, whales, and turtles. Captures are also reported by fishery, based on method (trawl, bottom longline, and surface longline) and target species. The report contains time series and maps of the observed and estimated captures.

In the 2007—08 fishing year there were 233, 37, and 40 birds observed caught in trawl, surface longline, and bottom longline fisheries, respectively. The most frequently caught bird species were sooty shearwater, white-chinned petrel, and white-capped albatross with 82, 74, and 44 observed caught, respectively. Other observed captures included one Westland petrel (Procellaria westlandica) caught in the West Coast South Island trawl fishery; four black petrels, or Parkinson's petrels (Procellaria parkinsoni), caught in scampi trawl and hapuku bottom longline fisheries; and one wandering albatross (Diomedea exulans) caught in the northeast bluenose longline fishery. Another wandering albatross was caught and released alive. All of these species are classified as vulnerable by the IUCN.

Estimated captures of seabirds in trawl fisheries decreased by 13.2% from 1023 (95% c.i.: 906 to 1150, based on 40.9% of effort) in 2006—07 to 911 (95% c.i.: 797 to 1 040, based on 40.8% of effort) in 2007—08. This decrease is most likely explained by the concurrent 13.9% decrease in effort across all trawl fisheries. The ratio estimate for bird captures in surface longline fisheries for 2007—08 was 449 (95% c.i.: 127 to 862, based on 98.2% of effort). The ratio estimate for bird captures in bottom longline fisheries for 2007—08 was 368 (95% c.i.: 224 to 539, based on 61.6% of effort). No snapper target bottom longline fishing was included in this estimate, as no observations were made in this fishery.

In addition to seabirds, 11 New Zealand sea lions, 151 New Zealand fur seals, 20 common dolphins (Delphinus delphis), 1 bottlenose dolphin (Tursiops truncatus), 1 whale, and 1 leatherback turtle (Dermochelys coriacea) were observed caught during 2007—08. The estimated number of New Zealand sea lions captures in all trawl fisheries for 2007—08 was 39 (95% c.i.: 27 to 51, based on 41.8% of effort); the lowest estimated catch in nine years. This figure does not include sea lions that may have escaped or been ejected by sea lion exclusion devices used in the Auckland Islands squid trawl fishery. Ratio estimates of fur seal and dolphin captures in all trawl fisheries were the highest for three years.

Observer coverage in inshore trawl fisheries remained very low. In 2007—08, only 158 inshore trawls were observed, 0.3% of the fishery. In the 2007—08 fishing year, 56.1% of all trawls were in inshore fisheries: estimates of captures were not made on any of this effort.