Identification and storage of cold-water coral bycatch 1 July 2020- 30 June 2021

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Summary

Many protected coral species occur as bycatch in commercial fisheries around New Zealand. Fisheries Observers on commercial fishing vessels are not always able to identify this bycatch at sea with high precision, with the confirmation of species often requiring identification from a coral taxonomist. For this reason, an ongoing research project was initiated in 2016, to determine, through the examination of returned coral specimens and specimen images, the taxon and the provenance of corals bycaught in New Zealand fisheries.

This report summarises the sample and image identifications of all observed coral bycatch collected under the project during the period 1 July 2020 to 30 June 2021. A total of 43 physical specimens in 32 samples were collected by Observers and returned for identification during the reporting period. Sub-samples from each live specimen were taken for future genetic studies (n=29). Additionally, there were three historical physical samples collected by Observers with revised higher-level identifications made during the reporting period. A total of 19 research trawl-collected specimens in 15 samples are also reported here. There were 251 specimens identified from digital images of catch reported as coral during the reporting period; 213 were protected coral taxa, and while Observers provided a label showing trip and tow number information for only 18 of the 257 processed images, all were able to be georeferenced.

The data summaries of protected coral by-catch occurring in New Zealand region fisheries are presented by Fisheries Management Areas (FMA), fishing method, and target fishery. The greatest number of protected coral specimen counts by images came from the SOU Southland (FMA5) and SOE South East (FMA4) regions. Most were taken by bottom trawl operations targeting the deep-sea species orange roughy and set net operations targeting school shark. Similarly, most protected corals identified from physical specimens came from SOE South-East (FMA4) bottom trawl operations targeting orange roughy.

While no formal analyses of accuracy have been carried out during this reporting period, between Observer and NIWA expert identifications, brief summaries of accuracy are provided. Agreement for some verified species identification codes are good, often down to family level, and for some groups such as stony cup corals and bubblegum corals, accurate to genus or species level. Other taxa remain problematic.

NIWA continue to provide information to brief Observers and give input into coral guide resources including the updated and revised Deepsea Coral Guide, to help improve overall accuracy of protected coral species identification at-sea. Through this programme, NIWA have facilitated the creation of 29 new protected coral species codes, and one non-coral code. As in previous reports, we stress in our recommendations to Observers the use of labels when images are taken, and consistency in specimen label and benthic form recording processes.