Preparation of data for protected species capture estimation, updated to 2016–17


Abraham, E. R., & Berkenbusch, K. (2019). Preparation of data for protected species capture estimation, updated to 2016–17. New Zealand Aquatic Environment and Biodiversity Report No. 233. 49 p.


Assessments of the capture of protected species in New Zealand commercial fisheries rely on observer and fisher-reported data. Fisheries observers onboard commercial fishing vessels document the captures of protected species. These observer records are linked to fisher-reported effort data. The current report presents the preparation of observer and fisher-reported data, to the 2016–17 fishing year, for the Protected Species Captures (PSC) database.

During preparation of the data to the end of the 2016–17 fishing year, the following significant updates were applied to the previous processing of some of the data:

  1. Early during the development of electronic reporting by observers (through the handheld Nomad devices), the data were not included in the Centralised Observer Database (COD), and the observer effort was recreated from fisher effort. During the data preparation for the current fishing year, the observer data from these devices were included directly in COD.

  2. The linking of observer effort and fisher effort was revised. This revision highlighted that some vessel keys recorded in COD were incorrect, leading to the inclusion of a process that identified observer trips that may have incorrect vessel keys.

  3. Some records of seabird captures had been created following review of photographs. Some of these records had no capture method associated with them. Following review of the photographs, some of these records were determined to be deck captures (which are not included in the seabird bycatch estimation).

  4. Imputation of the location of set-net data in West Coast North Island harbours was carried out, based on tracking of small vessels undertaken by Trident Systems.

The correction to the way that data from Nomad devices were processed during loading into the PSC database resulted in a decrease in observer effort in the small-vessel fisheries where these devices were used (while maintaining the same number of observed captures). The correction to vessel keys resulted in 27 black petrel captures moving from the East Cape to the Hauraki Gulf areas, with some captures changing from surface longline to bottom longline.

This report outlines the rationale and impact of these changes and updates on the PSC data, including a comparison with the previous data preparation to the 2015–16 fishing year.