Video observation of the FMA 1 bottom longline fishery in 2018–19 and 2019–20

Black petrel (Procellaria parkinsoni) and flesh-footed shearwater (Ardenna carneipes) are two of the seabird populations assessed as being at greatest risk from incidental captures in fisheries. These seabirds breed in north-eastern New Zealand, and are caught primarily by bottom longline vessels fishing in that area. In order to develop a methodology for monitoring seabird captures from video footage, and to gather data on capture rates, video cameras were used to film the hauling station on bottom longline vessels fishing within Fisheries Management Area (FMA) 1, off the north-east coast of New Zealand. This programme has been developed in collaboration with the fishers, who have volunteered their time and the use of their vessels.

Since 2016–17, this programme has been used to monitor between nine and twelve of the most active vessels in this fishery. In this report we present the results of the 2018–19 and 2019–20 data collection programme. Data were collected during 2019–20 as part of this project, with previous footage and data being made available by Trident Systems.

The electronic monitoring (EM) systems used for collecting footage consisted of a single camera on each vessel, positioned on a boom outboard from the hauling station. During 2019–20, a wheelhouse unit was used to record the footage, with the footage transferred into a review system using USB devices. Selected footage was reviewed to identify seabird captures, with selections sometimes being reviewed multiple times for quality control. Any seabird captures identified were then reviewed by a specialist to confirm the identification.

Footage collection during 2019–20 was impacted by several operational issues: the camera housings developed cracks that let water inside the housings; noisy fans and bright lights resulted in the crew switching the EM systems off, initially by removing fuses because switches were not installed; the system clock on one vessel failed leading to incorrect footage timings; and the coronavirus pandemic prevented system maintenance and data transfer during the lockdown period. In addition, one vessel had a fire as a result of damage to the EM system power cable which had a poorly located fuse. Despite these issues, footage was collected from 645 fishing events during November to May 2019–20 (17.7% of all bottom longline fishing events in FMA 1 over the period). In the snapper fishery (i.e., snapper target bottom longline events), footage was captured for 25.8% of the hooks set over this period, with 23.8% being reviewed for seabird captures. In contrast, 8.1% of hooks in the snapper fishery occurred during trips with human observers assigned to the vessel.

For the preceding season (November to May 2018–19), the footage collected by Trident Systems covered 700 bottom longline fishing events in FMA 1 (20.1%). In the snapper fishery, footage was captured for 26.2% of the hooks set over this period, with 24.7% being reviewed for seabird captures. Human observers were assigned to vessels in the snapper fishery for the period in which 7.4% of hooks were set. In total, 65 seabird captures were recorded by video monitoring during 2019–20 (one of which was on a fishing event outside FMA 1), with a capture rate of 0.032 captures per 1000 hooks. The highest number of captures recorded from a single vessel was 24 captures. Flesh-footed shearwater was the most frequently caught species (48 captures), followed by black petrel (13 captures). By using a statistical model, fitted to data from four years of video observation, to scale up these observed captures to the whole fishery, there were estimated to have been 296 (97.5% c.i.: 166 to 519) seabird captures in all bottom longline fishing in FMA 1 between October 2019 and May 2020. This corresponded to a capture rate of 0.038 (95% c.i.: 0.021 to 0.067) seabird captures per 1000 hooks set. Over the 2019 and 2020 fishing years, there were 251 seabird captures reported by fishers from bottom longline fishing within FMA 1. Of these captures, 127 were reported from vessels participating in the video monitoring trial (a capture rate of 0.0148 seabird captures per 1000 hooks). There were 124 captures reported from other vessels, with a capture rate of 0.0078 seabird captures per 1000 hooks. The rate of reporting by vessels participating in the trial was around twice as high as the rate of reporting by other vessels.

The multiple reviews identifed an issue with the review accuracy. There were many seabird captures that were missed during the first review of the footage (there were 51 captures on footage that was multiple-reviewed, and of these 20 were on sections of footage that had no capture detected by the first reviewer). The video monitoring programme is reliant on the accuracy of the video review, and without the multiple review this would have led to significant under-reporting of seabird captures. Overall, however, despite the operational challenges, and despite the discrepancies seen in multiple reviews, the programme demonstrates that video monitoring can be used to collect data on seabird captures in bottom longline fisheries. The programme has allowed the effective coverage in snapper bottom longline fisheries to be expanded well beyond what has been possible with a traditional observer programme. The ability to assess the reviewer accuracy is unique to video observation; there is no equivalent assessment of the accuracy of data from traditional observer coverage. As the technology and the systems continue to develop, it is likely that the efficiency and accuracy of the video-monitoring will increase.