Download FAR 2025/23 Acoustic biomass surveys of orange roughy spawning aggregations in ORH 3B NWCR and ORH 3B ESCR Chatham Rise, June/July 2022

An acoustic biomass survey of spawning orange roughy was undertaken on aggregations at Morgue and Graveyard hills in ORH 3B North-West Chatham Rise and at Rekohu, Spawn Plume and Mt Muck in ORH 3B East & South Chatham Rise, during June and July 2022 aboard FV San Waitaki.

Acoustic data were recorded using the vessel’s hull-mounted Simrad 38 kHz echosounder system and a dual-frequency (38 kHz & 120 kHz) Acoustic Optic System (AOS) deployed on the headrope of a trawl net.

In NWCR, spawning biomass at Morgue, a protected area, showed an increase over survey estimates in 2013, 2016 and 2021, while spawning biomass at Graveyard was considerably reduced compared to the previous survey estimate in 2013. In ESCR, spawning biomass at Rekohu in 2022 was lower than in 2013 and 2016, while at Spawn Plume the biomass was similar to that found in 2013 and 2016. At Mt Muck the biomass in 2022 was higher than the estimates in 2013 and 2016.