Quantifying seafloor contact

Trawling is a key fishing method that has been used in Aotearoa New Zealand for generations and is the method that catches most of our finfish. It is highly effective at catching fish but faces increasing pressure from those concerned about the effects of its impact on the life on the seafloor. 

Towed fishing gears and their components contact the seabed, but the level of any effect caused by this contact will depend on the type of trawl doors and the ground gear used, the way the gear is rigged and the physical and the biological characteristics of the seabed habitats in the fishing ground.

Understanding how, when, and where trawl gear contacts the seafloor is key to evidence-based decision making. We intend to demonstrate how collecting data on current gear use can better inform modifications and improvements to reduce contact where appropriate.

We are undertaking this research in 3 phases:

Phase 1: Development & deployment of low-cost, user-friendly bottom contact sensors

First, we are establishing the footprint of commonly used trawl gear on the seafloor. We are collaborating with ZebraTech to develop a low-cost, user-friendly sensor prototype.

Phase 2: Understand and minimise contact

The sensors will collect baseline data on points of contact (the footprint) between commonly used fishing gear and the seafloor over normal fishing operations. This baseline data will inform gear modifications to minimise and reduce contact with the seafloor.

We will trial this modified gear, collecting contact between the modified gear and the seafloor over a series of fishing trips. We will then compare the footprint of the commonly used gear versus the modified gear to test the effectiveness of the modified gear.

Phase 3: Evidence-based decision making

We will work with the Hawke’s Bay regional study to demonstrate how the data from these sensors can be used as decision-making tools for mitigating seafloor habitat disturbance by fishing gear. This research also aligns with Fisheries New Zealand (FNZ)’s Fisheries Change Programme.

We aim to produce a sensor prototype, footprints of commonly used and modified fishing gear contact with the seafloor based on real-world observational data, comparison of the footprints/maps to demonstrate changes in benthic interactions, and peer-reviewed reports.

Project partners

Fisheries Inshore New Zealand (FINZ); Wild Pacific Fisheries Research; ZebraTech; Fisheries New Zealand (FNZ); Ngāti Kahungungu; NIWA; FAST Lab – Alaska Pacific University.

FINZ will be contributing their time and expertise through their core-funding. Other contributions will be made through technical expertise by collaborative partners. Chartering fishing vessels can range from $3,000-7,000 per day, and so a commercial vessels’ time to collect the data over several days will be a significant contribution to this project. This in-kind contribution will be about $15,000. FNZ are providing approximately $5,000 of in-kind staff time as part of the technical advisory committee.