In 2019 Norway put forward a proposal to reintroduce the use of net monitoring cables (NMCs) on vessels on Norwegian trawl vessels using the continuous fishing method, targeting krill (WG-FSA-16/38). The use of net monitoring cables would allow a more effective monitoring of the fishing gear compared to the battery operated system currently in use and the fishing method and gear configuration currently employed has evolved significantly since the original ban on the cables since the 1994/95 season (CM 25-03). The main differences between conventional and continuous fishing methods, that would reduce the potential for seabird / gear interactions are:
- There is now a shorter length of NMC exposed to the air (reduced aerial extent: ~ 10+m (continuous) against ~100+m (conventional)).. Previous studies have shown that minimizing this distance has proved successful in reducing warp strikes by seabirds (Melvin et al., 2010) and has been incorporated into best practice advice in ACAP’s Summary advice (ACAP 2023) for reducing impact of trawl gear on seabirds;
- The NMC is in parallel and close to the warp and this configuration together would likely make them more visible to the birds;
- fewer sets and hauls are needed with the continuous trawling system, which reduces the time the nets spend on the surface. As setting and hauling are considered high-risk events for seabirds, minimising these should subsequently reduce the risk of any interactions with the gear;
- the mouth of each trawl is held open by a steel beam, in contrast to conventional trawls that use trawl doors (otter boards). This enables lower towing speeds; 1.5 – 2 knots compared to 3-4 knots with conventional krill trawls and ~ 5 knots for vessels targeting pelagic fish. This reduced towing speed makes it easier for birds to avoid the gear;
- the monitoring cable should no longer necessarily be considered a ‘third wire’ as it has previously been referred to, it is attached in parallel and close to the warp; and,
- the vessels do not discharge offal (this is prohibited by CCAMLR, south of 60 degrees), they do however discharge ‘stick water’, a product of processing carried out on board which is not attractive to birds, as defined in CM25-03.
Norway were permitted a derogation from CM 25-03 provided they developed mitigation measures and underwent a series of trials to test their effectiveness in preventing or reducing their impact on bird populations (SC-CAMLR-38/18). The results of these trials have been presented in a series of papers to FSA and IMAF respectively (WG-FSA-2021/13, WG-IMAF-2022/10, WG-IMAF-2022/11, and WG-IMAF-2023/01) with the trial being altered each season as appropriate according to advice from the Working Groups and SC. The changes made were primarily related to observer cover but also included recommendations for alterations to the mitigation measures themselves