Resources for trawl fisheries
IntroductionAn introduction to mitigation measures for fishing vessel crew involved in trawl fisheries.
Commercial trawl fisheries in New Zealand are divided in to inshore, deep-water/middle depth and scampi fisheries. Net fisheries are generally considered a relatively indiscriminate form of fishing in comparison to line fisheries. Trawl fisheries have the potential to interact, and impact upon, a wide range of marine protected species.
There are a range of mitigation practices that trawl vessels can employ to reduce harm or mortality to protected species. Mitigation measures focus on bird-scaring devices to deter seabirds coming into contact with warp cables and the net, these include bird bafflers, tori lines and other warp scaring devices. The discharge of offal and fish waste acts as an attractant to seabirds to areas of high risk, managing when and where this discharge occurs will greatly reduce the chance of interactions resulting in injuries and mortality of protected species.
Bird bafflers are an essential mitigation tool in deepwater trawl fisheries. The purpose of this device is to deter seabirds away from the area where the net and warp cables enter the water.
Tori lines and warp scaring devices
Tori lines are another essential bird scaring device in trawl fisheries. The purpose of this device is to deter seabirds from coming into contact with warp cables. The condition, position and areal extent of the tori line will determine how effective they are.
The discharge of offal and fish waste acts as an attractant to seabirds to areas of high risk, managing when and where this discharge occurs will greatly reduce the chance of interactions resulting in injuries and mortality of protected species. The clearing of stickers from the net and reducing the time of the net net on surface is important in reducing the chnce of incidental captures.
Night setting can greatly reduce the incidental capture of seabirds. Despite this, the moon phase effects light levels at night-time which can increase nocturnal birds ability to detect fishing activity. Keeping deck lighting to a minimum will reduce seabird attraction to fishing vessels.
Research and innovation
Research is continually underway to develop mitigation practices and devices in order to reduce the incidental capture of protected species in trawl fisheries. A current CSP project is looking into effective batching intervals of discards in the scampi trawl fishery as a potential measure to reduce the attraction and density of seabirds to areas of high risk. Another current project aims to review mitigation techniques to reduce the benthic impacts of trawling.
Fishers are responsible for handling all protected species appropriately in order to maximise the chance of survival. More more information on best practice methods of protected species bycatch and handling, check out the handling and release guide.
Commercial fishers are legally obliged to report any captures and releases of protected species, as well as noting the status of survival of the animal. It is not illegal to capture a protected species however it is illegal not to report it.