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No-tori-ous but still one of the best

Wednesday 12 October 2016

Johanna Pierre, DOC seabird bycatch co-ordinator and Director JPEC Ltd

Recent media has reminded us all that the law is clear – tori lines are required on every set made by bottom longliners over seven metres long and surface liners. But how can tori lines be made to work best, for fishers and seabirds?

 

A tori line showing its best side - this tori line’s height, bright-coloured streamers, and effective aerial extent mean it works well to deter birds. Image: David Goad

Some skippers swear by their designs, while others are coming to grips with a good one. Either way, tori lines are a core component of the seabird mitigation tool box. They look basic, they are basic, and there is a set of simple ideas that helps them work best.

Light is right: A light backbone material and light streamers are kept in the air with less drag weight. So, the lighter the tori line is, the more aerial extent will be achieved. This helps keep the tori line away from fishing gear for a greater distance astern and protects the hooks better from seabird attack.

Height: Deploying a tori line high also keeps it above the fishing gear further astern. This reduces the risk of tangles and makes the tori more effective. A pole will be needed to attach tori lines high enough on some smaller vessels.

Weak link: Adding a short loop of rope with lower breaking strain than the tori line backbone means you know better where it will break in case of a tangle.

Drag: The hardest bit of tori line design is getting the drag right. Got sag? Need drag! If a tori line is sagging, adding more drag will help, for example, using a heavier object at the end of the tori line. Floats and cones can work well. Or, if tangles are a concern, adding a length of thick mono or rope at the end of the tori line could be better. If the tori line is still sagging, it’s worth adding even more drag and thinking about how to reduce the weight of the tori (or setting it higher above the water).

Backbone: A rope backbone with 30kg breaking strain is a good start. That way, the tori line backbone will break before the main longline if there is a tangle.

Streamers: Light and bright is the way to go. Beauline International have some new tori material that is $1.50/m and specifically designed for small vessel tori lines. It’s light, bright, takes ages to fade, and will snap before the mainline does. That helps reduce issues if there is a tangle during setting. Also, streamers should run from the tori line backbone to the sea surface. Reducing seabird bycatch is a part of every fisher’s core business. It’s not always easy, but no-one does it better than fishers themselves. 

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