Bird-scaring Lines (BSLs) have become the primary and most commonly prescribed seabird bycatch mitigation measure in longline fisheries worldwide. These are usually composed of a backbone section, colourful streamers and a drag section or towing device. They are extremely effective at reducing seabird bycatch since they scare foraging birds away from the “danger zone” in which baited hooks are close to the surface and easily accessible.
However, since BSLs have primarily been developed for and on large vessels, there is an urgent need to adapt them to the reality of small vessels and the fishing gear and conditions found on these. In South Africa our domestic longline fleets are largely under 35 m and while some skippers report successfully deploying BSLs on a regular basis, others have reported concerns relating to difficulties with deployments in bad weather conditions, entanglements with fishing gear, lack of high attachment points and unnecessarily cumbersome and bulky BSLs.
With a clear challenge in hand we set out to design a BSL better suited to our smaller domestic longline vessels. We needed to ensure that the new design would both work from a conservation perspective (by achieving a minimum aerial extent of 75m) but also be readily accepted by the fishing crews of the longline fleet! To achieve this our design needed to minimise the propensity for entanglements with fishing gear and be cheap to produce. Moreover, it needed to be easy to replicate, repair, store and use onboard vessels.
We consulted with colleagues in New Zealand, Uruguay and Brazil about their choice of materials before embarking on a new design. We soon discarded materials used successfully elsewhere, such as multi-coloured packaging ribbons, which tended to fray in our rough sea conditions. While some fishermen were happy with a mono-filament backbone, other’s complained that it lacked grip, and after ATF instructor Bokamoso spent a good few hours on-board a vessel untangling a knotted mess of monofilament and ribbons, we quickly moved on from that design.
Whether the rope used was plaited or woven also turned out to be an important characteristic, seeing as the former causes hooks to become caught and disrupt fishing operations. By joining bundles of two-metre-long PVC tubes we were able to achieve just the right amount of drag. But they say patience is a virtue or in our case perseverance! After much trial and error we arrived at a new design that fulfils all the requirements.
This end result is by no means “ours” as it would not have been possible to achieve behind a computer or by playing with ropes and ribbons on land. Instead, in true ATF style, it is the result of a collaborative effort with fishing masters and crew who on occasion gave us sympathetic looks of encouragement when a colourful bunch or streamers went flying off. And similarly, we were all hands on deck helping out when the BSL caused entanglements with the fishing gear and frustration levels rose. We owe a great thanks to skippers and crew who actively contributed with ideas on the use of materials which will facilitate the deployment and storage of BSLs, enhance crew safety and prevent entanglements with fishing gear. The success of the future uptake and commitment to deploying BSLs – when no observer is on board – depends on their sense of ownership and participation.
Next up is training our partnering team of people with disabilities to manufacture the new BSL design, before we can roll it out to industry – but that is another story for another blog!
By Reason Nyengera (Instructor ATF South Africa) and Andrea Angel (Team leader ATF South Africa)
With many thanks to Bokamoso Lebepe (former ATF instructor) and Makhudu Masotla (former ATF intern) for hours of hard work.
We spend 90% of net income on conservation, public education and advocacy
The RSPB is a member of BirdLife International. Find out more about the partnership
© The Royal Society for the Protection of Birds (RSPB) is a registered charity: England and Wales no. 207076, Scotland no. SC037654