Project aim: To assess the suitability of the device
The aim of the trial was to assess the suitability of the device, ease of handling of nets fitted with the device and their impact on fishing operations.
Our Methods: Trialing the pingers with industry during comercial fishing activity
In co-operation with industry we trialed four models of pingers (by different manufacturers) on gillnets on commercial fishing vessels in the Irish Sea.
Key issues encountered during the trials included:
- Major tangles of the devices in gear
- Heavy damage to pingers due to collisions during fishing operations and poor general durability of pingers
- Negative buoyancy of pingers - negatively affecting performance of fishing gear
- Danger caused by lithium batteries being exposed to seawater in ruptured pingers
BIM addressed these issues by:
- Developing a modified attachment system which primarily consisted of mounting individual pinger units between floats, in bait bag tubing, and attaching the customised device at the interface between sheets of netting known as the ‘joins’.
- Reducing the impact of heavy collisions by the addition of net floats.
- Preventing the tangling of pingers in the fishing gear as the modified system was larger than the meshe size.
We also conduced trials on the effectiveness of the pingers at various distribution densities.
BIM's modified pinger attachment method was trialed on Irish commercial fishing vessels
Seeing the benefits: Economies in cost and handling of devices achieved
Our modified attachment method increased the durability of pingers.
Trials on the spacing of gillnet pingers demonstrated effective spacing of up to 500m instead of 200m which was subsequently legally permitted.
This resulted in:
- Reduced environmental pollution from lost or damaged pingers
- Reduced noise pollution and associated potential porpoise habitat limitation
- Improved economies in cost and handling of devices for fishermen
BIM also used data on bycatch of cetaceans from nets without pingers during the trials to provide an updated bycatch estimate for porpoises in the Celtic Sea in 2006. A major observed reduction in bycatch rates since 1993 was attributed to a major drop in gillnet fishing effort in the Celtic Sea over this period.