Pingers are a type of Acoustic Deterrent Device (ADD) – devices that emit sound at various audio frequencies, to alert marine mammals of fishing gear. Pingers are small, battery-operated and attach to nets at varying intervals. Pingers have been widely adopted on gillnets to deter small cetaceans, and have also been trialled and are used on trawls, longlines and pot/trap gear, to varying effects.
Pingers used in gillnets have relatively low acoustic outputs, whereas those trialled and used on trawls are louder, noting the loud operational conditions of trawls. The effectiveness of pingers in reducing bycatch differs between gillnet, trawl, longline and pot/trap gear. It is also likely to be more economically viable to deploy pingers on smaller, contained gear (such as static nets), rather than gear that extends over great distances (such as longlines).
There are different types of pinger, such the Dolphin Deterrent Device (DDD) and Fishtek Marine’s ‘Banana Pinger’ which has three variations, designed specifically to alert whales, dolphins and porpoise from static nets.
Certain pingers are required by law in various countries, including in the UK for vessels over 12m, using bottom set gill nets or entangling nets, in: the Celtic Sea (all year round); and the North Sea (all year round for net mesh size of 220mm or more, or from 1 August – 31 October for all nets of 400m or less).
A study between August 2012 and March 2013 in Cornwall suggested that the deployment of Fishtek Marine’s ‘Banana Pingers’ on fishing nets would likely reduce net-harbour porpoise interaction, and suggested that harbour porpoise did not habituate to pingers, nor did pinger use lead to long-term displacement of the species. A later study conducted in the Baltic Sea found that the same device once activated could cause some harbour porpoise to have an adverse behavioural reaction, whereas 25% of individuals did not respond at all. The strong behavioural responses observed may indicate that pinger use should be focused in space and time, or that acoustic devices which cause less severe behavioural responses are required.
Pingers have been found to be successful in reducing small cetacean bycatch in other gillnet fisheries. For example, a study of several Norway gillnet fisheries found an estimated 94% reduction in the risk of harbour porpoise bycatch with minimal impact on day-to-day fishing operations (in terms of time costs and catch rates). However, results for pingers appear to be species- and fishery-specific, rather than universal. How pingers are deployed also appears to be important, with a study of gillnet fisheries in the Baltic Sea finding that using a low prevalence of pingers can counterintuitively increase harbour porpoise bycatch in comparison to using no pingers at all; the researchers suggested that a low prevalence of pingers increases the movement of harbour porpoise, displacing the animals and thus increasing their chances of encountering gillnets which are unequipped with pingers. The researchers therefore recommended that if pingers are used, they need to be consistently deployed across a significant proportion of fishing vessels operating in the area, although the potential physiological risks to the animals of increasing noise pollution must also be taken into consideration
One alternative to pingers is an acoustic alerting device called Porpoise ALert (PAL). Whereas pingers emit artificial noise, the PAL is designed to mimic harbour porpoise communication signals. A trial in the Baltic Sea in 2020 found that the PAL is expected to reduce harbour porpoise bycatch in gillnets by between 65-80%. However, results were more unclear in trials in the Danish North Sea and around Iceland, suggesting that efficacy of the artificial communication signals may depend on the sex of the porpoises and/or regional differences in their dialect.
Evidence for the effectiveness of pingers in reducing cetacean bycatch in trawl fisheries is varied. It has been suggested that loud pingers, such as the Dolphin Deterrent Device (DDD) may reduce common dolphin bycatch in seabass pair trawl fisheries, although a 2018 study found that neither DDDs nor quieter pingers were effective in reducing bottlenose dolphin interactions in Australia’s Pilbara demersal ﬁsh trawl ﬁshery. However, a more recent study in the Bay of Biscay of a demersal pair trawler using the DDD®03H Dolphin Dissuasive Device found that common dolphin bycatch was reduced by 90%.
Design and deployment of pingers in longline fisheries has varied greatly. Hamilton & Baker (2019) have noted that there is no clear evidence that pingers effectively reduce cetacean bycatch in longline fisheries, potentially due to the difficultly in protecting longlines, which are set over significant distances.
Whilst pingers are a legal requirement in some fisheries around the world, they continue to be studied due to concerns that their effectiveness reduces over time (as marine mammals ‘habituate’). There are also concerns that pingers may be adding a further source of sounds to the environment, which could reduce the efficacy of the sounds that individual cetaceans rely upon for communication, foraging and navigation; may displace marine mammals from preferred habitat or deter them from important feeding grounds; and may pose physiological and other welfare risks to individual animals. Another concern is that pingers may act as a “dinner bell” for seals, however, a study in the Baltic Sea found no such effect with pingers used on static nets.
A review by the Joint Nature Conservation Committee of all the evidence available on the effectiveness of different Acoustic Deterrent Devices found that the risk of injury to marine mammals is generally low, although this depends on the context in which they are used. The JNCC’s review provides guidance on best practices in deploying pingers.
The FAO (2018) noted that pingers are not a ‘quick fix’, as their effectiveness varies over space and time, and differs between bycatch species and trawl, net, longline and pot/trap fisheries. Furthermore, pingers tend to reduce but not eliminate bycatch.
Interested in how this and other measures could mitigate bycatch in your fishery? Get in touch with us to collaborate or take part in a study.
This page was last updated on 12.10.23.