Bycatch of pelagic seabird species in longline fisheries is recognized as one of the most important and pervasive sources of mortality, contributing to an increased risk of their extinction. Uptake of mitigation measures to reduce seabird bycatch has not been widespread by the industry. Here, we present the results of 18 at‐sea trials conducted between 2011–2015 onboard pelagic longliners targeting tuna (Thunnus spp) and swordfish (Xiphias gladius) in South African, Brazilian and Australian waters, using a recently designed seabird bycatch mitigation device. The ‘Hookpod’ is a polycarbonate capsule that encases the point and barb of baited pelagic longline hooks to prevent seabirds from becoming hooked and drowning during line‐setting operations. The assessment was based on efficacy (i.e. reducing rates of seabird bycatch without impacting target catch rate) and practicality (i.e. how the Hookpod fitted into fishing operations). We observed 59 130 experimental branchlines over 129 sets and recorded a single seabird mortality on the Hookpod branchlines compared to 24 on the control branchlines, a bycatch rate of 0.04 birds/1000 hooks and 0.8 birds/1000 hooks, respectively. No difference in catch rate of target fish species between Hookpod and control treatments was detected. These findings demonstrate that Hookpods do not negatively affect catch rate of target species and could make an important contribution to halting the decline of many seabird populations if adopted as a mitigation measure by the pelagic longline fishing industry.

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Bycatch of seabirds in gillnet fisheries is a global conservation issue with an estimated 400 000 seabirds killed each year. To date, no underwater deterrents trialled have consistently reduced seabird bycatch across operational fisheries. Using a combination of insights from land-based strategies, seabirds' diving behaviours and their cognitive abilities, we developed a floating device exploring the effect of large eyespots and looming movement to prevent vulnerable seabirds from diving into gillnets. Here, we tested whether this novel above-water device called ‘Looming eyes buoy' (LEB) would consistently deter vulnerable seaducks from a focal area. We counted the number of birds present in areas with and without LEBs in a controlled experimental setting. We show that long-tailed duck Clangula hyemalis abundance declined by approximately 20–30% within a 50 m radius of the LEB and that the presence of LEBs was the most important variable explaining this decline. We found no evidence for a memory effect on long-tailed ducks but found some habituation to the LEB within the time frame of the project (62 days). While further research is needed, our preliminary trials indicate that above-water visual devices could potentially contribute to reduce seabird bycatch if appropriately deployed in coordination with other management measures.

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