As information on beaked whale responses to human activities in the ocean grows, it is increasingly necessary to improve our baseline understanding of their distribution, habitat use and ecology. Even small changes in the dive cycle of beaked whales, caused by anthropogenic disturbance, could cause decompression sickness since long dive times result in relatively high nitrogen concentration in their tissues, though such an acute outcome was not observed during controlled exposure studies (e.g. It has further been shown that shipping may affect beaked whale diving and foraging behaviour and intense sound sources from seismic surveys are also of concern. Observations and research in recent decades has shown beaked whales to be sensitive to several human maritime activities, particularly the use of mid-frequency military sonar which has been linked to behavioural changes, temporary area avoidance, and fatal mass stranding events. Globally, beaked whales are considered Data Deficient, except for the Cuvier’s beaked whale ( Ziphius cavirostris) and Southern bottlenose whale ( Hyperoodon planifrons) which have been categorized as species of Least Concern. Indeed, beaked whale foraging behaviour differs across species, oceans, habitats, time of day, and season. hypothesized that Ziphiids move between areas to optimize their access to prey in Hawaii. Ziphiid movements and distribution are likely driven by that of their prey. Their deep oceanic habitat and elusive behaviour including long, deep dives followed by short surface intervals have made these species difficult to study using traditional line-transect methods that are constrained by weather conditions. They occur worldwide, typically in offshore pelagic habitats where they show a preference for continental slope waters, deep ocean troughs, and canyons. Such issues are particularly topical for species belonging to the Ziphiidae family, known as beaked whales.īeaked whales are among the most diverse but least known cetaceans globally, with comparatively little information available on their distribution, ecology and population structure. This problem could result in inadequate conservation measures or a lack of compliance with international directives. Collecting reliable data on some cetacean species that are highly mobile, deep-diving, wide ranging, and rare is particularly challenging. The conservation and management of marine mammal populations is inherently constrained by the quantity and quality of available information on the ecology and distribution of the species of interest. This work provides insight into the significance of Irish waters for beaked whales and highlights the importance of using acoustics for beaked whale monitoring. s, did not appear to impact the mean daily number of Cuvier’s or Sowerby’s beaked whale click detections.Seismic airgun shots, with daily sound exposure levels as high as 175 dB re 1 μPa 2 Cuvier’s occurrence increased in late autumn 2015 off northwest Porcupine Bank, a region of higher relative occurrence for each species. Cuvier’s clicks were more abundant at lower latitudes while Sowerby’s were greater at higher latitudes, particularly in the spring, suggesting a spatial segregation between species, possibly driven by prey preference. There was a significant effect of month and station (latitude) on the mean daily number of click detections for both species. Cuvier’s and Sowerby’s clicks occurred at all stations throughout the monitoring period. Northern bottlenose whale clicks occurred in late summer and autumn, but were too few to allow further analysis. Analysis confirmed the occurrence of Sowerby’s and Cuvier’s beaked whales and Northern bottlenose whales. A sample of detections was manually validated to evaluate and optimize detector performance. Zero-crossing-based automated detectors identified beaked whale clicks. Recorders ran for 205 to 230 days, resulting in 4.09 TB of data sampled at 250 kHz which could capture beaked whale acoustic signals. To address this knowledge gap, static acoustic monitoring was carried out using eight fixed bottom-mounted autonomous acoustic recorders: four from May to December 2015 on Ireland’s northern slope and four from March to November 2016 on the western and southern slopes. Little is known of the spatio-temporal occurrence of beaked whales off western Ireland, limiting the ability of Regulators to implement appropriate management and conservation measures.
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