Quantifying the response of Blainville's beaked whales to U.S. naval sonar exercises in Hawaii

Abstract

Behavioral responses of beaked whales (family Ziphiidae) to naval use of mid-frequency active sonar (MFAS) have been quantified for some species and regions. We describe the effects of MFAS on the probability of detecting diving groups of Blainville's beaked whales on the U.S. Navy

Influences of natural and anthropogenic habitat variables on Indo-Pacific humpback dolphins Sousa chinensis in Hong Kong

“…Present knowledge of habitat preferences and requirements of the dolphins in HK and Pearl River Estuary waters is still qualitative and subject to data gaps. There are many different environmental factors suspected to impact the animals, both natural and anthropogenic, and the specific degree to which certain elements of the habitat affect the movements and density of the dolphins is not adequately understood (see Hung 2008, Chan & Karczmarski 2017, Jefferson 2018).…”

Using individual-based bioenergetic models to predict the aggregate effects of disturbance on populations: A case study with beaked whales and Navy sonar

“…The standardized sonar area implicitly accounts for sonar intensity in that louder sonar should be detected over a larger area. However, it does not explicitly account for sonar source level, distance to sonar source, number of sonar sources, sonar source type, or other naval training activities, all of which may influence behavioral response [ 43 , 79 ]. Similarly, we assumed that off-range areas were free of sonar, although in reality sonar can be detected throughout the wider area [ 30 ] and this will likely vary between AUTEC and SOAR, due to environmental and topographical differences between the two locations.…”

“…This resulted in 16,400 hours of data for AUTEC (1.87 years) and 11,925 hours for SOAR (1.36 years). Hydrophones were assigned to their spatial unit within each range (western vs eastern spatial units) and the area covered by each hydrophone was calculated using a tessellation algorithm (see [ 43 ] for details). Within each spatial unit, the areas associated with hydrophones on which sonar was detected were summed and scaled by the maximum area over which sonar was detected across the two years for each range.…”

“…Dive behaviors during exposure were comparable to behaviors post- and pre-exposure, although the proportion of time spent at depths consistent with foraging decreased during initial exposure to MFAS [ 31 ]. Passive acoustic monitoring using bottom-mounted range hydrophones at AUTEC and at the Pacific Missile Range Facility (PMRF) in Hawaii also indicated that Md either leave the range, or reduce foraging vocalization upon exposure to sonar [ 33 , 43 – 45 ], and that it may take 1–3 d post exposure before call rate returns to pre-exposure level [ 42 , 46 ]. Taken together, these are strong indications that MFAS use disrupts the behavior of beaked whales, leading to ‘lost foraging dives,’ either through cessation of foraging or displacement away from preferred foraging areas.…”

Odontocete spatial patterns and temporal drivers of detection at sites in the Hawaiian islands

“…Previous study on this range has noted that diel behavior of Blainville's beaked whales is impacted by multi‐day Navy training events, with no diel pattern before training events, but peaks in acoustic detections in both morning and afternoon during and after training events (Henderson et al, 2016). More recent research has found that both multiday training events and the presence of mid‐frequency active sonar can greatly reduce the presence of vocalizing whales (Jacobson et al, 2022).…”