Fine-scale foraging movements by fish-eating killer whales (Orcinus orca) relate to the vertical distributions and escape responses of salmonid prey (Oncorhynchus spp.)

Wright, Brianna M.; Ford, John K. B.; Ellis, Graeme M.; Deecke, Volker B.; Shapiro, Ari; Battaile, Brian C.; Trites, Andrew W.

doi:10.1186/s40462-017-0094-0

Cited by 44 publications

(68 citation statements)

References 67 publications

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“…Changes in observed behavior were scored based on Southall's severity scale (Southall et al, 2007) and related to the noise level during the passing vessel. In a second study, Wright et al (2017) used digital acoustic recording tags (DTAGs) in conjunction with GPS field measurements to record dive depths, whale movement and respiration rates of northern resident killer whales. These data were similarly analyzed for behavioral response to tugs, cruise ships and commercial fish transport vessels and similarly scored based on Southall's severity scale.…”

Section: Southern Resident Killer Whale Noise-exposure Modelmentioning

confidence: 99%

Potential Benefits of Vessel Slowdowns on Endangered Southern Resident Killer Whales

Joy

Tollit²,

Wood³

et al. 2019

Front. Mar. Sci.

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A voluntary commercial vessel slowdown trial was conducted through 16 nm of shipping lanes overlapping critical habitat of at-risk southern resident killer whales (SRKW) in the Salish Sea. From August 7 to October 6, 2017, the trial requested piloted vessels to slow to 11 knots speed-through-water. Analysis of AIS vessel tracking data showed that 350 of 951 (37%) piloted transits achieved this target speed, 421 of 951 (44%) transits achieved speeds within one knot of this target (i.e., ≤12 knots), and 55% achieved speeds ≤ 13 knots. Slowdown results were compared to 'Baseline' noise of the same region, matched across lunar months. A local hydrophone listening station in Lime Kiln State Park, 2.3 km from the shipping lane, recorded 1.2 dB reductions in median broadband noise (10-100,000 Hz, rms) compared to the Baseline period, despite longer transit. The median reduction was 2.5 dB when filtering only for periods when commercial vessels were within 6 km radius of Lime Kiln. The reductions were highest in the 1st decade band (−3.1 dB, 10-100 Hz) and lowest in the 4th decade band (−0.3 dB reduction, 10-100 kHz). A regional vessel noise model predicted noise for a range of traffic volume and vessel speed scenarios for a 1133 km 2 'Slowdown region' containing the 16 nm of shipping lanes. A temporally and spatially explicit simulation model evaluated the changes in traffic volume and speed on SRKW in their foraging habitat within this Slowdown region. The model tracked the number and magnitude of noise-exposure events that impacted each of 78 (simulated) SRKW across different traffic scenarios. These disturbance metrics were simplified to a cumulative effect termed 'potential lost foraging time' that corresponded to the sum of disturbance events described by assumptions of time that whales could not forage due to noise disturbance. The model predicted that the voluntary Slowdown trial achieved 22% reduction in 'potential lost foraging time' for SRKW, with 40% reductions under 100% 11-knot participation. Slower vessel speeds reduced underwater noise in the Slowdown area despite longer passage times and therefore suggest this is an effective way to benefit SRKW habitat function in the vicinity of shipping lanes.

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Section: Southern Resident Killer Whale Noise-exposure Modelmentioning

confidence: 99%

Potential Benefits of Vessel Slowdowns on Endangered Southern Resident Killer Whales

Joy

Tollit²,

Wood³

et al. 2019

Front. Mar. Sci.

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“…High-resolution data archives can be reliably retrieved from marine animals tagged with short-duration tags (e.g., suction cup attached) or that haul-out at known locations [17,27,41]. Also, for heavily exploited fish species, fish-borne archiving tags can be recovered in moderate numbers [7,29].…”

mentioning

confidence: 99%

Motes enhance data recovery from satellite-relayed biologgers and can facilitate collaborative research into marine habitat utilization

et al. 2017

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Background:The fields of biologging and telemetry have triggered significant advances in the understanding of animal behavior, physiological ecology and habitat utilization. Biologging devices ("tags") can also measure aspects of the physical and biological characteristics of the animals' environment. As marine ecosystems are less accessible than terrestrial ones and marine animals more elusive and difficult to study, data collected by tags attached to marine animals often have to be relayed via satellite. However, satellite availability is not continuous and decreases with decreasing latitude. Consequently, collection of sufficient data is even more challenging in the tropics and mid-latitudes than at the poles. To overcome this limitation and increase data throughput from biologgers, new land-based receiving stations (called Motes) that can receive, log and relay messages from devices transmitting on the Argos satellite frequency have been developed. Methods:We investigated the performance of Motes as enhancers of recovery of signals transmitted by tags normally destined for satellite relay. We quantified Mote reception range, coverage area, data throughput and data corruption rates and examined factors that might impact these parameters. To do so, we used all signals detected by two arrays of Motes installed in the Hawaiian Islands and in Southern California between latitudes 22 and 33°N. Second, using data from 12 sharks and 12 whales tagged near the two Mote arrays, we assessed how increased data recovery translated into improved ability to interpret the behavior of the tagged animals.Results: Motes were capable of receiving up to 100% of messages transmitted within their reception range and overall presented a ~three-to fivefold increase in data message recovery compared to satellites alone. Message reception performance of Motes depended on their coverage area which in turn was affected by station elevation, the presence or not of obstacles within their line of sight, and the directionality of antennas. Conclusions:The increased quantity of data enabled improved biological interpretation of the animals studied. As such, Motes can improve our knowledge of marine animals' ecology in relation to their physical and biological environments. Large-scale Mote arrays could potentially facilitate collaborative multi-disciplinary research projects, resulting in better ecosystem conservation and management.

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“…We also specified call frequency of 1200 Hz and duration of 1 s, representative of the 'N05' call type produced commonly by Northern Residents (but also bares similarity to several Southern Resident calls and call components; Ford 1987). To define a representative calling depth, we averaged all dive depths from digital acoustic recording tag (DTAG) data available from a previous study of Northern Resident foraging behaviour (Wright et al 2017), resulting in an average dive depth of 7 m across all behaviour types. Assuming that most calling behaviour occurs around the depth at which killer whales spend most of their time, we used 10 m as the representative calling depth, which was the closest depth bin in the transmission loss outputs.…”

Section: Estimation Of Killer Whale Detection Rangesmentioning

confidence: 99%

Passive acoustic monitoring off Vancouver Island reveals extensive use by at-risk Resident killer whale (Orcinus orca) populations

Riera¹,

Pilkington²,

Ford³

et al. 2019

Endang. Species. Res.

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Two sympatric populations of fish-eating Resident killer whales inhabit the coastal waters of British Columbia, Canada: Southern and Northern Resident killer whales. These populations are listed under Canada's Species at Risk Act (SARA) as 'endangered' and 'threatened', respectively. Relatively little is known about their habitat use outside of the sheltered waters along the east coast of Vancouver Island, especially during the winter. SARA requires the identification of critical habitat for these populations. High densities of Chinook salmon-their primary preyare found around Swiftsure Bank, an area identified as potential critical habitat for Southern Residents. However, it is a difficult area to survey for whales using conventional small-boat approaches. Here, we used 2 yr of data collected from an autonomous acoustic recorder deployed at Swiftsure Bank from 2009−2011 to assess the year-round habitat use of this area by Resident killer whales. Overall, Resident killer whales were detected on 244 of 680 monitored days (36%). Southern Residents were heard in all months, with activity peaking during the summer. Northern Residents were also heard throughout the year, but were mostly detected in the spring and fall, which indicates the 2 populations may differ in their strategies for using this common foraging area. High levels of use by both of these populations highlights the importance of Swiftsure Bank to both, supporting the expansion of Resident killer whale critical habitat to include this site.

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Fine-scale foraging movements by fish-eating killer whales (Orcinus orca) relate to the vertical distributions and escape responses of salmonid prey (Oncorhynchus spp.)

Cited by 44 publications

References 67 publications

Potential Benefits of Vessel Slowdowns on Endangered Southern Resident Killer Whales

Potential Benefits of Vessel Slowdowns on Endangered Southern Resident Killer Whales

Motes enhance data recovery from satellite-relayed biologgers and can facilitate collaborative research into marine habitat utilization

Passive acoustic monitoring off Vancouver Island reveals extensive use by at-risk Resident killer whale (Orcinus orca) populations

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