Declining Abundance of Beaked Whales (Family Ziphiidae) in the California Current Large Marine Ecosystem

Moore, Jeffrey E.; Barlow, Jay

doi:10.1371/journal.pone.0052770

Cited by 56 publications

(52 citation statements)

References 58 publications

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“…Where surveys have facilitated population size estimates, for example, west coast United States, it has been found that many beaked whale species have undergone significant population declines (Moore and Barlow, 2013). As beaked whales are particularly vulnerable to anthropogenic noise, it is speculated that these population declines are because of an increase in anthropogenic disturbance, further highlighting the need for a better understanding of the basic spatial requirements of all beaked whale species globally (Weilgart, 2007).…”

Section: Introductionmentioning

confidence: 99%

Bucking the trend: genetic analysis reveals high diversity, large population size and low differentiation in a deep ocean cetacean

et al. 2015

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Understanding the genetic structure of a population is essential to its conservation and management. We report the level of genetic diversity and determine the population structure of a cryptic deep ocean cetacean, the Gray's beaked whale (Mesoplodon grayi). We analysed 530 bp of mitochondrial control region and 12 microsatellite loci from 94 individuals stranded around New Zealand and Australia. The samples cover a large area of the species distribution (~6000 km) and were collected over a 22-year period. We show high genetic diversity (h = 0.933-0.987, π = 0.763-0.996% and R s = 4.22-4.37, H e = 0.624-0.675), and, in contrast to other cetaceans, we found a complete lack of genetic structure in both maternally and biparentally inherited markers. The oceanic habitats around New Zealand are diverse with extremely deep waters, seamounts and submarine canyons that are suitable for Gray's beaked whales and their prey. We propose that the abundance of this rich habitat has promoted genetic homogeneity in this species. Furthermore, it has been suggested that the lack of beaked whale sightings is the result of their low abundance, but this is in contrast to our estimates of female effective population size based on mitochondrial data. In conclusion, the high diversity and lack of genetic structure can be explained by a historically large population size, in combination with no known exploitation, few apparent behavioural barriers and abundant habitat.

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Section: Introductionmentioning

confidence: 99%

Bucking the trend: genetic analysis reveals high diversity, large population size and low differentiation in a deep ocean cetacean

et al. 2015

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“…Our findings suggest that managers have an important decision to make: if current levels of monitoring are inadequate to detect precipitous declines in a timely manner, is it appropriate to increase monitoring efforts to improve statistical power or should a metric, other than population decline, be used to trigger management intervention? The measures of precision for our abundance estimates are enviably high (CVs of 9 to 11%) by the standards of even wellmonitored marine mammal stocks e.g., Cuvier's beaked whale (Ziphius cavirostris) (CVs of 51 to 55%) (Moore and Barlow 2013), and managers in the region have other conservation issues competing for scarce funding for research and mitigation efforts (Forney et al 2011).…”

Section: Applications For Monitoringmentioning

confidence: 98%

Evaluating monitoring methods for cetaceans

Tyne

Loneragan

Johnston

et al. 2016

Biological Conservation

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With increasing human pressures on wildlife comes a responsibility to monitor them effectively, particularly in an environment of declining research funds. Scarce funding resources compromise the level and efficacy of monitoring possible to detect trends in abundance, highlighting the priority for developing cost-effective programs. A systematic and rigorous sampling regime was developed to estimate abundance of a small, genetically isolated spinner dolphin (Stenella longirostris) population exposed to high levels of human activities. Five monitoring scenarios to detect trends in abundance were evaluated by varying sampling effort, precision, power and sampling interval. Scenario 1 consisted of monthly surveys, each of 12 days, used to obtain the initial two consecutive annual abundance estimates. Scenarios 2, 3 and 4 consisted of a reduced effort, while Scenario 5 doubled the effort of Scenario 1. Scenarios with the greatest effort (1 and 5) produced the most precise abundance estimates (CV=0.09). Using a CV=0.09 and power of 80%, it would take nine years to detect a 5% annual change in abundance compared with 12 years at a power of 95%. Under this best-case monitoring scenario, if the trend was a decline, the population would have decreased by 37% and 46%, respectively, prior to detection of a significant decline. With the potential of a large decline in a small population prior to detection, the lower power level should be used to trigger a management intervention. The approach presented here is applicable across taxa for which individuals can be identified, including terrestrial and aquatic mammals, birds and reptiles.3

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“…Further, adult females showed high residency at the navy range, putting them at risk, especially when pregnant and lactating (Claridge, 2013). In California, naval activities were proposed as one of two plausible hypotheses, along with ecosystem change, to explain a precipitous decline in beaked whale populations in the California Current ecosystem (Moore and Barlow, 2013).…”

Section: The Received Levels Of Sonar and Beaked Whales Impactsmentioning

confidence: 99%

Impacts of Navy Sonar on Whales and Dolphins: Now beyond a Smoking Gun?

Parsons

2017

Front. Mar. Sci.

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The risks military sonar poses to cetaceans received international attention with a highly-publicized mass stranding of Cuvier's beaked whales (Ziphius cavirostris), Blainville's beaked whales (Mesoplodon densirostris), and northern minke whales (Balaenoptera acutorostrata) in the Bahamas in 2000. This was the first time that the US Government determined a stranding to be the result of mid-frequency active sonar use. Subsequently attention has been drawn to other mass strandings coincident with naval exercises, including events preceding the 2000 mass stranding. The list of species for which mass strandings have been linked to naval exercises has also increased to include other beaked whales, dwarf and pygmy sperm whales (Kogia spp.), pilot whales (Globicephala spp.), several dolphin species (Stenella sp. and Delphinus delphis), and harbor porpoises (Phocoena phocoena). In particular, there have been several mass strandings in the northern Indian Ocean coincident with naval exercises-including one of the largest (200-250 dolphins)-which have received little attention. Changes in beaked whale behavior, including evasive maneuvering, have been recorded at received levels below <100 dB re 1 µPa (rms) and mass stranding may occur at received levels potentially as low as 150-170 dB re 1 µPa. There is strong scientific evidence to suggest that a wide range of whale, dolphin and porpoise species can also be impacted by sound produced during military activities, with significant effects occurring at received levels lower than previously predicted. Although there are many stranding events that have occurred coincident with the presence of naval vessels or exercises, it is important to emphasize that even the absence of strandings in a region does not equate to an absence of deaths, i.e., absence of evidence does not mean evidence of absence. Strandings may be undetected, or be unlikely to be observed because of a lack of search effort or due to coastal topography or characteristics. There may also be "hidden" impacts of sonar and exercises not readily observable (e.g., stress responses). Due to the level of uncertainty related to this issue, ongoing baseline monitoring for cetaceans in exercise areas is important and managers should take a precautionary approach to mitigating impacts and protecting species.

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Declining Abundance of Beaked Whales (Family Ziphiidae) in the California Current Large Marine Ecosystem

Cited by 56 publications

References 58 publications

Bucking the trend: genetic analysis reveals high diversity, large population size and low differentiation in a deep ocean cetacean

Bucking the trend: genetic analysis reveals high diversity, large population size and low differentiation in a deep ocean cetacean

Evaluating monitoring methods for cetaceans

Impacts of Navy Sonar on Whales and Dolphins: Now beyond a Smoking Gun?

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