An Unusual Mortality Event of Harbor Porpoises (Phocoena phocoena) Off Central California: Increase in Blunt Trauma Rather Than an Epizootic

Wilkin, Sarah; Cordaro, Joe; Gulland, Frances M. D.; Wheeler, Elizabeth; Dunkin, Robin C.; Sigler, Teri; Casper, Dave; Berman, Michelle; Flannery, Moe; Fire, Spencer E.; Wang, Zhihong; Colegrove, Kathleen M.; Baker, Jason D.

doi:10.1578/am.38.3.2012.301

Cited by 18 publications

(18 citation statements)

References 27 publications

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“…Apart from human interactions, harbor porpoises are also susceptible to interactions with dolphins. Blunt-force trauma likely due to aggressive interactions with bottlenose dolphins (Tursiops truncatus) was identified as the most common identified cause of death in a multiyear sample of harbor porpoise strandings from California [18]. The findings were supported by direct observations of aggressive behaviors of bottlenose dolphins toward harbor porpoises in California [28].…”

Section: Introductionmentioning

confidence: 77%

“…The cause appeared to be an unknown pathogenic virus. Elevated strandings of harbor porpoises caused primarily by aggressive interactions with bottlenose dolphins occurred along the central coast of California from 2007-2009 [18]. Thus, the cause of unusually high stranding frequencies can be caused by various unrelated factors and the cause of harbor porpoise unusual stranding events in the western Atlantic and Belgium/northern France in 1999 [47] or the Danish coast in 2005 [24] seems unrelated.…”

Section: System Affectedmentioning

confidence: 99%

“…Noninfectious diseases found in harbor porpoises include colloid goiter [16] and dystocia [17]. Domoic acid toxicosis was identified in harbor porpoises from California [18]. From detailed postmortem examinations of 41 stranded harbor porpoises from the United Kingdom (UK), parasitic and bacterial pneumonia were common causes of death and nonfatal parasitic infestation was common [17].…”

Section: Introductionmentioning

confidence: 99%

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Unusual Mortality Events of Harbor Porpoise Strandings in North Carolina, 1997–2009

Hohn

Rotstein²,

Byrd

2013

Journal of Marine Biology

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A marked increase in the frequency of harbor porpoises (Phocoena phocoena) stranded in North Carolina in 2005 was declared as an Unusual Mortality Event (UME). Strandings occurred in January through May when harbor porpoises are seasonally present. Increased stranding rates were measured relative to a threshold to determine that the UME was occurring. The threshold analysis also revealed elevated strandings during 1999, an undeclared UME year. Recovered carcasses during 1999 and 2005 accounted for 39% of 261 strandings during 1997–2009. During 2005, of 43 strandings, primary or secondary causes of mortality included fishery interactions, emaciation, and interspecific aggression. Apart from small but significant differences in timing and condition of strandings, composition of strandings during UME and non-UME years was similar, with most being young-of-the-year and occurring during March and April, north of Cape Hatteras. Porpoises had high levels of parasitic infestation typical for this species. However, no indication of infectious disease and no cause of the 2005 event were found from gross and histologic findings. Response to UMEs is challenging, particularly along the expanses of North Carolina beaches, requiring additional effort to obtain carcasses in sufficiently fresh condition to determine the cause of these events.

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Section: Introductionmentioning

confidence: 77%

Section: System Affectedmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Unusual Mortality Events of Harbor Porpoise Strandings in North Carolina, 1997–2009

Hohn

Rotstein²,

Byrd

2013

Journal of Marine Biology

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“…1), the original seismic survey design would have excluded the Morro Bay harbor porpoise population from nearly all of its primary foraging habitat, with animals pushed either offshore into deeper wa ters, southward beyond the species' eastern Pacific range, or northward into an extremely narrow shelf region along the Big Sur coastline, where few porpoises have been seen on aerial surveys (Forney et al 2014). Any of these options would reduce foraging success for the duration of the displacement, and could increase other risks such as predation, inter-specific aggression (Cotter et al 2012, Wilkin et al 2012, Jacobson et al 2015, bycatch, or harmful stress effects. Harbor porpoises must consume about 5% of their body mass daily to meet metabolic requirements (Yasui & Gaskin 1986, Read & Westgate 1997, Lockyer 2007.…”

Section: Central California Harbor Porpoisesmentioning

confidence: 99%

Nowhere to go: noise impact assessments for marine mammal populations with high site fidelity

Forney¹,

Southall²,

Slooten³

et al. 2017

Endang. Species. Res.

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As awareness of the effects of anthropogenic noise on marine mammals has grown, research has broadened from evaluating physiological responses, including injury and mortality, to considering effects on behavior and acoustic communication. Most mitigation efforts attempt to minimize injury by enabling animals to move away as noise levels are increased gradually. Recent experiences demonstrate that this approach is inadequate or even counterproductive for small, localized marine mammal populations, for which displacement of animals may itself cause harm. Seismic surveys within the ranges of harbor porpoise Phocoena phocoena in California and Mā ui dolphin Cephalorhynchus hectori maui in New Zealand highlight the need to explicitly consider biological risks posed by displacement during survey planning, monitoring, and mitigation. Consequences of displacement are poorly understood, but likely include increased stress and reduced foraging success, with associated effects on survival and reproduction. In some cases, such as the Critically Endangered Mā ui dolphin, displacement by seismic activities risks exposing the remaining 55 dolphins to bycatch in nearby fisheries. Similar concerns about military and industrial activities exist for island-associated species such as melon-headed whales Peponocephala electra in Hawai'i; shelf-break associated species such as Cuvier's beaked whales Ziphius cavirostris off the US Atlantic coast, and whales foraging in coastal habitats, such as the Critically Endangered western gray whale Eschrichtius robustus. We present an expanded framework for considering disturbance effects that acknowledges scientific uncertainty, providing managers and operators a more robust means of assessing and avoiding potential harm associated with both displacement and direct effects of intense anthropogenic noise exposure.

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“…For example, the species composition of strandings may reflect the biodiversity of living populations in adjacent waters (Pyenson 2010, Byrd et al 2014). The relative number or composition of strandings can be used to monitor long-term (Peltier et al 2013) or cyclical (Evans et al 2005, Peltier et al 2014 shifts in distribution or anomalous strandings, such as unusual mortality events (UMEs; N MFS-OPR 2016), that indicate the presence of disease, high levels of fishery interactions, or other events or factors affecting the population (Byrd et al 2008, Yang et al 2008, Wilkin et al 2012, Litz et al 2014. Samples from stranded marine mammals can be used to obtain data for estimating demographic parameters of species or populations for which data are otherwise difficult to obtain (Hohn et al 1996, Lockyer & Kinze 2003, Mattson et al 2006.…”

Section: Introductionmentioning

confidence: 99%

Assigning stranded bottlenose dolphins to source stocks using stable isotope ratios following the Deepwater Horizon oil spill

Hohn¹,

Thomas²,

Carmichael³

et al. 2017

Endang. Species. Res.

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The potential for stranded dolphins to serve as a tool for monitoring free-ranging populations would be enhanced if their stocks of origin were known. We used stable isotopes of carbon, nitrogen, and sulfur from skin to assign stranded bottlenose dolphins Tursiops truncatus to different habitats, as a proxy for stocks (demographically independent populations), following the Deepwater Horizon oil spill. Model results from biopsy samples collected from dolphins from known habitats (n = 205) resulted in an 80.5% probability of correct assignment. These results were applied to data from stranded dolphins (n = 217), resulting in predicted assignment probabilities of 0.473, 0.172, and 0.355 to Estuarine, Barrier Island (BI), and Coastal stocks, respectively. Differences were found west and east of the Mississippi River, with more Coastal dolphins stranding in western Louisiana and more Estuarine dolphins stranding in Mississippi. Within the Estuarine East Stock, 2 groups were identified, one predominantly associated with Mississippi and Alabama estuaries and another with western Florida. δ 15 N values were higher in stranded samples for both Estuarine and BI stocks, potentially indicating nutritional stress. High probabilities of correct assignment of the biopsy samples indicate predictable variation in stable isotopes and fidelity to habitat. The power of δ 34 S to discriminate habitats relative to salinity was essential. Stable isotopes may provide guidance regarding where additional testing is warranted to confirm demographic independence and aid in determining the source habitat of stranded dolphins, thus increasing the value of biological data collected from stranded individuals.

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An Unusual Mortality Event of Harbor Porpoises (Phocoena phocoena) Off Central California: Increase in Blunt Trauma Rather Than an Epizootic

Cited by 18 publications

References 27 publications

Unusual Mortality Events of Harbor Porpoise Strandings in North Carolina, 1997–2009

Unusual Mortality Events of Harbor Porpoise Strandings in North Carolina, 1997–2009

Nowhere to go: noise impact assessments for marine mammal populations with high site fidelity

Assigning stranded bottlenose dolphins to source stocks using stable isotope ratios following the Deepwater Horizon oil spill

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