Reproduction in short-beaked common dolphins (Delphinus delphis) from the western North Atlantic

Westgate, Andrew J.; Read, Andrew J.

doi:10.1007/s00227-006-0394-1

Cited by 65 publications

(87 citation statements)

References 21 publications

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“…However, in common dolphins, the high PCB concentrations recorded in the French sample were associated with a pregnancy rate (0.30) that was slightly higher than the value for Ireland (0.28) reported by Murphy (2004). These figures and the overall pregnancy rate for common dolphins in this study (0.25) are consistent with recently published results for this species in the western North Atlantic, in which annual pregnancy rate was estimated to be between 25% and 33% (Westgate and Read, 2007).…”

Section: Discussionsupporting

confidence: 93%

Bioaccumulation of persistent organic pollutants in female common dolphins (Delphinus delphis) and harbour porpoises (Phocoena phocoena) from western European seas: Geographical trends, causal factors and effects on reproduction and mortality

Pierce

Santos

Murphy

et al. 2008

Environmental Pollution

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High PCB levels were recorded in porpoises and common dolphins from European coasts. AbstractConcentrations of polychlorinated biphenyls (PCBs) in blubber of female common dolphins and harbour porpoises from the Atlantic coast of Europe were frequently above the threshold at which effects on reproduction could be expected, in 40% and 47% of cases respectively. This rose to 74% for porpoises from the southern North Sea. PCB concentrations were also high in southern North Sea fish. The average pregnancy rate recorded in porpoises (42%) in the study area was lower than in the western Atlantic but that in common dolphins (25%) was similar to that of the western Atlantic population. Porpoises that died from disease or parasitic infection had higher concentrations of persistent organic pollutants (POPs) than animals dying from other causes. Few of the common dolphins sampled had died from disease or parasitic infection. POP profiles in common dolphin blubber were related to individual feeding history while those in porpoises were more strongly related to condition.

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Section: Discussionsupporting

confidence: 93%

Bioaccumulation of persistent organic pollutants in female common dolphins (Delphinus delphis) and harbour porpoises (Phocoena phocoena) from western European seas: Geographical trends, causal factors and effects on reproduction and mortality

Pierce

Santos

Murphy

et al. 2008

Environmental Pollution

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“…This was based on the following observations: CA number did not increase signifi cantly with age; pregnant D. delphis had ca 40% fewer scars than non-pregnant animals; and since all pregnant individuals were sampled between January and March, prior to the estimated calving period for the population. In contrast, studies undertaken on other populations of D. delphis, by Danil and Chivers (2007) in the eastern tropical Pacifi c, Westgate and Read (2007) in the western North Atlantic and Takahashi et al (2006) in waters off Japan have all reported a signifi cant increase in corpora number with age.…”

Section: Accumulation and Persistence Of Corpora Scarsmentioning

confidence: 83%

Assessing the effect of persistent organic pollutants on reproductive activity in common dolphins and harbour porpoises

Murphy¹,

Pierce²,

Law³

et al. 2010

J. Northw. Atl. Fish. Sci.

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As top predators, marine mammals can provide information on the accumulation of anthropogenic toxins which present the greatest risk to consumers. We assessed the impacts of persistent organic pollutants (POPs) on two cetacean species that feed on commercially important fi sh species in the eastern North Atlantic; the common dolphin (Delphinus delphis) and the harbour porpoise (Phocoena phocoena). In order to evaluate the possible long-term effects of POPs on the continued viability of these populations, we investigated their effects on reproductive activity in females, using ovarian scars as an index of reproductive activity. In harbour porpoises, high POP burdens tended to be associated with lower ovarian scar number, possibly indicating that high contaminant levels were inhibiting ovulation, or some females may go through a number of infertile ovulations prior to a successful pregnancy, birth, and survival of their fi rst offspring during early lactation. In contrast, initial results identifi ed that the common dolphins with contaminant burdens above a threshold level for adverse health effects in marine mammals (17 μg g -1 total PCBs lipid) were resting mature females, with high numbers of ovarian scars. This suggests that (a) due to high contaminant burdens, females may be unable to reproduce, thus continue ovulating, or (b) females are not reproducing for some other reason, either physical or social, and started accumulating higher levels of contaminants. Additional analyses were carried out on a control group of ''healthy'' D. delphis, i.e. stranded animals diagnosed as bycatch and were assessed for evidence of any infectious or non infectious disease that would inhibit reproduction. Results suggested that high contaminant burdens, above the threshold level, were not inhibiting ovulation, conception or implantation in female D. delphis, though the impact on the foetal survival rate (in both species) requires further examination. Investigations into accumulation and persistence of ovarian scars and use as an index of reproductive activity were also undertaken within this study.

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“…For example, juveniles were over-represented in some studies of by-caught animals (stranded and retrieved directly from fishing vessels) (Kirkwood et al 1997, Siebert et al 2001, Jauniaux et al 2002, Jepson 2006, while in other studies they were under-represented (Delphinus delphis and Stenella longirostris by-catch in tuna purse-seine fisheries) (Danil & Chivers 2007, Larese & Chivers 2009). Male D. delphis have been over-represented in both Pacific and Atlantic fisheries (Ferrero & Walker 1995, Murphy 2004, Westgate & Read 2007, Danil et al 2010 and there are anecdotal reports that juvenile male bottlenose dolphins Tursiops truncatus on the US east coast are also over-represented.…”

Section: Signalmentmentioning

confidence: 99%

Criteria and case definitions for serious injury and death of pinnipeds and cetaceans caused by anthropogenic trauma

Moore¹,

Hoop²,

Barco³

et al. 2013

Dis. Aquat. Org.

130

140

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Post-mortem examination of dead and live stranded beach-cast pinnipeds and cetaceans for determination of a cause of death provides valuable information for the management, mitigation and prosecution of unintentional and sometimes malicious human impacts, such as vessel collision, fishing gear entanglement and gunshot. Delayed discovery, inaccessibility, logistics, human safety concerns, and weather make these events challenging. Over the past 3 decades, in response to public concern and federal and state or provincial regulations mandating such investigations to inform mitigation efforts, there has been an increasing effort to objectively and systematically investigate these strandings from a diagnostic and forensic perspective. This Theme Section provides basic investigative methods, and case definitions for each of the more commonly recognized case presentations of human interactions in pinnipeds and cetaceans. Wild animals are often adversely affected by factors such as parasitism, anthropogenic contaminants, biotoxins, subclinical microbial infections and competing habitat uses, such as prey depletion and elevated background and episodic noise. Understanding the potential contribution of these subclinical factors in predisposing or contributing to a particular case of trauma of human origin is hampered, especially where putrefaction is significant and resources as well as expertise are limited. These case criteria descriptions attempt to acknowledge those confounding factors to enable an appreciation of the significance of the observed human-derived trauma in that broader context where possible.

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Reproduction in short-beaked common dolphins (Delphinus delphis) from the western North Atlantic

Cited by 65 publications

References 21 publications

Bioaccumulation of persistent organic pollutants in female common dolphins (Delphinus delphis) and harbour porpoises (Phocoena phocoena) from western European seas: Geographical trends, causal factors and effects on reproduction and mortality

Bioaccumulation of persistent organic pollutants in female common dolphins (Delphinus delphis) and harbour porpoises (Phocoena phocoena) from western European seas: Geographical trends, causal factors and effects on reproduction and mortality

Assessing the effect of persistent organic pollutants on reproductive activity in common dolphins and harbour porpoises

Criteria and case definitions for serious injury and death of pinnipeds and cetaceans caused by anthropogenic trauma

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