Reproduction and reproductive seasonality in Danish harbour porpoises,<i>Phocoena Phocoena</i>

Sørensen, Thomas Alrik; Kinze, Carl Christian

doi:10.1080/00785326.1994.10429541

Cited by 70 publications

(98 citation statements)

References 11 publications

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“…Nevertheless, they are consistent with a larger data set for Scotland, based on data from 1991 onwards, for which the pregnancy rate was 0.42 (Learmonth, 2006). The only other published pregnancy rate data available for the southern North Sea is from Danish waters during 1985e1991, where a pregnancy rate of 73% was estimated using the presence of a foetus (Sørensen and Kinze, 1994). Data from the western Atlantic suggest that the latter rate (or higher) may be more typical of porpoises: in the Bay of Fundy (1985e1988, n ¼ 75) and Gulf of Maine (1989e1993, n ¼ 14) the pregnancy rates were 0.74 and 0.93, respectively (Read, 1990;Read and Hohn, 1995).…”

Section: Discussionsupporting

confidence: 85%

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: 85%

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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“…The gap in sampling from June to August is therefore very unfortunate and the exact timing of the peak in births and mating remains unknown. The information on foetal growth, pregnancy status, testes weight (present study) and histological changes in gonads (see Halldórsson and Víkingsson 2003) from the Icelandic porpoises in late spring and autumn, however, indicates similar timing of the reproductive cycle as observed in northern European porpoises (vanUtreckt 1978, Sørensen and Kinze 1994, Lockyer 1995a, Lockyer and Kinze 2003 and West Greenland (Lockyer et al 2001) where parturition peaks in June and mating seems to occur in July and August. Histological studies on the testes of the Icelandic porpoises, furthermore, show that the mating period may be prolonged to the autumn (Halldórsson and Víkingsson 2003).…”

Section: Reproductive Cyclesupporting

confidence: 58%

“…Females have been found lactating in March in Danish waters, indicating that lactation there lasts up to 9 months (Sørensen and Kinze 1994). No sign of lactation was found in the present study in any of the 10 mature females in March that was not pimiparous.…”

Section: Reproductive Cyclecontrasting

confidence: 51%

“…A high pregnancy rate has also been reported from porpoises from the Gulf of Maine (0.93) (Read and Hohn 1995). Most studies in the North Atlantic have, on the other hand, shown considerably lower values (Møhl-Hansen 1954, Lockyer 2003, Lockyer and Kinze 2003, Lockyer et al 2001, Read and Gaskin 1990, Sørensen and Kinze 1994, Bjørge and Kaarstad MS 1996. Pregnancy rates in Norwegian and Swedish porpoises were estimated as 0.73 and 0.67 based on the presence of foetuses and corpora lutea, respectively (Bjørge and Kaarstad MS 1996).…”

Section: Nammco Scientific Publications Volumementioning

confidence: 93%

“…Of the 335 female porpoises sampled 22% were sexually mature and all but one of these were pregnant ( performed on the ovarian histology so we do not know whether the female was senescent (see Sørensen and Kinze 1994). The observed pregnancy rate per year is therefore 0.98 and regression analysis of the number of corpora against age indicated an ovulation rate about one per year ( Fig.…”

Section: Femalesmentioning

confidence: 99%

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Growth and reproduction in harbour porpoises (<i>Phocoena phocoena</i>) in Icelandic waters

et al. 2003

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A total of 1,268 harbour porpoises were obtained from fishing nets in Icelandic coastal waters from September to June in the years 1991 to 1997. Foetal sex ratio was 1.2:1 (male:female). The bias towards males increased further among older animals in the present collection. The modal year classes were 0 and 1 years but the oldest porpoise was a female estimated at 20 years of age. Length at birth was estimated as approximately 75 cm, and females grew faster and attained larger sizes than males. Asymptotic length was 149.6 cm for males and 160.1 cm for females. Estimated age and length at sexual maturity was 1.9 to 2.9 years and 135 cm for males and 2.1 to 4.4 years and 138 to 147 cm for females. Immature individuals were significantly shorter than pubertal and mature animals in both sexes in age classes 1 to 3. Testes weight increased only slightly with body size in immature males but increased rapidly around maturity. Pronounced seasonality was also observed in testes weight, indicating a peak in testes activity in summer. Lack of data from the summer makes the exact timing of parturition and mating unknown. Births do, however, most likely peak in June and July and lactation lasts at least 7 to 8 months. Ovulation and pregnancy rates were 0.98.

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Harbour porpoises respond to recreational boats by speeding up and moving away from the boat path

Hao,

Hamel,

Grandjean

et al. 2024

Ecology and Evolution

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Recreational boats are common in many coastal waters, yet their effects on cetaceans and other sensitive marine species remain poorly understood. To address this knowledge gap, we used drone video footage recorded from a recreational boat to quantify how harbour porpoises (Phocoena phocoena) responded to the boat approaching at different speeds (10 or 20 knots). Furthermore, we used a hydrophone to record boat noise levels at full bandwidth (0.1–150 kHz) and at the 1/3 octave 16 kHz frequency band for both experimental speeds. The experiments were carried out in shallow waters near Funen, Denmark (55.51° N, 10.79° E) between July and September 2022. Porpoises were more likely to move further away from the path of the boat when approached at 10 knots, but not when approached at 20 knots. In contrast, they swam faster when approached at 20 knots, but not when approached at 10 knots. The recorded received sound level did not depend on how fast the boat approached, suggesting that differences in porpoise responses were related to the speed of the approaching boat rather than to sound intensity. In addition, porpoises generally reacted within close proximity (<200 m) to the approaching boat and quickly (<50 s) resumed their natural behaviour once the boat had passed, indicating that the direct impact of small vessels on porpoise behaviour was most likely small. Nevertheless, repeated exposure to noise from small vessels may influence porpoises' activity or energy budget, and cause them to relocate from disturbed areas. The approach used in this study increases our understanding of recreational boats' impact on harbour porpoises and can be used to inform efficient mitigation measures to help focus conservation efforts.

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Reproduction and reproductive seasonality in Danish harbour porpoises,Phocoena Phocoena

Cited by 70 publications

References 11 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

Growth and reproduction in harbour porpoises (<i>Phocoena phocoena</i>) in Icelandic waters

Harbour porpoises respond to recreational boats by speeding up and moving away from the boat path

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