Seasonal and geographical variation of harbour porpoise (Phocoena phocoena) habitat use in the German Baltic Sea monitored by passive acoustic methods (PODs)

Verfuß, Ursula K.; Honnef, Christopher G.; Benke, Harald

doi:10.1007/3-540-33291-x_13

Cited by 2 publications

(7 citation statements)

References 8 publications

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“…The recurring seasonal pattern in porpoise presence (also shown by Verfuß et al 2007, Gallus et al 2012) was confirmed for a considerably longer period in the present study. Westward movements in winter into more saline waters possibly occur to avoid entrapment by sea ice (Verfuß et al 2007, Gallus et al 2012). Higher detection rates in summer compared to winter (Figs.…”

Section: Seasonal Occurrence and Trends In Harbour Porpoise Presencesupporting

confidence: 86%

“…The strong decrease in harbour porpoise densities from the Inner Danish Waters (Belt Sea) to the Pomeranian Bay was recorded repeatedly during various aerial surveys (Gillespie et al 2005, Scheidat et al 2008. The recurring seasonal pattern in porpoise presence (also shown by Verfuß et al 2007, Gallus et al 2012) was confirmed for a considerably longer period in the present study. Westward movements in winter into more saline waters possibly occur to avoid entrapment by sea ice (Verfuß et al 2007, Gallus et al 2012).…”

Section: Seasonal Occurrence and Trends In Harbour Porpoise Presencesupporting

confidence: 83%

“…The effective detection radius of the instruments was measured by Kyhn et al (2012) to be 17 to 108 m within 15 to 60 s snapshots, determined by tracking porpoises around T-PODs and comparing visual detection distances with simultaneous acoustic detections. The porpoise detectors are highly suitable for long-term monitoring (Verfuß et al 2007) at low cost per detection. Severe environmental conditions (such as ice formation during winter months) and bottom-trawling may pose a challenge for the deployment of instruments or produce large amounts of background noise.…”

Section: Previously Employed Visual Surveys For Harbour Porpoisesmentioning

confidence: 99%

“…Verfuß et al 2007Verfuß et al , 2008 for more details). Here, we present data from 12 stations that were installed as part of a monitoring programme and operated for 10 yr from 2002 to 2012 (Fig.…”

Section: Static Acoustic Monitoring With T-podsmentioning

confidence: 99%

“…Days with at least 1 visually confirmed porpoise detection were defined as DPDs. For additional details on instrument deployment and data analysis, see Verfuß et al (2007Verfuß et al ( , 2008 and Gallus et al (2012).…”

Section: Static Acoustic Monitoring With T-podsmentioning

confidence: 99%

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Baltic Sea harbour porpoise populations: status and conservation needs derived from recent survey results

Benke¹,

Bräger²,

Dähne³

et al. 2014

Mar. Ecol. Prog. Ser.

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During recent decades, the 2 distinct harbour porpoise populations of the Baltic Sea have decreased sharply in abundance. The Baltic Proper population is down to a few hundred individuals and is regarded as 'Critically Endangered' by IUCN; the more abundant Belt Sea population also appears to have experienced a severe decline. We summarize the results of extensive static acoustic monitoring in the German part of the Baltic Sea and compare them to published results of aerial and acoustic surveys. Acoustic monitoring confirmed seasonal changes in detection rates consistent with proposed east -west migrations. Detection rates, and thus presumably porpoise density, decrease from west to east from a long-term mean ( in Kadet Trench to 4.4% DPD mo −1 in Pomeranian Bay as one crosses the putative population boundary. Acoustic monitoring results show a recent increase in porpoise registration rates in the Kadet Trench and in Pomeranian Bay, although this does not necessarily indicate a population increase. This large dataset supports the previously suggested proposition that each population uses the boundary waters in Pomeranian Bay alternately, leading to the presence of registration peaks in (late) summer by Belt Sea porpoises, and in winter by Baltic Proper animals. The critical status of porpoises in the Baltic Sea highlights the urgent need for protective measures which still await national and international implementation.

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Section: Seasonal Occurrence and Trends In Harbour Porpoise Presencesupporting

confidence: 86%

Section: Seasonal Occurrence and Trends In Harbour Porpoise Presencesupporting

confidence: 83%

Section: Previously Employed Visual Surveys For Harbour Porpoisesmentioning

confidence: 99%

Section: Static Acoustic Monitoring With T-podsmentioning

confidence: 99%

Section: Static Acoustic Monitoring With T-podsmentioning

confidence: 99%

See 3 more Smart Citations

Baltic Sea harbour porpoise populations: status and conservation needs derived from recent survey results

Benke¹,

Bräger²,

Dähne³

et al. 2014

Mar. Ecol. Prog. Ser.

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Geographical and seasonal variation of harbour porpoise (Phocoena phocoena) presence in the German Baltic Sea revealed by passive acoustic monitoring

et al. 2007

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The harbour porpoise is the only resident cetacean species in the German Baltic Sea. Within the last several decades this harbour porpoise stock declined drastically, causing deep concern about its status. Plans of the German government for proposing Marine Protected Areas (MPAs) to implement Natura 2000 and for assessing the impact of offshore windmill constructions on the marine environment led to an increased research effort on the harbour porpoise in German waters. For the first time, long-term passive acoustic monitoring has been conducted in the German Baltic Sea from the Kiel Bight to the Pomeranian Bay from August 2002 to December 2005. Porpoise detectors (T-PODs) have been installed five to seven metres below the water surface at up to 42 measuring positions throughout the investigated area, registering the exact times of echolocation signals of passing harbour porpoises. The proportion of monitored days with porpoise detection in each quarter of the years has been analysed. A correlation of the results with the longitude of the measuring position revealed a significant decrease from west to east in the percentage of days with porpoise detections. Comparison of data gathered in the first quarters with the third quarters of the monitoring years displayed a seasonal variation with fewer days of porpoise detections in winter time than in summer time. Nevertheless, harbour porpoises have been detected year-round at most of the measuring positions in the German Baltic Sea. The present study clearly indicates a regular use of the German Baltic Sea by harbour porpoises with a geographical and seasonal variation in the usage of the German Baltic Sea. The larger numbers of harbour porpoise detections in spring to autumn compared with winter suggests that the German Baltic Sea is an important breeding and mating area for these animals.

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Seasonal and geographical variation of harbour porpoise (Phocoena phocoena) habitat use in the German Baltic Sea monitored by passive acoustic methods (PODs)

Cited by 2 publications

References 8 publications

Baltic Sea harbour porpoise populations: status and conservation needs derived from recent survey results

Baltic Sea harbour porpoise populations: status and conservation needs derived from recent survey results

Geographical and seasonal variation of harbour porpoise (Phocoena phocoena) presence in the German Baltic Sea revealed by passive acoustic monitoring

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