A decade of harbour porpoise occurrence in German waters—Analyses of aerial surveys, incidental sightings and strandings

Siebert, Ursula; Gilles, Anita; Lücke, Klaus; Ludwig, Martje; Benke, Harald; Kock, Karl-Hermann; Scheidat, Meike

doi:10.1016/j.seares.2006.01.003

Cited by 75 publications

(112 citation statements)

References 16 publications

Supporting

Mentioning

100

Contrasting

Order By: Relevance

“…August and September have been proposed as the months with peak numbers of porpoise encounters in this as well as in other coastal regions off Scotland (Evans et al 2003. Seasonal migrations in this species have also been documented in other geographical areas such as the German Baltic Sea (Siebert et al 2006, Verfuß et al 2007) and the northwest Atlantic where there is an overall tendency for increased use of coastal areas during the summer months (Read 1999). Unfortunately, no ad hoc survey has yet been conducted to address seasonality patterns in relation to the northwest of Scotland, and available 307 Mar Ecol Prog Ser 381: [297][298][299][300][301][302][303][304][305][306][307][308][309][310] 2009 datasets are biased by much greater survey effort in summer.…”

Section: Discussionmentioning

confidence: 73%

Habitat preferences and interannual variability in occurrence of the harbour porpoise Phocoena phocoena off northwest Scotland

Marubini¹,

Gimona²,

Evans

et al. 2009

Mar. Ecol. Prog. Ser.

View full text Add to dashboard Cite

The harbour porpoise Phocoena phocoena is the most common cetacean around the British Isles, but knowledge of its ecology, habitat preferences and inter-annual variability is still inadequate. Here, sightings collected by the Sea Watch Foundation during vessel surveys in West Scotland (August during the years 1993, 1994, 1996 and 1997) were critically analysed and used to construct a predictive habitat model for harbour porpoises in the Greater Minch. Generalised additive models were used to analyse relative abundance in relation to environmental variables; a preference for waters within 15 km from the shore and between 50 and 150 m depth was clearly identified. A relationship between tidal variables and porpoise distribution was also recognised with more sightings predicted for high tidal stream speed areas as well as during times of high tide. Maps constructed from the model were used to identify potential 'hotspots'and compare between years. Four areas with high relative abundance were identified in (1) the region between Ardnamurchan, Coll and the Small Isles, (2) southeast of Barra, (3) northeast of Skye to Gairloch, and (4) west of Pairc Peninsula (Isle of Lewis) to Shiant Islands. Number of sightings fluctuated up to 4-fold between consecutive years; such extreme variability in relative abundance is offered as a bench-mark for comparing trends in the future as well as evidence that the Greater Minch represents only a small part of the effective range of this population. KEY WORDS: Phocoena phocoena · Habitat preference · Relative abundance · Inter-annual variability Resale or republication not permitted without written consent of the publisherMar Ecol Prog Ser 381: [297][298][299][300][301][302][303][304][305][306][307][308][309][310] 2009 being commercial fisheries. Parties to the Agreement on the Conservation of Small Cetaceans of the Baltic and North Seas (ASCOBANS) have agreed to work towards reducing by-catch levels to below 1.7% per year of the North Sea porpoise population (ASCO-BANS 2000) to ensure that this species is maintained in a favourable conservation status. Robust estimates of population size are necessary to quantify the impact of by-catch; to this end the large-scale surveys known as SCANS I & II (Small Cetacean Abundance in the North Sea) were carried out in 1994 and again in 2005, during the month of July (Hammond et al. 2002, Hammond & Macleod 2006. In addition, different types of disturbance (e.g. noise, chemical pollutions, aquaculture) might result in temporal redistributions of animals among adjacent areas rather than changes at the population level.For conservation measures to be most effective, greater knowledge of habitat use and habitat preference is highly desirable at a variety of spatial scales from the national to the local spatial scale, especially as spatial planning is becoming the framework for management of human activities within the marine realm (Defra 2006). Furthermore, as the harbour porpoise is on Appendix 2 of the EC Habitats Directive (Council ...

show abstract

Section: Discussionmentioning

confidence: 73%

Habitat preferences and interannual variability in occurrence of the harbour porpoise Phocoena phocoena off northwest Scotland

Marubini¹,

Gimona²,

Evans

et al. 2009

Mar. Ecol. Prog. Ser.

View full text Add to dashboard Cite

show abstract

“…That would explain the relatively high densities we found in February, April, May and July. It would also explain the comparably high number of calves we found in certain surveys, as Northern Frisia and adjacent waters might function as a calving ground for porpoises in the North Sea (Sonntag et al 1999;Hammond et al 2002;Siebert et al 2006). Another or an additional way to interpret the results would be that porpoises transit the central German Bight during migratory movements from Northern Frisia into oVshore areas in fall and winter.…”

Section: Discussionmentioning

confidence: 72%

“…In contrast to other areas, the occurrence of porpoises was not correlated with seasons (e.g. Thomsen et al 2006b;Scheidat et al 2006;Siebert et al 2006), but characterized by rather erratic peaks in density in certain months and in all seasons.…”

Section: Discussionmentioning

confidence: 82%

“…From previous studies, it is apparent that the central German Bight is located between two regions with high densities of harbour porpoises during diVerent times of the year. One is located oV Northern Frisia with high densities between May and August (Hammond et al 2002;Scheidat et al 2004a, b;Siebert et al 2006). The other is located oV Eastern Frisia, with high occurrence of porpoises from February to the beginning of May (Camphuysen 2004;Haelters et al 2004;Thomsen et al 2006b).…”

Section: Discussionmentioning

confidence: 99%

“…In the summer of 1994, Hammond et al (2002) found high densities in the eastern part, along the coast of Northern Frisia and Denmark, but decreasing densities in the centre of the Bight and in the southern areas oV Eastern Frisia (coast of Netherlands and Lower-Saxony, Germany). Later investigations, using data from aerial surveys (1995/1996; 2002-2005), incidental sightings and strandings, conWrmed the high summer-densities of porpoises oV Northern Frisia (Sonntag et al 1999;Scheidat et al 2004aScheidat et al , b, 2006Siebert et al 2006). However, densities in the southern part of the German Bight and surrounding waters were higher than expected based on previous Wndings, especially between February and May (Camphuysen 1994(Camphuysen , 2004Witte et al 1998;Haelters et al 2004;Scheidat et al 2006;Thomsen et al 2006b; for a preview of SCANS II results see Hammond 2006).…”

Section: Introductionmentioning

confidence: 96%

See 2 more Smart Citations

The harbour porpoise (Phocoena phocoena) in the central German Bight: phenology, abundance and distribution in 2002–2004

Thomsen

Laczny²,

Piper³

2007

Helgol Mar Res

View full text Add to dashboard Cite

Functional Morphology of the Nasal Complex in the Harbor Porpoise (Phocoena phocoena L.)

Huggenberger

Rauschmann

Vogl

et al. 2009

The Anatomical Record

View full text Add to dashboard Cite

Toothed whales (Odontoceti, Cetacea) are the only aquatic mammals known to echolocate, and probably all of them are able to produce click sounds and to synthesize their echoes into a three-dimensional ''acoustic image'' of their environment. In contrast to other mammals, toothed whales generate their vocalizations (i.e., echolocation clicks) by a pneumatically-driven process in their nasal complex. This study is dedicated to a better understanding of sound generation and emission in toothed whales based on morphological documentation and bioacoustic interpretation. We present an extensive description of the nasal morphology including the nasal muscles in the harbor porpoise (Phocoena phocoena) using macroscopical dissections, computer-assisted tomography, magnetic resonance imaging, and histological sections. In general, the morphological data presented here substantiate and extend the unified ''phonic lips'' hypothesis of sound generation in toothed whales suggested by Cranford et al. (J Morphol 1996;228:223-285). There are, however, some morphological peculiarities in the porpoise nasal complex which might help explain the typical polycyclic structure of the clicks emitted. We hypothesize that the tough connective tissue capsule (porpoise capsule) surrounding the sound generating apparatus is a structural prerequisite for the production of these high-frequency clicks. The topography of the deep rostral nasal air sacs (anterior nasofrontal and premaxillary sacs), narrowing the potential acoustic pathway from the phonic lips to the melon (a large fat body in front of the nasal passage), and the surrounding musculature should be crucial factors in the formation of focused narrowbanded sound beams in the harbor porpoise. Anat Rec, 292:902-920, 2009. 2009 Wiley-Liss, Inc.

show abstract

A decade of harbour porpoise occurrence in German waters—Analyses of aerial surveys, incidental sightings and strandings

Cited by 75 publications

References 16 publications

Habitat preferences and interannual variability in occurrence of the harbour porpoise Phocoena phocoena off northwest Scotland

Habitat preferences and interannual variability in occurrence of the harbour porpoise Phocoena phocoena off northwest Scotland

The harbour porpoise (Phocoena phocoena) in the central German Bight: phenology, abundance and distribution in 2002–2004

Functional Morphology of the Nasal Complex in the Harbor Porpoise (Phocoena phocoena L.)

Contact Info

Product

Resources

About