Group characteristics, site fidelity, and photo‐identification of harbor porpoises,<i>Phocoena phocoena</i>, in Burrows Pass, Fidalgo Island, Washington

Elliser, Cindy R.; MacIver, Katrina; Green, Michelle L.

doi:10.1111/mms.12459

Cited by 24 publications

(29 citation statements)

References 53 publications

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“…This group may have a degree of site fidelity as it was systematically seen with the presence of the white individual during dedicated surveys and by locals. Site fidelity for harbour porpoises has been reported (Elliser and MacIver 2017) although lack of previous observations in the area (other than reports from local sea-users) prevent us from drawing such conclusions. Further dedicated surveys during the whole year are recommended to assess whether this is a resident group or if there is a seasonality in its distribution.…”

Section: Discussionmentioning

confidence: 87%

“…The land-based point of observation is marked with a pin minutes. Since the observation effort was highly heterogeneous between surveys and months, the number of sightings per number of surveys was used as a measure of sightings per unit effort (SPUE) correcting for uneven effort (Elliser and MacIver 2017). The data on survey effort, sightings and SPUE was compiled by month for the duration of the monitoring programme.…”

Section: Methodsmentioning

confidence: 99%

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Records of harbour porpoise (Phocoena phocoena) in the mouth of the Douro River (northern Portugal) with presence of an anomalous white individual

2019

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Background: Harbour porpoise (Phocoena phocoena) is listed under the Annex II of the European Habitats Directive (Directive 92/43/CEE) and Member States are required to designate special areas of conservation to protect their populations. Although harbour porpoise distribution in the Iberian Peninsula has been described, the mouth of the Douro River was never reported as part of its range of distribution. Methods: Observations from a pier in the mouth of the Douro were carried out to monitor the presence of the harbour porpoises. A monthly measure of sightings per unit of effort was calculated. Information on the sightings, group sizes and records of the white individual is presented. Results: Twenty six surveys were performed resulting in 22 sightings with group size varying from one to three animals. The white individual was sighted 12 times and recorded both in photographs and video. July was the month with the lowest number of sightings per unit of effort (SPUE), while October had the highest SPUE. Conclusions: Evidences, such as the presence of an easily recognizable white individual and the reports from local sea-users suggest a degree of site fidelity from this group of harbour porpoises in the mouth of the Douro River. However, further studies are needed to support the effective management and conservation of this group.

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Section: Discussionmentioning

confidence: 87%

Section: Methodsmentioning

confidence: 99%

Records of harbour porpoise (Phocoena phocoena) in the mouth of the Douro River (northern Portugal) with presence of an anomalous white individual

2019

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“…In theory it optimizes the energy expenditure of an animal in a steady or fast changing environment, depending on prey availability and other biologically significant factors. Reports from a photo-identification study from Washington State (USA) suggest that at least some porpoises show high site fidelity [ 79 ] and this has also been hypothesized for porpoises from Morro Bay, California [ 80 ]. However, telemetry studies from the Danish Belt Sea and Skagerrak waters aimed at estimating population home ranges [ 81 ].…”

Section: Discussionmentioning

confidence: 99%

Time and tide: Seasonal, diel and tidal rhythms in Wadden Sea Harbour porpoises (Phocoena phocoena)

et al. 2019

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Odontocetes have evolved a rich diversity of prey- and habitat-specific foraging strategies, which allows them to feed opportunistically on locally and temporally abundant prey. While habitat-specific foraging strategies have been documented for some odontocete species, this is less known for the harbour porpoise (Phocoena phocoena). We collected multiple years of acoustic data using echolocation click loggers to analyse porpoise occurrence and buzzing behaviour, indicating feeding, in the German Wadden Sea (North Sea). Seasonal, diel and tidal effects were studied using Generalised Estimating Equations (GEE-GAMs). Locally season, time of day and tidal time significantly influenced the probability of porpoise detections and detection of foraging sequences (buzzes). Hunting strategies, and therefore frequency of buzzes, were likely affected by prey distribution and large differences between POD locations indicated that porpoises used highly specific behaviour adapted to tide and time of day to efficiently feed on the available prey. Strong seasonal and spatial variation in diel and tidal effects underline the importance of long-term observations. Studies on porpoise behaviour are often based on short-term observations and might rather reflect a seasonal than a general pattern. The results of this study show clearly that significant changes in porpoise behaviour can be found in short and long-term observations. Here some features are based on short term determinants and others are stable over years and care should be taken about drawing general conclusions based on local patterns. Highly variable spatio-temporal patterns indicate a high flexibility of porpoises in a highly variable environment and address a challenge for complex conservation management plans.

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“…This is also known from tagging studies of porpoises in Greenland (Nielsen et al, 2018); however, these individuals also exhibit a high degree of site fidelity, with many individuals returning to the tagging site after their seasonal migration. Other harbor porpoise populations show a remarkably high residency and limited large-scale movements, such as on the US East and West Coast (Read and Westgate, 1997;Johnston et al, 2005;Forney et al, 2017;Elliser et al, 2018). There are also indications that harbor porpoises from the North Sea show site fidelity and high residency over weeks and months, based on offshore observations in the Netherlands (Camphuysen and Krop, 2011) and satellite tracking studies in the Danish Wadden Sea Stalder et al, 2020).…”

Section: German North Sea Eezmentioning

confidence: 99%

Small Cetacean in a Human High-Use Area: Trends in Harbor Porpoise Abundance in the North Sea Over Two Decades

et al. 2021

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The North Sea is one of the most heavily used shelf regions worldwide with a diversity of human impacts, including shipping, pollution, fisheries, and offshore constructions. These stressors on the environment can have consequences for marine organisms, such as our study species, the harbor porpoise (Phocoena phocoena), which is regarded as a sentinel species and hence has a high conservation priority in the European Union (EU). As EU member states are obliged to monitor the population status, the present study aims to estimate trends in absolute harbor porpoise abundance in the German North Sea based on almost two decades of aerial surveys (2002–2019) using line-transect methodology. Furthermore, we were interested in trends in three Natura2000 Special Areas of Conservation (SACs), which include the harbor porpoise as designated feature. Trends were estimated for each SAC and two seasons (spring and summer) as well as the complete area of the German North Sea. For the trend analysis we applied a Bayesian framework to a series of replicated visual surveys, allowing to propagate the error structure of the original abundance estimates to the final trend estimate and designed to deal with spatio-temporal heterogeneity and other sources of uncertainty. In general, harbor porpoise abundance decreased in northern areas and increased in the south, such as in the SAC Borkum Reef Ground. A particularly strong decline with a high probability (94.9%) was detected in the core area and main reproduction site in summer, the SAC Sylt Outer Reef (−3.79% per year). The overall trend for the German North Sea revealed a decrease in harbor porpoise abundance over the whole study period (−1.79% per year) with high probability (95.1%). The assessment of these trends in abundance based on systematic monitoring should now form the basis for adaptive management, especially in the SAC Sylt Outer Reef, where the underlying causes and drivers for the large decline remain unknown and deserve further investigation, also in a regional North Sea wide context.

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Group characteristics, site fidelity, and photo‐identification of harbor porpoises,Phocoena phocoena, in Burrows Pass, Fidalgo Island, Washington

Cited by 24 publications

References 53 publications

Records of harbour porpoise (Phocoena phocoena) in the mouth of the Douro River (northern Portugal) with presence of an anomalous white individual

Records of harbour porpoise (Phocoena phocoena) in the mouth of the Douro River (northern Portugal) with presence of an anomalous white individual

Time and tide: Seasonal, diel and tidal rhythms in Wadden Sea Harbour porpoises (Phocoena phocoena)

Small Cetacean in a Human High-Use Area: Trends in Harbor Porpoise Abundance in the North Sea Over Two Decades

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