Porpoises: Conservation

(asked on 4th September 2015) - View Source

Question to the Department for Environment, Food and Rural Affairs:

To ask the Secretary of State for Environment, Food and Rural Affairs, with reference to Report No. 544 of the Joint Nature Conservation Committee, on the identification of discrete and persistent areas of relatively high harbour porpoise density in the wider UK marine area, published in March 2015, for what reasons the 90th percentile was used as the cut-off point for the threshold of the prediction of porpoise presence; whether the same cut-off point is used (a) for prediction of other marine mammals and (b) by other EU countries; and if she will make a statement.


Answered by
George Eustice Portrait
George Eustice
This question was answered on 9th September 2015

Predicted porpoise density at or above the 90th percentile (i.e. areas that had the top 10% of predicted porpoise density) was chosen as the threshold to define ‘high density’ based on a method used by Embling et al. (2010)[i]. This method considered boundary placement to delineate protected areas for harbour porpoise using a perimeter length to area ratio approach. By comparing areas with the top 1%, 5% and 10% of porpoise densities, the perimeter–area ratio was lowest (desirable) and its confidence interval was narrowest (greater certainty) for areas defined by the top 10% threshold (i.e. equivalent to the 90th percentile). The Inter-Agency Marine Mammal Working Group therefore considered it appropriate to adopt this published approach for the analyses undertaken in Report 544. Both Embling et al. (2010) and Report 544 have been subject to peer review by experts.

Member States, including the UK, use Annex III of the Habitats Directive and additional EU Guidance in the identification of Special Areas of Conservation (SACs), but decisions on implementation are taken at the national level. This includes the determination of appropriate thresholds.

The identification of breeding sites for porpoise is not a requirement of Annex III of the EU Habitats Directive. A representative large-scale picture of porpoise calve distribution could not be attained from the data set that informed Report 544, and therefore was unable to support the identification of breeding areas.

The CCW Atlas of Marine Mammals of Wales included data collected and reported on in Pierpoint 2006 and 2008. All data from the Atlas were submitted to the Joint Cetacean Protocol, which provided the dataset that informed Report 544 where consents from the data providers were given.

The designation of SACs is a devolved responsibility, and decisions with regards to the Swansea Bay area are for the Welsh Government.

Report 544 is one step in wider assessment of information towards the identification of possible SACs for harbour porpoise, carried out by the Joint Nature Conservation Committee and Country Statutory Nature Conservation Bodies. Full information on the assessment process and other key documentation would be made available in a public consultation, providing an opportunity to comment on the scientific process undertaken.

[i] Embling, C. B., Gilibrand, P. A., Gordon, J., Shrimpton, J., Stevick, P. T. & Hammond, P. S. 2010. Using habitat models to identify suitable sites for marine protected areas for harbour porpoises (Phocoena phocoena). Biological Conservation 143, 267–279.

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