The Essex Harbour Porpoise Phocoena phocoena L., 2003 survey
MARK ILEY
Biodiversity Project Officer, Essex Biodiversity Project
Joan Elliot Visitor Centre, Abbotts Hall Farm, Great Wigborough, Colchester,
Essex C05 7RZ
Background
Historically porpoises, dolphins and whales (cetaceans) have not been well recorded in the southern
North Sea, including Essex coastal waters. Anecdotal evidence suggests a substantial decline during
the last 50 years. In 1995 the Harbour Porpoise was added to the UK Biodiversity Action Plan list
and in 1999 it was included in the Essex Biodiversity Action Plan. The majority of the actions
outlined in the plan related to obtaining more records and trying to identify which parts of the coast
are most used by porpoises and other cetaceans.
The survey card recording project
This was launched in June 1999 to increase the number of records from Essex coastal waters. The
aim was to give water users such as fishermen, yacht owners, harbour authorities and sea watchers
the chance of reporting any cetacean sightings to increase the number of records around Essex. The
survey cards included identification details of the five species most likely to be seen and, on the
reverse, space to fill in details about a sighting. In 2003 cards were distributed to 24 marinas,
chandlers and sailing clubs in Essex and Suffolk. In June 2003 two training events were held with
SeaWatch to assist with cetacean identification and establish a network of vessels which will take
observers.
Result: Eleven completed survey cards were returned during 2003 including cards returned from
London, Suffolk and Holland.
POD monitoring project
To obtain further records a listening device called the 'POD' was deployed. This device is tethered
to the seabed and records the sonar calls of cetaceans at various frequencies. The POD was retrieved
every fortnight, (the maximum battery life) and the data downloaded onto a computer to be viewed
and analysed. In 2003 the POD was deployed five times between April and September and was
operational for approximately 70 days. It was located twice around the Gunfleet Sands area offshore
from Clacton-on-Sea and three times at various points in the Blackwater estuary.
Result: Porpoise recordings were obtained from two deployments in June and July 2003.
Discussion
In total 42 records of 59 animals were received via the record cards and other correspondence. The
only species recorded during 2003 was the Harbour Porpoise (including 2 records of 2 unidentified
animals most probably Harbour Porpoise). There were 6 records of dead porpoises (including an
individual put-down on site) and 3 carcasses were sent for autopsy. Porpoises were recorded in
groups of up to 6 but most frequently they were seen individually or in pairs.
Records were spread through the year with a peak of sightings in May and a second peak in August.
This follows the general pattern of previous years and anecdotal reports indicate a regular spring
peak. The earliest sighting was 1st March with the latest sighting on the 25th November.
Essex Naturalist (New Series) 21 (2004)
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