earll, jones, clear, jenkins 2015 porpoises
DESCRIPTION
The ecology of porpoises in the south west – what we know and what we don’tHannah & Duncan Jones, Bob Earll, Dave Jenkins Version 5th March 2015 This is the first draft of this ‘living document’ which will be developed with inputs from colleagues over time. It highlights what we know and what we don’t.Author contact details: Hannah & Duncan Jones, Marine Discovery E: [email protected]; Bob Earll, [email protected]; Dave Jenkins [email protected], Phone: 07970 0115542MethodologiesThere will be a set of points on methodologies, observing and recordings porpoises from shore and boat based work as well as strandings observations.Dave Jenkins ‘I have been observing marine life on the North Devon coast for many years, but more systematically for the last 20 years. Porpoise are difficult to see and can only be seen in winds of less than force 2; in these conditions observations of porpoise are frequent throughout the year (approximately 90% of visits). I watch the porpoise from local headlands, and animals are visible on tidal races further offshore, as well as reefs very close in. One key indicator of likely porpoise presence is gannets feeding in the vicinity. The series of photographs presented to SWME14 illustrates some of the interesting behaviours I have observed in that time. Most of the photographs were taken with a Nikon 5000 with a 70/300mm telephoto lens. Frequency: I visit headlands in North Devon three or four times a week throughout the year. Locations: The main locations I watch from are the headlands of Bull Point, Morte Point and Baggy Point, in the Morte Bay, Woolacombe area.’ Description of the speciesThe harbour porpoise is one of six species of porpoise found in the world and is the only porpoise species resident in the UK. It is the UK's smallest cetacean with adults ranging from 1.4m to 1.9m in length. They are thought to live for between 12 and 20 years. Harbour porpoises are distributed widely across the northern hemispheres shelf seas in both the Pacific and Atlantic oceans as well as in the Black Sea. They are recorded north of the Arctic Circle and in the Atlantic as far south as the Moroccan Coast. The IUCN considers them to be of least concern as they are abundant in much of their range, although they are critically endangered in some areas.Geographic distribution re the south west [Expectations]In the South West they are distributed widely across the Celtic Shelf and also in the English Channel. There are notable densities off the Pembrokeshire, Irish, Cornish and Devon coasts. There is a good chance of seeing them from the coast if a watcher goes to the right places.Bob Earll But what the right places? I have routinely watched areas of sea in ideal viewing conditions [ in excess of 50 hours during various states of the tide over the last 4 years] off a number of headlands at Bolt Tail, Bolt Head, Prawle Point and Start Point. Although I have seen porpoises with Dave Jenkins off North Devon on 3 different visits (3/3) and in 2014 within 5 minutes of setting up at Strumble Head, Pembrokeshire, I have yet to see a single porpoise off these south Devon headlands. This begs the question about porpoise distribution at these inshore sites; how long do you have to record zero observations / hour to register this as a real absence? Population size [Relative abundance. How many? How do the animals we see relate to the wider population?] The world population is considered to be around 700, 000 and the UK population somewhere between 341,000 and 385,600. The Celtic Shelf population is thought to be 80,600 and the English Channel has around 40,900 Evans PGH and Prior JS (2012).Population movements [Migrations? Seasonality]Harbour Porpoises seems to exhibit seasonal migrations. The Spring finds them widely spread out over shelf areas while the Summer sees them aggregating along the coastlines and focusing in particular areas. These aggTRANSCRIPT
-
The Ecology of the harbour porpoise in the south west
What we know & What we dont know
Developing an accessible story
-
The IDEA - What do we know? What dont we know?
Example: Porpoises (it could have been sunfish or Manx shearwaters etc)
Making the meetings work harder The idea is that we use the collective expertise (resource) in the room and at the meeting and other contacts to develop an accessible narrative that highlights what we know and what more we need to know
Pulling information together A reality is that often our records and observations are made in isolation geographically by different methods this a device for pulling information together in a systematic way (ie not ad hoc)
The paper will be developed by a number of authors in an iterative way and stored in an accessible archive
What we dont know drives innovation and often new studies and methodologies
-
Example Basking sharks MCS 1990 Seasonal movements (migration)
Distribution Population size
5
0
BehaviourFeeding ecology
Interaction with other species
-
Headings Draft paper in the Delegate Note The first versionDescription of the species
Methodologies (on shore, near shore offshore)
Geographic distribution re the south west (Expectations)Population size (Relative abundance How many? How do the animals we see relate to the wider population?)
Population movements (Migrations? Seasonality)
Breeding ecology (courtship and social interactions)
Feeding ecology and interactions with physical environment (seabed topography and oceanography)
Interaction with other species (Bottlenose dolphins, seals, co-feeding)
Interactions with man
References and links
-
Geographic distribution South Devon a contrast to Cornwall
There are no porpoises in the photograph or none that I saw
In over 50 hours of sea watching from cliff locations (Bolt Head, Bolt Tail, Prawle Point and Start Point, Berry Head) . Ive not seen a single porpoise
Ive seen them with Dave Jenkins 3/3 on the north Devon coast, and off Strumble Head in 2014 saw many, the first within 5 minutes of setting up
Questions: At what point is zero sightings / hour real .
If this is a genuine absence Why? Are they off in Lyme Bay having fun?
Strandings data from Devon Biological Records centre
-
What do we mean when we talk about the South West?
-
World population and how the South West UK population fits
lIUCN world pop estimate 700 000
l328,200 total UK pop estimate European Environment Agency
lSCANS II pop estimate 385 617
lEvans PGH and Prior JS (2012)
-
Management Units
lEvans PGH and Prior JS (2012)
-
Abundance and seasonal variation in Mount's Bay
Marine Discovery 2008-2014 and Penzance Scilly surveys 2007 average monthly abundance
Pz Scilly survey on board Gry Maritha, Surveyor : Marijke de Boer
-
Abundance and seasonal variation
lSightings of harbour
porpoises during shipboard and aerial surveys during
lSCANS II in July 2005
lHammond P (2006)
-
Foraging techniques relating to pod
size and hydrography
lUnderwater pinnacles 'Eric's Patch' key porpoise foraging habitat
-
Index of Abundance (porpoises/km) 2010-2014By Marijke de Boer and Marine Discovery
-
Above : Mulberry Dock Wreck
Right : Epson Shoal
40 metre high
pinnacle
-
North Devon Dave Jenkins the presence of feeding gannets almost always signifies that porpoises are feeding in the inshore reefs - co-feeding
-
CWT Marine Strandings Network
The total number of harbour porpoise dead strandings reported to MSN since its founding in 1993.
Source: CWT Marine Strandings Network, hosted by ERCCIS
-
CWT Marine Strandings Network
The proportion of harbour porpoise dead strandings reported to MSN since its founding in 1993, which exhibit external evidence of Bottlenose Dolphin interaction, or COD was confirmed as a Bottlenose Dolphin
attack.
Source: CWT Marine Strandings Network, hosted by ERCCIS
-
0%
10%
20%
30%
40%
50%
60%
% B
ycat
ch
Proportion of HP with evidance of bycatch/entanglement in Cornwall
CWT Marine Strandings Network
The proportion of harbour porpoise dead strandings reported to MSN since its founding in 1993, which exhibit external evidence of bycatch/entanglement, or COD was confirmed as a bycatch.
Source: CWT Marine Strandings Network, hosted by ERCCIS
-
Breeding ecology
When
Where
Behaviour
Dave Jenkins, North Devon
-
References
l1. Evans PGH and Prior JS (2012) Protecting the Harbour Porpoise in UK seas. WWF
UK
http://assets.wwf.org.uk/downloads/protecting_the_harbour_porpoise_in_uk_seas_aug20
12.pdf
l2. de Boer M and Saulino J (2009) Southwest England Cetacean Survey
l3. Hammond P (2006) Small Cetaceans in the European Atlantic and North Sea (SCANS
II) http://biology.st-andrews.ac.uk/scans2/documents/final/SCANS-II_final_report.pdf
l4. NOAA/NEFSC (2010) HARBOR PORPOISE (Phocoena phocoena phocoena): Gulf of
Maine/Bay of Fundy Stock.
http://www.nefsc.noaa.gov/publications/tm/tm219/165_HAPO.pdf
-
End
-
Courtship and social interaction
-
What do we know? What dont we know?
Nothing A full picture?
0 1 2 3 4 5
The lower the score the bigger the research potential
The lower the score for important headings . The bigger the challenge