Bottlenose dolphin conservation: a critical assessment

Simon Ingram

Marine Vertebrate Research Group Marine Coastal Policy Research Centre, Plymouth University

Bottlenose dolphins around the UK

Bottlenose dolphins (Tursiops truncatus)

Explanation of grades

A Outstanding examples of the feature in a European context.

B Excellent examples of the feature, significantly above the threshold for SSSI/ASSI notification but of somewhat lower value than grade A sites.

C Examples of the feature which are of at least national importance. These features are not the primary reason for SACs being selected.

D Features of below SSSI quality occurring on SACs These are non-qualifying features (non-significant presence), indicated by a letter D, but this is not a formal global grade.

Moray Firth SAC

Cardigan Bay SAC

Shannon Estuary SAC

One of the most northern populations

Isolated

The Moray Firth bottlenose dolphin SAC

050

100

150

200

250

300

1989 1991 1993 1995 1997 1999 2001 2003 2005

Ye ar

Ab

un

da

nc

e e

sti

ma

teBottlenose dolphin population monitoring in the moray Firth

Modelled population trends Population Viability Analysis (PVA) Sparked concern about a decline in numbers

Population Model

N t+1 = N t + B - D + I - E

1990-1995

1996-2000

Community structure

Lusseau et al. (2006), J. Animal Ecology

The Shannon Estuary bottlenose dolphin SAC

Designated under the EU Habitats Directive

Seasonal changes in rates of use of the SAC

0

5

10

15

20

25

Jan (n=5)

Feb (n=5)

Mar (n=6)

Apr (n=6)

May (n=5)

Jun (n=6)

Jul (n=31)

Aug (n=43)

Sep (n=40)

Oct (n=8)

Nov (n=6)

Dec (n=2)

0

5

10

15

20

25

Jan (n=5)

Feb (n=5)

Mar (n=6)

Apr (n=6)

May (n=5)

Jun (n=6)

Jul (n=31)

Aug (n=43)

Sep (n=40)

Oct (n=8)

Nov (n=6)

Dec (n=2)

Strong seasonal pattern in site use Site use is highly variable Suggests the SAC only represents a part of the range of the animals

Bottlenose dolphins seen at many

sites outside the MPA

One or several populations?

Bottlenose dolphins on the west coast of Ireland

Molecular genetics analysis of skin biopsies from free ranging and beach stranded animals

Mirimin et al., Aquatic Conservation (in press)

Map of Ireland showing sampling location of individually stranded dolphins (stars), Shannon Estuary (circle), Connemara-Mayo (triangles) and Cork Harbour (diamond). Numbers of multiple samples from the same area are shown in brackets.

Proportion of each individual genotype (vertical bars) assigned to cluster one (black),

cluster two (white) and cluster three (grey), using STRUCTURE..

Mirimin et al., Animal Conservation (2011)

More than one population using inshore coastal waters

Populations have different ranging behaviour/site fidelity

Evidence for a third pelagic population?

Bottlenose dolphins on the west coast of Ireland

Analysis of tissue samples from in Mediterranean and NE Atlantic

Louis et al 2014 Molecular Ecology

Bayesian assignment into putative populations

Coastal animals appear genetically distinct from

pelagic population

Louis et al 2014 Molecular Ecology

Some evidence of steretoyped dorsal fin damage

Bottlenose dolphins around Cornwall during the 1990s

(Wood 1998 J. Zool.)

~50 individuals identified from unique markings

Indications of a decline in sightings frequency and school size

Pikesley et al JMBA, 2011

Lack of recent analysis or efficient data management

Likely to be declining conservation priority? appropriate action

Anecdotal evidence of historical local feeding tradition by bottlenose dolphins

at the mouth of Hooe Lake, Plymouth (Nick Tregenza pers. Comm.)

Loss of local culture with declining local habitat use/abundance

Jon Miles

o MPAs essential for resident coastal populations

o Issues relating to shifting ranges of animals protected by fixed area MPAs

o Problems applying fixed area protection for mobile populations

o Coastal dolphins distinct from pelagic populations (but we do not have the

US inshore offshore distinct ecotypes)

o So whats the best conservation approach for the SW dolphins?

o Clear need for more data, photo-id, biopsy, occupancy

o Collaboration

Summary