Post on 02-Oct-2015
description
The status of basking
sharks in Cornwall
Tom Horton
The Project
Previous works suggesting decline in numbers
Following another "interesting year . . .
Long-term aim is to categorise and understandlong-term trends in abundance
Work in progress . . .
Overview
Basking sharks in the UK and Cornwall
2014
Long-term trends
Implications
The future
BASKING SHARKS
IN THE UK
Seasonal visitors
Fished 1946-1997
Wildlife and Countryside Act (1981)
Listed on CITES & CMS
Vulnerable IUCN Red List (1996-)
SW England regional hotspot
Witt et.al., 20
12
BASKING SHARKS
IN CORNWALL
ICONIC species
Synonymous with Porthcurno& Sennen
Income through wildlife tour operators
Multiple sightings programs
Proposed to be listed in MCZs
How about numbers?
2014
01
2
3
4
5
6
7
8
9
10Independent UoE Project
2014 totals
59 records
91 sharks
1998 - 2014 average
273 records
1226 sharks
Record
s
Map to show shark locations on 4.5.2014
4.5.2014
4.5.2014
59 records comprising 91 sharks
Mostly South coast
No large shoals
60% of records 23.4.2014-7.5.2-2014
Long-term trends
1997- present1988- present 1997- present
2007- present2007- 2011
1. Public recording
2. Effort-based
2008 - 2012
Long-term trends
1997- present1988- present 1997- present
2007- present2007- 2011
1. Public recording
2. Effort-based
2008 - 2012
Seawatch Southwest
Marine Discovery
547
221194
218
1459
115
13
0
100
200
300
400
500
600
0
5
10
15
20
25
30
35
40
2007 2008 2009 2010 2011 2012 2013 2014
March
April
May
June
July
August
Sept
Oct
Nov
Sharks
SWSWS
hark
s h
-1
Sh
ark
s y
ea
r-1
Shark
s 1
00km
-1
Sh
ark
s y
ea
r-1
Yearly average:156 sharks
MDYearly average:
173 sharks
458
209
51 4713
0
50
100
150
200
250
300
350
400
450
500
0
0.1
0.2
0.3
0.4
0.5
0.6
2007 2008 2009 2010 2011
July
August
Sept
Oct
Sharks
Sh
ark
s y
ea
r-1
JuneSept
Cornwall Wildlife Trust
1711
2200
728
13851219
599
317
786
2929
4001
1607
1069
796
77
1050
28391
0
500
1000
1500
2000
2500
3000
3500
4000
4500
0
50
100
150
200
250
300January
February
March
April
May
Reco
rds
Sh
ark
s y
ea
r-1
SWSW & MD Start
So what is this telling us?
Shark sightings have declined in the SW
1. Species assemblage
change
2. Zooplankton density
3. Temperature
Calanus helgolandicus @
L4
0.00
50.00
100.00
150.00
200.00
250.00
300.00
350.00
400.00
450.00
MD 2013 peak CWT 2014 peak
Ind
ivid
ua
ls m
3
Data courtesy of Rachel Harmer @ PML
basking shark status
CWT dataset shows periodicity +/-
SWSW & MD show decline -
A need for the inclusion of long-term prey and SST data
Sub-surface sharks?
Importance of monitoring schemes
Moving Forwards
Summary
Raw data show a decline in sightings since 2006/07
Combined effects of SST & prey rather than a population decline
Still defined need for long-term monitoring
Fingers crossed for 2015!
Thanks for listening