Cetacean Distribution & Relative Abundance Survey · R.V. Celtic Explorer – OSS Oceanographic Survey 2010 Cetacean Distribution & Relative Abundance Survey 16th May – 22nd May

R.V. Celtic Explorer – OSS Oceanographic Survey 2010

Cetacean Distribution & Relative Abundance Survey

16th May – 22nd May 2010

Surveyor: Dave Wall

Ship Surveys Programme Irish Whale and Dolphin Group Marine Biodiversity Research Group Galway-Mayo Institute of Technology

Basking sharks (© Dave Wall)

Introduction

The waters of Ireland’s Exclusive Economic Zone (EEZ) are thought to represent

one of the most important cetacean (whales, dolphins and porpoise) habitats in

Europe. To date 24 species of cetacean have been recorded (Appendix I), with

seven of these having been confirmed as calving within the Irish EEZ, while a

number of other species are possibly calving (e.g. minke whale and northern

bottlenose whale) (Berrow 2001). In recognition of their importance for

cetaceans, the Irish government declared all Irish waters (within the EEZ) to be a

whale and dolphin sanctuary in 1991 (Rogan and Berrow 1995). Despite this

recognition, information on the distribution and relative abundance of cetaceans

within the Irish EEZ, especially in offshore waters, is very limited (Wall et al.

2006).

The Irish Whale and Dolphin Group (IWDG) have been collecting data on the

distribution and relative abundance of cetaceans in Irish waters (including

Northern Ireland) since 1991. The IWDG casual and constant effort sightings

schemes record data mainly from land-based sightings and surveys (Berrow et

al. 2001). The IWDG has conducted cetacean surveys on board commercial

ferries since 2001, on board research vessels since 2003 and on board naval

service vessels since 2008.

In 2008, the IWDG in collaboration with the Galway-Mayo Institute of

Technology commenced PReCAST, a three-year project (2008-2011) which aims

to provide robust scientific data to support conservation policy and provide

guidance to state agencies in implementing national and international

obligations. PReCAST is committed to gaining a more complete understanding of

the seasonal distribution, relative abundance and habitat use of cetaceans within

the Irish EEZ.

As part of this project a cetacean distribution and relative abundance survey was

conducted on board the Marine Institute vessel Celtic Explorer during the OSS

Oceanographic Survey from 16th – 22nd May 2010.

Methods

The survey was conducted on board the Marine Institute vessel Celtic Explorer

during the OSS Oceanographic Survey between the 16th and 22nd May 2010. The

survey area covered waters over the Irish Shelf to the west and south of Ireland.

The survey areas were opportunistic and based on survey transects chosen for

the OSS Oceanographic Survey 2010.

Visual Survey

A single marine mammal observer was present on board during the survey and

conducted watches from the ships crow’s nest located 18m above sea level.

Observer effort focused on a 90-degree arc ahead of the ship; however sightings

located up to 90 degrees to port and starboard were also included. The observer

scanned the area by eye and using 10 X 40 binoculars. Bearings to sightings were

measured using an angle board and distances were estimated with the aid of

distance measuring stick. Environmental data were recorded every 15 minutes

using Logger 2000 software (IFAW 2000). Sightings were also recorded using

Logger 2000. Automated position data were obtained through a laptop computer

linked to GPS receiver.

As this was a survey onboard a vessel of opportunity, the survey was conducted

in ‘passing mode’ and cetaceans sighted were not approached. Sightings were

identified to species level where possible, with species identifications being

graded as definite, probable or possible. Where species identification could not

be confirmed, sightings were downgraded (e.g. unidentified dolphin /

unidentified whale / unidentified beaked whale etc.) according to criteria

established for the IWDG’s cetacean sightings database (IWDG 2010).

Passive Acoustic Survey

A towed hydrophone setup was used onboard the Celtic Explorer. This consisted

of a 200m array having two elements separated at 25cm and no depth sensor.

This MagRec built hydrophone had its elements refitted by the Sea Mammal

Research Unit (SMRU), St. Andrew’s, Scotland in August 2009. Two channels

were sampled at 140 ks/sec, providing a 2-70 kHz frequency range. The acoustic

array was connected to a MACREC LTD HP-27st bufferbox. The output from the

buffer-box was fed to a laptop with a Realtek HD Soundcard.

This laptop used IFAW´s Logger (ver. 4.06.0001), RainbowClick (ver. 4.08.0001)

software and PAMQUARD (ver. 1.5.01) Beta software for data acquisition and

click detection. An external GPS unit provided GPS data to the set-up. A 2 TB

hard drive provided storage and backup facility for the data collected. Raw

recordings and click files were stored on the laptop and backed up to the hard

drive every day.

During transects the hydrophone was deployed and monitored by a single

observer for the majority of the deployment time. Raw recordings and click files

were stored to the laptop and backed up to hard drive for later analysis.

Results

Environmental Conditions

Environmental data was collected at 131 stations. Sea state was ≤ 3 at 84.7% of

environmental stations, ≤ 4 at 91.6% of stations and ≤ 5 at 100% of stations.

Visibility was >5km at 28.2% of stations and 1–5km at 55% of stations and 500-

1000m at 12.9% of stations. Rainfall was recorded at 4.5% of stations and

fog/mist was recorded at 75.6% of stations (fig. 1). One full days of survey effort

and one half day were lost due to bad weather (sea state 6 or more) and/or the

dense fog.

Figure 1. Sea state, swell conditions and visibility recorded twice daily during days on survey.

Cetacean Visual Survey Results

30.4 hours of survey time were logged with 83.6% (25.4 hrs) of this at Beaufort

sea state three or less; 91.4% (27.8hrs) at Beaufort sea state four or less and

100% at Beaufort sea state five or less. 38 sightings of three cetacean species and

one seal species, totalling 170 individuals were recorded (fig. 2).

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Figure 2. Distribution and group size of cetacean species recorded during the survey.

Figure 3. Distribution and group size of cetacean species recorded during the survey.

Identified cetacean species were common dolphin (Delphinus delphis), harbour

porpoise (Phocoena phocoena) and minke whale (Balaenoptera acutorostrata).

Grey seals (Halichoerus grypus) were sighted in offshore shelf waters, with

feeding noted in several cases. Two basking sharks (Cetorhinus maximus) were

also sighted, west of Aranmore, one of which breached close to the ship.

Table 1. Sightings, counts and group size ranges for cetaceans sighted during the visual survey.

Species

No. Sightings

No. Individuals

Range of Group Size

Juveniles/ Calves

Common dolphin 10 129 2-20 2

Harbour porpoise 14 25 1-3 -

Minke whale 2 2 - -

Grey seal 11 12 1-2 -

Cetacean Passive Acoustic Survey Results

46 hours of acoustic time were logged during the survey. Most of this effort was

conducted with an observer monitoring the software and noting acoustic

detections as they happened. All hydrophone recordings were saved and will

undergo a full re-analysis of all the acoustic data recorded during the survey.

Following preliminary analysis, a total of 47 identified acoustic detection events

were logged (table 2). As these results were based on a preliminary analysis of

the data, changes in the final dataset should be expected.

Table 2. Acoustic detections recorded during the Cetacean Passive Acoustic Survey.

Species

No. Detections

Common Dolphin 2

Unidentified dolphin whistles 29

Unidentified dolphin clicks 16

Fig. 4 Distribution of dolphin acoustic detections recorded during the survey.

The only confirmed species detected was common dolphin (fig. 4). All dolphin

acoustic detections where species was not confirmed by a sighting were classes

as unidentified dolphins, pending further analysis of the data.

Bird Activity

Daily species lists were made of all seabird species seen around the survey

vessel. 13 seabird species were recorded during the survey: arctic tern (Sterna

paradisaea), guillemot (Uria aalge); razorbill (Alca torda), puffin (Fratercula

arctica), gannet (Morus bassanus); fulmar (Fulmarus glacialis); manx shearwater

(Puffinus puffinus), kittiwake (Rissa tridactyla); lesser black backed gull (Larus

fuscus); great skua (Stercorarius skua), pomarine skua (Stercorarius pomarinus),

storm petrel (Hydrobates pelagicus) and great northern diver (Gavia immer).

References

Berrow, S.D., Whooley, P. and Ferriss, S. (2001) Irish Whale and Dolphin

Group cetacean sighting schemes: development of a system to record sightings of

cetaceans (whales, dolphins and porpoises) in Irish waters. Final report to the

Heritage Council (Ireland), Kilkenny.

IFAW (2000) Logger 2000 software. Inter-national Fund for Animal Welfare,

London.

IWDG (2009) IWDG Cetacean Sightings Database (Rep. Ireland & Northern

Ireland). http://www.iwdg.ie/Iscope/

Ó Cadhla, O., Mackey, M., Aguilar de Soto, N., Rogan, E. & Connolly, N. (2004).

Cetaceans and Seabirds of Ireland’s Atlantic Margin. Volume II – Cetacean

distribution & abundance. Report on research carried out under the Irish

Infrastructure Programme (PIP): Rockall Studies Group (RSG) projects 98/6 and

00/13, Porcupine Studies Group project P00/15 and Offshore Support Group (OSG)

project 99/38. 82pp.

Rogan, E. and Berrow, S.D. (1995) The management of Irish waters as a whale

and dolphin sanctuary. In A.S. Blix, L. Walløe and Ø. Ulltang (eds), Whales, seals,

fish and man, 671..81. Amsterdam. Elsevier Science.

Wall D., O’Brien J., Meade J. & Allen B.M. (2006) Summer distribution and

relative abundance of cetaceans off the west coast of Ireland. Biology and

Environment: Proceedings of the Royal Irish Academy, 106B (2), 135 - 142.

Previous Survey Reports

Wall D. (2010) Cetacean Distribution and

Relative Abundance Survey during FRS Mackerel

Egg Survey 2010. Report to the Fisheries Research

Services, Aberdeen, Scotland.


Relative Abundance Survey during FSS Mackerel

Egg Survey 2010. Report to the Marine Institute,

Oranmore, Galway, Ireland.

Wall D. et al. (2010) Cetaceans on the Frontier

Survey 2010. Cruise report to the Marine Institute,


O’Brien J. (2010) Cetacean Distribution and

Relative Abundance Survey during the Marine

Institute Oceanographic Survey 2010. Report to

the Marine Institute, Oranmore, Galway, Ireland.


Relative Abundance Survey during the LE Roisín

& LE Niamh January Patrol 2010. Cruise Report to

Irish Naval Service, Haulbowline, Cork, Ireland.


Relative Abundance Survey during FSS

Deepwater Survey 2009. Report to the Marine

Institute, Oranmore, Galway, Ireland.



Groundfish Survey 2009. Report to the Marine




Southwest Herring Acoustic Survey 2009. Report

to the Marine Institute, Oranmore, Galway,

Ireland.

Wall D. and O’Brien J. (2009) Cetacean

Distribution and Relative Abundance Survey

during the NPWS Geogenic Reef Habitat Mapping

Survey 2009. Cruise Report to the National Parks

and Wildlife Service, 7 Ely Place, Dublin 2.

Murray C. (2009) Cetacean Distribution and

Relative Abundance Survey during the AFBI

Autumn Herring Acoustic Survey 2009. Cruise

Report to the Agriculture, Food and Biosciences

Institute, Belfast.

Wall D. et al. (2009) Cetaceans on the Frontier

Survey 2009. Cruise report to the Marine Institute,




Biological Oceanography Survey 2009. Cruise


Institute, Belfast.



Nephrops Survey 2009. Cruise Report to the

Agriculture, Food and Biosciences Institute,

Belfast.



Summer Herring Acoustic Survey 2009. Cruise


Institute, Belfast.

Kavanagh L. (2009) Cetacean Distribution and


Northwest Herring Acoustic Survey 2009. Cruise

Report to the Marine Institute, Oranmore, Galway,

Ireland.


Relative Abundance Survey during the NUI

Galway, Climate Change Survey 2009. Cruise

Report to National University of Ireland, Galway,

Ireland.



Juvenile Gadoid Survey 2009. Cruise Report to the


Belfast.


Relative Abundance Survey during the NUI

Galway, Coralfish Survey 2009. Cruise Report to

National University of Ireland, Galway, Ireland.


Relative Abundance Survey during the LE Emer

April Patrol 2009. Cruise Report to Irish Naval

Service, Haulbowline, Cork, Ireland.


Relative Abundance Survey during the Tridens

Blue Whiting Survey 2009. Report to the Dutch

Ministry of Agriculture, Nature and Food Quality

(LNV), Den Haag, The Netherlands.



Groundfish Survey 2009. Report to the


Belfast.



Institute Oceanographic Survey 2009. Report to


Tuffy P. (2009) Cetacean Distribution and

Relative Abundance Survey during AFBI Gadoid

Survey 2009. Report to the Agriculture, Food and

Biosciences Institute, Belfast.



Institute Nutrient Survey 2009. Report to the

Marine Institute, Oranmore, Galway, Ireland.


Relative Abundance Survey during the LE Niamh

January Patrol 2009. Report to Irish Naval Service,

Haulbowline, Cork, Ireland.


Relative Abundance Survey during the LE Róisín

December Patrol 2008. Report to Irish Naval

Service, Haulbowline, Cork, Ireland.


Relative Abundance Survey during IFREMER

Groundfish Survey 2008. Report to the French

Institute for the Exploitation of the Sea.


Relative Abundance Survey during CEFAS

Groundfish Survey 2008. Report to the Centre for

Environment, Food and Agriculture Sciences,

Suffolk, England.


Relative Abundance Survey during AFBI

Groundfish Survey 2008. Report to the


Belfast.





Ireland.


Relative Abundance Survey during FSS Deep

Water Survey 2008. Report to the Marine



Relative Abundance Survey during AFBI

Nephrops Assessment Survey 2008. Report to the

Agri-Food and Biosciences Institute, Northern

Ireland.


Relative Abundance Survey during NIOZ Cold

Water Coral Fish Survey 2008. Report to the

Royal Netherlands Institute for Sea Research and



Relative Abundance Survey during FSS Blue

Whiting Acoustic Survey 2008. Report to the


Baer J. (2008) Cetacean Distribution and

Relative Abundance Survey during CEFAS Irish

Sea Plankton Survey 2008. Report to the Centre

for Environment, Fisheries & Aquaculture Science

and the Marine Institute, Oranmore, Galway,

Ireland.





Ireland.






Relative Abundance Survey during NIOZ Canyons

Survey 2007. Report to the Royal Netherlands

Institute for Sea Research and the Marine



Relative Abundance Survey during Rockall

Trough Oceanographic Survey 2007. Report to




Northwest Herring Acoustic Survey 2007. Report


Ireland.





Ireland.









Ireland.


Relative Abundance Survey during Irish Seabed

Survey: Leg 17. Report to the Marine Institute,


Wall D., O’Brien J., Meade J. & Allen B.M.

(2004) Summer Distribution and Relative

Abundance of Cetaceans off the West Coast of

Ireland. Final report to the Heritage Council,

Kilkenny, Ireland.



Northwest Herring Acoustic Survey 2004. Report


Ireland.


Relative Abundance Survey during FSS Blue

Whiting Survey 2004. Report to the Marine



Relative Abundance Survey during the Celtic Sea

Herring Acoustic Survey 2004. Report to the


All reports are available online at:

www.iwdg.ie/shipsurveys/

Appendix I: List of cetacean species recorded within the Irish EEZ and

adjacent waters.

Atlantic White-Sided Dolphin Lagenorhynchus acutus

Beluga Delphinapterus leucas†

Blue Whale Balaenoptera musculus

Bottlenose Dolphin Tursiops truncatus

Common Dolphin Delphinus delphis

Cuvier's Beaked Whale Ziphius cavirostris

False Killer Whale Pseudorca crassidens

Fin Whale Balaenoptera physalus

Gervais’ Beaked Whale Mesoplodon europaeus*

Harbour Porpoise Phocoena phocoena

Humpback Whale Megaptera novaeangliae

Killer Whale Orcinus orca

Minke Whale Balaenoptera acutorostrata

Northern Bottlenose Whale Hyperoodon ampullatus

Northern Right Whale Eubalaena glacialis

Pilot Whale (long-finned) Globicephala melas

Pygmy Sperm Whale Kogia breviceps

Risso's Dolphin Grampus griseus

Sei Whale Balaenoptera borealis

Sowerby's Beaked Whale Mesplodon bidens

Sperm Whale Physeter macrocephalus

Striped Dolphin Stenella coeruleoalba

True's Beaked Whale Mesplodon mirus

White-Beaked Dolphin Lagenorhynchus albirostris

† Vagrant * Recorded only from Stranding

Documents

Cetacean Distribution & Relative Abundance Survey · R.V. Celtic Explorer – OSS Oceanographic Survey 2010 Cetacean Distribution & Relative Abundance Survey 16th May – 22nd May