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INVESTIGATING THE ROLES OF CETACEANS IN MARINE ECOSYSTEMS – Venice, 28-31 January 2004
CIESM Workshop Monographs n°25
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CIESM Workshop Monographs n°25
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INVESTIGATING THE ROLES OF CETACEANS IN MARINE ECOSYSTEMS – Venice, 28-31 January 2004
CIESM Workshop Monographs n°25
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INVESTIGATING THE ROLES OF CETACEANS IN MARINE ECOSYSTEMS – Venice, 28-31 January 2004
CIESM Workshop Monographs n°25
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Table 1 . Cetacean species known to be regular in the Mediterranean.
Regular
species Habitat Sub-reg.
distrib. Residence Prey Estimated
numbers Threats Conservation
status
Fin whale Mostly
pelagic
Mainly
W & C,
rare in E
Mostly Euphausiids
(small squid,
fish?)
Low 1000s Ship strikes Least concern
Sperm whale
Deep water.
Shelf edge
E, W Maybe females
resident, males
observed also in
Strait of Gibraltar
Deepwater
squid, maybe
fish
Probably
100s
At least 40-50
killed in
driftnets in
Italy alone;
ship strikes
Vulnerable;
ACCOBAMS
priority
species
Cuvier’s
beaked whale
Deep water,
shelf edge
E, W Likely Deep water
squid
? Acoustics;
some killed in
driftnets
Data deficient
Long-finned
pilot whale
Mostly
pelagic
W ? Oceanic squid,
fish
? Killed in
driftnets
Data deficient
Risso’s
dolphin
Shelf edge E, W Likely. Movements
unknown within
photo-identified
populations
Coastal
cephalopods
? Killed in
driftnets
Data deficient
Bottlenose
dolphin
Nearshore E, W Resident Fish, varied
species, mostly
inshore, some
pelagic
? Fisheries;
Pollution?
Vulnerable;
ACCOBAMS
priority
species
Common
dolphin
Nearshore
and pelagic
E, W Resident Varied (fish,
cephalopods,
mostly oceanic)
? Fisheries,
pollution?
Endangered;
ACCOBAMS
priority
species
Striped
dolphin
Pelagic E, W Likely Varied (fish,
cephalopods,
pelagic
crustaceans –
pelagic and
nearshore
species)
Low
100,000s
Epizootics,
killed in
driftnets
Least concern
INVESTIGATING THE ROLES OF CETACEANS IN MARINE ECOSYSTEMS – Venice, 28-31 January 2004
CIESM Workshop Monographs n°25
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Table 2. Methods for estimating abundance and distribution of cetacean populations.
ABUNDANCE/DISTRIBUTION
Distance sampling
Method of data collection Advantages Disadvantages
Dedicated shipboard visual
surveys
Methodology well developed and
documented, can collect data on
environmental covariates simultaneously
Expensive to conduct, not good for species that are
difficult to see (eg Ziphius). Cannot be conducted
close to shore.
Dedicated shipboard acoustic
surveys
Can detect species that are difficult to sea,
less weather dependent than visual
surveys, can be conducted at night.
Analysis methods not yet developed
Dedicated aerial surveys Can cover large areas in a short time Cannot be conducted in some areas (eg open ocean)
Platforms of opportunity Cheap, can make repeated measurements to
detect seasonal and longer term trends,
sometimes possible to collect data on
environmental covariates simultaneously.
Cannot be used to estimate abundance (only
density), geographical coverage restricted to areas
where suitable platforms (ferries etc.) are available.
Capture/recapture
Method of data collection Advantages Disadvantages
Photo-identification Relatively cheap to conduct, also provides
estimates of demographic rates (survival,
migration).
Only suitable for relatively small populations.
Requires repeated surveys. Only suitable for
species where individuals can be distinguished.
DISTRIBUTION
Nature of information obtained depends on way surveys are stratified. However, techniques are being developed to generate maps
of density distribution from the results of line transect surveys.
INVESTIGATING THE ROLES OF CETACEANS IN MARINE ECOSYSTEMS – Venice, 28-31 January 2004
CIESM Workshop Monographs n°25
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CIESM Workshop Monographs n°25
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CIESM Workshop Monographs n°25
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INVESTIGATING THE ROLES OF CETACEANS IN MARINE ECOSYSTEMS – Venice, 28-31 January 2004
CIESM Workshop Monographs n°25
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Table 3. Illustrative scheme of the minimum data requirements to answer some frequently asked questions on the
roles of cetaceans in their ecosystem. The “x” indicates a necessary requirement, while “o” indicates those
elements that can improve the assessment or be necessary depending the specific context.
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INVESTIGATING THE ROLES OF CETACEANS IN MARINE ECOSYSTEMS – Venice, 28-31 January 2004
CIESM Workshop Monographs n°25
Table 4. Some schematic features of ecological models.
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INVESTIGATING THE ROLES OF CETACEANS IN MARINE ECOSYSTEMS – Venice, 28-31 January 2004
CIESM Workshop Monographs n°25
Table 5. Minimum required features of ecological models to address frequently asked questions. If more than one
category is marked, this indicates that any of them can be appropriate.
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Time
Scores
Time
Scores
Total landings
Demersal
Pelagic
Shellfish
Fishermen
BoatsSmall
BoatsLarge
Canonical correlations axis 1
Total landings
Demersal
Pelagic
Shellfish
Fishermen
BoatsSmall
BoatsLarge
Canonical correlations axis 2
Figure 1. Results of MAFA for fishing activity data for Scotland. Upper left graph: first MAF. Upper right
graph: second MAF, lower left graph: canonical correlations for MAF 1, lower right graph: canonical
correlations for MAF 2.
INVESTIGATING THE ROLES OF CETACEANS IN MARINE ECOSYSTEMS – Venice, 28-31 January 2004
CIESM Workshop Monographs n°25
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The various approaches and technical methods discussed during this workshop would be valuable tools
to test such a working hypothesis.
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