Cetacean Diving Behavior
I have been examining the diving and night-time behaviour of a number of species of cetaceans, using suction-cup attached TDRs. This has involved work in eastern and western Canada (Nova Scotia and British Columbia), off Japan, New Zealand, the United States (Washington, Alaska, and Hawaii) French Polynesia (Moorea), Iceland, and Italy. Species studied include Dall's porpoise, northern bottlenose whales, dense-beaked whales, Cuvier's beaked whales, short-finned pilot whales, long-finned pilot whales, rough-toothed dolphins, bottlenose dolphins, pantropical spotted dolphins, false killer whales, killer whales, and humpback whales.
Spotted dolphin with suction-cup attached time-depth recorder, off Maui, Hawaii, March 4, 1999. (photo copyright Pacific Whale Foundation 1999)
The following is the (slightly modified, expanded and updated) text of slides from a presentation entitled:
Using remotely-deployed suction-cup attached tags to study sub-surface behaviour of odontocetes
presented at the Workshop on Methods for Assessing Behavioral Impacts on Marine Mammals from Human Activities, Monaco, January 19, 1998.
Cetaceans spend the vast majority of their time beneath the water’s surface, where they are difficult to observe and study. Unlike pinnipeds, attachment of tags for recording underwater behaviour is problematic. Penetrating tags can only be remotely-deployed on species with thick blubber layers, or by capturing animals (which is logistically difficult, expensive, and potentially injurious to the animals). Penetrating tags are usually not recoverable, and thus new tags are needed for each deployment. By contrast, suction-cup attached tags are recoverable, reusable, relatively inexpensive (thus larger numbers of individuals can be sampled), and can be used on small cetaceans while avoiding the risks and costs of capture operations. Suction-cup attached tags can be remotely deployed using either a crossbow or pole, or can be attached to captured or rehabilitated animals. For sampling diving behaviour, while satellite-linked tags can only transmit coarse-level data, recoverable data-logging time-depth recorders (TDRs) can sample and store high resolution data. Commercially available off-the-shelf TDRs can be set to sample parameters such as depth, swimming speed, and water temperature at rates up to once per second. Remotely-deployed suction-cup TDR/VHF tags have recently been used on a number of species of odontocetes, including killer whales, Dall’s porpoise, northern bottlenose whales, short-finned pilot whales, Pantropical spotted dolphins and bottlenose dolphins. Tags can sometimes remain attached for relatively long periods (12-31 hours) on even fast moving species such as Dall’s porpoise, Pantropical spotted dolphins and killer whales. Reactions to tagging attempts vary between species; most species for which these tags have been used show low-level or moderate reactions to tagging. Data collected can be used to address both management-based questions (such as surfacing and diving patterns for survey calibration, or determining exposure and/or reactions to depth-specific threats such as fishing gear, vessel traffic or high-intensity underwater sounds), and questions regarding the basic biology of a species (diurnal behaviour patterns, ontogeny of diving etc).
Cetaceans spend the vast majority of their time beneath the water’s surface, yet there are few easy, inexpensive ways of studying sub-surface behaviour. There are a number of problems associated with tagging small cetaceans:
- Remotely-deployed penetrating tags can only be used with species with thick blubber layers.
- Capture-operations for smaller species can be dangerous, expensive and logistically difficult.
- Penetrating tags are usually not recoverable, thus a new tag is needed for each deployment (though some researchers are developing methods of remotely releasing tags).
- Satellite-linked tags can only transmit coarse-level data.
- Acoustic tags are not suitable for many species of odontocetes, since the frequency of transponders overlaps with the hearing range of most species.
THERE ARE A NUMBER OF MANAGEMENT USES OF DIVING DATA
- Surfacing and diving information for survey calibration
- Evaluating exposure to depth-specific threats (e.g. fishing gear, high-intensity underwater sounds)
- Measuring responses to potential threats (e.g. vessel traffic, sound sources)
- Examining foraging behaviour in relation to human fishing activity or food-web dynamics
The technique of using suction-cup attached tags, first developed by Jeff Goodyear in 1981, overcomes many of the difficulties outlined above.
ADVANTAGES OF REMOTELY-DEPLOYED SUCTION-CUP ATTACHED TDR/VHF TAGS:
- Recoverable and reusable
- Relatively in-expensive
- Large number of individuals can be sampled
- Avoid risks associated with capturing animals
- Can be used on small cetaceans
- Less intrusive than penetrating tags
- High resolution dive data
TAG COMPONENTS (and costs in U.S. dollars):
- Tag body (syntactic foam for flotation, covered with yellow plastic for protection and to make the tag more visible when in the water). Cost: $100-200
- VHF radio transmitter (for following whales and re-locating tag when detatched). Cost: $200-400
- Time-depth recorder (I currently use Wildlife Computers Mk6 TDRs, which are commercially available and very reliable- for recording depth, velocity, temperature, and light levels). Cost: $1400-1600
- Suction-cup (Canadian Tire, automobile roof-rack suction-cup - attached to tag body with flexible tubing). Cost: $2
The components are mounted in the tag housing in such a way that when released from an animal, the tag floats with the VHF antenna clear of the water.
- only applicable for species which bow-ride (e.g. Dall’s porpoise, spotted dolphins) or slower moving, larger species (e.g. fin whales)
- useful with approachable medium-sized or large species (e.g. killer whales, pilot whales)
- as an adjunct to capture or release operations, to monitor short-term reactions to capture or outcome of release
One limitation to suction-cup tagging is that there is little control over the precise location of the tag on an animal's body, and even when attached, tags will sometimes slide along the body. Thus obtaining good VHF signals for tracking animals can be difficult, if not impossible at times.
REACTIONS TO REMOTELY-DEPLOYED SUCTION-CUP TAGS
Reactions can be evaluated in several ways:
- Magnitude and duration of "unusual" visible surface behaviours (e.g., flinch, fast dive, tail lob, leaps, high speed swimming, etc...)
- Comparisons with behaviour of other individuals in group (e.g., all engaged in same behaviour)
- Analysis of tag data, for changes in dive parameters (e.g., rate of descent, depth) or velocity over time, giving duration of reaction
REACTIONS SEEM TO BE SPECIES-SPECIFIC:
- KILLER WHALES (n>160 attempts with 41 successes, crossbow deployment) - no reaction or low-intensity, short duration (e.g., flinch)
- SHORT-FINNED PILOT WHALES (n=6 attempts with 2 successes, crossbow deployment) - low to moderate intensity, short duration (e.g., tail flick, fast dive), some group reaction?
- DALL’S PORPOISE (n=15 attempts with 1 success, pole deployment) - low to moderate intensity, short duration. Five tags have also been deployed on Dall's porpoise which have been captured and temporarily restrained
- BOTTLENOSE DOLPHINS (n=17 attempts with 5 "successes", primarily pole deployment) - high-intensity, long-duration reactions, by entire group
- NORTHERN BOTTLENOSE WHALES (n>50 attempts with 5 successes, crossbow deployment) - low to moderate intensity, short duration?, possibly some group reaction
In terms of the amount of effort needed to deploy tags, with one population of killer whales off the west coast of North America, we were able to deploy eight tags in nine days of field effort, spending approximately three to four hours each day trying to tag animals. About one out of every three crossbow shots resulted in successful taggings, and tags remained attached for an average of almost 16 hours. In previous years a magnesium-release mechanism was used, to make sure tags fell off animals after shorter periods (to increase the probability of recovery).
In over 50 deployments of tags on the species mentioned above, we have lost only two tags, both on a very deep diving species (northern bottlenose whale). The VHF transmitters in both tags probably failed due to the extreme depth to which bottlenose whales dive.
TAGGING PROJECTS MENTIONED ABOVE HAVE INVOLVED A NUMBER OF COLLABORATORS/CO-INVESTIGATORS:
- Killer whales - Larry Dill (Simon Fraser U.), Brad Hanson (National Marine Mammal Lab) and Sascha Hooker (Dalhousie)
- Dall’s porpoise - Brad Hanson (PI)
- Northern bottlenose whales - Sascha Hooker (PI)
- Short-finned pilot whales - Masao Amano (PI) (Otsuchi Marine Research Center, U. Tokyo)
- Bottlenose dolphins - Karsten Schneider (PI) and Steve Dawson (University of Otago)
REFERENCES ON THE SUCTION-CUP TAGGING, DIVING BEHAVIOUR, AND REACTIONS TO TAGGING
Baird, R.W. 1994. Foraging behaviour and ecology of transient killer whales (Orcinus orca). Ph.D. Thesis. Simon Fraser University, Burnaby, B.C.
Baird, R.W. 1998. Studying diving behavior of whales and dolphins using suction-cup attached tags. Whalewatcher 32(1):3-7.
Baird, R.W., and M.B. Hanson. 1996. Dall's porpoise diving behaviour and reactions to tagging attempts using a remotely-deployed suction-cup tag. Report prepared under Contract No. 43ABNF601492 to the National Marine Mammal Laboratory, National Marine Fisheries Service, Seattle, WA.
Baird, R.W., A.D. Ligon and S.K. Hooker. 2000. Sub-surface and night-time behavior of humpback whales off Maui, Hawaii: a preliminary report.(###) Report prepared under Contract #40ABNC050729 from the Hawaiian Islands Humpback Whale National Marine Sanctuary, Kihei, HI, to the Hawaii Wildlife Fund, Paia, HI.
Baird, R.W., A.D. Ligon, S.K. Hooker, and A.M. Gorgone. 2001.Sub-surface and night-time behaviour of pantropical spotted dolphins in Hawaii. Canadian Journal of Zoology 79: 988-996. Download Adobe PDF copy
Baird, R.W., J.F. Borsani, M.B. Hanson, and P.L. Tyack. 2002. Diving and night-time behaviour of long-finned pilot whales in the Ligurian Sea. Marine Ecology Progress Series 237:301-305. Download PDF copy
Baird, R.W., M.B. Hanson, E.E. Ashe, M.R. Heithaus and G.J. Marshall. 2003. Studies of foraging in "southern resident" killer whales during July 2002: dive depths, bursts in speed, and the use of a "Crittercam" system for examining sub-surface behavior. Report prepared under Order Number AB133F-02-SE-1744 for the National Marine Mammal Laboratory, National Marine Fisheries Service, Seattle, WA. Download PDF copy
Hanson, M.B., and R.W. Baird. 1998. Dall’s porpoise reactions to tagging attempts using a remotely-deployed suction-cup attached tag. Marine Technology Society Journal 32(2):18-23.
Hanson, M.B., R.W. Baird and R.L. DeLong. 1998. Short-term movements and dive behavior of tagged Dall's porpoise in Haro Strait, Washington. Page 59 in Abstracts of the World Marine Mammal Science Conference, 20-24 January 1998, Monaco.
Hooker, S.K., and R.W. Baird. 1999. Deep-diving behaviour of the northern bottlenose whale, Hyperoodon ampullatus (Cetacea: Ziiphidae). Proceedings of the Royal Society of London B. 266:671-676.Download Adobe PDF copy
Hooker, S.K., R.W. Baird, S. Al-Omari, S. Gowans and H. Whitehead. 2001. Behavioral reactions of northern bottlenose whales to biopsy and tagging procedures. Fishery Bulletin, U.S. 99:303-308. Download Adobe PDF copy
Hooker, S.K., and R.W. Baird. 2001. Diving and ranging behaviour of odontocetes: a methodological review and critique. Mammal Review 31:81-105. Download Adobe PDF copy
Schneider, K., R.W. Baird, S. Dawson, I. Visser and S. Childerhouse. 1998. Reactions of bottlenose dolphins to tagging attempts using a remotely-deployed suction-cup tag. Marine Mammal Science 14:316-324.
Last Updated August 2003 by Robin W. Baird