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Report of the Workshop on the Scientific Aspects of Managing Whale Watching

5.5 Short-term impacts: experimental vs observational approaches to designing studies

Observational studies and anecdotal reports indicate that cetaceans may react to a variety of disturbances related to whale watching and other human activities. However, there remain many questions primarily due to issues of controlling all the variables which may be contributing to the response of the animals. Two alternative approaches to studying short-term impacts are experimental and observational.

1. Experimental

In the past, few rigorous experiments have been conducted, but there may be opportunities for such work. For example, there are areas where whale-watching intensity may vary in space or time, thus allowing a comparative experimental approach (eg, southern right whales [Eubalaena australis] at Golfo San José and Golfo Nuevo, Península Valdés, Argentina). In other areas, whale watching platforms may be absent but could be introduced experimentally. These situations may be especially important for answering outstanding questions such as, "how does vessel type, its acoustic signature or behaviour affect the response of cetaceans?"

2. Observational

Since it is difficult to control experimental situations in the wild, observational studies may be the most
feasible approach. The likely success of such studies is increased by large sample size, continuity in data collection, consistency of approach and appropriate temporal and spatial scales. A number of considerations were identified for experimental and observational studies.

Objectives of a research programme on whale watching should include the following:

  1. Measure changes in distribution and habitat-use patterns of whales as they may be influenced by whale watching through long-term monitoring of changes in:

    • cetacean distribution and relative abundance
    • distribution and relative abundance of whale watching platforms
    • ecological variables (particularly prey biomass, distribution and resource partitioning)
    • other human activities potentially influencing cetaceans

    Changes in the above parameters can then be compared to determine the impacts of whale watching on cetaceans.

  2. Document and interpret changes in behaviour, at the same time minimising the influence of confounding variables by conducting experiments on:

    • changes in parameters under experimental conditions
    • comparative research using indicators of whale-watching intensity

  3. Develop, measure and standardise indicators of overt stress, to gain insight into, among other things, the nature of whales' interactions with humans in order:

    • to provide a foundation for (2) above
    • to develop an index of use ("watchedness") for individual animals

  4. Analyze the vital characteristics of both individuals and populations over the long term by monitoring:

    • the index of use (3 above) for individuals within populations
    • calving rate for the same individuals
    • a variety of fitness parameters for the same individuals using measures such as length/girth photogrammetry, blubber thickness, and use emerging techniques in remote telemetry and physiological monitoring where possible

    5.6 Existing long-term studies

    Certain continuing long-term studies of cetaceans may present an opportunity to investigate the impacts of whale watching on reproduction, recruitment and other long-term parameters. It is a sound strategy to bring these data into play as foundations for advancing future research whenever possible. In the waters of the Gulf of Maine, a long-term study of individually identified humpback whales [Megaptera novaeangliae] was begun by the Center for Coastal Studies in 1975. See also working papers MMW/95/39 and 38 regarding humpback whales in Hervey Bay, Australia and MMW/95/45 on gray whales in Clayoquot Sound, Canada for other potential examples.

    As the Gulf of Maine population of humpbacks has become intensely targeted by whale watching companies, the database developed for this population may be useful for the purposes of investigating impacts of such activities on population parameters. The database from the last 20 years has been collected largely from whale-watching vessels whose vessel type and method of operation has remained relatively unchanged over the years. The primary database (collected from the Dolphin Fleet whale- watching vessels) encompasses approximately 30 000 records with another 30 000 from other sources. Approximately 15 000 whale-watching cruises are covered in the combined databases. This database associates the individual identification of some 900 whales with location, sighting times from whale- watching boats, and the presence of calves (assigned with an ID number). It is possible that these databases could be used to determine "whale use indices" by individual for comparison with calving by individuals (approximately 250 calves documented.). Fitness sampling, blubber thickness and length-girth studies of these individuals have not been attempted, but may be useful in the future.

    5.7 Other studies - reactions of terrestrial mammals to human activities

    With research into whale watching and its impact on cetaceans still in its infancy, one productive avenue for designing new studies and gauging the probable impacts of whale watching is to evaluate research that has been conducted on land mammals.

    Studies on terrestrial mammals show us that we can make broad generalisations from one species to another based on noise variability, the indication of danger posed by the noise due to past experience and other factors such as the reproductive or behavioural status of the animals. However, such studies also indicate to us that extrapolations within and among populations, habitats and species must be done with

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