Cetaceans sustain a depth of fascination that is almost without parallel in nature. Along with primates, they are among the most intelligent of all mammals; but while this might account for the allure of primates, the natural environment of cetaceans also adds to the interest of this order of animals. Encounters with cetaceans are difficult to contrive because they inhabit a world that is largely unseen. Despite increased attention in recent years, the oceans remain places of mystery; the ecological processes that underlie observable patterns in marine communities are largely unknown and seem almost arcane.

 

 

Compared with many terrestrial mammals, little is known of cetacean natural history . Indeed, knowledge of some species comes from only a handful of dead specimens, and new species are still being either recognised or discovered relatively frequently. Again, this is not surprising for animals that usually only briefly break the surface of the sea.

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That cetaceans are difficult to observe, however, should not disguise the fact that populations of some species are very large.This is true not only in seas traditionally thought of as high in cetacean abundance but also of the Atlantic and associated seas around Europe. For example, in north-west European and adjacent waters there may be more than 100,000 minke whales present at certain times of the year (Schweder et al. 1997).The seas of north-west Europe also host a rich variety of cetacean species. More than 20 species may be seen here regularly throughout the year, about half as many again as occur regularly in the south-west Atlantic at similar latitudes (White et al. 2002). This represents a diversity of form and function that demands effective conservation.

 

The proper conservation of cetaceans depends on knowledge of many aspects of their population ecology. Ideally, information on population size, structure and seasonal distribution, as well as data on mortality, breeding productivity, and emigration and immigration rates should be available. For the reasons outlined above such information for most cetaceans is largely non-existent.

 

However, cetacean populations in some parts of the world are rather better known than in others. In north-west European waters, for example, there are many data available that may aid in the conservation of populations here. In particular, the increasing number of at-sea surveys adds to knowledge of the distribution, and in some cases the abundance, of our animals. Perhaps the best example here is the SCANS survey, which investigated the distribution and estimated the population size of harbour porpoises in the North Sea and adjacent waters in July 1994 (Hammond et al. 1995, 2002). Such large-scale surveys aid in placing subsequent mortality events, chronic or otherwise, in the proper population and geographical contexts. For example, the estimated magnitude of fishery bycatches of porpoises in the North Sea has allowed an assessment of the sustainability of current bycatch levels to be made (Vinther 1999; Hammond et al. 2002). Identification of patterns of cetacean distribution and abundance is an important early goal of research that aims to underpin conservation measures, as well as being one that can be relatively easily achieved. In conjunction with other information, knowledge of cetacean dispersion also aids in the investigation of the ecological determinants of dispersion, of the biological and physical processes that might generate dispersion patterns, and consequently of the habitat requirements of the various species. If time series data are also available then any detected distributional shifts, or changes in population size, of these top predators may be indicative of more far-reaching changes, or even disruption, to ecosystem processes.

 

It is perhaps as a natural heritage resource in their own right, however, that cetaceans are increasingly the focus of conservation research.The array of potential threats to cetacean populations has never been greater. Anthropogenic effects in the form of oil and chemical pollution, disturbance, noise pollution, habitat degradation and even deliberate persecution persist, although impacts on populations remain either minimal or obscure. While hunting currently poses little or no threat, notwithstanding the fact that the minke and pilot whales are still exploited by Norway and the Faroe Islands in the north-east Atlantic, interactions with fisheries do result in detectable changes at the population level. It is now widely accepted that fisheries have played a major role in the dramatic decline of porpoises in the Baltic in recent decades (ASCOBANS 2002), and there is also serious cause for concern that current or recent bycatch levels of porpoises in the North Sea and Celtic Sea may be unsustainable (Harwood et al. 1999;Tregenza et al. 1997).

For whatever reason, populations of some species in the north-east Atlantic have been extirpated from localised areas (e.g. the harbour porpoise in the eastern Channel) or even from much larger areas (e.g. the grey whale in the Atlantic).

 

The increasing diversity of possible threats to cetacean populations has seen a concomitant rise in the number of government agencies and non-governmental organisations (NGOs) devoted to their study. The former have instigated investigations on national and international scales, while NGOs have focused mostly on more restricted areas. In the UK, the principal and longest established NGO that carries out conservation research into cetaceans in British and Irish waters is the Sea Watch Foundation, which has been doing so in collaboration with other, smaller NGOs since 1973. The UK Government's advisor on nature conservation, the Joint Nature Conservation Committee (JNCC, formerly the Nature Conservancy Council), has also, since 1979, been carrying out research on the distribution of cetaceans from a much wider sea area of the north-east Atlantic. In association with other European government bodies and NGOs (listed in the Acknowledgements), the JNCC acts as a focus for the collation of effort-related sightings data of cetaceans over the north-west European continental shelf. The Sea Mammal Research Unit, part of the UK Government's Natural Environment Research Council and now also of the University of St Andrews, Scotland, has also been pursuing collaborative research on cetaceans with international conterparts since its formation in 1978.These organisations, with the longest track records of cetacean research in Europe, and their collaborators have contributed cetacean sightings data to a co-operative venture, the Joint Cetacean Database (JCD), and it is the data from this resource that are depicted in this Atlas.

 

The JCD comprises the most comprehensive information on the distribution of cetaceans in north-west European waters and this Atlas contains the most complete quantitative description of cetacean dispersion in this region.The distributional data herein presented for many of the more commonly occurring species are, for the first time at this broad geographical scale, effort-related; the user of the Atlas is thus accorded a greater degree of interpretative scope than previously available.The Atlas and database therefore aim to function as a practical conservation tool; as a first step in an audit of the occurrence of cetaceans at this scale their use can, with caution (see Methods), enable the proper contexting of new information on cetacean distribution and abundance, and they may also inform efforts to identify areas that might be particularly important for cetaceans. Indeed the database has already fulfilled this latter function with respect to the possible identification of Special Areas of Conservation for harbour porpoise (Bravington et al. 2002; Evans and Wang 2003).

 

The JCD is the product of a very fertile collaboration between different organisations both within the UK and in Europe as a whole. In the longer term, the JCD has the potential for growth as the existing collaborators continue to collect and contribute data, and as new partners join the venture. Such development should widen the scope and utility of the database and may enable identification of seasonal patterns of cetacean dispersion as well as habitat associations; perhaps it will foster more process-related research.

This Atlas aims to provide an account and snapshot of the distribution of all 28 cetacean species that are known certainly to have occurred in the waters off north-west Europe in the last 25 years, but including also narwhal and melon-headed whale for which records are as recent only as the 1940s. It cannot function as a 'where to watch cetaceans' guide and the reader is advised to read carefully the Methods chapter in order to aid interpretation of the maps. Most of the book comprises chapters covering individual species. In the majority of these, a brief account of the natural history of the species is presented, including information on identification, behaviour and social organisation, diet, and habitat preferences, inasmuch as such information is known.There follows some details of the species' worldwide distribution and its status in the north Atlantic, and then a description of its occurrence in north-west Europe accompanied by a map depicting this.

 

The Methods chapter describes data collection methods, database establishment, brief details of the analytical methods that were applied to render the data from many sources compatible, and the important section on map interpretation. In other chapters, the nature of the marine environment of the study area is described and information is presented on the current legislative instruments aimed at protecting cetaceans.