Marine protected areas for whales, dolphins, and porpoises: a world ...

2 Marine Protected Areas for Whales, Dolphins and Porpoises
BOX I.1 CRITICAL HABITAT
Critical habitat refers to those parts of a cetacean’s range, either a whole species
or a particular population of that species, that are essential for day-to-day survival,
as well as for maintaining a healthy population growth rate. Areas that are regularly
used for feeding (including hunting), breeding (all aspects of courtship) and raising
calves, as well as, sometimes, migrating, are part of critical habitat, especially if
these areas are regularly used.
Unlike land-based critical habitat, however, marine critical habitat boundaries
may be less fixed, especially in terms of hunting and feeding areas which are
dependent on upwelling and other ever-changing oceanographic conditions.
Baleen whales, for example, are known to feed in and around upwellings, which
vary depending on local and large-scale oceanographic conditions to some extent
during a season and from year to year. The implication for MPA design is that more
flexible definitions of MPAs for cetaceans are needed in some cases. This book
argues for larger overall biosphere reserve-type areas which would include a
number of highly protected ‘core areas’ corresponding to cetacean critical habitat
with boundaries that can be adjusted as needed from year to year or even within
seasons. Such adjustments should be adaptive, constantly reviewed and sensitive
to signals from the wider environment. To achieve this fine-grained kind of critical
habitat management, it will be necessary to unravel and understand ecosystem
processes and the impacts that humans can have on such processes. An
appropriate tool for this is ecosystem-based management (see Box I.2).
Critical habitat for cetaceans is a fairly new idea, yet to be fully explored, much
less implemented. In the comprehensive US blueprint for MPAs, ‘critical habitats’
are areas ‘such as spawning grounds, nursery grounds, or other areas harboring
vulnerable life stages’ (Commission on Geosciences, Environment, and
Resources, 2000). According to this document, ‘the primary consideration for
implementing marine reserves should be the needs of each biogeographical
region based on protecting critical habitats’. It is becoming clear that identifying
the critical habitat of cetaceans, the crucial core areas, will be the first step towards
good marine management of MPAs with cetaceans.
Critical habitat is identified under the US Endangered Species Act of 1973 but,
to date, has mainly been applied to land-based endangered species. The
Endangered Species Act prohibits federal government agencies from allowing
activities that adversely affect critical habitat. Federal permits for fishing, oil and
mineral development activities within critical habitat areas must show that critical
habitat will not be harmed. Taylor et al (2004) showed that designation of critical
habitat under the Endangered Species Act is significantly associated with
improving population trends for species listed as endangered.
Much research over the next few decades will be focused on defining, locating
and understanding the parameters for cetacean critical habitat. Some of these are
conventional geographical aspects and others are the more fluid oceanographic
parameters such as temperature, salinity and current. For example, a recent study
attempting to quantify cetacean habitat patterns in the California Current using a
broad suite of oceanographic data was 48 per cent successful in predicting
cetacean presence, ranging from 70 per cent for Dall’s porpoises to less than 10
per cent for fin whales (Reilly et al, 1997). As understanding and measurement of
the appropriate parameters becomes sharper, this predictive ability should
improve. Thus, critical habitat may be defined as not only the fixed and seasonally
changing boundaries of the places cetaceans habitually use, but also as the less-