The world-wide use of toxic substances and a tendency to dispose
of them in the ocean after use are important factors driving marine
pollution. During the past century alone, over 20,000 human-made
chemicals have been introduced into the environment, many of which
have entered food webs. Although very little is known about the
quantities produced and released each year, there are clear signs
that in many places the oceans ability to neutralise pollutants
has been reached or exceeded.
Research has lagged behind industrial development, and the environmental
effects of introducing such a large number of new compounds are
still poorly understood. Many of these pollutants are being distributed
globally, and can enter the New Zealand marine environment through
air and water currents.
The Trust has done its bit by collecting samples from dead whales
and dolphins, killed in fishing gear or found dead on a beach. These
samples have been analysed by pollution experts, including Dr Paul
Jones (formerly at Environmental Science and Research in Wellington,
currently at the Aquatic Toxicology Laboratory, Michigan State University,
USA). Several human-made compounds have been found in Hectors
dolphin tissues, including DDTs, PCBs, dioxins and other toxins.
Levels are not as high as in marine mammals from more densely populated
areas (e.g. Europe, Japan). However, pollutant levels are noticeably
higher in coastal marine mammals, especially Hectors dolphins,
than in offshore species like minke and blue whales. These pollutant
levels make Hectors dolphins arguably the most contaminated
animal in New Zealand. For a species struggling to hold its own,
this is the last thing it needs.
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