Download Marine Mammals and Anthropogenic Sound - WUWNet

Extended Abstract: Marine Mammals and
Anthropogenic Sound
John A. Hildebrand
Scripps Institution of Oceanography University of California, San Diego
9500 Gilman Drive, La Jolla, California 92093-0205
[email protected]
1.
INTRODUCTION
There is growing concern that sound introduced into the sea by
human activities has detrimental effects on marine mammals. Evidence suggests that high-intensity anthropogenic sound from sonar
leads to strandings of beaked whales, although the mechanisms of
injury in these events remains unresolved. A more pervasive problem is the effect of increased noise levels from increased commercial shipping. Acoustic communication networks are an emerging
source of underwater noise at mid-and high-frequencies.
Sound is an extremely efficient way to propagate energy through
the ocean, and marine mammals have evolved to exploit its potential. Marine mammals use sound as a primary means for underwater communication and sensing. Toothed whales have developed
sophisticated echolocation systems to sense and track the presence
of prey and engage in complex exchanges of vocalizations with
members of their own species. Baleen whales have developed longrange acoustic communication systems to facilitate mating and social interaction. Some baleen whales produce intricately patterned
songs that continue for hours or days. Marine mammals may use
sound from natural sources as a guide for navigation, prey detection, and avoidance of predation. The sound environment of the
ocean is an important aspect of marine mammal habitat and we
can expect marine mammals to choose their locations and modify
their behavior based, in part, on the presence of natural and anthropogenic sounds.
High levels of anthropogenic noise may interfere with marine
mammals’ ability to detect sounds, such as calls of members of
their own species, echoes from prey, or natural sounds that aid in
navigation or foraging. Noise may affect reproductive or immune
functions and cause more generalized stress. If marine mammals
tend to avoid the vicinity of an anthropogenic sound source, they
may be kept away from an ecologically important area.
Evidence suggests that given the opportunity, marine mammals
avoid high-intensity sound. Acoustic pingers have been demonstrated to be an effective way to keep marine mammals from becoming entangled in fishing gear. It has likewise been shown that
acoustic harassment devices can exclude marine mammals from areas of their usage.
A major impediment to assessment of the biological effects of
noise is the lack of knowledge about marine mammal behavioral
responses to sound. Behavioral data from the wild are needed to
Permission to make digital or hard copies of all or part of this work for
personal or classroom use is granted without fee provided that copies are
not made or distributed for profit or commercial advantage and that copies
bear this notice and the full citation on the first page. To copy otherwise, to
republish, to post on servers or to redistribute to lists, requires prior specific
permission and/or a fee.
WUWNet’12, Nov. 5 - 6, 2012 Los Angeles, California, USA.
Copyright 2012 ACM 978-1-4503-1773-3/12/11 ... $15.00.
examine those responses so that effects can be assessed. Significant effects may prove to be confined to a few individuals exposed at high sound pressure levels, or they may be occurring at
a population level as a result of widespread exposure. Discerning
population-level effects is challenging since the observations must
be conducted over great distances and long time periods.