Large-scale
developments, such as offshore wind turbine farms, oil platforms, and bridges often
occur in areas that overlap ecologically important habitats for sensitive
marine life.
Marine mammals make up an important component of a region’s ecological system,
and the acoustic overlap between coastal construction activities and the
habitat of such animals is an international concern. A mounting body of
evidence shows habitat use changes as a key concern among stakeholders, with
much data showing these changes (such as habitat exclusions from important
foraging grounds) during or after construction. Understanding where important
foraging habitats may be before or during the environmental impact assessment
phase of future developments is thus fundamental for the conservation of marine
mammals.
The study in this paper focuses on Indo-Pacific humpback dolphins in the Pearl
River Estuary (PRE) in China, utilizing passive acoustic monitoring to
eavesdrop on chorusing fish, a key prey item of the dolphins. Five listening
stations consisting of autonomous acoustic recorders were set up within the
estuary, continuously recording the underwater soundscape. Doing so revealed
several different fish chorus-types that show associations of co-existing fish species
(assemblages) are not consistent around the estuary. This new data provides the
first baseline record for noisy fish, as a main prey item for the dolphins, in
the PRE. It thus forms a basis for identifying potentially important foraging
habitats which, after being overlaid with acoustic detections of foraging
dolphins, should be afforded the highest priority for protection.
