Auckland, New Zealand, is where Ocean Acoustics Ltd was founded and is currently based. Studying the propagation loss of signals in shallow waters through modelling and empirical measurements during the pre- and post-consenting phase of coastal developments has become a key part of our daily work life in New Zealand. Using passive acoustics to monitor the presence of marine mammals around busy harbours and coastal developments, as well as seismic surveys, is also a key part of our New Zealand-based work.
Engaged by clients around the country has lead to the development of state-of-the-art monitoring techniques and efficient data handling and software developments that have been tailored for each individual project (and client).
Continued research and development of signal processing software PAMScan for New Zealand
The arrival of affordable state-of-the-art underwater autonomous recorders to market has exploded in recent years. Underwater acoustics is now being used as a tool in a variety of marine fields. That means recording data from multiple sites simultaneously for extended periods of time is now possible, and being done all over the world. It also means big data – really big data. For example, one of our monitoring projects pulls in well over 22 TB a year.
To get around this, we have developed a suite of software modules in-house that together form the PAMScan software package that allows the processing of large acoustic datasets for a variety of purposes. Since every project is unique in its objectives and deliverables, we have been able to further develop and improve PAMScan’s capabilities. Custom-designed detectors for vessels, marine mammals and fish, ambient soundscape analyses, noise measurements, eco-indices computations, noise budget calculations, sound source localisation and audio editing can all be undertaken in PAMScan.
Passive acoustic monitoring of whales and dolphins in the Cook Strait
Engaged by Cawthron Institute, OAL is working with Dr Deanna Clement and Dr Simon Childerhouse who deployed four SoundTrap recorders near east Cook Strait. The recorders were programmed to record continuously to monitor the presence of whales and dolphins by detection of their calls, whistles and echolocation clicks. Thousands of hours in total from all recorders have been collected and are being processed in PAMScan, exposing the presence of several whale species and dolphins over all hours of the day and night.
Sound source verification of airgun pulse signals off Taranaki
OAL was engaged by Blue Planet Marine to perform the acoustic data analyses of 2-months of monitoring using four SoundTrap recorders. The aim of the project was to compare modelled airgun noise data with the empirical data, in addition to the official streamer-based verification data. Two custom-designed moorings were developed for this work, deployed within a commercial seismic survey area and the West Coast Marine Mammal Sanctuary off Taranaki. Data were processed in PAMScan, using the impulse signal detector, and ambient soundscape modules. The AIS data from the seismic survey vessel was also incorporated, generating a slant range for each measured airgun pulse detected, ranging from 120m to 70km.
Auditory masking from vessel noise for sensitive marine life in the Hauraki Gulf
The greatest impacts from anthropogenic underwater sound pollution are likely to occur in coastal areas with highly productive waters that are close to major port cities. Auckland City in New Zealand is such an example, as it is a port city at the base of the Hauraki Gulf, a large embayment (1.2 M Ha) that is characterised by highly productive coastal waters.
The biodiversity of the Hauraki Gulf Marine Park in northern New Zealand is regarded as outstanding and consequently has been protected through its own legislation, the Hauraki Gulf Marine Park Act 2000.
This research project was done in close collaboration with Assoc. Professors Craig Radford and Andrew Jeffs of the University of Auckland. Together, we investigated the detectability of vessel noise in marine mammals, fish and crustaceans The project looked particularly at recreational vessels that do not have automatic identification systems (AIS) and so not as easy to understand their movements within the Hauraki Gulf Marine Park as commercial shipping.
The findings show that the sound emanating from both recreational and commercial vessels within the Hauraki Gulf will be significantly raising background sound levels and is likely to have a wide ranging masking impact on marine life.