Dr Simon Childerhouse (BPM) and Dr Joshua Smith (Murdoch University)
Dr Jessica Redfern (NOAA)
Mr Thomas Moore (NOAA)
Dr David Peel (CSIRO)
Dr Natalie Kelly (CSIRO)
There have been recent improvements in our understanding of the distribution of humpback whales on their breeding ground in the Great Barrier Reef World Heritage Area through the use of spatial habitat models and aerial surveys. It has been possible to identify the main wintering aggregation areas for the peak time of the breeding season. High density areas of humpback whales on their breeding ground occur offshore of areas undergoing significant and unprecedented coastal development, including port expansions for coal and liquefied natural gas export. There is predicted to be significantly increased levels of shipping traffic associated with the export of natural resources as well as increasing levels of recreational vessel registrations in areas adjacent to the GBRMP, potentially increasing the risk of whale fatalities from vessel strikes. The East coast humpback whale population is currently recovering at almost 11% per annum, and therefore human interactions, including ship strikes, with breeding humpback whales in the GBRWHA are likely to increase.
Collisions with ships is one of the main causes of anthropogenic mortality to baleen whales worldwide. Conservative estimates of the projected increase in vessels transiting the Great Barrier Reef (GBR) have it at least doubling by 2020. Humpbacks are one of the most frequently reported victim of vessel strikes worldwide, however there has been little focus on the impacts of vessel strikes on whales in Australian waters. This project will use existing and new data to quantitatively assess the risk of ship strike to humpback whales in the GBR.
1) develop and implement a modeling framework to conduct a quantitative assessment of the risk of ship strikes to humpback whales in the GBRWHA using current
distribution data from the peak times of the breeding season and
2) to determine the coastal distribution of humpback whales around major coastal and port areas in the GBRWHA to assess temporal changes in whale distribution
and assess the risk of ship strike in inshore areas.
While the focus of this project is on assessing the risk of ship strike for humpback whales in the GBR, the major outcome is a flexible modelling framework that can be used to quantitatively assess the risk of ship strike across a range of species and areas, including tools to estimate risk projected into the future to account for increasing vessel traffic and population recovery.
This project will be undertaken in four mutually related phases of work. Fundamentally, the work builds on and extends two pieces of existing published research on the quantitative assessment of ship strike risk to baleen whales (Redfern et al. 2013 in Conservation Biology) and on the quantitative assessment of humpback whale habitat in the GBR (Smith et al. 2012 in Marine Ecology Progress Series).
A modelling framework based on methodologies used in Redfern et al. (2013) will be developed. In essence, the framework will include the development of a whale-habitat model and assumed ship-strike risk for shipping routes that are proportional to the number of whales predicted by the models to occur within each route and the density of shipping traffic.
There will then be an extension to the application of the modelling framework to include:
(i) the estimation of parameter uncertainty into estimates of risk and (ii) explore options with respect to ship speed.
It is unknown whether there are higher densities of whales closer to the coast offshore of Gladstone and Mackay later in the breeding season when the whales are migrating back to their feeding grounds. Consequently, new distribution data will be obtained through aerial surveys of these two regions which are both proposed to undergo significant expansion to accommodate increasing exports of coal and LNG.
Following on from the aerial surveys, this data will be integrated into the revised modelling framework developed. The resulting outputs will allow for informed decisions to be made about existing and future port developments and potential mitigation strategies (e.g. alternative shipping routes, temporal controls on routes and/or speeds).