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An experimental program was run by the Centre for Marine Science and Technology of Curtin University between March 1996 and October 1999 to study the environmental implications of offshore seismic survey noise. This work was initiated and sponsored by the Australian Petroleum Production and Exploration Association. The program:characterised air gun signal measurements; modelled air gun array sources and horizontal air gun signal propagation;developed an 'exposure model' to predict the scale of potential biological effects for a given seismic survey over its duration;made observations of humpback whales traversing a 3D seismic survey;carried out experiments of approaching humpback whales with a single operating air gun;carried out trials with an air gun approaching a cage containing sea turtles, fishes or squid; andmodelled the response of fish hearing systems to airgun signals.The generalised response of migrating humpback whales to a 3D seismic vessel was to take some avoidance manoeuvre at >4 km then to allow the seismic vessel to pass no closer than 3 km. Humpback pods containing cows which were involved in resting behaviour in key habitat types, as opposed to migrating animals, were more sensitive and showed an avoidance response estimated at 7−12 km from a large seismic source. Male humpbacks were attracted to a single operating air gun due to what was believed the similarity of an air gun signal and a whale breaching event (leaping clear of the water and slamming back in). Based on the response of captive animals to an approaching single air gun and scaling these results, indicated sea turtles displayed a general 'alarm' response at an estimated 2 km range from an operating seismic vessel and behaviour indicative of avoidance estimated at 1 km. Similar trials with captive fishes showed a generic fish 'alarm' response of swimming faster, swimming to the bottom, tightening school structure, or all three, at an estimated 2−5 km from a seismic source. Modelling the fish ear predicted that at ranges

Certain populations of killer whales Orcinus orca feed primarily or exclusively on marine mammals. However, whether or not baleen whales represent an important prey source for killer whales is debatable. A hypothesis by Springer et al. (2003) suggested that overexploitation of large whales by industrial whaling forced killer whales to prey-switch from baleen whales to pinnipeds and sea otters, resulting in population declines for these smaller marine mammals in the North Pacific and southern Bering Sea. This prey-switching hypothesis is in part contingent upon the idea that killer whales commonly attack mysticetes while they are in these high-latitude areas. In this study, we used photographic and sighting data from long-term studies of baleen whales in 24 regions worldwide to determine the proportion of whales that bear scars (rake marks) from killer whale attacks, and to examine the timing of scar acquisition. The results of this study show that there is considerable geographic variation in the proportion of whales with rake marks, ranging from 0% to > 40% in different regions. In every region, the great majority of the scars seen were present on the whales' bodies when the animals were first sighted. Less than 7% (9 of 132) of scarred humpback whales with multi-year sighting histories acquired new scars after the first sighting. This suggests that most killer whale attacks on baleen whales target young animals, probably calves on their first migration from low-latitude breeding and calving areas to high-latitude feeding grounds. Overall, our results imply that adult baleen whales are not an important prey source for killer whales in high latitudes, and therefore that one of the primary assumptions underlying the Springer et al. (2003) prey-switching hypothesis (and its purported link to industrial whaling) is invalid.

Despite being identified as a driver of mobile predator aggregations (hotspots) in both marine and terrestrial environments, topographic complexity has long remained a challenging concept for scientists to visualise and a difficult parameter to estimate. It is only with the advent of high-speed computers and the recent popularisation of geographical information systems (GIS) that terrain attributes have begun to be quantitatively measured in three-dimensional space and related to wildlife dynamics, making the well-established field of geomorphometry (or 'digital terrain modelling') a discipline of growing appeal to biologists. Although a diverse array of numerical metrics is now available to describe the shape, geometry and physical properties of natural habitats, few of these are known to, or adequately used by, ecologists. In this review, we examine the nature and usage of 56 geomorphometrics extracted from the ecological modelling literature over a period of 32 years (1979-2011). We show that, in studies of mobile predators, numerous topographic variables have largely been overlooked in favour of single basic metrics that do not, on their own, fully capture the complexity of continuous landscapes. Based on a simulation approach, we assess the redundancy and correlation structure of these metrics and demonstrate that a majority are highly collinear. We highlight a suite of 7-8 complementary metrics which best explain topographic patterns across a bathymetric grid of the west Australian seafloor, and contend that field and analytical protocols should prioritise variables of these types, particularly when the responses of predator populations to physical habitat features are of interest. We suggest that prominent structures such as canyons, seamounts or mountain chains can serve as useful proxies for predator hotspots, especially in remote locations where access to high-resolution biological data is often limited.

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Changes in the relative abundance of marine megafauna (whales, dolphins, sharks, turtles, manta rays, dugongs) from aerial survey sightings in the waters adjacent to Ningaloo Reef between June 2000 and April 2002 are described. Generalised linear models were used to explore relationships between different trophic guilds of animals (based on animal sighting biomass estimates) and biophysical features of the oceanscape that were likely to indicate foraging habitats (regions of primary/secondary production) including sea surface temperature (SST), SST gradient, chlorophyll-a (Chl-a), bathymetry (BTH) and bathymetry gradient (BTHg). Relative biomass of krill feeders (i.e. minke whales, whale sharks, manta rays) were related to SST, Chl-a and bathymetry (model [AICc] weight = 0.45) and the model combining these variables explained a relatively large amount (32.3%) of the variation in relative biomass. Relative biomass of fish/cephalopod feeders (dolphins, sharks) were weakly correlated with changes in SST, whereas that of other invertebrate/macroalgal feeders (turtles, dugong) was weakly correlated with changes in steepness of the shelf (bathymetry gradient). Our results indicate that biophysical variables describe only a small proportion of the variance in the relative abundance and biomass of marine megafauna at Ningaloo reef.

The worldwide distribution of blue whales (Balaenoptera musculus) has not prevented this species from becoming endangered due to twentieth century whaling. In Australia there are two known feeding aggregations of blue whales, which most likely are the pygmy subspecies (B. m. brevicauda). It is unknown whether individuals from these feeding aggregations belong to one breeding stock, or multiple breeding stocks that either share or occupy separate feeding grounds. This was investigated using ten microsatellite loci and mitochondrial DNA control region sequences (N = 110). Both sets of markers revealed no significant genetic structure, suggesting that these whales are likely to belong to the same breeding stock.

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