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| From: "Simon Mustoe" <simonmustoe@...> Date: Wed Mar 27, 2002 11:16 pm Subject: Blue Whale Watching in Australia | |
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Just got back from a weekend spent looking for cetaceans along the Great Ocean Road between Port Fairy and Portland on the Great Ocean Road in southern Victoria, Australia. The trip was a great success with Blue Whales seen on both days, including a boat trip on the Sunday. Despite having favourable conditions on Saturday we did not get out to sea. The reasons are still somewhat unclear! Instead, we headed out for sunrise to Cape Bridgewater and the aptly named 'blowhole' - which is actually a rock / wave phenomenon...you know the sort. The Cape is the furthest west of two that form a peninsula on which Portland is also situated. It was a cool morning with a refreshing light north easterly wind. We trudged slightly eastwards to a cliff edge where we would get a good panoramic view of the horizon. Within about 20 minutes we had found our first enormous whale blow about 4 miles out to sea. The Blues feed on krill which is super-abundant along an area of upwelling which is most prevalent between Cape Otway and the border with South Australia. The so-called 'Bonney upwelling' is caused by winds that blow along the shore from west to east during the late summer months. Instead of blowing surface water eastwards however, it actually causes surface water to be transported out to sea - this phenomenon is known as Ekman transport. Deep water is frictionally coupled to the seabed and is caused to spin with the earth's rotation. The nearer you get to the surface of the sea, the less friction there is as surface layers slide over each other. Essentially you get a spiralling effect with the greatest movement at the bottom and the least movement at the surface. The net result is that the surface tends to move away from the coast when wind conditions are along the shore in the Otway basin. As the surface water moves away, deeper Antarctic water from beyond the continental shelf circulates up to fill the space and collides with the warm coastal water. This upwelling is several degrees cooler and the nutrients it carries are concentrated along the boundary between the water masses. There are two principle examples of where Ekman transport fuels upwelling and krill blooms occur: here in the Otway basin and off Monterey Bay in California. Both areas support reliable seasonal aggregations of feeding Blue Whales and are internationally significant for the species. At Cape Bridgewater the whales seemed to be feeding along the edge of two water masses as we could see an area of calmer glassy water between the whales and us. After about an hour we had managed to confirm the presence of three Blue Whales. A brief trip to Cape Nelson yielded another baleen whale blow near the horizon. This animal was also likely to be a Blue. The rest of the day was spent doing a bit of birding before an early meal, a few beers and bed. On Sunday morning we left Port Fairy at 6am as we wanted to get out into deep water as early as possible. On the way out we were treated to encounters with several Yellow-nosed Albatrosses, Black-browed Albatrosses and a Wandering Albatross. There were also a number of Prions as well as a Grey-backed Storm Petrel and many White-faced Storm Petrels. With only a few hours of observation time left we decided to take a course that would loop back around towards Portland towards a region of upwelling where Blue Whales and a number of dolphins had been seen the day before. The following two hours was disappointing with no dolphins and extremely low numbers of seabirds. At about 12:30 we stopped the boat and scanned the horizon for whale blows. We soon sighted a surface disturbance at about 2 miles followed by a single blow. We headed slowly towards the area and were delighted to find a second whale that was slightly 'smaller' - probably only about 20 metres long! Both whales were Blue Whales. They were feeding and on several occasions the larger of the two would break the surface with a pectoral fin in the air as it rolled on its side and gulped a mouthful of krill. The two animals were significantly different sizes and although at one point they were swimming side by side it is only possible to speculate on whether they were a mother and calf. The Otway Basin hasn't been identified as a place that Blue Whales breed and in fact we do not know where they breed at all. Identification of them as Blues was simple enough. The Blues break the surface with a massive blow about 10 metres high. The rostrum (the flat area in front of the splash guards) is flat and rarely breaks the surface. The splash guards are of volcanic dimensions and protrude ridiculously high out of the water as though they would be an encumbrance for travelling through water (see http://www.orcaweb.org/gallery.html for some pictures). Occasionally the smaller of the two animals would log at the surface and the dorsal fin would be above the surface. The larger animal often did not show the dorsal which is not unusual for Blue Whales which are so long that they are below the surface by the time the dorsal fin passes. The region behind the head is extraordinarily wide and the spine appears like a massive muscular column down a broad rotund back. The next nearest whale in size would be Fin Whale which have been recorded in the Otway Basin occasionally. Fin Whales are generally about 20 metres long but are far slimmer than Blues appearing more bullet shaped at the front and are less obviously massive in proportions. From the side the Blue Whale breaks high above the surface when it rolls forward to dive and is usually coloured pale grey-blue with dapples of lighter grey, the patterning of which is unique for individual animals and will shortly be the subject of a photo-identification study at Deakin University. Although Blue Whales are often photographed fluking (throwing their tails in the air), this does not happen often and wasn't observed once on Sunday. This behaviour probably depends on how deep the whales are diving to feed. Margi Morrice - who works on Blue Whales at Deakin University and to to whom we are indebted for her expert advice on the trip - netted some krill (Nyctiphanes australis) for us to have a look at; each tiny animal being about a centimetre in length. The krill species Nyctiphanes australis comprises the majority of what the Blues feed on here. We continued to sit, watch and marvel for about two hours during which time the whales continued to feed before we decided to head home. If any of my photos come out reasonably I will put them on the ORCA website for everyone to have a look at (www.orcaweb.org) but this won't be for perhaps a week or so. For information, the weather and sea conditions are generally unfavourable in this area and we were very lucky to get a weekend like we did. So it is not likely to take off as a place to go whale watching. However, if you do find yourself on the Great Ocean Road in March / April (or even as early as February and as late as May) you stand a good chance of seeing Blues from the Capes just west of Portland. If you are not fortunate enough to be there in the austral summer then go to nearby Warnambool instead where in about July to September the Right Whales are usually around - just follow the signs from the main road. Regards, Simon. |
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Simon Mustoe - Director
AES Applied Ecology Solutions Pty Ltd.
59 Joan Avenue
Ferntree Gully
Melbourne
Victoria 3156
AUSTRALIA
59 Joan Avenue
Ferntree Gully
Melbourne
Victoria 3156
AUSTRALIA
Telephone 03 9762 2616
International Telephone +61 (0) 3 9762 2616
Mobile 0405 220830
Website www.ecology-solutions.com.au
International Telephone +61 (0) 3 9762 2616
Mobile 0405 220830
Website www.ecology-solutions.com.au
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