Often we see a dramatic story on T.V., showing us a large pod of stranded whales and people's desperate efforts to save and guide these animals back to deeper waters, not always successfully.
These are generally toothed whales, relying largely on their echolocation, a system similar to a depth sounder on a boat. The animals send out a signal and if it does not return, there is nothing in front, but if the signal returns, the computer-like brain tells the animal how far the object is away and by sending more signals, the size, its movement etc. can be established.
But picture a large pod of whales, led by an elderly, perhaps sick leader, unable to properly interpret its own echolocation signals and swimming towards shallow waters where the signal cannot return, because it can't bounce off an object. Perhaps the other whales will follow the leader to death, something we occasionally see in the human world. The recent death of a number of pilot whales in New Zealand suggests, that these animals were driven ashore by a pod of Orcas or killer whales. Why? Again we don't know. Other explanations suggest that, when a pod is suffering from parasites or an illness, they commit mass suicide and in doing so, return to where the came from: the beach. Could it be that they prefer to die on the beach to drowning in deeper water? To be attacked by sharks and killer whales? The full reasons behind these mass stranding's are not conclusive and will remain a mystery at least for the time being.
Again Hervey Bay is lucky, in as much that Humpback whales are baleen whales and because they do not have such a developed echolocation system, there is no record of mass stranding. Then how do they navigate? We are not certain, but it appears they combine a large number of sensors available to them e.g. water temperature, memory, the earth magnetic fields, the currents, the tides, the depth and perhaps many more.
Humpback whales are totally at ease in very shallow water, as has been seen in the Bay on many occasions. In 1992 a pod of whales was swimming in an area South of Moon Point along the sandbars, but a few minutes past eleven they suddenly moved out to deeper waters. A quick look at the tide guide told us the reason: the turn of the tide was at that precise moment.
Often whales are seen swimming along the beach of the West coast of Fraser Island, sometimes for miles at less than 100 metres of the beach. They also seem to enjoy cruising along the edges of the Outer Banks, so clearly visible by the two-toning of the water. During the season it is not unusual to find Humpback whales as close as Woody Island or near Pelican Bank, but generally only at high tide.
Some years ago a Humpback crossed a sand bar near Coongull Creek, on it's belly with both pectoral fins working overtime, well above the water, but on an incoming tide. There is no evidence that Humpback whales ever tried to navigate through the Great Sandy Straits.
