Whales Hervey Bay

A Growing Population

There is believed to be approximately 2,000 humpback whales now on the migration path past Hervey Bay and it is encouraging to see this number edge up every year.

The whales commence entering the Hervey Bay Marine Park in late July or early August and continue until early November. The humpbacks entering the Marine Park seem to be taking time out from their migration back to Antarctica and they appear to be relaxed and playful in the calm sheltered waters of Hervey Bay. This makes Hervey Bay one of the best places in the world to see the humpback whales.

There are 19 vessels permitted to operate commercial whale watch tours. They operate under strict guidelines from the Department of Environment to ensure the least amount of impact on the whales and the sustainability of the industry.

The Migration

Humpback whales find an abundance of their main food supply near the Arctic circle and Antarctica, but every year they start their annual migration from their food supply to warmer waters. Why such a long migration? The answer is quite simple.

The females must give birth to their calves in warm waters, because the calves are born without the layer of blubber, and could not survive in the icy waters of polar region. There are some eighteen separate migration routes for humpback whales around the world, and here in Hervey

Bay we are lucky to be near one of them, from Antarctica to the Great Barrier Reef, a return trip of some 10,000 kilometres!

Why do the whales come into Hervey Bay? This had the scientists puzzled for some time, but the answer seems fairly simple: R & R or rest and recreation.

The females bring their four to six weeks old calves into the Bay; where they have no fear of killer whale or pack-shark attack; where mums can recover after the stresses of calving; and feed their young the enormous amount of milk they require to gain weight and the layer of blubber, vital to their survival in the icy waters of Antarctica.

The following year the female and the now developed yearling again call into the Bay, before going South, where junior has to learn how and what to eat and to survive without the constant attention of mum.

It appears that adults continue their stopover in the Bay, which now emerges as a regular cycle:

August – mainly adults

September – adults, juveniles, mothers and calves

October – mainly mothers and calves, sometimes in company of an “escort”, another adult.

They stay only for an average 2 to 5 days, some longer and some whales do not come in at all.

However, during the 1993 whale watch season a number of tour operators reported that they identified whales that were sighted very early in August and again sighted much later

It only takes two or three days for whales to travel from Hervey Bay to the East coast of Moreton Island.

It is encouraging to know that there has been an annual increase in the number of humpback whales of 13.5% since 1990, but the humpbacks are still the third most endangered species of all the big whales.

Their name came from hunchback, describing the way they bend their body before they dive. The humpback is not just your any whale. It has the largest pectoral fins and is the most acrobatic. It is very playful, very inquisitive, and therefore often enjoys the company of vessels (and their passengers).

They sing a love song, which is the most complex of perhaps all animals. It appears that all humpbacks within a certain group sing the same song at a certain time. They all make the same changes to that song during the mating season and remember the song last sung in September when they start singing again the following mating season in June.

Again we are lucky in Hervey Bay, as often humpback whales are heard singing. We are not certain whether these are actual love songs or merely “chit-chat” between mother and calf or other communication between the animals, but when the song is heard by one of the whale watch vessels through a hydrophone, they will amplify it to enable it to be heard by the passengers.

It is a haunting kind of sound, that changes from a deep moan to a high pitch screech and once heard it is never forgotten. If the singer is close to a vessel there is no need for a hydrophone or amplification, the sound will travel through the hull. No wonder that the early sailors aboard their wooden square-riggers told the stories of ghosts, trying to communicate in some mysterious way.

A recording of the song of the humpback whale is aboard the space-probes Voyager I and II, travelling into outer space – perhaps beings out there can understand the complicated, yet precise sequence of sounds.

Feeding

The ability of the female to feed junior without feeding herself is hard to comprehend. The mother is capable of producing up to 600 litres (or three 44 gallon drums) a day and the calf’s daily growth-rate is between 45 and 60 kg!

The milk is squirted directly into the calf’s mouth and often whale watchers can see from the calf’s behaviour pattern that it is being fed. Mum and calf will dive down and, whilst the female stays there for half an hour, junior returns to the surface after 4 to 5 minutes (feeding) for a breath of air, swims in a circle for 2 to 3 minutes, and dives again for another feed.

Another interesting method of feeding has occasionally been observed by lucky whale watchers, where mum will position herself vertically, with her tail out of the water, just like a beacon, for as long as twenty minutes to feed her calf.

The female continues to feed the calf for up to twelve months. This is roughly the duration of their migration until they return to the warmer waters the following year.

Breeding

Humpback whales mature in less than 10 years. Mating and birthing is believed to take place near the southern area of The Great Barrier Reef. This results in many calves entering the Bay in late September and October – there are reports of calves only a day or so old being sighted in the Hervey Bay Marine Park.

Gestation takes almost a year and the calf, when born, will be nursed by its mother for up to 11 months by which time it will have increased its weight to around 6 tonnes and grown to approximately 8 metres in length.

The female generally has a calf every 1-3 years.

Viewing guidelines

While the whales are free to approach the vessels in the Marine Park, boats wishing to view the humpback whales in Hervey Bay are obliged by law to adhere to the following guidelines set down by the Department of Environment.

not to approach within 100 metres of a whale,

not to approach within 300 metres of a whale if 3 or more vessel are within 300 metres of that whale.

not to approach a whale head on.

not to heard, chase, or otherwise prevent the free movement of whales.

not to separate a group of whales, or to come between a mother and calf.

not to attempt to feed whales, or to throw rubbish into the vicinity of whales

If within 300 metres of a whale a boat skipper shall:

manoeuvre constantly at less than 4 knots.

avoid sudden changes in direction.

allow motors to idle before stopping, and raise outboards (if applicable).

idle motors before moving off slowly until 300 metres away.

abandon contact with a whale of there is any sign of the whale becoming disturbed or alarmed.

Aircraft must stay 300 metres above the whales and helicopters must not be used for whale watching

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