Marine Matters – by Phil Coulthard – Operations Manager & Marine Biologist, Dolphin Discovery Centre
As featured in the South Western Times
Take a look at this incredible photo snapped on board a SW whale watching charter boat in Geographe Bay last weekend. This unforgettable image of a female Humpback Whale breaching out of the water alongside her new-born calf must rate as one of the best I have ever seen. Rarely if ever do you see both a mother and calf breach at the same time so to be in the right place at the right time to take the photo was a job very well done by the photographer Fiona Harvey. Why both the mum and calf would synchronise their breaching behaviour is difficult to explain however the act of breaching is a well-known method of communication between whales and can also assist in cleaning the body of parasites and dead skin. I would expect that mum was in the process of educating her new baby and may have been just as surprised as we were to see the youngster leap out of the water alongside.
For those who are unfamiliar with the migration patterns of Humpback Whales, they have now spent the entire winter and spring period travelling the Australian coastline in search of the perfect breeding and birthing grounds. Although we are still a few years away from fully understanding where these locations might be, a preference for the warm tropical waters of Ningaloo right through to the Kimberly’s appears to be their preferred destinations. The females in particular spend a lot of time in these tropical regions ensuring their calves are born in a warm and protected environment where they have the best chance of survival.
The males often travel in groups, searching for females that are not pregnant and ready to mate. They can be very acrobatic and aggressive when in the presence of a female and will constantly sing the same song over and over again in hope the she will find their voice irresistible. Known as whale songs, scientists have found that these songs are well organised units of sound sung by all the males within the region. They can last up to 20 minutes, can be heard from a distance of 200 kilometres or more, and will be repeated regularly throughout the breeding season in anticipation for a female response.
Both the males and females are now in desperate need of food and will soon return to the cold waters of the Antarctic where microscopic crustaceans called Krill will be available to eat. Unfortunately an increasing number of whales will not be strong enough to make it back due to sickness, injury or old age, leaving them stranded in our south west waters and easy prey for large sharks such as the Great White. A dramatic increase in the population of Humpback Whales following their protection from commercial whaling in the 1970’s has seen a significant spike in the number of whale carcasses found floating or stranded along our south west coast and may be the reason why the number of large shark sightings and ultimately, the increase in shark attacks on humans have occurred.
As the population of whales continues to age we should also expect the number of dead and dying animals to also increase leaving us with no choice but to avoid entering the water in areas of high risk at this time of year. Managing our own actions rather than introducing costly and inappropriate management strategies such as shark culling or deterrent devices will not only ensure we remain safe from harm, but ultimately promote a healthier marine environment. More photos of these Whales can be found on our Facebook Site.