Up Close and Personal with… Humpback Whales

These majestic and often inquisitive giants roam most of our ocean planet, swooping down into the darkened depths before racing to the surface, leaping, arching and crashing back down into the blue. Many of us love and admire these creatures but do we really know about their daily lives?

There are 12 distinct populations of humpback whale in our oceans which carry out extraordinary migrations each year, with some of their routes reaching up to 5,000 miles. The whales migrating from Hawaii to Alaska have been found to cover their incredible 3,000 mile journey in only 36 days! Humpbacks use our cold polar regions as feeding grounds, an essential site as they often only eat for four months of the year, fasting for the remaining months as they travel to the tropics to mate and raise young. In order to fill up on enough food to sustain their incredible voyage, they must consume 4% of their body weight each day by filter feeding through small bristle-like structures on tiny krill and small fish. In the Antarctic, they have been observed to lounge about lazily through the day before taking a deep dive in the late afternoon to keep an eye on how their tea is looking for the evening. At night, they take advantage of krill rising to the sea surface and feed on these huge clusters of tiny shrimp-like creatures.

Once full and restless in their icy environment, the whales begin their annual trip to tropical waters with juveniles and their mothers leaving first, followed by adult males and single females before finally the pregnant females follow after topping up on extra krill to ensure they have enough energy to produce milk. Humpbacks then congregate in warm waters in locations such as Australia, Mexico, Brazil and Madagascar where they fast, mate and teach their young how to feed and swim in the same magnificent manoeuvres seen by the adults. Somehow the calves also find time to drink up to 600 litres of milk a day!

One of the most well known threats to whales is whaling which, in previous centuries, hunted whales to 1% of their original population but the hunting of humpbacks was banned in the 1960s although illegal activities arguably continued for a decade and in some regions still prevail. However, today there are a range of different issues which our beautiful creatures need protecting against.

Whilst noise may sound like an unusual danger, it actually forms a large problem for whales which rely on clicks and whistles to communicate with their pods over large distances. Songs are also extremely important for mating where the male will blow air through the airhole to create a mystical and haunting melody to attract females, with each song lasting roughly ten minutes. However, we increasingly use the ocean for our own activities, from shipping to military torpedo testing to seismic surveys which are used to locate oil and gas in addition to the actual drilling of the seafloor for fossil fuels. Whales use sonar to find food, navigate around complex coastlines and to guide their migration but increasing use of sonar and general noise from our ships leaves them both stressed and confused as they fail to find their pod and prey. Once exposed to noise, whales are found to move erratically and this can often lead to stranding where their organs collapse under their own extreme weight. Lynne Cox, a record-breaking swimmer and now author, had a beautiful encounter with a baby grey whale after it became separated from its mother, possibly due to the noise of a local oil rig. Lynne then spent several hours swimming side by side with the whale in the hope mother and calf would be reunited before the inexperienced youngster became stranded. However, many lost whales are not so lucky yet conservationists are hoping to improve this issue by working with boat owners to use quieter engines while also pushing for the creation of ‘quiet sanctuaries’ around feeding grounds and important migration routes.

Unsurprisingly but disappointingly, humpbacks, or indeed whales in general, are another of the hundreds of species impacted by ocean plastic. Humpback whales are hit particularly hard due to their filter feeding technique. These gentle giants of the ocean are demising due to the tiny but destructive microplastics which are often accidentally filtered through their baleen bristles along with krill and plankton. This leaves their stomachs filled with unnourishing human waste which cannot sustain their immense migratory journey. Plastics abandoned to float in the ocean often attract toxic chemicals such as PCBs. PCBs are chemicals that were commonly used in building materials despite their hazardous nature and were not banned until 2004. However, despite no longer being in production, the improper disposal of old material leaves this toxin leaching into the sea where it can persist for decades. Once plastic coated in these chemicals has been ingested by low feeders such as small fish, they travel up the food chain with higher concentrations accumulating in each animal, leaving top predators such as whales with a dangerous chemical cocktail inside them. This is particularly dangerous in whales and dolphins as when natural food sources run low, they break down their blubber to act as an extra food source. Little do their bodies know that PCBs stored in this fatty tissue are simultaneously flushed into their bodies. If this wasn’t bad enough, recent research has found that new mothers pass significant levels of their chemical burden onto their first born calf which then may become infertile right from birth.

Macro-plastics also find their way into these creatures as bags, flip flops and bottles are easily swept into their gaping mouths. The Bowhead whale can live for an absolutely astonishing 200 years yet our simple throwaway plastic we believe to last five minutes actually outlives this species. In fact, plastic bottles could outlive two Bowhead whales with an average lifespan of 450 years. This all sounds far beyond our reaches as mere individuals standing on the shore but we can all decrease our consumption of plastic by switching to the plethora of alternatives now easily available in shops. You can also join organised beach cleans or simply take a few minutes on your next stroll to collect whatever you can carry to prevent it entering our precious waters. If you want to get further involved, there are many citizen science projects which aim to help both whales and dolphins with the simplest recording their location on an app to help us understand their movements. Ordinary citizens can also take part in often one day surveying courses which teach you how to spot, identify and record sightings of species and the data collected is used in reports to understand local populations and their health. If lots of individuals get involved, we can collect a much larger dataset than scientists on their own and the results help accurately inform our conservation policies which shape the future of our blue planet.

By Neve McCracken-Heywood