How Whales Protect the Planet

7th of April 2022 is the World Health Organization’s commemoration of World Health Day. Each year World Health Day draws attention to a specific health topic of concern to people all over the world. This year’s theme is “Our planet, our health”, focusing this year on urgent actions needed to keep humans and the planet healthy. The WHO estimates that more than 13 million deaths around the world each year are due to avoidable environmental causes. This includes the climate crisis which is the single biggest health threat facing humanity. The climate crisis is also a health crisis, and whales play an important part in maintaining the health of our oceans.

Whales inhabit every ocean, and the Hauraki Gulf is no exception. Here, we have the Brydes whale, a semi-residential species. These whales can grow up to 15 meters in length and weigh up to 40 tonnes. A study conducted in Auckland suggests there is a population of 140 Bryde’s whales. For that reason, they have a nationally critical status in New Zealand.

There are two types of whales, toothed and baleen. Let’s begin with toothed whales, which are named so because of their conical teeth. They can travel at high speeds and are better equipped to catch prey. This category includes whales with teeth but also dolphins and porpoises.

Second, there are baleen whales, which is what Brydes whales are. These whales have baleen plates that are suspended from the roof of their mouths. These plates are made of keratin, which is the same material as our nails and hair. When the whale takes a big mouthful of water they use the baleen like a comb and filter out the water and trap their prey. Baleen whales are generally larger and long-lived and also include the largest whale the blue whale.

In the Hauraki Gulf, more than 22 species of whales and dolphins can be spotted. In total there are 88 species of whales and dolphins, so we support 25% of all whales and dolphins are the world!

Whales Balance the Ecosystem:

Whales are key to maintaining a healthy ocean. They keep the food chain balanced and ensure that one species, in particular, doesn’t overpopulate the ocean. For example, a blue whale can consume around 40 million krill a day! There would be big changes and impacts on the ecosystem if whales were to become extinct. When one species in the food chain is removed it allows other species to thrive.

Initially, it appears to be a good thing when another population thrives by no longer having predators to face. However eventually, these animals will overpopulate and could destroy the population of species that feeds on it affecting the whole food chain.

Whale Scat & Plankton:

Even whale scat plays an important role in the environment, by offsetting the carbon in the atmosphere.

Studies have shown that the nutrients from whale scat help promote phytoplankton growth. This is great news as phytoplankton draws in carbon from the atmosphere and converts it into clean breathing air for all of us. Each year whales extract about 400,000 tonnes of carbon from the air!

As well as being a carbon sink, phytoplankton is also the very important initial first step in the marine food chain. Whale scat stimulates the growth of phytoplankton meaning that it helps other species that consume phytoplankton, which helps the whole food chain.

I bet you didn’t think whale scat would play such a major role in the cycle of ocean life! It’s just one of the many benefits of whales.

Whales & Climate Change:

Whales are at the top of the marine food chain and are vital for the overall health of the ocean. They play a significant role in capturing carbon from the atmosphere. Each whale accumulates an estimated 33 tons of carbon in their bodies during its life. Therefore they are playing their role in the fight against climate change.

As whales migrate and travel around the oceans they move nutrients thousands of miles and defecate creating new areas of productivity and carbon absorption. The nutrients can support fish stocks and ecotourism allowing communities to thrive. In more remote places such as Antarctica where iron is limited, marine life is very reliant on whales to bring iron and nitrogen scat into the area so that new life can grow and flourish.

When whales die their giant bodies sink to the bottom of the ocean taking with them all the carbon they have stored in their bodies. Removing the carbon produced by humans helps prevent the impacts of climate change. It also provides food and habitats for other species.

Whales bring up nutrients from the ocean floor each time they dive and surface in turn helping more phytoplankton to grow and absorb more carbon dioxide from the atmosphere.

How we affect the Gulf:

Whales and dolphins face a range of impacts, which are linked to human activities. Climate change, noise pollution, boat strikes, pollution, declining fish stocks, and habitat degradation.

Commercial and recreational fishing has played a big role in threatening whales and dolphins. They can become trapped in trawl nets and unfortunately drown. Overfishing is causing whales to change their diet to predominantly zooplankton, which can contain high amounts of microplastics. Auckland Council’s state of the Gulf report shows us that since our arrival the Hauraki Gulfs’ fish stocks have declined by over 50%, sharks by 85%, and whales and dolphins by 97%.

A study led by the University of Auckland discovered that on average whales ingest about 25,000 microplastics per mouthful. These tiny plastics are less than 5mm in length and are found in every marine environment studied to date. It is hard to estimate how many animals ingest microplastics each day. Microplastics come from our clothing, plastic objects, and even the buoys and rope in the water as they wear down.

The Hauraki Gulf is one of the busiest ports in New Zealand, used by 1,500 ships per year. The Gulf is also a very popular cruising destination. On average two Bryde’s whales were killed every year as a result of boat strikes. With the population already classed as nationally critical losing whales at this rate is detrimental to the population.

Bryde’s whales spend 90% of their time in the top 12 meters of water, which is the very part of the water column that ships’ hulls reach, most large ships draught draw between 10 – 12 meters.

This problem isn’t specific to the Hauraki Gulf, boat strikes are an issue all over the world. Off the eastern seaboard of the USA and Canada boat strikes with the Northern Atlantic Right Whale were becoming an issue. A traffic separation scheme was implemented to lower casualties along with speed restrictions and vessel avoidance areas.

The research was conducted in the Hauraki Gulf to see if these changes would also be appropriate. However, it was discovered that the Brydes whales in the Hauraki Gulf are not confined to any certain area, being wild animals they go wherever they like. So using a traffic separation scheme would be unlikely to work. The most effective adaption to reduce the risk of boat strikes was to implement a speed reduction for large vessels traveling through the gulf to 10 knots or less.

The primary changes in the Gulf include speed reduction, keeping watch, and reporting. Evidence shows that if a whale is struck by a boat at 20 knots there is only a 10% chance of survival. If the boat was traveling at 10 knots the chance of survival rises to 75%.

It is also important to maintain a good lookout when traveling in the Gulf, if a ship spots a whale it must alter its course and maintain a distance of 1000m. If a whale is spotted in the gulf it must also be reported to Ports of Auckland, Harbour control then broadcast the message, with coordinates, to all vessels in the area so they can change course.

The ocean can be a surprisingly noisy place and it’s continuing to get louder. Noise from vessels using sonar or from construction all contributes to the marine soundscape, which is potentially making it harder for marine mammals to communicate with each other. It can also cause physiological changes which force species to change their behavior in an attempt to avoid noise. Marine species use sound for socializing, foraging, navigation, territorial defense, and reproductive courtship.

Marine animals have a wide range of receptors to detect sound. Studies even suggest that it is not just whales and dolphins that detect sound but also a wide range of marine life including jellyfish, crabs, and fish.

During lockdown a study on bottlenose dolphins and bigeyes fish. Both species maintain social groups using acoustic communication. They looked at the communication range before and during the lockdown. The communication range is the distance between one individual making a sound and the second individual receiving the sound. Scientists relate it to what happens at a crowded party, the more people in the room the harder is to hear the person next to you. With fewer boats on the water, the Hauraki Gulf became much quieter dropping to 8 percent of normal levels, increasing the communication range for both dolphins and bigeyes. The further from the city the communication range continued to increase. The maximum median range in which dolphins were able to hear each other in the Rangitoto Channel was calculated at 400m prior to lockdown but increased to 565m once lockdown began. Further from the city at the Ahaaha Rocks the dolphin communication range grew from 2.9km to nearly 4km and from 4m to 70m for bigeye fish.

Ways we can help whales and dolphins:

The first way we can help our whales and dolphins is by thinking twice about the fish on your dinner plate. Fishing plays a massive role in the global economy with 700 million people relying on it for their livelihood. Unfortunately, there are negative effects, bycatch results in more than 300,000 marine mammal deaths each year. If you enjoy seafood then it is important to educate yourself around which stocks are healthy and what products are really “dolphin friendly”.

Be a green kiwi and dispose of waste responsibly. Each year about 8 million tonnes of plastic end up in the ocean. Whales and dolphins can easily be entangled and subsequently drown. Dolphins can mistake floating plastic bags as food and ingest them clogging their digestive system. Other marine species like turtles and sea birds can also fall victim to rubbish. Recycle what you can and pick up rubbish you find. Remember to use keep cups, beeswax wraps, reusable containers, and take your own shopping bags to the supermarket! There are plenty of other ways to help the environment as well.

The third way to help whales and dolphins all over the world is to see them in the wild. In captivity, they go through immense mental and physical stress. They are deprived of everything that is natural and important to them. Seeing whales and dolphins in the wild is such an amazing experience you don’t want to miss out on. If you’re in Auckland why not spend your day with us!

Sources

World Health Organization (2022, April). World Health Day 2022. https://www.who.int/campaigns/world-health-day/2022
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The University of Auckland. (2021, February 11). The ocean is getting noisier – The University of Auckland. The University of Auckland. https://www.auckland.ac.nz/en/news/2021/02/11/the-ocean-is-getting-noisier.html
The University of Auckland. (2021, July 22). Lockdown: when the ocean went quiet – The University of Auckland. https://www.auckland.ac.nz/en/news/2021/07/21/lockdown–when-the-ocean-went-quiet.html
Asmutis-Silvia, R. (2015). 5 Things You Can Do To Help Whales and Our Planet Right Now. One Green Planet. https://www.onegreenplanet.org/animalsandnature/fivethings-you-can-do-to-help-whales-and-our-planet-right-now/