By Rosie Williams and Ellen Coombs
A whale buffet
It’s a fact: Monterey Bay is one of the best places in the world to go whale watching. One of the reasons for this is the Monterey Submarine Canyon – a huge underwater canyon that runs perpendicular to the coast, stretching a mile from the ocean surface down to the sea floor in some places. This peculiar underwater geology funnels cold water from the deep sea into the canyon, bringing plenty of nutrients with it and making the perfect buffet for a plethora of cetaceans (whales, dolphins and porpoises).
On the morning of Thursday 16th March, we (the London NERC DTP, cohort 3) waited excitedly at Moss Landing harbour, situated about half way up Monterey Bay at the opening of the canyon.
A sea mist hung in the air, obscuring the ocean that rippled beyond the harbour.
We started the day with student talks on how to ID and sample whales, and an overview of the movement, feeding and behavioural ecology of the gray whale (Eschrichtius robustus) and the humpback whale (Megaptera novangelae).
Our guide and marine biologist at Sanctuary Cruises Whale Watching, Dorris, then took us to the boat to start our journey. We chose Sanctuary Cruises because they are a small whale watching company who run their boats on waste cooking oil (bio oil) collected from local restaurants and have a good environmental ethos.
As we travelled out of the harbour and over the canyon, everyone began scanning the horizon, cameras poised.
Sunny side up
Within 25 minutes, we had our first sighting. A mola (Mola mola), or ocean sunfish – the heaviest boned fish in the world – was resting at the surface just near our boat. The fish was carrying out some characteristic horizontal basking behaviour, giving us a good chance to look at the whole of its profile. It is thought that molas bask at the surface to ‘thermally recharge’ after diving down into deeper, colder waters.
Our encounter with this remarkable fish was abruptly interrupted by the characteristic ‘pfffft!’ sound of a whale exhaling behind us. Everyone rushed to the other side of the boat just in time to see the backs and dorsal fins of two humpback whales disappearing back into the water.
Quite a splash
The Californian population of humpback whales visit Monterey Bay to feed. Their prey (primarily anchovies and krill) concentrates around the edge of the submarine canyon, so they are often observed very close to the shore. The Monterey population tend to arrive in the bay in late April (which made our unlikely encounter extra special!), having migrated north from their mating and calving grounds off the coast of Mexico.
We watched as the whales periodically surfaced to breathe before diving down again to reach their prey. Humpback whales can dive for up to 30 minutes, but luckily this pair were only diving for around 5 minutes at a time, so we got quite a few chances to get the perfect photo!
After some time watching the humpbacks feed and dive, we were once again looking out in anticipation for them to surface again when suddenly, right off the bow of the boat, one of the whales leapt completely out of the water!
Witnessing a full body breach is very rare and we were completely awestruck.
The reasons why cetaceans breach still aren’t fully understood and scientists have proposed several explanations. Many believe that whales breach as a form of communication or to stun their prey. Another widely accepted explanation is that whales breach to dislodge parasites from their skin, whilst some scientists think it might simply be a form of play.
Whatever the reason for breaching, it is without a doubt the most dramatic cetacean behaviour you can observe and we all felt extremely lucky to have been so close to the splashzone!
A killer time
After all that excitement, we continued to head further into the bay. People huddled at the front of the boat, chatting excitedly, and then fell silent to scan the horizon once again. The water was still, like a millpond, and the mist was still present, but starting to clear. This is perfect whale watching weather – there is no glare from the sun, and fins and spouts can be seen easily in calm water.
The silence was broken by our colleague, Dan Nicholson, shouting ‘KILLER WHALE!’ at the top of his voice, and gesticulating towards the front of the boat. At that moment, the distinctive tall, black dorsal fin of a huge bull killer whale (Orcinus orca) sliced through the water’s surface as he exhaled, making that spine-tingling ‘pfffft!’ noise.
Killer whales are present in the bay all year but they aren’t commonly spotted, so this was yet another very lucky encounter for us!
The killer whales in Monterey Bay are a notorious bunch – their pods are known to hunt gray whale calves by chasing them for hours, eventually separating them from their mother and drowning them. Luckily or unluckily (depending on who’s side you’re on) the orca we saw was a solitary male so we didn’t have to go through the emotional turmoil of witnessing a calf hunt!
Nevertheless, we did get to observe lots of other orca behaviour as this male seemed particularly interested in our boat, and stuck around to play with us. Having heard in the introductory talk about three key examples of cetacean behaviour to look out for – breaching, tail lobbing and spy hopping – we couldn’t believe our luck when this male orca gave us the hat trick!
As with humpback whales, the true reason why orcas breach remains unknown. However, spy hopping (when a whale holds a vertical position partially out of the water, just like a human treading water) is a very well understood behaviour and the simple explanation is nosiness! The whale’s eyes are usually positioned just above the water, allowing it to see what is on the surface, and in our case take a good look at our boat.
Tail slapping (or lob tailing) is when a whale lifts its fluke out of the water and slaps it hard and fast back down onto the water. There is no conclusive explanation as to why whales lobtail but the slap can be heard underwater from several hundred metres, leading to speculation that it might be another form of communication.
The gray whale tail
There are many cetacean species in Monterey Bay, both resident and transient. The most famous transient individuals are the gray whales, and every year around 22,000 gray whales in the North Pacific population migrate the thousands of miles from Baja, California Sur where they breed and calve, up to northern most Alaska to pack on the pounds feasting on crustaceans.
In March the whales are travelling up from Mexico, some with calves, others hastily heading north to feed, and most of them taking a pit-stop at the Monterey Bay buffet. These whales stay close to the shoreline to avoid the offshore killer whale pods lurking in deeper waters waiting for their vulnerable calves. Although we didn’t see them on this trip, we were lucky enough to see gray whales breaching and travelling in the waters near Santa Cruz island (Channel Island National Park) a few days earlier.
The porpoise of our visit
Our purpose for travelling to Monterey Bay was to observe these animals in their natural habitat, and to undertake some I.D and sampling work. Many elusive cetacean species spend >92% of their time beneath the surface, and it is important to know what distinguishable signs to look for when they do surface to breathe. We were lucky to spot such an array of marine life, including many seabirds, such as pelicans and shearwaters.
We certainly had a whale of a time!