WDC Blog - From the Front Line

Occasionally accounts come our way of observations on whales that are unusual and very interesting. I recently heard of one such incident and asked the guy who told me the story, Bertie Gregory, who is a student at the University of Bristol, if he would write it up so that we could share it.

He kindly did and here is that account beautifully illustrated by some of his own photographs:

Last summer I visited the west coast of Vancouver Island in Canada, to aid a wildlife tour guide on his boat. The majority of our trips involved searching inlets and sounds for black bears, bald eagles and the mysterious coastal wolf. About once a week however, we’d take guests out to sea to find grey and humpback whales. During the summer months, these two species come in huge numbers to feed on the explosion of aquatic life. The grey whales spend most of their time in shallow water, often less than 20m deep, feeding on mud dwelling invertebrates. The more charismatic humpbacks meanwhile, feed on small fish further offshore.

As a result of their huge numbers, we saw both species on every trip. All the while on the water we’d always be watching out and listening on the radio for orca (killer whales). The pods which visited the waters we searched for were the ‘transient’ variety, they feed on marine mammals and are notoriously hard to find as they’re constantly on the move up and down the coast. For that reason it was common for there to be only one sighting a week by the tour operators. The other variety, known as ‘resident’ killer whales tend to stay around the same area feeding on fish. There is much debate over the taxonomy (evolutionary classification) of killer whales and its generally agreed that there is probably more than one species as the different ‘cultures’ have not interbred for thousands of years.

I was particularly keen on finding them as up to then my sightings were limited to the various BBC landmark series! On one particular afternoon, we had a full boat of 12 guests and decided to make our way to Cow’s bay, an area we had consistently seen grey whales for the past few weeks. Just as we exited the harbour, I heard the boat’s radio crackle briefly; my boss, the boat’s captain, took it off the latch and held it to his ear. After a couple more crackles he turned to me and smiled, ‘the black and whites are out there’, he said. In very good spirit, all the tour companies work together and let each other know where the various animals are. Whenever the possibility of a rarer sighting came up, as with the coastal wolves, we didn’t tell the guests immediately because as quickly as they’re spotted, they may just disappear. My boss changed the course of our 20 foot Boston Whaler away from Cow’s bay, directly out to sea. As we got closer to the GPS coordinates we had been given, more details came through. A voice once again crackled on the radio, ‘there’s more than ten of them’, my ears pricked up. I stood up out my seat and scoured the water ahead of us with my binoculars; 500m ahead was the boat we’d been hearing from. Suddenly, I spotted numerous ejections of water-vapour, firing high up into the air, the tell-tale sign of whales.

Whale watching regulations state that boats aren’t allowed to approach the whales closer than 100m, but the killer whales didn’t know this as all twelve headed towards us. I’m a passionate wildlife photographer but these whales were proving tough to get good pictures of. Their faces were only up for a fraction of a second, followed by their proportionally massive dorsal fin, before they dived back under the surface.

I then heard another pair of exhalations but this time from behind the boat, they sounded deeper and louder to what we’d heard so far that day. I turned to see two adult humpback whale surface 30m from the boat. The killer whales weren’t approaching us, they were approaching the humpbacks, we just happened to be in their way! The killer whales got closer and closer to us, barely 5m away before they dove under our boat towards the humpbacks. Then everything went eerily quiet. All the whales were under the water, the boat engines were long switched off.

The silence was broken by an almighty trumpet from underneath the water; it vibrated our stomachs right down to the core. The sound was made by one of the humpbacks and moments later it surfaced continuing to let out these very elephant like noises. The killer whales then surfaced all around it, rolling on their sides and tail slapping. Never before had any of the guides (some with 30 years experience) seen killer whales attacking adult humpbacks. What’s more, within the pod of orca were a couple of juveniles- signified by their white skin having a yellow tone. These two youngsters were getting stuck in swimming just metres from the humpbacks, as they tried to join in on the action.

After a good half hour of the killer whales tail slapping, harassing and chasing the humpbacks, the tables turned, the 15m long humpback adults had had enough. The next time all the whales surfaced, it was the humpbacks that were doing the chasing.

Unfortunately, our time on the water was up, what should have been a two hour whale watching trip had already become three and an half. I begged my boss to stay but (apparently!) the customer is always right and understandably some of the small children on board were getting very cold. I’ll never know how the story ended. I feel very privileged to have witnessed such an incredibly rare event. I’ll be going back next summer to try my luck again!

Bertie Gregory
Bertiegregoryphotography.com

Some of my colleagues are going to accuse me of going off on one with this, and for it being 'too scientific', but I am peeved at an article I read this morning and needed to get some comments off my chest. It's in the vein of my last entry on the way science is presented, so you could say that it's at least following a theme.

Headlines can be deceptive and misleading and I have to take issue with the National Geographic’s headline -  ‘Penguin Numbers Plummeting—Whales Partly to Blame?

The article states that ‘Penguin populations have plunged by as much as 50 percent during the past three decades in the West Antarctic Peninsula and Scotia Sea, scientists report.’ The article goes onto say that the report the article is based on, in Proceedings of the National Academy of Sciences states that ‘The problem appears to be a shortage of krill, the seabirds' primary fare, caused by rising regional air temperatures and rebounding populations of hungry whales.’ But hold your horses. It seems that penguins only started eating krill when the ecosystem was changed by human impacts.

It appears that the seabirds abandoned their 38,000-year diet of fish in favour of krill, shrimp-like crustaceans that are a major component in the diets of fur seals and baleen whales only when the krill became available because whaling and sealing wiped out huge numbers of marine mammals.

When discussing whales the original paper references ‘Reilly, S., Hedley, S.L., Borberg, J., Hewitt, R., Thiele, D., Watkins, J., Naganobu, M. 2004. Biomass and energy transfer to baleen whales in the South Atlantic sector of the Southern Ocean. Deep Sea Research II 51, 1397-1409’  which states that the amount of krill consumed by whales estimated from a 2000 Antarctic survey amounted to some ‘4–6% of the estimated krill biomass in the region (and probably less than this percentage of the total annual krill production).’

The Reilly et al. paper does not appear to set out to blame whales for low krill population numbers but indeed, seems to say that any future krill fishery should be managed so as to allow for recovery of whales, - it states in the abstract that, ‘the depleted numbers of baleen whales resulting from past or current whaling activities should be taken into account when setting quotas for the commercial exploitation of krill if there is to be a recovery to pre-exploitation biomass levels of baleen whales’

An earlier article in National Geographic (2007) supports the theory that Antarctic sealing and whaling led to a krill population explosion, and that the penguins apparently took advantage of the surplus. But now the krill has seen a decline in the last 30 years, but a corresponding increased percentage of fish are not appearing in the penguins diet

The report does later on note that, ‘fish stocks have also been heavily fished out by Russian trawlers’ and so denying the penguins their food of choice. The report also notes that krill fishing is increasing. The earlier 2007 National Geographic story fully acknowledges that overfishing is a negative impactor. In this report researchers are noted to say, ‘"And now with krill on a decline and fish harvested out in a lot of areas … that's a concern…. What do [the penguins] have left to switch to? They don't really have any options left…. In addition, fishers are now actively taking krill, which are used as feed in fish farms. This "will further cause problems,"’ One other note of concern is that the Academy of Sciences paper reports that, ‘In addition, the Marine Stewardship Council’s recent certification of one company’s krill fishing as being sustainable* and the introduction of new products (e.g., Omega-3 krill oil, a popular dietary supplement) suggest that the [krill] fishery may be poised to expand further in the near future.'

Reading the original paper in in Proceedings of the National Academy of Sciences we see that it states that, ‘The West Antarctic Peninsula (WAP) and adjacent Scotia Sea support abundant wildlife populations, many of which were nearly extirpated by humans. This region is also among the fastest- warming areas on the planet, with 5–6 °C increases in mean winter air temperatures and associated decreases in winter sea-ice cover. These biological and physical perturbations have affected the ecosystem profoundly.’

The abstract concludes that, ‘Linking trends in penguin abundance with trends in krill biomass explains why populations of Adélie and chinstrap penguins increased after competitors (fur seals, baleen whales, and some fishes) were nearly extirpated in the 19th to mid-20th centuries and currently are decreasing in response to climate change.'

So whilst the Academy of Sciences paper tests the hypothesis that the reduction of whaling is removing fewer whales from the Antarctic ecosystem and they are eating more krill, the significant conclusion is that the major impact on the penguins is ... yes you guessed it...climate change.

I suggest we should all be wary of extracting the comments from papers, in this case about whales being ‘partly to blame?’, and therefore giving overdue inference to just one element of a complex issue. There are enough people willing to abuse the science without respected journals helping them with juicy spin.