Ecotourism and nature-based tourism isn’t just gaining in popularity in some parts of the world – it has in some cases been heralded as a way in which we can help look after species that are struggling in the face of human activities that hamper their survival. The reasoning behind this broadly falls into a couple of main camps. First, by taking people like you and me out to see nature’s glory we may be more inclined to want to take care of it (“In the end we will conserve only what we love, love only what we understand, and understand only what we are taught.” ~ Baba Dioum). Secondly, if we can give species some economic value through something like tourism, then taking care of them becomes important from an economic – and then political – point of view.
This sort of tourism isn’t without its controversy, with some activities having a larger environmental footprint than we may hope. Even non-consumptive forms of eco and nature-based tourism – such as wildlife watching – can have a negative impact on the very species we are hoping to see and protect. The waters around the Hawaiian Islands is a crucial area for humpback whales (Megaptera novaeangliae).
During December to April every year, thousands of humpback whales gather in these waters to breed. So good are these waters, it is thought around 55% of the North Pacific population congregate in these waters to breed. Some humpbacks even calve and nurse their young here. This congregation isn’t just handy for the whales but also for people. From a research, protection, and management perspective having a huge chunk of the North Pacific population entering one area every year makes life much easier for monitoring population levels. And on that front we have some good news – humpbacks in the North Pacific seem to be on the up, with at least one study back in 2008 estimating around a 6% annual increase in population size (although the population still remained ‘Endangered’). Research isn’t the only human activity to benefit from this congregation. Humans have been interacting with whales since they first set out into the ocean. Commercial whaling on an industrial scale has impacted on humpbacks over the last couple of centuries, reducing their population size to a small fraction of its pre-whaling size.
Commercial whaling has now largely subsided and in more recent decades we have switched from consumptive use of these whales to non-consumptive - whale watching. Hawaii with its large congregation is a great place to spot whales – and a great place to set up a whale-watching business. Whale watching seems a pretty benign activity right? You go out, spot some whales, take some photos, perhaps listen to their calls if the boat is fitted with hydrophones, and if you have a good guide, you’ll get to learn something about these magnificent creatures. Unfortunately, research by Marc Lammers of the University of Hawaii and colleagues has revealed that even these activities can cause harm to the humpbacks.
Marc and his team analysed reported boat strikes on the humpbacks in Hawaiian waters between 1975 and 2011. Their work uncovered 68 reported collisions, 63% of which struck calves and juveniles. These guys tend to spend much more time at the surface than adults so it isn’t that surprising that the most strikes would be on this group. None of these reported strikes lead to immediate fatality, but it isn’t known how the collisions may affect the whales in the long-term. We do know that strikes can eventually lead to death, as evidenced by one calf discovered dead with severe wounds consistent with propeller damage. What was interesting is what sorts of vessels were involved in strikes. Yup you guessed it – 61% of the collisions involved tour boats – that’s the whale watchers, divers, and snorkelers. There is legislation in place that states boats should not be within 100 yards (~91.4 meters) of a whale, and it may be that most vessels are adhering to this. Speed of vessel at the time of the collision was only reported in 57% of the collisions, but this data showed that the mean maximum speed at the time of collision was 12.33 knots. These boats weren’t watching the whales – they were travelling to find the whales (or return to their port). It is also interesting to note that not all strikes were reported as the boats hitting the whales. 20% of the reported collisions where of the whales hit the boat. Yes it can happen – check this video out of a dramatic (and now famous) whale hitting a yacht in South Africa and a slightly less dramatic one in Hawaii.
We are pretty sure that whale numbers are on the up, and as bad it is to strike a whale 68 reported strikes over 36 years doesn’t appear to be impacting on the population growth. Now these are only reported strikes. It is likely that more than 68 whales were struck during this period but the strikes were never reported, and the authors note "The lack of incidents reported involving large ships is somewhat curious". However, that population trend is still going up. Never the less, the team’s research hints at caution. Reported strikes have increased in more recent years, with the data suggesting that this is more a function of increased small boat traffic rather than purely down to the increasing number of whales. Hawaii has both a legislative and ethical responsibility to looking after these whales, and another piece of the research hints at a possible route that could be taken to reducing collision. 75% of reported collisions occur during February – March, and 63% of all reported collisions occurring in a region called Maui Nui. Directed management of vessels during these peak times and in peak areas just might prevent the death of a young animal.
The paper is published in the journal Journal of Cetacean Research and Management . The paper is open access but a bit of a faff to download to read. Here’s what you need to do. First go here and then scroll down the list of papers (or search) for 13_2p073_080Lammers.pdf. It’s the second one from the bottom. Hit download, which then takes you to another page where they want you to say why you want the paper. It doesn’t matter what you write – fill it in, hit download on this page and the paper is yours.
If you want to read up a little more on humpbacks and the status of the Pacific population, head over to the IUCN Red List.
Image: Humpback whale. Credit Christopher Michel/Flickr (CC BY 2.0)