ShipStrike Update - Ruth Coxon
2nd Aug 2017
In the first of a new series of updates, former ORCA Wildlife Officer Ruth Coxon talks about the groundbreaking new research she is conducting into ship strikes of large whales in the Bay of Biscay in partnership with ORCA and Brittany Ferries.
As part of a Biodiversity Conservation Master’s Degree at Nottingham Trent University, I have teamed up with ORCA, one of the UK’s leading whale and dolphin conservation charities, and Brittany Ferries to conduct important research on the behavioural responses of fin whales, (Balaenoptera physalus) to large ferries for my thesis. Having been thoroughly involved with ORCA since March 2014 and even witnessing a suspected fin whale ship strike casualty in the outer Bay of Biscay in autumn 2015, I have been keen to get involved with this vital research.
The project involves collecting behavioural and spatial data over two months on board Brittany Ferries Flagship the Pont Aven, a large cruise ferry travelling on twice weekly return trips over the Bay of Biscay where fin whales can be found in abundance. The aim is to investigate the pressing issue of ships colliding with these endangered whales, since it is thought to be a largely underreported and global issue, suspected to cause 20-30% of total fin whale mortalities in some areas. Along with other cetaceans, these species evolved in oceans far quieter than today, with ambient (background) noise levels having risen 15 – 20dB since pre-industrial times. Highest change has been in the Northern hemisphere, specifically due to increased shipping. With marine traffic still on the rise, these whales are likely to feel the consequences directly, unless measures are put in place to reduce ship strikes with these enigmatic whales.
Fin whales are particularly vulnerable to ship strike as their large body size makes them a big target. This coupled with their feeding habits within the sunlight zone (<200m) brings them more often towards the surface within the impact-risk zone. Not only this, but they lack the ability to echolocate like dolphins and toothed whales, which means that they may struggle to precisely pinpoint a sound source. Through detailed analysis of their behaviour, I aim to reveal whether sight, sound or a combination of both mechanisms are used by the whales in determining ships relative locations to them to facilitate their evasive avoidance response.
The project’s intent then is to analyse fin whale’s real-time observations and HD video recordings from the bridge of the Pont Aven. Each time I encounter a whale, I am recording the whale’s distance, angle in relation to the ship as well as the whale’s own heading. Important too is the recording of the mammal’s inhalations, inferred from the visual blows seen when the animal surfaces. From this, respiratory rates, dive durations and surface intervals can be calculated and compared with their spatial movements as a measure of the whale’s stress response.
Progress so far:
I am now about halfway through the project and have collected data on 23 fin whale sightings, totalling 28 whales as some of these were of 2 or 3 individuals. Interestingly, 43% of whale encounters so far have come within 500 metres of the ship, half of these being groups. On a few occasions, the bridge crew even altered the ships course to avoid the risk of collision! In accordance with other research, it seems that groups and particularly young or inexperienced whales may be at heightened risk. Whether this is resulting from a preoccupation with feeding or socialising activities or actions of younger more inexperienced whales, further research has yet to discover. Video footage captured on board demonstrates a concerning reaction of a group of whales, including a juvenile, seemingly heading towards the ship’s direction of travel - into the high-risk zone.
It begs the question why whales put themselves in this high-risk position as it seems to be occurring at a greater probability than simply chance. Many suggestions point to a lack of awareness on the whale’s part, until it is too close for comfort. I believe there is indeed a detectability issue, hindered by the fact that they are ‘acoustically challenged’. One of these is that their vocalisations overlap the frequency at which shipping noise is produced, likely making communication more difficult. Not only this but sounds produced from ships propellers and engines are thought to radiate asymmetrically, with least sound travelling ahead of the ship – something called the ‘bow-null effect’ or ‘acoustic shadowing’, a phenomenon produced by some ships with particularly long or wide dimensions, or high set propellers. This could then be creating a muffled or reduced sound zone in which these animals gravitate towards as a refuge. The additive influences of ‘Lloyd’s mirror effect’ in which sound waves can be reflected away from its original path when they hit the water’s surface may also mask the noise produced by ships when whale’s surface to breathe.
Whilst it is still too early to draw any concrete conclusions from these preliminary results, I do feel that both auditory and visual cues may have a part to play in whale’s detection of approaching ships. Especially, since fin whales are ‘rod monochromats’ meaning that they do not see most colour pigments and their eyes are light-dark adapted for the effective detection of bioluminescent prey. Reduced in-air vision (compared to water), may also hinder their visual detection of ships in certain environmental conditions.
I board the ship again on the 6th August and hope to encounter an increased rate of whales during these final three weeks, as they are known to aggregate in the Bay of Biscay during the summer months when food sources are at their highest. With this I can hope to gain more definitive data.
I look forward to witnessing more encounters with the second largest animal on Earth, but they aren’t the only species I am likely to see! Already I have been lucky to observe elusive Cuvier’s beaked whales and their less common long-beaked relatives, the Sowerby’s beaked whales – one of which was even breaching! Another highlight was also encountering my first pod of orca (killer whales) towards the French coast, a species which has previously eluded me.
The crew on board Brittany Ferries Pont Aven have been incredibly supportive and engaged with the project. I hope that some insights are revealed through this work which may lead to ship strike mitigation measures being implemented on board and to other shipping companies in future.
Thank you, ORCA and Brittany Ferries, for your continued support to save the whales. Without your unique partnership, this wouldn’t be possible. I’ll keep doing my best to get to the root of the issue in efforts to conserve these wonderful whales!
For more information and future updates, keep an eye out on www.orcaweb.org.uk/news.