Cetaceans are very susceptible to serious injury and mortality from vessel strikes
The waters of British Columbia are host to high densities of both cetaceans and marine traffic1. Vessel strikes are a recognized cause of mortality for cetaceans worldwide, and pose a real risk to many species found in B.C. waters2.
The Problem
Thirty cetacean-vessel collisions were reported to the B.C. Marine Mammal Response Network hotline and investigated by Fisheries and Oceans Canada from 2004-2011. These collisions involved killer whales, humpback whales, grey whales, fin whales, and harbour porpoise3. The majority of these witnessed and reported strikes involved smaller vessels (less than 15m); however, the involvement of larger vessels is likely underreported, as they are less likely to detect a strike. Many strikes undoubtedly go undetected, especially by large vessels or those involving small species, resulting in an underestimation of this threat in B.C.
Species at Risk
Humpback whales experience the second highest strike rate of any whale species and are the most commonly struck cetacean in B.C. This is due to their relative abundance and their tendency to feed on or near the surface4. Fin whales are the most commonly struck cetacean species worldwide4, and vessel strikes are the greatest human-caused threat to fin whales in BC. Fin whales are commonly distributed along the shelf break in locations that frequently coincide with shipping lanes5. The endangered blue whale is also particularly vulnerable to ship strikes due to their tendency to feed at the surface and their slow and shallow dive response to vessels6. Ship strike also poses a risk to smaller cetaceans. In April 2011, Pacific white-sided dolphins foraging in Howe Sound displayed the tell-tale scars and injuries inflicted from a boat propeller. In December of 2016, a southern resident killer whale J34 (Double Stuf) was found floating dead near Sechelt. A necropsy indicated that blunt force trauma from a ship strike was the most likely cause of death for this animal.
Vessels at Risk
Studies have shown that while all vessel types are implicated in vessel-cetacean collisions, those involving large and fast-moving vessels have a more severe impact and pose a higher risk of mortality for cetaceans4. Reducing speed in areas where vessels and cetaceans overlap may decrease the probability of a strike, as slower speeds increase the likelihood of detecting and avoiding cetaceans and allows more time for the animal to respond and avoid the oncoming vessel. Studies have demonstrated that travel below 10 knots greatly decreases the likelihood of vessel strikes2. Cetacean-vessel collision also poses a serious risk to boaters. In May 2013, a humpback whale unexpectedly breached in front of a boat, cracking the hull and sending the boat’s operator through the windshield. You can read the story here.
Reducing the Impact
Understanding the distribution of cetaceans helps identify and map high-risk areas for vessel strikes, and a large amount of these valuable data come from sightings reported by coastal residents and mariners. You can help researchers learn more about high density whale areas by reporting your sightings. In 2018, the B.C. Cetacean Sightings Network launched the WhaleReport Alert System. This system uses real-time sightings, reported by observers using the WhaleReport app, to alert large commercial vessels of whales in their vicinity. This awareness better enables vessels to undertake adaptive mitigation measures, such as slowing down or altering course in the presence of cetaceans, to reduce the risk of collision and disturbance.
[ays_quiz id=”3″]
Photo credit: Graham Ellis Northern resident killer whale A82 showing propeller scars from a vessel collision.
Photo credit: Kathy Heise Pacific white-sided dolphin seen in Howe Sound in April 2011 displaying tell-tale injuries inflicted from a boat. This animal has a severed dorsal fin.
Photo credit: Jared Towers This humpback whale, known as “Slash”, has a severed dorsal fin along her back from a boat propeller.
What can you do to help?
Vessel traffic, both commercial and recreational, has increased significantly along the British Columbia Coast. This rise in vessl traffic has caused an increase in physical and acoustic disturbance in cetacean habitat.
Follow the Be Whale Wise Guidelines
Follow the Be Whale Wise Guidelines when out on the water. Slow down to less than 7 knots when within 400m of whales. Do not approach any marine mammal within 100m (200m for killer whales).
Report Marine Mammal Harassment and Violations
In Canada: 1-800-465-4336 In the USA: 1-800-853-1964
Watch Whales from Shore
The BC Cetacean Sightings Network has partnered with the Whale Trail to establish a network of land-based whale watching sites in British Columbia. Since 2015, 12 sites have been established throughout BC. Learn more about BC’s land-based whale watching initiative, the Whale Trail BC.
Tools for Commercial Mariners
If you belong to a professional marine organization and are a pilot or member of the bridge crew of a ship, use the WhaleReport Alert System to receive real-time alerts of whales in your vicinity. Mariners can learn more about their impacts and mitigation measures to vessel disturbance in the Mariner’s Guide to Whales, Dolphins, and Porpoises of Western Canada.
References
- Erbe C., Reichmuth C.J., Cunningham K., Lucke K. and Dooling R. (2016) Communication masking in marine mammals: A review and research strategy. Marine Pollution Bulletin 103: 15-38.
- Holt, M.M, Noren, D.P., Viers, V., Emmons, C.K., Veirs, S. 2009. Speaking up: Killer whales (Orcinus orca) increase their call amplitude in response to vessel noise. Journal of Acoustic Society of America. 125 (1): EL27-EL32.
- Fisheries and Oceans Canada (2009) Management Plan for the Pacific Harbour Porpoise (Phocoena phocoena) in Canada. Species at Risk Act Management Plan Series. Fisheries and Oceans Canada, Ottawa. v + 49 pp.
- Lachmuth, C., Barrett-Lennard, L.G., Steyn, D.Q., Milsom, W.K. (2011) Estimation of southern resident killer whale exposure to exhaust emissions from whalewatching vessels and potential adverse health effects and toxicity thresholds. Marine Pollution Bulletin 62: 792-805.
- Lusseau, D., Bain, D.E., Williams, R. Smith, J.C. (2009) Vessel traffic disrupts the foraging behaviours of southern resident killer whales, Orcinus orca. Endangered Species Research 6: 211-221.
- Lusseau, D., Bejder, L. (2007) The long-term consequences of short-term responses to disturbance experiences from whalewatching impact assessment. International Journal of Comparative Psychology 20: 228-236.
- Neilson, J. L., Gabriele, C.M. (2010) Results of humpback whale population monitoring in Glacier Bay and adjacent waters: 2010. Report to the National Park Service, Glacier Bay National Park and Preserve, Gustavus, AK. 20 pp.
- Noren, D., Johnson A.H., Rehder D., and Larson A. (2009) Close approaches by vessels elicit surface active behaviors by southern resident killer whales. Endangered Species Research 8:179–192.
- Province of British Columbia (2016). “Marine Emissions”. B.C. Air Quality. Retrieved from: http://www.bcairquality.ca/topics/ marine-emissions.html)
- Thorpe, L., Personal Communication, April 2011 p.c (2011)
- Williams, R., Lusseau, D., Hammond, P. (2006) Estimating relative energetic costs of human disturbance to killer whales (Orcinus orca). Biological Conservation 133(3): 301-311.
- Williams, R., Krkosek, M., Ashe, E. Branch, T.A., Clark, P.S. Hammond, P., Hoyt, E., Noren, D.P., Rosen, D., Winship, A. (2011) Competing conservation objectives for predators and prey: estimating killer whale prey requirements for Chinook salmon PLoS ONE 6: e26738.
