Whales and Boating
Over the past century vessel traffic has been dramatically increased in the Salish Sea. Cargo traffic in the Port of Vancouver has increased by 66% since 2009, and currently 11,000 large vessels pass through the Salish Sea annually. Furthermore, large vessels make up a small portion of the boats on our oceans. Recent studies have found that there are up to four times more recreational boats in the Salish Sea than large vessels. Increased vessel traffic means more pressure on the marine life that call the Salish Sea home. However, there are a number of steps that you can take to lessen your impact as a vessel operator. You can help the Galiano Conservancy and make a difference by understanding, and mitigating threats to cetaceans next time you and your family spend a day on the water!
Underwater Noise (Acoustic Disturbance)
Orcas use a variety of low and high frequency sounds to stay together and to coordinate hunts, often needing to communicate across distances as far as several kilometres. As they move they echolocate shorelines and the ocean floor in order to navigate complex coastlines. This also enables them to locate prey in dark, and turbid waters. They also use songs to locate appropriate mates, and sometimes will even use bursts of loud noise to confuse prey. Unfortunately, orcas ability to use sound for any of these crucial survival strategies is compromised if there is excessive underwater noise, which is increasing dramatically in our oceans today. In the North Pacific, underwater noise has been doubling in intensity every decade for the past 60 years. Sources of noise include dredging, drilling, construction, seismic testing, military sonars, and most importantly, vessel traffic. In some areas, vessel noise has reduced the ability for cetaceans to communicate by around 90%. Excessive noise causes erratic behaviour, unusually long or loud calls, avoidance of certain areas, and mass stranding. It can also prevent whales from hunting effectively, causing many whales to become emaciated.
Whale Watching and Physical Disturbance
Along with increased general vessel traffic came an increase in the number of whale watchers, which expanded from 1000 passengers annually in the 1970’s to half a million in 1998. There are many accounts of short-term behavioural changes of whales when exposed to whale watching vessels or recreational boaters, such as travelling in less predictable paths, altering dive lengths, and moving to more open water. The long-term effects of whale watching are less known, but prolonged exposure is thought to induce chronic stress and cause certain whales to abandon entire areas. Abandoning areas affects whales both because of the energy expenditure on locating new foraging grounds, and also the new area may be less well suited to the population of whales. Additionally, whales that are food stressed (such as the Southern Resident Killer Whales), may face severe consequences if vessel disturbance results in reductions in foraging time budgets. Although, no studies have researched the direct impact of these stressors on the survival of the Killer Whales, a study on Bottle-Nose Dolphins found that behaviour disruption through boating lowered their reproductive rates.
Vessel Strikes
Few studies have been done on the impact of vessel strikes on the Southern Resident Killer Whales, however we can look to other whales for clues. On the Atlantic Coast, it is thought that vessel strikes could make the difference between extinction and survival of Right Whales, and in BC, boat strikes are the biggest threat to Fin Whales. Thirty collisions were reported to the BC marine mammal response unit between 2004 and 2011, the majority from small recreational vessels. Many more go unreported or unnoticed, especially collisions by large vessels, which oftentimes will not recognize the shake/impact on the vessel. In recent years, there has been one confirmed death of a Southern Resident Killer Whale from a vessel strike. It is important to note that vessel strikes are not just a concern for large boats, recreational vessels and jet-skis can also pose a threat to marine life. Many times, Cetacean are underwater and are not seen until it is too late. Researchers at SFU (Simon Fraser University) are currently working on a project that uses hydrophones to provide real-time data to vessels to predict the Southern Resident Killer Whales’ paths and decrease the chance of a vessel strike.
Fishing Vessel Conflict and Entanglement
The increase of recreational boaters is indicative of an increase in recreational fishing in the Salish Sea. Recreational fishers make up large portions of many fisheries, interestingly accounting for 89% of the rockfish fishery in the Salish Sea. Increased fishing pressure results in decreased prey abundance for cetaceans, especially SRKW, which are often in direct competition with fishers for Chinook salmon. More fishing activity also increases the chance of irresponsible disposal of fishing gear. Several Southern Resident Killer Whales have been found with recreational fishing lines in their stomachs, and there has been one confirmed death due to fishing gear.
Oil Spills
Orcas are also highly vulnerable to stochastic (random) events such as oil spills. For example, on March 24, 1989, the tanker, ‘Exxon Valdez’ ran aground in Prince William Sound, Alaska, resulting in a crude oil spill of 42 million litres. The slick drifted uncontrollably via storms and currents, coating 1,100 km of coastline and travelling as far as 900 km from the spill location. The implications for marine mammals were substantial. Mortalities within the 1989 – 1990 window were reported at 13 deaths within the resident pod, and 9 deaths within the AT1 transient group. Although there is uncertainty in the exact causes of death, several factors are likely, including inhalation of volatile organic compounds (VOCs), oil ingestion, oil contact, or even declines in prey species due to the spill.
Unfortunately, for the transient group, the spill proved to be detrimental. Since 1984 there has been no viable production of a calf, and the group was declared as a ‘depleted stock’ under the Marine Mammal Protection Act in 2004. In contrast, AB pod lost a significant quantity of reproductive females, and population growth has slowed greatly.
It is safe to say that if the same sort of oil spill happened in the Salish Sea, the continuity of our endangered SRKW would be unlikely.
Practising Whale Wise Boating
Numerous regulations have been implemented to mitigate boating around Whales, and there are many more actions you can take while boating in order to safely share our oceans with marine life!
- Slow down anytime you see a marine mammal. Slowing your boat down can significantly decrease engine noise, allowing marine mammals to communicate effectively.
- It is mandatory to slow down to 7 knots when you are 1000 m away from whales.
- Keep your engine and hull maintained and clean, to further reduce noise.
- You can additionally modify your engine to make it quieter by:
- Insulate the ships engine and use resilient mountings for onboard machinery.
- Incorporate vessel quieting consideration during re-fits and vessel construction.
- Modify your route to avoid whales.
- Steer clear of orcas while boating: 400 m recommended and 200m minimum. https://www.bewhalewise.org/federal-regulations/
- Steer clear of all other cetaceans a minimum of 100 m while boating.
- Before your next boating trip, learn about new regulations here.
- Properly dispose your fishing equipment in the landfill. Do not throw it in the oceans!
- Choose a responsible way for whale watching, e.g. whale trails established along BC’s Coast
References/ Further Reading
http://noaacontent.nroc.org/lesson13/l13la2.html
https://wildwhales.org/threats/noise-and-cetaceans/
https://www.fisheries.noaa.gov/insight/understanding-vessel-strikes
https://meopar.files.wordpress.com/2018/05/smallvesseltrafficstudy_report_uvic2018.pdf
https://www.hindawi.com/journals/jmb/2012/807294/
https://wildwhales.org/threats/collisions/
https://www.sfu.ca/sfunews/stories/2019/07/sfu-developing-warning-system-to-protect-orcas.html
https://www.sfu.ca/sfunews/stories/2019/07/sfu-developing-warning-system-to-protect-orcas.html
