Entanglement & Ship Strikes

Entanglement and ship strike events are major conservation concerns for whales globally.

Findings from our 2022 scar analysis study revealed that upwards of 47% of humpback whales in northern BC have suffered from and survived an entanglement. This number does not take into account the number of whales that did not survive, or the full health impacts that may linger following an entanglement or ship strike accident. We must come together and report when these accidents occur to give whales and all other marine life the best chance at survival.

The marine environment of coastal British Columbia is vast in its expanses and critical in supporting a variety of species of whales, dolphins, and porpoises.

As they move through the water column and along our coastal shelf, there is a high risk of interacting with vessels of all sizes and speeds – in addition to active, lost, or discarded fishing gear. Entanglement and ship strikes have been identified by scientists, governmental, and non-governmental organizations as extreme threats to the wellbeing and recovery of many species. Critically, humpback whales and fin whales are among the species which seem to be disproportionately affected.

Negative interactions between whales and ships are often underreported or unnoticed. This is especially true in areas where major shipping routes coincide with whale habitat. Blunt force trauma and serious injury from ship strikes have been identified as major causes of mortality for whales on an international scale. This shocking reality is of particular concern for species of large baleen whales, whose populations have already suffered from being heavily targeted by commercial whaling. Fin whales, for example, face ship strikes as the primary factor limiting their growth and recovery. This is in part a result of their behavioural ecology as fin whales are found in the upper reaches of the water column far more often during the night than during the day in their feeding habitats, and in areas where this feeding habitat coincides with major shipping routes, the ship strike risk increases dramatically as they are less likely to be detected by crew members during the night, and collision avoidance strategies are not able to be implemented. The severity of injury and likelihood that it will result in mortality increases as vessel speed and size increase, but collisions can be lethal even at speeds of less than 10 knots. Some shipping routes in Canada and the United States have been altered and speed limits placed on large vessels in an attempt to mitigate the frequency and severity of collisions between ships and whales.

Moon the Resident Whale

Moon has been a seasonally resident whale to Gitga’at Territory for more than a decade with many historical sightings, none of which showed evidence of the injury detected in 2022. Following the end of the 2022 field season, we received reports of a humpback whale with a severe spinal injury, whale lice infestation, and emaciated condition in Hawaiian waters. Communications with the Pacific Whale Foundation in Hawaii revealed that this whale was Moon. Despite the severe injury, she completed her 3000+ kilometer migration to Hawaii without the use of her flukes. Without the use of drones to investigate scar presence, this injury would have gone unnoticed in BC waters. Read more about Moon in the News. 

The Extent of Ship Strikes

The extent of the impacts ship strikes can have on the individuals who survive collision is poorly understood and extremely difficult to study. Within our own research area in the Kitimat Fjord System, we bore witness as a humpback whale nicknamed “Habit” (BCX1225) arrived back to the feeding grounds in 2015 with a substantial wound from a ship strike event. This is a whale we know intimately, and we have documented her presence nearly every year since 2006.

The first year she was seen with a calf in tow was 2010, and the last was 2014. Even though she was able to miraculously heal from her injury, she has not calved and has instead taken to escorting other mothers with their calves. This is incredibly important to bear in mind; the consequences of vessel strikes go beyond mortality, and may have lasting impacts on the behaviours and viabilities of survivors.

Even in the absence of vessels, marine exploitation continues, and synthetic materials interfere with the natural world. Ropes and nets from fisheries and discarded or lost marine debris are introducing high levels of human induced mortality on bycaught marine life and contribute to growing problems of human-wildlife conflict and animal welfare. In Canadian waters, a pressing and related concern is the frequency of whales becoming entangled in this synthetic material. Entanglement is occurring at high rates, and largely stems from whales swimming through the ground or vertical lines from fixed line fishing gear, though any rope or netting in the water poses a threat. Depending on the severity of the entanglement, whales may experience minor to severe injuries and infections, altered hormones and stress levels, decreased calving rates, and death.

Dangers of Entanglement

It is possible that whales that have become entangled can dislodge fishing gear on their own, however, based on the frequency and severity of entanglement scarring observed on baleen whales in Canada, this is more than likely a lengthy, painful, and exhausting process. ‘

There is also the possibility that fishing gear dislodgement attempts will result in further chronic or acute entanglement scenarios in which chances of survival are low. 

Chronic entanglement of baleen whales typically occurs when an entangled whale is initially able to dislodge or break away from a portion of the fishing gear and avoid acute death via drowning, but remaining lines (most commonly attached to one or more of the: flukes, caudal peduncle, pectoral flippers, and jaws) over time will lead to energetic deterioration and ultimately the death of the individual from secondary causes like starvation.

How to Report a Whale in Distress

If you see a marine mammal in distress in BC waters the most important steps to take are:

Do Not Intervene

 If you are documenting an entanglement, do not attempt to disentangle the animal. Cutting the entangling ropes could lead to your death and the death of the distressed animal. Specialized equipment and trained professionals are needed for a successful disentanglement. Instead, take as many photos/videos as possible while maintaining a safe distance away (remain a minimum of 200m away from all orca in northern BC, 400m away from southern resident orca, and 100m away from all other whales).

Observe and Document

Take note of the species, any entangling gear or visible injuries, the animal’s behaviour and direction of travel, the date, time, location, and GPS coordinates of the distressed animal.

Report what you see

  • In areas of cell signal report what you see directly to the DFO incident reporting hotline at 1-800-465-4336.

  • If you do not have cell signal, report the incident to coastguard on VHF channel 16,

  • and document the details in the “Remote Report” app.


To make detailed observations simple in remote places, we have created the Remote Report app. Remote Report allows users to fully document marine mammals in distress in real time to ensure no details are lost before leaving the scene. Submitting your report through the Remote Report app will automatically notify key researchers and response personnel to the incident and increase the chances of survival for that animal. If you are reporting in a region without access to cellular data or internet, the report will be stored on your phone and submitted automatically as soon as an internet connection is restored.