Two Months and Two Humpbacks Entangled at the Same Location – What Can We Learn?

[UPDATE: November 29: Another Humpback Whale has died in open-net fish farm gear. This is the 2nd Humpback Whale dead at a fish farm in two weeks and the 3rd that is known to have been entangled in fish farm gear in 2.5 months. See this link for information on the latest death (at Grieg Seafood’s Atrevida farm in Nootka Sound).]

As a result of our research to understand and reduce risk of entanglement for Humpbacks and our efforts to increase awareness about what to do if an entanglement is witnessed, we’ve been getting a lot of questions about the latest known Humpback entanglement on BC’s Central Coast. Many of the questions were generated by Marine Harvest’s November 17th release “Whale found dead at empty aquaculture site”.

For the sake of efficiency and awareness raising, we’ve strived to answer the questions below and will update this information as we learn more. Our aim is to help ensure that what is learned from entanglements leads to measures that reduce the risk.

Questions: 

1. Was the November 15th entanglement at the same site as the September 12th entanglement?
Marine Harvest has reported that both whales were entangled on the same anchor system at the fallow Sheep Passage open-net farm site near Klemtu.

2. Why was the anchor system not removed?
The latest entanglement is under investigation by Fisheries and Ocean’s Canada (DFO). We are striving to find out if the results will be made public and if the results may inform policy and regulations around open-net fish farm anchor systems.

3. Did the whale entangled at this site on September 12th survive?
The Humpback caught up in the same anchor system on September 12th was disentangled by those with training (disentanglement must be coordinated by DFO and done by those with training, see #9 below). This was a very complex entanglement (see photo and video below) but all gear was successfully removed from the whale. It is not possible however to definitively say that the whale survived the injuries as there have been no documented re-sightings.

4. How did the whale found on November 15th die?
Whales are mammals and therefore need to come to the surface to breathe. They will drown if they are anchored to the bottom because of being trapped in ropes or fishing gear. It is hoped that the DFO investigation will provide insight into the specifics of this anchor system and how the Humpback died. Wherever there are lines or fishing gear in the ocean, there is the potential for entanglement, especially in areas where Humpbacks are feeding. They feed on krill and small schooling fish like herring and it can be expected that these prey are in the same areas as open-net fish farms. It is essential to realize that Humpbacks do not have the biosonar that toothed whales like Orca have and they can be extremely oblivious of boats, let alone fishing gear.
Also note that if whales have enough mobility to swim away, entanglement also can also cause death due to the fishing gear in which they are wrapped leading to serious injuries and infections, and/or because the gear makes it impossible for them to travel and feed effectively.

5. How often to whales die from entanglement on BC’s coast?
Preliminary research conducted by the Marine Education and Research Society and DFO supports that 47% of Humpbacks have scarring on their tailstocks that indicate that they have been entangled and survived, i.e. almost one in two Humpbacks that feed on BC’s coast have been entangled at some point in their lives (>1,000 Humpbacks). This indicates how widespread the risk of entanglement is, but does not indicate how many Humpbacks die due to entanglement. Dead whales most often sink to the ocean bottom whereby their deaths cannot be documented. If their bodies do wash ashore on BC’s vast coastline, often they are so decayed that cause of death cannot be determined.

6. Have there only been two Humpback Whales entangled in Marine Harvest open-net salmon farms in the last 30 years?
Yes, specifically at Marine Harvest farms, and specifically for this marine mammal species, there have been two reported cases of Humpback entanglement. There was another documented case of a dead Humpback Whale at an open net fish farm in March 2013 near Tofino at a Mainstream Canada site (now Cermaq). The statement regarding “30 years” in “Whale found dead at empty aquaculture site” must be weighted out against the reality that Humpbacks were extremely rare on BC’s coast even 15 years ago. Humpbacks were whaled in BC waters up to 1966. To give an indication of how Humpback numbers have increased since then, our research shows that in the islands outside Telegraph Cove on NE Vancouver Island alone, we documented just 7 Humpbacks in 2004 and, this year to date, we have documented 83 individuals (some just passing through). The population estimate for Humpbacks feeding in BC waters is at least 2,000 individuals. With more Humpbacks, there is more risk of entanglement. 

7. Are there regulations around the gear left at fallow fish farms?
No, there are not. It is hoped this will be an outcome of what is learned from these entanglements. See #10 below for what regulations do pertain to aquaculture and marine mammals.

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8. Is the ID of the dead Humpback known?
No, it is not known. It is hoped that as part of the investigation, Humpback researchers like ourselves may be able to be of use in trying to identify who this whale was.

9. What should be done if someone witnesses an entanglement?
• With great urgency, report the entanglement with location to the DFO Incident Line / VHF 16. 1-800-465-4336.
• If at all possible, remain with the whale at a distance until trained help arrives or another boat takes over tracking, otherwise the chances of relocating the whale are greatly diminished
• Take whatever video/photos are possible but maintain a distance that doesn’t stress the whale (at least 100 metres).
Do NOT attempt to remove any fishing gear or rope from the whale as it risks human and whale safety (has led to human death). Professional training and equipment are needed to assess the entanglement and proceed safely with the greatest chance of success. Often, much of the fishing gear in which the whale is entangled is not visible at the surface. If well-intentioned members of the public remove the gear at the surface, it is made much more difficult to: (1) recognize that the whale is entangled; and (2) disentangle the whale even if it is relocated. Trailing gear at the surface provides the opportunity for trained responders to attach a tag to track the whale and/or to attach floatation to maintain contact with and slow down an entangled whale. Loss of this gear can significantly reduce rescuers’ ability to save the whale.

For more information regarding reducing the risk of vessel strike and entanglement, see www.SeeABlowGoSlow.org.

10. What regulations are there around reporting and reducing the risk of entanglement at finfish aquaculture sites?
In the Pacific Aquaculture Regulations, marine mammals are regulated under the term “nuisance fish” and there is obligatory reporting on “the number and species of nuisance fish that die as a result of the aquaculture facility’s operations.”
• Section 10 of the Marine Finfish Aquaculture License specifies conditions around “management of Marine Mammal Interactions” and includes “The licence holder must notify the Department [DFO] of any marine mammal drowning mortality or entanglement (live or dead) not later than 24 hours after discovery.”
• The Marine Mammal Regulations state that there is to be no disturbance of a marine mammal but “disturbance” is not defined. Specifically the language in section 7 is “No person shall disturb a marine mammal except when fishing for marine mammals under the authority of these Regulations.”
• Under Canada’s Species at Risk Act, North Pacific Humpbacks are recognized as a threatened population. General prohibitions include “No person shall kill, harm, harass, capture or take an individual of a wildlife species that is listed as an extirpated species, an endangered species or a threatened species.”


An important development in the United States is that as of January 1, 2017, foreign fisheries must adhere to the provisions of the Marine Mammal Protection Act (MMPA) which address the incidental mortality and serious injury of marine mammals. These include: 

  •  With respect to foreign fisheries, section 101(a)(2) of the MMPA states that the Secretary of the Treasury shall ban the importation of commercial fish or products from fish which have been caught with commercial fishing technology which results in the incidental kill or incidental serious injury of ocean mammals in excess of United States standards. For purposes of applying the preceding sentence, the Secretary of Commerce shall insist on reasonable proof from the government of any nation from which fish or fish products will be exported to the United States of the effects on ocean mammals of the commercial fishing technology in use for such fish or fish products exported from such nation to the United States. (16 U.S.C. 1371(a)(2))
  • Section 102 (c)(3) of the MMPA states that it is unlawful to import into the United States any fish, whether fresh, frozen, or otherwise prepared, if such fish was caught in a manner which the Secretary of Commerce (Secretary) has proscribed for persons subject to the jurisdiction of the United States, whether or not any marine mammals were in fact taken incident to the catching of the fish. (16 U.S.C. 1372(c)(3)).

Contact information: For further information regarding the work of MERS to understand the risk of entanglement to Humpbacks: Email info@mersociety.org. Phone  250-956-3525 or 250-230-7136.

How important are herring to humpback whales?

Each spring, humpback whales in the eastern North Pacific Ocean travel from warm waters off Hawaii or Mexico up to the cooler, temperate waters off B.C. and Alaska.  What brings them back up here is food; the tropical and sub-tropical areas where humpback whales mate and give birth during winter have very little food for whales, so humpbacks must obtain almost all the energy they need for a year’s worth of activity while they are in our cold, rich waters during the summer and fall.

A humpback whale feeding on herring

Humpbacks feed on krill (small crustaceans), as well as small, schooling fish such as herring and sandlance.  Off B.C., however, it is not yet known how important different prey species are to humpbacks, or to what extent individual humpback whales may specialize on specific foraging locations and prey types.

In some areas, krill (these small crustaceans) make up a large proportion of humpback whale diet
In some areas, krill (these small crustaceans) make up a large proportion of humpback whale diet

In eastern Queen Charlotte Strait, herring congregate in dense schools, locally known as “bait balls”, during the late summer and fall.  Humpback whales in this area appear to specialize on herring during this time, targeting bait balls and lunge-feeding on them.  As part of my Master’s research through Simon Fraser University, I am working on estimating how much of humpback whales’ energetic requirements are obtained from feeding on these herring.

Humpback whale "Guardian" lunge-feeding on herring
Humpback whale “Guardian” lunge-feeding on herring

To help answer these questions, I need to estimate how often humpback whales are feeding on herring, and how much herring they consume each time they feed.  To predict how often humpback whales are feeding, I first identify a whale as an individual, and then watch it for an hour and record each time that it feeds and what type of prey it eats (tracking animal behaviour in this way is called “focal following”).  To figure out how much herring they eat during each feeding event, I have been taking underwater video of herring bait balls.  By also measuring the size of the herring in the bait ball, I can use their actual size, compared with their size on the video, to estimate the dimensions and therefore the volume of the bait balls.  By combining the results of the focal follows and bait ball videos with an energetic model for humpback whales, I can predict what proportion of the energy requirements of these humpbacks are provided by the herring bait balls that they are feeding on.

a dense school of herring, or "bait ball", filmed underwater

The results of my research will have implications for managing humpback whale populations.  Although human impacts such as overfishing and habitat degradation may not be sufficient to affect humpback whale prey species at the population level, they may cause depletion of these species on a local scale.  It is not yet understood whether B.C. humpback whales have the ability to easily switch to a different prey source and foraging location if availability of their preferred prey declines, so it is possible that local prey depletion may have impacts on humpback whales that feed in B.C.

A humpback whale breaching off the west coast of Vancouver Island
A humpback whale breaching off the west coast of Vancouver Island

This summer will be my second field season of gathering the information that I need to estimate how important these herring are to humpback whales in eastern Queen Charlotte Strait. Huge thanks to everyone who has helped out with and supported this study so far, especially Stacey Hrushowy, Jared Towers, and Jackie Hildering.

Click here to learn more about MERS humpback whale research, or here to donate to MERS’ work.  Also, please feel free to e-mail me at mersociety@gmail.com with any questions.

~ Christie