A Humpback With 11 Birds in His Mouth?
Humpback Whales and Their Bycatch
Over the years we at MERS have documented several cases of Humpback Whale bycatch; that is other animals that inadvertently end up in their mouths. This often occurs because Humpback Whales approach dense schools of Pacific Herring at great speed while other species are also feeding on them.
The other animals can thereby end up engulfed with the Herring. Then what happens? Consider that anything the size of a Gull or larger cannot be swallowed since the throats of Humpbacks are narrow and because, as baleen whales, they do not have teeth for chewing prey into smaller pieces.
We’ve previously shared the footage below of a Pacific Harbour Seal escaping from the mouth of a trap-feeding Humpback Whale.
Video by Gord Thompson and Dennis and Stephanie Parsons.
We’ve also documented Humpback Whales opening their mouths to release birds like Common Murres. See photos below of a Common Murre escaping from Guardian the Humpback Whale’s mouth.
On many occasions, we have also documented bycaught Gulls. The afternoon of October 18th was no exception.
From our research vessel Merlin we noticed in the distance an adult Humpback we know as Backsplash lunge feed at the surface on a large school of Herring that was being fed on from below the surface by Common Murres and from above by Herring and California Gulls.
When we arrived about three minutes later Backsplash was slowly circling the remains of the school of Herring and then lunged on it again, effectively capturing all or most of the remaining fish that were left over from the first lunge. Seconds later Backsplash opened his mouth at the surface, vigorously shook his upper jaw and 11 Gulls came floating up to the surface.
We approached the scene and could see all Gulls were completely saturated – 9 appeared dead (from impact or drowning), and 2 were clinging to what appeared to be their last moments alive. We immediately grabbed the two survivors, both immature Herring Gulls, and wrapped them in a dry towel that I happened to have aboard.
We then noticed that one of the birds we previously thought was dead was resting itself on the floating body or another. There was no room in the towel for this bird, a young California Gull, so I texted our colleagues at nearby OrcaLab on Hanson Island and we raced over for some support.
Moments later we were met on shore with towels and over the next little while dried off the birds while sitting next to the wood stove. We ended up leaving one of the Herring Gulls and the California Gull with our friends at OrcaLab and took the other Herring Gull back home to Alert Bay.
Once completely dry all birds were released at the shoreline. They each took to the water and then the sky, although the final fate of the poor California Gull is apparently unknown because it subsequently escaped attack by a Bald Eagle but then moved out of sight while the hunt was still in progress, as if being captured by a Humpback Whale wasn’t already enough!
I’m a strong believer that we should always be conscious of our impact on the environment and its inhabitants and this often means not interfering in interactions between predators and prey. However, in a case such as this where the by-product of a feeding predator happens to be some incidentally captured Gulls I have always felt compelled to help out, even though the Gulls typically appear resentful and aggressive as soon as they are warm and dry again.
Blog written by MERS team member – Jackie Hildering Education and Communications Director, Humpback Researcher, MERS Co-Founder
Try to stop the tears from welling up in your eyes. I couldn’t. Because this is where hope, whales, and children intersect.
If you were in Canada in 1980 and of an age to understand the magnitude of what Terry Fox was striving to do, just an image of him will already make you emotional.
Terry Fox was a beacon of hope, courage, integrity, positivity, strength and defiance of cancer. He was only 18 when he lost most of his right leg to bone cancer.
He was 21 when he dipped his artificial leg into the Atlantic Ocean and began his “Marathon of Hope” on April 12, 1980. He planned to run across Canada, from Newfoundland back to his home in British Columbia, to raise money for cancer research
He ran for 143 days, covering 5,373 kilometres and then Terry had to stop. The cancer had spread to his lung. He had run as far as Thunder Bay, Ontario.
He was one month short of turning 23 when he died on June 28th, 1981.
BCX1100 is a Humpback Whale. This is one of the Humpbacks that has been seen this year near Port Alice on NW Vancouver Island.The whale was documented travelling with Humpback “Whiskers” and her 2019 calf by photographer Darrell McIntosh. As is the case for so many areas off British Columbia’s coast, we have a second chance with these giants. The whales off Port Alice are part of a Humpback comeback to where they used to be whaled (up to 1966).
Note in the photo above that Humpback BCX100 has an injured fluke. The right side is limped over. We do not know the cause. The injury dates back to before 2010 and possible causes include vessel strike and entanglement.
“Whiskers” is the nickname for Humpback BCZ0200 (photo below). Catalogue designations like “BCZ0200” are difficult to remember so we nickname the Humpbacks for distinctive features. See what looks like a cat face on Whiskers’ tail?
Sure you do!
These nicknames allow for the potential for greater public engagement and thereby, conservation. The nicknames also really, really help us recognize the whales which is the foundation of all our other research.
When we learned that Whiskers had a calf this year and had been sighted outside Port Alice, we of course wanted local children to suggest nicknames. Then Darrell also documented the other whale with mom and calf, whereby we asked the children to suggest a nickname for both Whiskers’ calf and BCX1100.
There are just 37 students at Sea View School in Port Alice. I had a video call with them while we were on the water on the other side of Vancouver Island doing Humpback research. In the call I helped explain how the nicknames were like a clue for who the whale was. We discussed the most identifiable features of the two whales and they asked questions that reflected concern for the whales and how the whale with the injury might not be able to swim as well as other Humpbacks.
And then it came – the message that the students had come up with their suggestions. They thought that BCX1100, the whale with the injured right fluke who was able to make it all the way to Port Alice from Hawaii or Mexico despite a handicap, should be nicknamed . . “Terry”.
The tears. Oh the tears. To get personal here, I was 16 when Terry Fox began his Marathon of Hope. I graduated from high school shortly after he died. His life ended. My adult life was just beginning.
To this day, at age 56, I have the paper on which my 16-year-old hand wrote this quote from Terry:
“How many people do something they believe in? I just wish people would realize that anything’s possible if you try – dreams are made if people try”. Terrence Stanley Fox.
He had an undefinable yet undeniably large impact on who I am and the strength for which I strive to stand for what I believe in: nature, whales. . . children. For me it is always about the best chances of lives of hope and meaning for children.
Tomorrow, on September 26th, the children in Port Alice and across Canada will participate in the 38th annual Terry Fox School Run.
From the Terry Fox Foundation webpage: “Terry showed us all that the impossible is possible. He reminded us all that we can make a difference in the world and change people’s lives for the better.”
The children of Port Alice are certainly making a difference.
Friend, school secretary and driving force – Natalie Stewart. We are hoping there will be media interest in this story.
Please contact Natalie at email@example.com, (250) 284-3315.
Photographers – Darrell McIntosh, David Love, Douglas Bradshaw
Principal of Sea View School – Gloria Gadacz
Heather Jack – Grades K/1
Rebecca Herbert – Grades 2/3/4
Brenda Karch and Rhiannon Heim – Grades 5/6/7 & 10
Kathleen O’Reilly – North Island Eagle
Many other Port Alice community members:
And what was the nickname chosen by the students for Whiskers’ 2019 calf? Poseidon!
Notice the distinctive white lines on the calf’s tail that look like Poseidon’s trident? The students understood that this was the most distinctive marking that would likely still be discernable as the calf aged. The light white colouration on the tail will likely fade.
In the height of summer, when MERS research, education and response work is at its peak, and our new office is full of busy summer staff, it is hard to believe that this organization started a mere nine years ago as a group of friends wanting to better understand and protect marine mammals in British Columbia (with our core study area and base being Northeastern Vancouver Island).
We have grown so much in nine years and there is so much more to come.
It’s time to grow our team once again! To help support and nurture MERS, we need more hands-on-deck. Could this be you?
This fall, we are looking to add up to two new volunteer board members to help guide this organization into its second decade of operation and make an even bigger positive impact on marine conservation along B.C.’s coast.
Interested? Here are the details:
Board Member at Large – potentially two positions available
Board of Directors position / unpaid
MERS Marine Education and Research Society
Preferably British Columbia, but candidates from other areas considered
A Little About Us: The Marine Education and Research Society (MERS) is a registered Canadian charity dedicated to promoting conservation and understanding of marine ecosystems through scientific research, environmental education, and marine wildlife response. We are based on Vancouver Island, British Columbia and incorporated in 2010.
Our team is comprised of marine biologists and educators highly dedicated to marine conservation. While based on Canada’s west coast, team members have worked in many countries and oceans. Click here for background on our team.
We are a small organization doing big work.
Our research is primarily focused on investigating Humpback and Minke Whales, and that the threats that impact them in British Columbia. We also provide marine wildlife monitoring and incident response. Education is key to our strategy to reduce risks to marine species. Our work includes the See a Blow? Go Slow! campaign to reduce the risk of collision between whales and boaters and How to Save a Whalewhich educates about whale entanglement. MERS educational activities also include a comprehensive outreach plan of presentations, workshops, training sessions and programs aimed at a wide audience.
Responsibilities of the Board Member:
Provide leadership to MERS and help to set our strategic direction
Provide oversight and ensure new projects align with our established mission, vision and values
Provide governance and ensure MERS and its board adhere to by-laws
Attend and participate in bi-monthly board meetings (via teleconference)
Participate in fundraising initiatives
Help to spread the word about our organization and our work
Assist the organization in attracting the expertise, funding and resources needed for MERS to better achieve its goals
Attend bi-monthly board meeting, participate in at least one sub-committee and participate in an annual weekend-long board retreat/planning session
Qualifications: MERS is currently seeking candidates with the following skills and expertise:
Experience in/commitment to environmental issues;
Experience on not-for-profit boards or strong willingness to learn; and
Fundraising experience and knowledge.
Marketing, Communications or PR;
Accounting or Finance.
A two-year commitment is requested of all Board Members.
Candidates who feel they have other skills or experience that is applicable to our mission are also encouraged to apply.
To Apply: Please send a note about your relevant experience, skills and interest in MERS, and a CV to firstname.lastname@example.org before September 30th.
Our MERS board is a fantastic group of professionals dedicated to guiding MERS as it grows, providing solid governance, insight AND oversight, sharing their skills, and ensuring MERS fulfills its mission and strategic plan.
If you are looking for a meaningful way to make a difference in the world of marine conservation, apply to join our board today!
Marine Education and Research Society Office Assistant – Outreach / Retail / Data Part-Time
The Marine Education and Research Society (MERS) is a non-profit organization dedicated to promoting conservation and understanding of marine ecosystems through scientific research, environmental education, and marine wildlife response. We are based in Port McNeill, on NE Vancouver Island. For information about MERS’ research, education and wildlife response efforts, see www.mersociety.org.
The Office Assistant will be essential in MERS’ efforts to educate the public about local marine mammals and boater safety, and to study and protect marine mammals in British Columbia. The focus is on Humpback Whales with our research dating back to before 2004. With Humpback Whales having made an astounding comeback to the coast of BC, it necessitates a better understanding of this population. This includes education for boaters about how to mitigate the threats of entanglement and vessel strike to Humpbacks, as this species behaves very differently than the Killer Whales most boaters are accustomed to (see our “See a Blow? Go Slow!” campaign at www.SeeABlowGoSlow.org.
Key to understanding the population is for the whales to catalogued and identified as individuals.
This position also has a retail component whereby funds are raised for our work.
Duties will include:
Greeting visitors and aiding in MERS’ work to serve as a resource to the local community (with a focus on local ecotourism and boat operators) in order to: enhance the value of wildlife viewing experiences; contribute to boater safety; and reduce risks to marine life.
Processing retail and donation transactions to help support MERS’ efforts.
Maintaining a clean and presentable office and retail space.
Conducting ID matching, data entry and database management for Humpback Whale sighting and photographic data.
Other office-based work as needed.
Have knowledge of the biology and ecology of marine mammals in British Columbia. It is a significant asset to have completed a MERS Marine Mammal Naturalist Workshop.
Familiarity with POS systems and cash handling.
Work well independently and with minimal supervision.
Have exceptional organizational skills.
Have proven successful experience with public outreach and science communication.
Have strong computer skills. Previous experience with some or all of the following programs is an asset: Microsoft Excel, Photo Mechanic, Filemaker, Adobe Lightroom, and QGIS.
Able to demonstrate strong abilities in matching whale flukes and fins for identification.
Have proven dedication to reducing impacts to the environment.
Reside near Port McNeill and have strong local knowledge.
Based on experience (minimum $15/hour)
Part-time (12 hours/week; 2 x 6-hour shifts; Friday and Saturday )
Anticipated start date of September 20, 2019
August 18, 2019.
Interviews may be conducted before the application deadline.
Applications must include a cover letter specifically addressing position requirements, resume, and 3 references (name, position and email address) with a minimum of 2 being employment contacts.
Announced yesterday, the protection of Fin Whales off Canada’s Pacific Coast is being reconsidered.
The independent panel of experts tasked with assessing species potentially at risk in Canada is the Committee on the Status of Endangered Wildlife in Canada (COSEWIC). Their May 2019 recommendations include that Fin Whales off Canada’s Pacific coast be down-listed from “Threatened” to of “Special Concern”. If this reassessment is accepted by the Federal Government, it means the population would receive less protection under Canada’s Species at Risk Act (SARA) e.g. critical habitat would not be assigned and there would be no prohibitions under SARA that make it “an offence to kill, harm, harass, capture, or take an individual of the species”
While it is very positive that Fin Whale numbers appear to be increasing after having been intensely whaled prior to their protection in 1976, the reassessment is based on the data for Fin Whale abundance in US waters. There is no population estimate nor confirmed trend for the number of Fin Whales in Pacific Canadian waters.
This current absence of information is a concern were the decision to be made now to change the status of Fin Whales under SARA. It is all the more a concern since ship strikes are known to be a significant threat for Fin Whales and that vessel traffic off the coast of British Columbia is increasing.
Also from the SARA Recovery Strategy: “Blue and Fin whales often occupy shelf-break locations that frequently coincide with shipping lanes, which concentrate large vessel traffic. In a review of 292 records of ship strikes, Jensen and Silber (2004) reported that Fin Whales were the most commonly struck species . . . However, ship strikes offshore are more likely to go undetected. The mortality rate associated with ship strikes is 70-80% (Jensen and Silber 2004).”
From Nichol and Ford (2018) “Ships travelling at speeds above 10 knots in close proximity to Fin Whales have a relatively high probability of colliding with whales (Vanderlaan and Taggart 2007). Although it is difficult to quantify the frequency with which ship strikes involving Fin Whales occur, evidence (in the form of dead carcasses) confirms this species is struck by fast moving ocean going vessels. It is not known whether the possibility of being struck affects the behaviour of Fin Whales, but it is possible that expending energy to avoid ships displaces Fin Whales from important life activities of foraging and breeding (McKenna et al. 2015). Shipping traffic that results in a loss of foraging opportunities and mating opportunities in otherwise important habitat, should be considered a reduction in the area available for foraging and mating in the critical habitat.”
And from Nichol et al (2017)“Ship traffic is predicted to increase as a result of port expansions and developments in both BC and Washington State. We therefore tested future shipping projections from two sources and incorporated these predicted increases in ship traffic into our models to estimate the change in relative risk of ship strike and lethal ship strike by 2030 . . .” There was estimated to be a “10.5-fold difference in average lethal strike risk between high-risk locations and the remainder of the study area in 2030.”
We will update here as more information becomes available about what process there might be to provide input into these concerns.
Marine Education and Research Society Summer Positions:
Data Analysts/Outreach Assistants (2)
The Marine Education and Research Society (MERS) is a non-profit organization dedicated to promoting conservation and understanding of marine ecosystems through scientific research, environmental education, and marine wildlife response. We are based in Port McNeill, on NE Vancouver Island, British Columbia. For information about MERS’ research, education and wildlife response efforts, see www.mersociety.org.
The Whale Data Analysts / Outreach Assistants will be essential in MERS’ efforts to study and protect marine mammals in British Columbia. The focus is on Humpback Whales with our research dating back to before 2004. With Humpback Whales having made an astounding comeback to the coast of BC, it necessitates a better understanding of this population. This includes education for boaters about how to mitigate the threats of entanglement and vessel strike to Humpbacks, as this species behaves very differently than the Killer Whales most boaters are accustomed to. Key to understanding the population is for the whales to catalogued and identified as individuals.
The work of the Data Analysts / Outreach Assistants includes conducting preliminary analyses of Humpback Whale sighting and photo-identification data as part of our collaboration to update the province-wide catalogue for Humpback Whales off the coast of British Columbia. This project is being conducted in collaboration with DFO and with colleaguescataloguing Humpbacks in other parts of coastal British Columbia andwill allow for enhanced knowledge of the abundance, habitat use, social associations, movements, and threats of Humpbacks in B.C., for the purpose of conservation. In addition, the Data Analysts / Outreach Assistants will contribute to expanded educational outreach in local communities by promoting MERS’ “See a Blow? Go Slow!” campaign (www.SeeABlowGoSlow.org) to educate about the presence of Humpback Whales around Vancouver Island, help promote boater safety, and provide information about the Marine Mammal Regulations.
Duties will include:
Conducting comparative analyses of BC Humpback Whale catalogues to determine the identification of individual whales;
Data entry and database management for Humpback Whale sighting and photographic data;
Assisting in supervising volunteers during data entry and photographic data analysis in order to maintain the quality of the MERS databases;
Aiding in MERS’ work to serve as a resource to the local community (with a focus on local ecotourism and boat operators) in order to enhance the economics/value of wildlife viewing experiences and contribute to boater safety;
Conducting community outreach at local events, marinas and docks to increase awareness of threats to whales and how to mitigate them.
Other office-based work as needed. The Data Analysts/Outreach Assistants will gain experience with Microsoft Excel, Photo Mechanic, Filemaker, and Adobe Lightroom computer programs.This is an office-based position but there may also be some opportunities for the Data Analyst to accompany MERS researchers on boat-based surveys to collect Humpback Whale photo-identification data.
Are Canadian citizens, permanent residents or have refugee protection under the Immigration and Refugee Protection Act.
Have graduated from or are undertaking post-secondary education in scientific fields, especially biology, environmental science, resource management or related field.
Have knowledge of the biology and ecology of marine mammals in British Columbia.
Are between 15-30 years of age (funding requirement).
Have strong computer skills. Previous experience with some or all of the following programs an asset: Microsoft Excel, Photo Mechanic, Filemaker, Adobe Lightroom, and QGIS.
Work well independently and with minimal supervision.
Have experience with data entry.
Have exceptional organizational skills.
Are able to demonstrate strong abilities in matching whale flukes and fins for identification.
Have proven successful experience with public outreach and science communication.
Have proven dedication to reducing impacts to the environment.
Are able to reside in Port McNeill for the duration of the contract.
Work term: 8-week contract at 35 hours/week with an anticipated start date of June 3rd, 2019
Hiring priorities: Youth who self-identify as being part of underrepresented groups or have additional barriers to the labour market e.g. women in STEM, Indigenous youth, and youth who are recent immigrants or refugees.
Application deadline: May 10, 2019
Application format: Applications must include a cover letter specifically addressing position requirements, resume, and 3 references (name, position and email address) with a minimum of 2 being employment contacts. Applications should be emailed to MERS Operations Director: email@example.com
References of short-listed candidates contacted.
Short-listed candidates interviewed via SKYPE.
Final interviews held in person in Vancouver, Victoria or Port McNeill. Candidates will be asked to complete an exercise to assess their ability to match whale IDs.
Please note that only short-listed applicants will be contacted and that this would happen before May 17th.
The following is intended as a fact-based resource with regard to considerations around killing seals and sea lions off the coast of British Columbia. This resource will be updated with additional research and sources.
It has been catalyzed by our being asked questions by media and members of the public due to:
(1) The “Proposal for Commercial Harvesting of Pinnipeds* in British Columbia” which has been put forward to Fisheries and Oceans Canada by the Pacific Balance Pinniped Society (PBPS). *”Pinnipedia” is the group name (infraorder) to which seals, sea lions and walruses belong. The target pinniped species in the Proposal are Pacific Harbour Seals, Steller Sea Lions and California Sea Lions.
(2) Recent shootings and disturbances of pinnipeds leading to increased public attention to seal and sea lion populations in British Columbia.
Examples of March 2019 headlines:
What is the “Proposal for Commercial Harvesting of Pinnipeds in British Columbia”?
While the Proposal is not currently available to the public, there has been considerable media attention to the Proposal and the Pacific Balance Pinniped Society allowing for the following insights:
The Proposal is for a harvest, not for sustenance hunting. Considerations include marketing the meat to China and Europe (Zussman, 2018andPBPS, 2019).
The rationale provided for the harvest includes the thinking that killing seals and sea lions would leave more Chinook salmon for endangered Southern Resident Killer Whales (currently at only 75 members).
Quotes provided by Pacific Balance Pinniped Society board members indicate that the proposal is for killing up to 50 percent of BC’s seals and sea lions(Rasmussen, 2018).
The Proposal would have to receive Federal approval to be exempted from the Marine Mammal Regulationsunder which it is illegal to harm or disturb a marine mammal.
The Pacific Balance Pinniped Society “was established in July 2018 and includes a number of First Nations, commercial and sport fishers and fur industry representatives” (Larsen, 2019).
The screen shot above shows abundant sea lions during the fishery for Pacific Herring. It is from a video by Shalaine Lawson posted on social media on March 15th, 2019 . It is included here to help provide understanding of why there are frustrations and further negative emotions regarding seals and sea lions during these localized events where the overlap between humans and pinnipeds is extreme.
Emotions may be amplified as a result of concern for the endangered Southern Residents and the potential of additional fishing restrictions impacting livelihoods.
Great caution is required where emotions run high on both sides of an issue and may include animosity and vilification. In such cases, decisions with far-reaching consequences have high risk of being impacted more by politics and perception, than by facts and precaution.
Are seals and sea lions responsible for the decline in the numbers of endangered Southern Resident Killer Whales?
The number of Pacific Harbour Seals off the coast of British Columbia has not increased in 20 years. Yet the population of endangered Southern Residents has declined significantly. In fact, the total number of Southern Residents increased for a few years after the number of seals reached carrying capacity. See graphs below.
The current population size of Pacific Harbour seals, now at carrying capacity, appears to be similar to pre-exploitation levels that occurred in the 1880s when salmon would have been plentiful (Olesiuk, 2010).
Steller Sea Lions are protected as a species of Special Concern under Canada’s Species at Risk Act. This means that they are an at-risk species that may become threatened or endangered because of a combination of biological characteristics and identified threats (Fisheries and Oceans Canada, 2010 with reassessment in 2013 and Chandler et al, 2017).
It is worthy of note that research near the Scott Islands, BC (Spalding, 1964) found that there was little evidence that historical culls had positive effects on salmon stocks. As quoted in COSEWIC, 2013 “there is little evidence that Steller Sea Lion control programs had any beneficial effect on fisheries as salmon catches did not increase noticeably following the reduction of sea lion numbers.”
California Sea Lion numbers have increased steadily since the 1970s. The population is reported to have reached carrying capacity as of 2008. However, research also found that population growth can decrease dramatically with increases in sea surface temperatures (research from NOAA Fisheries’ Alaska Fisheries Science Center and Southwest Fisheries Science Center, NOAA Fisheries, 2018andLaake et al, 2018).
Source of above graph: NOAA Fisheries, 2018.Caption provided: “California Sea Lion numbers have grown steadily since the 1970s . . . The yellow band reflects the approximate population size, while K represents carrying capacity and MNPL is maximum net productivity level (the population level for maximum growth). The range above MNPL and below K is the optimum sustainable population, which the Marine Mammal Protection Act [USA] sets as the goal for protected species.”
See further detail on population numbers near the end of this blog.
What are potential unintended impacts for other species?
Impacts to Mammal-Eating Killer Whales
Seals and sea lions are of great importance in the diet of mammal-eating Killer Whales known as Bigg’s Killer Whales (also known as “West Coast Transients”).
This is a distinct population protected as threatened under Canada’s Species at Risk Act. They are genetically, acoustically, and culturally distinct from other Killer Whale populations.
It is believed that reductions in pinniped populations negatively impacted Bigg’s Killer Whales and that their recent resurgence is directly correlated to the number of seals.
FromFord et al. 2013: “Large scale culls and harvests of pinnipeds in the late 1800s to mid 1900s depleted populations of Harbour Seals and Steller Sea Lions (COSEWIC 2003; Olesiuk 2010). This likely had a major effect on the abundance and distribution of WCT whales [West Coast Transients] in BC waters. Occurrence of WCT whales in the Strait of Georgia has shown a strong increase over the past four decades, associated with the return of Harbour Seal abundance to historical levels in this area (Ford et al. 2007).”
The Recovery Strategy for Bigg’s Killer Whales (West Coast Transients) includes the following as a recommended approach to address threats and aid in the recovery of this population, indicating that a seal and sea lion harvest would be in violation of this recommendation: “Maintain current harvest restrictions and ensure research, nuisance seal, or other authorized removals do not cause pinniped population level reductions” (Fisheries and Oceans Canada, 2007).
Harbour Seals compose 52% of Bigg’s Killer Whales’ diet, and Steller Sea Lions compose 13% .Thereby, these two species alone make up 65% of the prey consumed by these whales (Ford et al 2013).
Though Bigg’s do consume other marine mammal species (e.g. Harbour Porpoises, Dall’s Porpoises, Pacific White-Sided Dolphins, Minke Whales), the foraging efficiency and energetics for different prey types are not well understood. The size and speed of other potential prey may make it less energetically profitable for Bigg’s Killer Whales to forage on these prey types instead of seals and sea lions. Seals are predictable in where they can be found and do not have defences like the speed of dolphins and porpoises.
Further, maintaining sufficient prey availability for Bigg’s Killer Whales depends on more than just the overall number of seals, seal lions, and other prey species. They also need a sufficiently wide distribution of prey to be able to forage effectively.
Research from Ford et al 2013 that provides insight into why this is needs to be a consideration includes that Bigg’s Killer Whales most often hunt by stealth and surprise attack. Once the element of surprise is gone, with prey knowing their predators are in the area, it is likely more profitable for a group of Bigg’s Killer Whales to a new area in search of new prey unaware of their presence.
Note that there is considerable misunderstanding of the total number of Bigg’s Killer Whales (West Coast Transients) off the coast of British Columbia. The last published population estimate is 304 individuals in the inner coast subpopulation (DFO, 2013). In addition to this and, importantly, not included in previous WCT population estimates, is knowledge about additional mammal-eating killer whales that are typically much further off BC’s coast i.e. “an additional 217 rarely-seen individuals are considered to be members of the outer coast WCT subpopulation. The inner coast subpopulation appears to be increasing. The status of the outer coast subpopulation is unknown. (DFO, 2013)
Other considerations regarding potential ecosystem impacts?
Seals and sea lions are opportunistic predators that feed on other fish species, including Hake and Pacific Herring (Barrett-Lennard, 2018).
Hake feed on juvenile salmon. Thereby, a reduction in the number of pinnipeds could lead to an increase in the number of Hake, and thereby fewer salmon. (Barrett-Lennard, 2018).
Pacific Herring compete with juvenile salmon. Thereby, a reduction in the number of pinnipeds could lead to an increase in this salmon predator at salmon at a critical stage of their development. (Barrett-Lennard, 2018).
Note that there are more than 135 other species that predate on salmon in addition to seals and sea lions (Wallace, 2018).
For further understanding of how to assess potential success of harvests or culls, please see the video and table below from the presentation “Will Seal Culls Save the Southern Resident Killer Whales“ by Dr. Lance Barrett-Lennard of the Coastal Ocean Research Institute provided at the 26th Annual BC Marine Mammal Symposium on November 24th, 2018.
Do seals and sea lions eat a lot of salmon?
Some seals and sea lions in some areas eat a lot of salmon (and herring).
However, caution is very much needed in extrapolating these localized and seasonal studies to inform management decisions across larger geographic areas for larger units of time.
For example: Preliminary research by Sheena Majewski, DFO, using DNA analysis of non-estuary seal scat samples, reveals the following shift in diet between spring and fall. (Pynn, 2018).
Further research is being conducted to better inform coast-wide and year-round understanding of seal and sea lion diet to address knowledge gaps. As per the information above however, due to the complexity of marine food webs, there will always be some uncertainty about their diet and how it impacts other species.
Further detail on population numbers and history of culling pinnipeds in British Columbia:
Updated estimates based on 2016-17 data anticipated for this fall/winter (2019).
“The Pacific Harbour Seal population in B.C. suffered significant declines as a result of commercial fur harvests (1879- 1914, 1962-1968) and predator control programs (1914-1964). By the time the species was first protected in B.C. in 1970, the coast-wide population had been reduced to an estimated 10,000 seals, but it has since increased dramatically (Majewski & Ellis In press). Current coast-wide abundance (approximately 105,000 seals) is considered to represent a successful recovery to pre-exploitation levels (Majewski & Ellis In press). In the Strait of Georgia, Harbour Seal numbers grew at a rate of 11.5% annually (95% CI 10.9-12.6%) from 3,600 individuals in 1973 to 39,000 in the mid-1990s, when numbers stabilized (Majewski & Ellis In press; Figure 25-3).” (Chandler et al, 2017).
“Steller Sea Lions were depleted by commercial harvesting and predator control programs that removed 55,000 animals between 1912 and 1968. By the 1970s, the B.C. breeding population had been reduced to 25-33% of peak historic levels (Olesiuk, 2018). The population began rebounding in the early 1970s, with non-pup numbers shifting from stable to 4.9% growth annually in the early 1980s (Figure 25-4). Pup abundance also exhibited an increase in annual growth rate in the mid-1980s, up from about 1.7 to 7.0% per year (Olesiuk In press). The summer 2013 breeding season survey estimated 39,200 (95% CI 33,600-44,800) Steller Sea Lions coast-wide, slightly lower than the winter 2009-2010 population estimate of 48,000 (95% CI 38,100-58,900) (Olesiuk, 2018). The Steller Sea Lion was designated as Special Concern by COSEWIC in both 2003 and 2013, and has also been legally listed under SARA at the same level” (Chandler et al, 2017).
“Market hunting, bounties, pollutants such as DDT and other forces depressed [California] sea lion numbers in the middle of the last century . . the species then rose from less than 90,000 animals in 1975 to an estimated 281,450 in 2008, which was roughly the carrying capacity for sea lions in the California Current Ecosystem at that time. It then fluctuated around that level, reaching a high of 306,220 in 2012 before declining below the carrying capacity in the years since as ocean conditions changed” (NOAA Fisheries, 2018).
Ford, J.K.B., G.M. Ellis, and J.W. Durban. 2007. An assessment of the potential for recovery of West Coast transient killer whales using coastal waters of British Columbia. DFO Can. Sci. Advis. Sec. Res. Doc. 2007/088. Iv + 34 pp.