Southern Resident Killer Whales – What’s Going On?

Southern Resident Killer Whales (SRKW) have been in the news a lot lately (well the scientific and environmental news). A pregnant female washed up dead on a beach in British Colombia at the beginning of December and even more tragically was pregnant at the time which, has brought them further into the public eye.

All the SRKW belong to one clan – or “extended family” – therefore they are all related. This clan – J Clan – is made up of three pods – J, K , and L – with 77 individuals of which, only 12 are reproductive females. Four individuals of the population were lost this year which is a big blow for this small clan.

The populations is struggling to recover their numbers back to a viable level and in this post I will discuss why.

Prey Availability

Chinook Salmon. Photo: NOAA.

Chinook Salmon. Photo: NOAA.

SRKW favour Chinook Salmon almost exclusively feeding on it. The problem is that Chinook salmon are struggling to spawn and their numbers are also dwindling due to unsuitable habitats to spawn in. This means that SRKW are facing a depleted prey source and nutritional stress.

Nutritional stress has been shown to affect Glucocorticoids (cortisol) and thyroid hormone in killer whales. Glucocorticoids affect glucose metabolism for a quick response to an immediate threat over a short time frame (indicator of a short term stress), while thyroid hormone lowers metabolism to conserve energy stores over a longer time frame (indicator of long term/sustained stress).

Chinook salmon decline has been caused by activities such as logging and road construction have reduced the habitat condition degrading, fragmenting and eliminating key areas. To turn around their decline river habitats need to be restored to encourage spawning of salmon. This includes the removal/modification of dams on streams and the improvement of water quality and flow.

This issue can be fixed and would be a positive for both the killer whales and local fishermen.

Historic Capture

SRKW captured in 1964 - UBC professor Pat McGeer administers penicillin to Moby Doll at Burrard Dry Dock in North Vancouver in July 1964.  Photo Supplied, Vince Penfold. Via

SRKW captured in 1964 – UBC professor Pat McGeer administers penicillin to Moby Doll at Burrard Dry Dock in North Vancouver in July 1964. Photo Supplied, Vince Penfold. Via

In the middle of the last century the SRKW populations took a large hit when many members and sometimes whole families were removed in the live-capture industry.
Individuals/groups were removed to be put on display. With the removal of whole family groups the structure and populations numbers were severely disrupted. The SRKW were the most affected populations with 36 whales collected and at least 11 dying. There is nothing we can do now to correct this however there is a ban on the removal of all individuals in North America.


Happy #GivingTuesday!

After the excesses of the long week and weekend of Black Friday and Cyber Monday sales comes a day of relief and giving…Giving Tuesday! Today is a day where you can give back a little (or a lot) to a charity of your choice!

I thought I would give some of my favourite options this Giving Tuesday!

  • Oceans Initiative – now you know I love this group having had the opportunity to go out and see what they do and collaborate on my Masters research with them.
  • Jane Goodall Institue – she is an amazing lady and you can donate to help her and her institutes work against the illegal bushmeat trade among other important causes.
  • Channel Islands Cetacean Research Unit (CICRU) – a small but leading esearch group working on cetacean health who believe in “One Ocean, One Health”.
  • Sea Turtle Conservancy – working towards ensuring the survival of sea turtle species throughout the Pacific, Atlantic and Caribbean.
  • WildAid – a charity fighting illegal wildlife trade a cause that is extremely important and needs to be supported. It is close to my heart as I have good friends who work to fight illegal wildlife trade.
  • Ocean Conservancy – a big charity that do a lot of good work that covers vast areas of marine conservation rather than one specific cause.

This list is obviously not exhaustive and I will add to it when I can but, think about giving a little to an environmental charity and cause you believe in this Giving Tuesday!

Ocean Clouds

You can also follow along on the Deep Blue Conversations Facebook Page. I post interesting articles related to marine conservation, share awesome stories as well as photos from the marine conservation and environmental world in general. Come on over and have a look!

Positive News For Antarctic Sea Ice

The AUV SeaBED robot under the Antarctic sea ice (Photo : WHOI).

The AUV SeaBED robot under the Antarctic sea ice (Photo : WHOI).

A new robotic study conducted by a coalition of scientist from the United Kingdom, Australia and United States has shown that the Antarctic sea ice is thicker than previously thought.

The SeaBED autonomous underwater vehicle (AUV) has allowed for more in-depth sea ice analysis than scientists have previously been able to garner from drill data measurements, ship visual measurements (that are unable to access thicker areas) and satellite images (snow cover hinders analysis of images) alone. SeaBED is able to access areas that have previously been inaccessible to researchers.

The SeaBED AUV from Woods Hole Oceanographic Institution (WHOI) is fitted with a camera that enables it to map the underside of the sea ice. Maps were made of three regions of the continent; Weddell, Bellingshausen, and the Wilkes Land. The robot covered an area of 500,000 square metres, the size of 100 football pitches.

Scientist found that the sea ice has an average thickness of between 1.4 meters and 5.5 meters, with some areas having a maximum ice thickness of 17 meters. 76 percent of the ice that was mapped was found to be deformed, this suggests that over the winter period the ice floes repeatedly collided to create a large denser body of ice (“This is in contrast to what scientists previously understood from the Arctic, where larger sections of sea ice, under constant pressure, produce longer linear ‘ridge’ features.“).

Dr. Guy Williams from Institute of Antarctic and Marine Studies adds (co-author on the paper) adds that:


Impact of Marine Dredging on Marine Mammals – New Paper

Fascinating new paper out reviewing the likely impacts that dredging may have on marine mammals. The paper by Dr. Victoria Todd and colleagues can be read here.

It is a great review of the effects both positive and negative that dredging can have on marine life. I like that is has done this as I would have gone all BAD, BAD, BAD! However there are some positives. The paper focuses mainly on marine dredging although it is important to remember it also occurs in rivers and lakes.

Marine Dredger. Photo: United States Environmental Protection Agency (EPA) (

Marine Dredger. Photo: United States Environmental Protection Agency (EPA) (

Start with the bad…

The paper delves into the direct and indirect impacts of dredging on marine mammals and the potential severity of those.

The direct impacts are interactions that cause physical injury to mortality. These include Noise Pollution, Turbidity and Collision.

Noise pollution occurs at lots of different levels and in areas that are already heavily trafficked. Our knowledge of the hearing range of marine mammals is still limited so we can not be sure of all the effects. However it is possible that the noise emitted could cause masking of marine mammal calls particularly cetaceans. I talk about this more in this blog post. The effects are likely to be over the short to medium term and occur as behavioural changes such as area avoidance and call masking. All this will occur concurrently with other industrial activities so it is hard to tease out the specific impacts of just dredging.

In regards to collision, the slow speed of active dredgers means that there is low risk of collisions taking place especially if managed well and avoids critical habitat and calving areas. The bigger risk would be when dredging vessels are in transit but if this is occurring in an already heavily transmitted area as tends to be the case for dredging this won’t significantly add to the risk already in place.

The seabed disturbance caused by dredging leads to increased turbidity and sediment suspension. However, many marine mammals are use to turbid environments and limited vision is not an issue even for species that do not use echolocation for prey detection.

Indirectly marine mammals can be affected by changes to their environment and also to prey availability due to dredging. The paper lists the possibilities as:

  • Entrainment,
  • Habitat degradation,
  • Noise,
  • Remobilization of contaminants,
  • Sedimentation, and
  • Increases in suspended sediment concentrations.

Entrainment is the removal of species from their environment and while no data is available on this impact on marine mammals it has been noted that it can affect their prey species by removing them and their eggs along with the sediment. Therefore along as dredging is restricted during important egg and larval stages of prey species then effects are unlikely to be detrimental.

The degradation of marine habitats is something that I would be really worried about as dredgers go about their process especially since “45 case studies worldwide found that 21 023 ha of seagrass beds were lost as a result of 26 dredging projects over a 50-year period”. Sirenians (e.g. manatees and dugongs) are entirely dependent on seagrass beds while other marine mammals utilise them for prey and they are an important habitat for prey species. However, from this review I am enlightened to the fact that due to mitigation measure the impact on seagrass habitats has been reduced and that as long as mitigation is followed and planning is conducted with care the effects are minimal.