At the Friends of Skagit Beaches Annual Meeting this past week, Emily Grason, PhD, came and spoke to us about the European Green Crabs that have been found in our area. She works for WA Sea Grant - a program run by the College of Environment at the University of Washington.
Why is this important?
Because the European green crab is one of the worst invasive species on the planet. They disrupt and threaten our native species habitats - and these little guys aren't ever going to be hunted for their tasty flesh. They are little - think about a woman's fist as the size of the shell at their largest size.
I've been hearing about the green crabs over the last year - especially last summer when 4 were found in Padilla Bay. The first green crab in the inland waters of the Salish Sea was caught over in Westcott Bay on San Juan Island earlier last year. Link to press release
The European green crab came over to the east coast of the United States early in the 19th century. That population is still increasing its territory. The east coast green crabs were found in San Francisco bay in 1989. They knew where these greens came from due to genetic testing. It has been theorized that El Nino events in the Pacific have brought the green crabs up the coast to the Pacific Northwest.
It was in 2012 that a well established colony in Sooke Bay was discovered.
The Crab Team started up in 2015 with the goal to use citizen science to monitor habitats that the green crabs like. They have 26 sites up and down the sound with 100 volunteers. The volunteers use baited traps, molt searches and habitat (soils) monitoring.
It's not easy to catch these little guys - and they are little compared to our full-size Dungeness and Rock crabs. They do take over habitats of the little hairy crabs - those muddy, salt water embankments and eel grass beds.
Shore crabs the Hairy shore crab and (bottom) the
Purple shore crab
"Both native shore crabs can be green in color but have only 3 marginal teeth (from eye heading back on the carapace)." - from Crab Team webpage
Crab team gets a lot of calls about our little friends to the left - so its good to know how to identify our native shore crabs against the characteristics of the European green crab - who preys on these guys as well as the juvenile dungeness crabs that like the same habitats for growth and nourishment.
The green crabs that turned up in Westcott and Padilla bay most likely washed into the Strait of Juan de Fuca about a year ago as a larvae group - possibly from Sooke. It is illegal for ships to clear their ballast tanks in the NW - which is probably how the crabs came across the Atlantic years ago. There isn't any sign of colonies establishing themselves.
Dr. Grason laid out Where Do We Go From Here?
If we do nothing: There is a high likelihood that we will see a hit in our seafood and not just because they are eating little dungeness crabs. Crabs like shellfish - a lot. They also destroy eel grass beds. Our grass is a bit different then what is off the Atlantic, but the damage would still be felt in all the other species that utilize eel grass as a habitat. We're talking forage fish that salmon eat and the other critters up the food chain.
How to manage this invasive species: Trapping is still the best option. Some other ideas have been floated that - things like introducing a parasite that stops them from breeding - but unfortunately those options would impact other crabs as well. It was also be helpful if British Columbia @ Sooke took the invasive colony seriously and attempted to control it.
Best Next Steps: To continue with volunteer monitoring. She proposes to make sure residents and shellfish growers stay vigilant.
What to do if you think you spot one? TAKE PICTURES ONLY, take down as detailed of location as you can (coordinates on a phone compass are great) and report it to crabteam@UW.edu.
Dr. Calambokidis put on a great presentation detailing some of the latest findings on the other whales that utilize the Salish Sea.
Regarding Humpback Whales:
The SPLASH study - Structure of Populations, Levels of Abundance, and Status of Humpbacks - involved over 400 researchers from 10 different countries between 2004 and 2006 in the Pacific Oceans. It was the largest collaborative study of its kind and its goal was to expand the working knowledge around migratory patterns for Humpback whales. Using photo identification (those flukes) and genetic studies some very interesting data was unearthed.
First of all, the study identified approximately 20,000 animals. Dr. Calambokidis described one of the primary patterns that they discovered was that humpback "herds" stayed loyal to certain feeding areas. You might have multiple "herds" in Hawaii but they would travel to different areas in Alaska or the Bering Sea for feeding.
Researchers have been able to identify 14 distinct populations around the world. Some of these populations have been delisted from the Endangered Species Act, while some are listed as threaten or endangered. As an example, the Hawaii population has been delisted, while the Mexico population is listed as "threatened" and the Central Americal population is listed as "Endangered." All of these population migrate north and feed in the cold waters off of Alaska.
A question: How do we apply conservation where it is needed?
Another question that has arisen due to the fact that the number of whales seems to have leveled off - has the Pacific reached its carrying capacity for Humpbacks?
As a matter of fact, there have been areas of expanded territories - which includes San Francisco Bay and the Salish Sea. In the Salish Sea, the estimated abundance has gone from about 100 - 500 from 1995 to 2016.
The fact is, however, that the humpbacks are returning to the Salish Sea - they were here before. They were abundant enough that in the early 1900s there was a whaling station off the south end of Vancouver Island. That whaling station decimated the humpback population. It is hypothesized that it has taken this long for the humpback whales to recolonize this region.
The Eastern Pacific gray whales breed off the coast of Baja and travel up along the coast to the Artic waters. There are many subsets of this group that are designated by their feeding areas. The subset of most interest to us here in the Salish sea has the designation PCFA (Pacific Coast Feeding Aggregation) - but the feeding areas are further broken down into SJF (Strait of Juan de Fuca), NWA (North Washington Coast), and SVI (Southern Vancouver Island). Only a small number - estimated around 200 - gray whales are sticking around the Salish Sea over the summer months (sighted between June 1 and November 30th) while most migrate much farther north. Read the study.
(And if I have some of my facts wrong or confused, let me know!)
A question the Macah tribe needs to currently answer is which population they can take their yearly quota of whales from.
One of the most interesting activities Dr. Calambokidis talked about was the high risk feeding strategy that some gray whales are engaged in here. Off the east side of Whidbey Island where the muddy sediment is rich with ghost shrimp, these gray whales are feeding in sometimes six feet of water.
Gray whale feeding pits off of Everett courtesy of Google Earth
Findings have found that the years when the number of gray whales is higher who practice this off-migration feeding corroborates data on gray whale strandings and mortality events. This makes sense given how shallow the waters are in the specific area where the whales are feeding. Dr. Calambokidis and his team were asked to come in and determine whether the whales were feeding in any other areas and through the use of tag sensor data, they found out that the gray whales were exclusively going after the ghost shrimp in the shallow waters.
One of the things that seemed to come out of this gray whale study - or at least the impact I felt - was that by collecting data on the activity of the whales helped answer a very specific question regarding the needs of the animal - and helped humans craft a response.
Dr. Calambokidis then spent some time talking about different tagging strategies that have been used. Satellite tags are anchored in muscle and last longer but the the data collected is very limited. Limpet tags have a more medium duration and again, are invasive - thru the skin. There are concerns and issues with both of these types of tags especially after one of the southern killer whales washed up on shore after being tagged with the limpet tag. Dr. C and his team use suction cup tags that record a ton of data but may only stay on for a day at most. Retrieval has been tricky on a few tags but the amount of archival data - including video - has been phenomenal.
Here's a video of his team tagging a humpback - with video off the whale's tag: Video Tag Deployment
Dr. C, in talking about the different types of tags, says you have to consider whether or not the impact of the tag is worth the invasiveness; you have to weigh the worth of what you are trying to learn against that impact.
He talked about some of the work they've done with the NRDC and the Navy regarding sonar and whales. I've got some ready to do on those studies. Another way that the collection of data has led to some limited human change was done in a study of blue whales off the coast of Los Angeles. The areas that the blue whales feed and travel was directly under the shipping lanes. After determining that the whales were not responding to shipping traffic by getting out of the way - and they travel quite slowly - the shipping lanes were moved a kilometer. Same in San Francisco. Small steps - but at least they responded.
The takeaways from the lecture, in Dr. C's words were this:
Migration patterns are much more complex than we have known.
Humpback whales stay loyal to regions and will switch prey before leaving those regions while...
Gray whales move with the krill and respond to conditions - which is why some of them practice the high risk ghost shrimp strategy.
My takeaways:
There are ways to incorporate the needs of other species into our human world of shipping lanes and naval maneuvering.
We can't do that without the research and data that groups like Cascadia Research provide.
When we see the complexity of behavior in another species, it becomes increasingly difficult to not see how our human actions impact these amazing creatures. It becomes very difficult to relegate other species to the 'dumb animal' category.
It also becomes increasingly difficult to simply shrug the shoulders and say - these animals will simply adapt to changing conditions. By studying behavior and the ecosystem within which they move, we see how some species may attempt new adaptation strategies - but are hamstrung by human behavior such as noise pollution, sonar, toxins in the water.
Basically, the more we know about these complex creatures and the ecosystems that overlap with our own the more we humans can understand how we are just one of many creatures who depend on a healthy environment to thrive.
Sources:
Calambokidis, J., J.L. Laake, and A. Klimak. 2010. Abundance and population structure of seasonal gray whales in the Pacific Northwest, 1998-2008. Paper SC/62/BRG32 presented to the IWC Scientific Committee.
