Jason Toft is a Principal Research Scientist in the University of Washington’s School of Aquatic and Fishery Sciences. In these audio cuts he speaks to HistoryLink’s Jennifer Ott and Dominic Black about his involvement in designing the replacement seawall along Seattle's central waterfront. He outlines the key design features devised to make the environment as hospitable as possible for juvenile salmon, especially Chinook and Chum salmon, as they out-migrate from the river system to the ocean. Toft was interviewed at the University of Washington Fishery Sciences Building on July 30, 2022.
Habitat Rehabilitation on the Waterfront
Jason Toft: In general it seems that small fish like to live, not all small fish, but there's certain fish when they're small like to live close to shore in shallow water. And that can be a refuge from predation because there's bigger fish that live in deeper water. And so specifically for the Seattle region when juvenile Chinook salmon are out-migrating along our shorelines from the rivers out into deeper waters of Puget Sound in the ocean, when Chinook salmon first come down they're often close to shore.
And same with other salmon species like Chum salmon are in very shallow water often, and so they're seeking that shallow water and the shallow water is close to shore. So even in downtown Seattle, where there's a pretty steep seawall there, they're still often close to the shoreline because they're looking for that shallow water edge. And that goes true with other small larval, post-larval fish. And not all, certainly there's a lot of fish in deeper waters schooling offshore, but for what we're interested in – which is often juvenile salmon – we're really interested in that water’s edge.
Dominic Black: How did you come to be involved in the seawall project then?
JT: Yeah, that's a good history, it's been gradual over the years. Our lab group is called the Wetland Ecosystem Team. And so Si Simenstad and Jeff Cordell have worked in their area for a long time, and I showed up in '97. And so there was work in the region ongoing already.
And for the seawall project it was a gradual transition, I guess. We worked on the Olympic Sculpture Park. So from 2005 before the Olympic Sculpture park was created, which is just on the north side of downtown Seattle, we worked on that. So I led up that project for looking at how salmon and what they're feeding on can be ... hopefully they can benefit from whatever is being constructed down there. And so the Olympic Sculpture Park has a little created beach down there and has a small bench sticking out from the Northern edge of the seawall there.
And so that was one of the first case studies in a way, along the waterfront, that proved to be successful. We found that juvenile salmon were gaining something from that slightly restored shoreline. So we work in restoration ecology, and it's hard. Oftentimes in the urban element you're not truly restoring habitat to a historic condition, you're enhancing it or just trying to rehabilitate it a bit. And in that project we worked a lot with the City of Seattle as well, and so it was a logical step when the downtown Seattle seawall proper was starting to be planned for how it was going to be constructed to have a seat at the table. And that's really what you want. These projects are big and there's a lot of different interest groups and a lot of different specialties. So to be at a meeting with the city planners and engineers and designers is a really important thing, just so you can all speak to your specialty and see where the project goes.
Designing a Tidal Bench and Seawall for Invertebrates
JT: So we study fish, and Chinook salmon are listed under the Endangered Species Act, which is a huge thing in our region, and that right there is the main reason why we would have a seat at that table. And so anyone doing construction along the waterfront has to acknowledge that, and there's permitting involved in all that, and so oftentimes it's very important to monitor shorelines to see how they're working, especially if you're doing a big construction project.
And so we would be contacted to be like, 'Hey, this group at UW, they know how to monitor fish. They know how to tell what the fish are eating and the invertebrate identifications.'
And so that's usually the situation where we're contacted.
DB: You mentioned a bench there, a little bench. So what is that?
JT: Yeah, and ... along the Olympic Sculpture Park. Again, we learned from past studies that the fish we're interested in are craving that shallow water habitat. And so speaking of the Olympic Sculpture Park, the pocket beach there was excavated landward and so it was actually possible to recreate a beach there.
Along the seawall itself there it was not possible to do that, and so you can mimic what a natural shoreline would look like by creating a bench at a low tide level sticking out from that sea wall. And so again, when those fish are close to shore, instead of it being very deep water there, it can be shallower water.
DB: Oh, I see. So it's a shelf and they place themselves between the surface of the shelf and the top of the water.
JT: You got it, yep.
DB: Great. So how did that inform how you began to approach the larger seawall project along the waterfront?
JT: Yeah, a lot of the elements were similar. And so for the seawall stretch from pretty much the Seattle Aquarium south to the ferry terminal, that was a similar situation of reforming that sea wall there, and how can you do it in a more ecological friendly way? And so one of the methods was to put a similar bench there at a low tide level to mimic that shallow water habitat. So that was similar to Olympic Sculpture Park. And what was new was the seawall face itself. And so how can you pour concrete instead of it being a straight wall?
In the case of the downtown Seattle seawall it ended up being more like say, in a climbing gym, where you have cobbles along the wall and little ledges sticking out. And that is good, we learned, for the invertebrates and algae that attached themselves to the seawall. And again, that plays into the food web for what juvenile salmon can hopefully feed on when they're swimming along those shorelines.
So we're speaking of marine invertebrates in this situation, living in the intertidal zone, and I'll speak to two types of invertebrates that live there, both Crustaceans. And so there's small copepods called harpacticoid copepods that live close to the sediments or whatever the bottom of the sea floor is. And so those are important, especially for small Chum salmon. So these Chum salmon, when they're out-migrating are say four centimeters long to five centimeters, and that's an important prey item for those juvenile Chum salmon.
And those harpacticoid copepods, again, like the low intertidal zone where there's algae and things for them to live along, around. And also anthropod crustaceans, they're small shrimp like crustaceans, they're a little bit bigger. You can see them with your eye, I guess. And that's something that Chinook salmon when they're small like to eat as well. And these are just part of what they could feed on, juvenile Chinook salmon feed on many things. They feed on crustaceans or other invertebrates that are in the water. They also feed on things like crab larvae that are in the water column themselves, and things like insects. So they can feed from the water surface from an insect if they land on top of the water. So that kind of diversity of invertebrates for them to feed on is really important.
Glass Blocks to Aid Salmon Feeding
JT: Chinook salmon are visual feeders, and so that plays into light as well. Another component of the Seattle seawall, you may have noticed the glass blocks in the sidewalk if you're walking down there.
Let's see ... we did a study that would've been around say I think it was the 2011 to 2013 time range, where we went out and we actually snorkeled underneath piers, downtown Seattle and between piers. And again, we found that the fish, when we saw juvenile salmon, they weren't feeding under piers – they did not like that artificial shade.
And so there's another part of the seawall construction that adds into this, and that is that when the new seawall was created, it was actually built back a bit from the old seawall. And that was just the reality – they put up this temporary seawall to hold back the water so they could do the construction, and so it led into there being a cantilevered sidewalk. And so, since the seawall was going to have a bit of shade, for the area in between piers it’s important to try to get some light down there still, and again underneath the piers to try to get any kind of light underneath there, so that juvenile salmon, being visual feeders, could feed.
And so for the design part of that, well, what was really cool about this is being able to test that. And so at Pier 62, before the new Pier 62 which has recently been finished off was done, we were allowed to go underneath there and test some different techniques.
And so again, the City of Seattle put out a few different things that could be used. And so grading was one, glass blocks was one, and then a solar tube was another way. And so there was three small applications of that in Pier 62 just to see how they worked and what we could observe underneath those.
DB: What's a solar tube?
JT: A solar tube is something you might have in your house actually just to get a skylight in, just having a tube going down and bringing the light underneath.
Anyway, being able to test that is a great thing to do. And we were able to do that with the seawall face itself. Back in 2008 to 2011 the city put some test panels along the seawall testing different situations of say that climbing gym bump scenario of, okay, what bumps should we put in there? What should the ledges look like? Is it better than just a plain seawall face?
And so that test and the test of the glass blocks, those are really important to inform a final design when you're putting it at the scale of that whole stretch of Seattle seawall. And so, since the glass blocks have been put in, it's not ambient light conditions at all, but it's enough light that we do observe them feeding more often when they're in that shaded area.
DB: I'm curious a little bit about the process of when you're talking to the city and you're in planning meetings and so on. Is it entirely collaborative? Is there ever a tension between the needs of the city in terms of cost and the needs that you have in terms of making it an effective project and getting what you need out of it?
JT: Second question, I'm not sure I'm the right person to answer it. Maybe because I try not to get tense, but I think if there is tension, which I'm sure there is, because these are very expensive projects, it's in the planning process for ...
DB: You mean the planners leave the meeting and then they go to their own offices and go, 'Glass blocks, they want glass blocks?'
JT: Well again, okay. So no, these are good questions. I think, and maybe because I've been around just long enough, I think when I was younger it's interesting being at these meetings when you know for your own specialty what you think should happen, say. And that's probably not what's going to happen. You want to get your voice out there enough to say, 'I think this is important,' and then have elements of that carry through to the final design. And that's the way to approach it, because otherwise tension isn't useful to anyone. And so just trying to get your voice heard there.
And it's really important throughout this whole project to recognize that, again, this is a major urban city. This is a working waterfront. There's lots of cultural and economic reasons why things happen. And certainly the business owners down there and the tourists, and certainly with tribal fisheries in the area there's a lot of voices to be heard. And again, you just want to be one of those voices.
Benches, Beaches, Bumps, and Salmon Migration
JT: Benches, beaches, and bumps. And benches, beaches, and bumps kept coming up in planning meetings really, on the quick way to describe what's going on. And I should back up and say it's published with ... Jeff Cordell is first author in a book on living shorelines that I co-edited. And so 'living shorelines' is a term I'm just going to describe briefly as when you're trying to restore shorelines but recognizing that there's human involvement, and oftentimes you might need some engineering involved.
And so that's a cool piece of terminology, and so benches, beaches, and bumps. So benches again are those benches coming out away from the seawall at a low intertidal level to mimic shallow water, natural habitat. The bumps are along the seawall face, again, something you might see in your head as like if you're at a climbing gym, something like that.
And then beaches would be places like at the Olympic Sculpture Park where you can actually excavate a beach there. And now more recently just south of the ferry terminal downtown there's a created beach there as well that was created waterward from where the seawall is. So there are options. So basically where there's options to try to recreate a beach, that's a best-case scenario. And then when you need more of an engineering approach, often we call that eco-engineering. You could go more into these benches and bumps.
DB: How do young salmon actually use the space of the bay as they're coming through?
JT: Yes, fascinating because the Green-Duwamish River system comes into downtown Seattle, and it has been crazily modified by humans over the years, lots of industrial use. And so these salmon are spawning upstream up in the Green River, and so they migrate down that system.
And there's a few different species involved, I'll just focus on two, Chinook and Chum. And so when those Chinook salmon are coming down the Green-Duwamish there's obviously a lot of diversity that can be involved with that on timing and size and all that. Oftentimes when they hit Elliott Bay the Chinook salmon are say from seven centimeters to 10 centimeters long. But for species like Chum salmon, they out-migrate really early when they're quite small.
And so you can get Chum salmon that are three and a half centimeters long. So they tend to out-migrate pretty quickly. So there's diversity really within species and across salmon species on how they're out-migrating from the Green-Duwamish.
And so when they hit Elliott Bay, this estuary and transition is hugely important. They start out in freshwater and have to get used to salt water. And so even in urban areas they need to do that transition. And for Chum salmon they out-migrate pretty early. So they're at a smaller size when they're coming in Elliott Bay, say from three and a half centimeters even and on up. And so that would be more in March and April, and then in May and June you'll get them around five, six centimeters. And so for Elliott Bay at least and the Green-Duwamish, really from February through July is the range of when there's good numbers of small salmon coming along our shorelines.
And again, for a system like the Green-Duwamish River ... there's a large hatchery influence. So salmon grown up in hatcheries and [are] released, and really probably around 80 percent or so of the fish we see might be hatchery fish, depending on the month. And one other note on that is fish swim around. We do know that for fish that we get in Elliott Bay, they don't all come from the Green-Duwamish River. They could come from other river systems in Puget Sound. And so that connection is very important.
To really think about restoring Puget Sound you have to have pieces in every part of the Sound, just restoring one part or protecting one part won't keep the whole system healthy.