Think Out Loud

How shad and other species affect Pacific Northwest salmon

By Elizabeth Castillo (OPB)
Feb. 15, 2022 5:55 p.m. Updated: Feb. 22, 2022 10:36 p.m.

Broadcast: Tuesday, Feb. 15

In recent years, non-native American shad migrating past Bonneville Dam greatly outnumbered the total salmon and steelhead.

In recent years, non-native American shad migrating past Bonneville Dam greatly outnumbered the total salmon and steelhead.

Smithsonian Environmental Research Center / Flickr Creative Commons


Shad is a species of non-native fish that has become increasingly common along the West. How can this fish affect resources for salmon? What other non-native fish and invasive species pose an even greater risk to salmon? We dive into these questions and learn more from Stuart Ellis, a harvest management biologist with the Columbia River Inter-Tribal Fish Commission.

This transcript was created by a computer and edited by a volunteer.

Dave Miller:  This is salmon country. It has been for millions of years. But fishing dams, logging, a warming ocean and non native species have changed the makeup of our rivers in innumerable ways. According to a recent report for the Northwest Power and Conservation Council there are actually more shad these days than salmon or steelhead in the Columbia River basin. People brought shad from the east coast to the west coast in the late 19th century. Like salmon, they go from rivers to the ocean and then back to the river. But in recent years, 90% of the fish that make the return trip up the Columbia are shad. So what does this mean for native fish and what can be done about it? Stuart Ellis is a harvest management biologist for the Columbia River Inter-Tribal Fish Commission and he joins us now on the line. It’s good to have you on the show. What exactly are shad?

Stuart Ellis:  So shad are a fish in the herring family. In the Columbia they weigh typically between two and 4 pounds. Probably most of them are around 2 or 3 pounds. They’re fairly long lived fish. They can live up to about 10 years. And as you said, they have a lifecycle somewhat like salmon in that they are born in freshwater, they migrate to the ocean as juveniles, spend a few years in the ocean and then return as adults. Most shad die after spawning, which is when they lay their eggs. And a few of them can survive and make it out and migrate out to the ocean and do it again later. They have light colored meat. They are considered rather bony compared to salmon and trout. But they are good food fish. They’ve been considered a valuable food fish on the east coast forever. The native people on the east coast always ate shad. And they don’t necessarily have a great reputation as a food fish on the west coast, but they are a great source of protein and we have a lot of them in the Columbia basin now.

Miller:  Can you give us a sense for what you mean? When you say we have a lot now, I mean, what are the numbers these days?

Ellis:  Last year’s return was the fourth highest ever and it was almost 5.6 million. Our record return was in 2019, and that was almost 7.5 million fish passing Bonneville Dam. The past four years have had all four of the four largest runs. It’s bounced around a little bit in that timeframe, but the trend has been for increasing numbers of fish. Shad have been counted at Bonneville Dam since 1946. They probably were around before then. But during that time, shad runs were fairly stable at maybe around 5,000 to 25,000 a year. But in the last 15 to 20 years, shad numbers have really dramatically increased.

Miller:  At a time that has seen a continual decline of wild salmon runs, shad are booming. Is that a fair way to put it?

Ellis:  Yeah, although the wild salmon runs have also been bouncing around some. But certainly in the past couple of years, we’ve had a low productivity cycle for most salmon stocks in the Columbia and Willamette and shad have boomed during that time, and we don’t know exactly why.

Miller:  Could it be connected to a warming world?

Ellis:  It may very well be. The shad have a higher temperature tolerance than salmon do. Shad spawn in the reservoirs themselves. So, the habitat that shad spawn in are plentiful and available. Shad have actually moved up through the system. They started out passing just Bonneville and then made their way up. And now shad are occasionally seen above all of the dams with fish passage in the main stem [of the Columbia] at least, and they regularly spawn in most of the reservoirs, we think. And it seems to be a good habitat for them. We don’t know a lot about where shad go in the Pacific ocean or what they’re doing out there. So it’s a little hard to know what kind of factors in the ocean are affecting them. But whatever their conditions are out there, it seems to not be bad for them.


Miller:  If, in some recent years, nine out of 10 fish returning from the Pacific up the Columbia are shad, if there are way more shad than salmon or steelhead now, do we know how that shad population is affecting salmon and steelhead?

Ellis:  We don’t have a lot of real detailed information, unlike some of the other invasive fish in the Columbia that we’ve got better data on, adverse impacts. There’s been a lot of uncertainty. There are, most people do think that the shad ah do pose a negative impact on salmon. There may be a couple of mechanisms that do that. One may be that the juvenile’s may compete for resources with some species of juvenile salmon and steelhead. And it’s also quite possible that the number of juvenile shad out there (a shad can lay up to 600,000 eggs) and can produce a lot of juveniles potentially. And those juveniles may provide resources for predators that also feed on salmon. And at times when there’s not a lot of juvenile salmon around, shad juveniles tend to migrate out of the system a little bit later than most juvenile salmon and steelhead. So they may be providing resources to predators who can then survive for the next year to prey on salmon and steelhead again.

Miller:  That could include things like bald eagles. For example, we talked about bald eagles about a month ago.

Ellis:  Yeah, more probably like fish predators, but certainly bald eagles. So the bald eagles live in the system all year long. And during some times of the year there’re fewer fish available. And other other predatory birds like cormorants and terns and things like that can also feed on these fish. So if you’re just providing groceries during otherwise lean times, then that tide them over until there’s more salmon available. So that can have an effect on salmon. And there may just be a lot of competition for available food among the juveniles. Their impacts may not always be negative in every aspect though.

The abundance of shad, many of which will die after spawning, may actually be a pretty good resource for sturgeon in the Columbia upstream of Bonneville Dam. And so with a lot of these things, it’s not necessarily that their impacts are necessarily completely bad. But we do think that there are too many shad and that it would be good to make efforts to make the Columbia a little less hospitable for them. Nobody seriously thinks we could ever get rid of shad. Our history in dealing with invasive species is once you get them, you almost never can get rid of them. But maybe there are some things that we can do to cut down on their population some.

Miller:  One way to do that would be a bigger fishery for them. What would it take for there to be a commercial shad fishery in the Columbia basin, the way there have long been shad fisheries on the Atlantic?

Ellis:  So currently there has been a small, non indian commercial fishery that occurs most years. It’s limited a little bit by the marketability of the shad, finding buyers for them. The tribes have also, at times, had some commercial fisheries. We had a fishery using a trap just upstream of the Dallas Dam for a number of years and did pretty well catching shad. But it was challenging enough to market these fish that it was never financially that successful. Some of our tribal fishers sell shad that they catch direct to members of the public as well. So there’s a little bit of commercial fishing, but really the big thing is that we need an established market for shad.

And the buyers and processors that might be interested in shad also need reliability. One of the difficulties that we have with shad is that their run timing overlaps with the tail end of the spring chinook run and with the sockeye run.  And both of which have very strict harvest limits in the Columbia. So it’s proven challenging to expand these fisheries without impacting other species which people are also interested in catching and which have strict harvest limits.

So if we can resolve those kinds of things, if we can figure out ways to catch shad more cleanly without catching other fish, that would be one way to do it. And then just making sure that the market would pay enough for people to get out there and really want to catch the shad.

Miller:  Which in some places it would be with their row, which I think are very prized, and the flesh, which a lot of people do like. Just briefly, we’ve been talking about shad, but before we say goodbye, I want to ask you about northern pike, another non-native fish. How concerned should we be about the possibility of northern pike becoming a major nuisance in the Columbia basin?

Ellis:  I think we should be more concerned than we are with shad. So shad have been around for ages and we observed very limited risk of real severe adverse impacts. But northern pike are a fish that look quite ferocious. They look rather like a barracuda.  They’re a long bodied fish with great big teeth. They can eat a fish that’s really almost as large as they are. They’re nothing but teeth and stock and they are native to the northern Midwest and Canada. They were introduced into some of the very uppermost lakes in the Columbia system and migrated downstream as far as Lake Roosevelt, which is the reservoir behind Grand Coulee Dam.

The tribes along with Washington Fish and Wildlife do have some monitoring and I’ve been working on some control measures for those fish, basically catching them to try and limit the risk (music background gets louder) that they’ll get downstream of Grand Coulee and Chief Joseph, which is the regulating dam. And then they’d have free access to the rest of the Columbia.

Miller:  Stuart Ellis, unfortunately, the music means we’re out of time, but thanks so much for joining us.  Stuart Ellis is the harvest management biologist for the Columbia River Inter Tribal Fish Commission.

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