PORTLAND, Ore. (KOIN) – For the past 20-30 years, Shad populations in the Columbia River have skyrocketed while salmon populations have declined dramatically. This contrast between a thriving species of fish and another ailing one led the Northwest Power and Conservation Council to question whether shad was contributing to the salmon’s downfall.

Northwestern Energy and Conservation Council aims to balance the environment and energy needs of Oregon, Washington, Idaho and Montana and monitors populations of shad, rainbow trout and salmon in the river Columbia for decades.

The council says the non-native shad is now the main oceanic migratory fish in the Columbia River Basin, its numbers eclipsing that of native rainbow trout and salmon.

That’s what made them wonder: does shad have an impact on salmon and the Columbia Basin ecosystem?

The board asked the Independent Scientific Advisory Board review the numbers and make recommendations to improve research and management of shad populations in the river. Prior to that, little research in the Northwest had focused on shad and the species’ potential impact on the environment.

Table published a report on October 22, 2021, but concluded that more research needs to be done to determine whether shad poses a direct risk to salmonids. The report states that a large number of non-native shad may indicate long-term effects, but these effects remain to be discovered.

The council drew its figures from outside sources and did not collect any new data for the report it published.

So the question remains: why shad thrives while salmon suffer?

Dr John Epifanio, one of the researchers on the Independent Scientific Advisory Board, said some of the environmental impacts that could harm salmon could be the cause of the shad overgrowth.

“There’s probably no direct link to the decline in salmon caused by shad,” he said. “It appears to be a few conditions, changes in flow through the system, changes in temperature to which slower water movement is related, and then ocean conditions.”

Epifanio said warming ocean temperatures appear to be favorable for shad. The study indicated that these changing environmental conditions will likely continue to contribute to further decline in native species and be favorable to non-native species, such as shad.

Shad populations also increased sharply after the completion of the Dalles Dam in 1957. The dam completion flooded Celilo Falls, which previously acted as a barrier to upstream migration of shad. The ISAB says that since 1960, shad has grown at a rate of about 5% per year with no evidence showing that population growth is slowing or stabilizing.

American Shad is a member of the herring family and was introduced to the Columbia River in the 1870s and 1880s due to the popularity of the fish in the eastern United States.

However, fish are bony and fatty, and they never gained popularity in the West.

Fish is also of no importance to the tribes of the Columbia River Basin. Dr. Zach Penney, the Director of the Department of Fisheries Sciences with the Columbia River Intertribal Fish Commission, said tribes in the area are concerned about the negative impacts the shad could have on native fish populations.

“I don’t really want to disparage Shad just yet. This is another thing to keep in mind about invasive fish. It’s not like they’re, you know, having a manic laugh once they get to a place where they don’t exist. They just do what the shad does, ”he said.

Penney said more studies need to focus on what’s going on with the Columbia River populations in case it becomes a bigger issue.

He also believes that populations need to be better managed in one way or another. At present, There is no limit on how many shads fishermen can catch in the Columbia River and they can be fished year round in most areas.

Because the fish are so bony, Penney said not many people catch and eat them. He said they are good smoked and canned so the bones will soften but otherwise they are not very desirable. He said some people use them as bait for other fish and some have tried to market shad, but he hasn’t heard of enough demand to keep it going.

“So right now I would say the Columbia River is primarily a recreational fishery. When it comes to tribal fisheries, shad exists mainly as a bycatch, ”he said. “Shad just accidentally gets caught in the nets and in fact some fishermen are very irritated by them because they are a little bristly. ”

Penney said the tribes of the Columbia River area are “salmon people, not shad people.”

As shad multiplies rapidly in the Columbia River, ISAB researchers found that populations were not doing as well in their native rivers on the east coast. Their abundance has dropped dramatically since the 1950s. Researchers say this is due to blockages, such as dams, that prevent them from swimming upstream to their original spawning sites.

Overall, the researchers point out that more research needs to be done, especially if shad populations continue to increase without showing signs of leveling off in the Columbia River. They said it was essential that shad numbers continue to be monitored and suggested more research on the impact of shad on certain habitats and competition for resources with native fish.

“I would hate to see the Pacific Northwest become ‘Shad Nation’ instead of ‘Salmon Nation’,” Epifanio said.