The Necanicum River became a mass grave for fish as thousands of anchovies died trying to swim upriver at Seaside, Oregon on July 28.

The anchovies entered the Necanicum River in downtown Seaside. They entered the river at high tide, and died there.

It's not unusual for anchovies to die on the river. When there is a high tide, many anchovies try to swim upstream and get stranded there. They either return to the ocean or are eaten by birds.

According to KPTV-TV, Tiffany Boothe, a spokesperson for the Oregon Coast Aquarium, said that the fish died this week because there was not enough oxygen in the river to support all of the fish that entered. She said that although this was not unusual, there were more dead fish than there would normally be. The dead anchovies could be a good thing for birdwatchers, because the dead wish will likely attract a lot of birds, who feed off of the fish.

However, Boothe said, "It's going to smell for a couple of days probably." She added, "It kind of looks like the apocalypse."

Penny Russell, a spectator who was visiting from Portland, told WGNO.com, "I saw thousands of fish and I thought, 'That's sad. What's happened?' I've never seen anything like this before."

Melyssa Graeper, coordinator for the Necanicum Watershed Council, said, "It's kind of a cool and good indicator that things are working right now." She said that this is a positive sign for the anchovy population - it means the anchovy population is strong and "there are so many of them they're looking for other places to go," she said. Aside from that, the dead fish are good for the river. When the fish decompose, their nutrients are absorbed by the river and plants that live near the river.

Events like this happen about every ten years on a regular basis, experts said. In a few days, the anchovies should have decomposed and the river will continue flowing, like it always does.

Anchovies are small, oily fish which dwell in oceans around the world. They typically range from about 0.79 to 15.75 inches in length. Anchovies are nutrient-rich fish, and are an important food source for animals in the wild, like dolphins, sharks, and pelicans. The type of anchovy found in Oregonian waters is known as the Northern anchovy.

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