Experts puzzled by salmon decline

SNELLING -- Tiny Chinook salmon -- from fingerlings the size of paperclips to slightly bigger fry -- darted around long troughs at the Merced River Hatchery in Snelling.

Fish and wildlife technicians Mary Serr and Lester Yamaguchi scooped up an ounce of the small fish to check their development. The goal is to keep as many young salmon as possible alive and healthy.

Ones that survive are now being released right next to the hatchery into the Merced River. The hope is that enough will return in the fall to spawn and begin the process all over again.

Unfortunately, that isn't happening. Chinook salmon numbers have been dismal.

Surveys taken between October and early January found only 520 salmon in the river, said Tim Heyne, senior biologist with the California Department of Fish and Game. Last year that number was 1,470, and the year before had 1,921.

In 2001 and 2002, about 10,000 fish were counted in the river.

This drastic decline is causing wildlife managers and fishermen around the Tuolumne, Sacramento, Merced and Stanislaus Rivers -- which are all experiencing record-low numbers -- to use words like "crisis" and "disaster."

State officials even warned fishermen during a meeting in Santa Rosa last week to expect restricted salmon fishing in the upcoming year.

Chinook salmon, also called king, typically range around 36 inches long and weigh 30-40 pounds, although some weighing more than 120 pounds have been recorded. They usually spend one to eight years in the ocean before returning to spawn in freshwater. Then they die.

Meanwhile, experts are trying to figure out exactly what's causing the recent local decline.

Fishery scientists recently blamed poor ocean conditions. Chinook salmon spend about three years at sea before returning to streams to spawn. But unusual currents and temperatures measured the last decade in the ocean have hurt the fish and the nutrients that feed them.

However, studies have shown that many fish aren't even making it out to sea. "Regardless of what happens in the ocean, they weren't getting out of the river," Heyne said.

Poor river water quality, low flows, higher temperatures and predators were also named as possible factors.

Heyne brought up the pesticides detected in February near Ballico in the Merced River. Storm run-off after orchard spraying sent organophosphates into the water. "This is an example of stuff that happens all the time in the river," he said.

Many of the pesticides that leak in aren't harmful to the fish, but they wipe out their food. This -- combined with other murky river conditions -- spells health problems. "Basically, everything has been so rearranged with the river systems in the delta, it's extremely difficult to pinpoint what bad thing is worse," he said.

Patterns in fish populations can also be connected to years with high or low rain and snow fall, said Michael Cozart, manager of the hatchery in Snelling. A good water year in 1989 was reflected by a higher population in 1992 because of the salmon's three-year spawning cycle.

Whatever the reasons, fewer fish in the Merced River means that fewer fish reach the hatchery. And that means fewer eggs.

The fish arriving at the Snelling hatchery this year totaled 79, producing 275,477 eggs. That's about half last year's volume when 150 fish made it to the hatchery, producing 402,792 eggs. And last year's number was already low, Cozart said.

Hatchery workers hope each year to collect at least 2 million eggs, which come from about 200 fish.

The collection process starts when fish swim up the Merced River and enter the holding trap at the hatchery. They are pulled into the facility and divided into males and females.

Monday and Thursday are spawning days. That's when the female salmon have their eggs removed. A productive 3-year-old salmon produces about 5,500 eggs, Cozart said.

The eggs are taken out to the incubation area across the hatchery. There they hatch and mature until they take shape as little fishes. They are placed into various troughs and raceways as they grow.

Yamaguchi and Serr demonstrated what they do each Friday -- measure ounces of fish to see how many are in each ounce. The results provide fish and wildlife technicians a laundry list of data: how well they are growing, if the fish are getting enough food, if their water is muddy and if the temperature is right. "We keep track of them all the way through," Yamaguchi said.

However, some fish are lost along the way. The hatchery hopes each year to get a million fish into its raceway, where the larger fish are kept before they are released.

The goal number for release is about 660,000.

Logically, starting with a low number of eggs leads to a low number of releases. About 350,000 young Chinook salmon were last released into the Merced River, Cozart said.

The last time the hatchery revealed its goal number was in 2003 with about 870,000.

The fish are entering the Merced River in healthy condition, Yamaguchi said. And salmon collected for spawning are arriving to the hatchery in good health.

"We aren't noticing a problem when they leave or come back," he said. "They are just arriving in smaller numbers. You never know -- but we have to figure it out."

Reporter Dhyana Levey can be reached at 209 385-2472 or

Something's fishy

The spawning numbers for the Chinook salmon have dropped drastically in recent years. Both the number of fish and the number of eggs are just a fraction of the totals just five years ago.


Year fish Eggs

2007 79 275,477

2006 150 402,720

2005 421 1,199,888

2004 1,050 1,921, 671

2003 549 1,249, 075

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