Salmon and the Redwoods

The salmon are gone – just like the mills and the old-growth redwoods. Once salmon were so plentiful in the rivers along the Mendocino Coast you could catch them with your hands.

Salmon Cannery in Noyo Harbor in Fort Bragg

Salmon fishing was a major industry. There were salmon canning plants in Noyo harbor in Fort Bragg.

The fishermen were mostly of Portuguese extraction (from the Azores) and their houses were often adorned with abalone shells. There were over one hundred fishing boats operating from Gualala to Westport in the 1920’s.

Now there is virtually no sport fishing and commercial fishing for salmon is banned. So what happened? The answer is that logging destroyed the salmon habitat. How?

Noyo Harbor in the 1930’s

Salmon and other native fish evolved in certain river conditions and flourish when those conditions exist. These conditions include clear and cold water, deep pools, spawning habitat (clean gravels), lots of aquatic invertebrates (water bugs), places to hide from predators, and a place to rest (side channels, slack-water pools. These conditions are facilitated by rivers and streams that flow through forests. The trees that are best for salmon are the redwoods in an old-growth forest. While not the best, second-growth and third-growth forests are also good for the salmon. They are infinitely better than the logged-up clear cuts or barren hills chomped naked by cows or sheep.

Clear water: Juvenile salmon cannot see to find water bugs in dirty, cloudy water. Erosion puts silt (dirt) in the water, raising the level of turbidity (muddiness, as when the partials and sediment are stirred up). Erosion is caused by a multitude of things, including road cuts, overgrazing, clear cuts, poorly planned railroads, off-road vehicles and you.

Culverts under logging roads are a major contributor to mud and soil in the rivers and streams. Instead of the rain gently entering the river or stream along its entire length the culverts concentrate the water into torrents which scour the earth in their path and dump the soil and detritus the torrents collected into the water.

Tree roots stabilize soil, even on steep slopes. When a clear cut (an example taken from p8 of the Albion Branch of the Western Railroader) happens on a hill side, the roots that keep the stumps in place continue their soil-holding function for a few more years after the tree is dead. But when those roots rot, we have tragic landslide events. Sometimes people’s home are destroyed, but almost every time it is the salmon’s homes that are destroyed.

Cold water: Some fish like salmon, need more dissolved oxygen in the water than others. Cold water holds more dissolved oxygen than warm water. Cold water also discourages some fish diseases as well as invasive fish that thrive in warm water such as pike minnows. Salmon prefer temperatures somewhere between 48 and 65 degrees Fahrenheit. Shady rivers are cooler rivers, and big trees like the redwoods provide that shade. Riverside trees were usually the first ones cut in the old days when logs were rolled or dragged down hills into streams and floated to mills. Livestock also did their deforesting by consuming any young sprouts attempting to replace the mature willows, alders, and cottonwoods that shaded the tributary streams.

The shallower the river, the more quickly it can warm. Much of the water in our rivers and streams these days is diverted for human use. It is critical to the survival of the salmon to maintain the volume of water in the rivers and streams.

Deep pools: The bottoms of pools are nice and cool. Pools are great places for humans to go swimming and relax. Pools are also good places for fish too. Deep pools provide a break from the constant barrage of a ripping current for a fish. Pools are also good places for fish to hide from predators like osprey and kingfishers. During lower flows the current downstream of a pool is often moving faster than the pool itself and therefore able to sort gravel in such a way that is good for spawning habitat.

Trees and branches that fall into the water create a dynamic known as “scouring”. A tree that falls with one end resting underwater on the riverbed and one end on the bank causes the water to dig (scour) around it and create a pool. To help the streams recover conservationist will put “digger” logs into the river.

Spawning habitat (clean gravels): Trees create spawning habitat and keep gravels clean. Why do Salmon need clean gravels? Because salmon eggs breathe. Spawning salmon dig a hole with their starved bodies (they stop eating once they enter fresh water but will strike at anything that looks like food, which is why you can catch salmon with a lure), then they fertilize their eggs in the hole. Next, they go a short distance upstream of that hole and dig another one. The current washes the gravels stirred up by the digging to cover the salmon’s first hole and the eggs. If mud were used for this purpose, their air-breathing eggs would be smothered. But since salmon use gravel, the cold, dissolved oxygen-containing water can infiltrate the spaces between the gravel and keep the salmon progeny alive.

Erosion also embeds potential spawning gravel in a dirty cement-like compaction that makes it really hard or impossible for the salmon to make a nest (red) with their emaciated bodies.

Lots of aquatic invertebrates (water bugs): Juvenile salmon like bugs and big trees are a prime source. Leaves and other tree parts that fall into the river are food habitat, and nutrients for aquatic insects. Redwoods support a viable ecological system for aquatic invertebrates in many other ways. Everything is connected to everything. A food source needs a food source to be a food source. Without connectivity we all starve to death.

Places to hide from predators and places to rest (side channels, slack-water pools): Juvenile salmon cannot resist a strong current. They just get swept away. This is why side channels , slack-water pools, and slow moving river edges are so important to the salmon.

And there is a little good news. Last year (2009) for the first time in some 50 years juvenile coho salmon were found in the river at Gualala.