Migratory Fish

Spawning Coho Salmon

Say Goodbye ?

Coho Salmon have been extirpated from the San Lorenzo River. This means that they have been driven into extinction in this watershed. No Coho have been recorded in the river for many years. Salmon are divided into Evolutionarily Significant Units or ESUs. This is a way to group fish from nearby watersheds that could be able to use a neighboring stream to spawn. Salmonids have to be adapted to the streams to which they return after their time in the Ocean. Instinctual knowledge of the hydrological cycle, season of year, whether the time is right to migrate or wait in a deep pool for conditions to change, are among the factors that allow salmon to use a particular river to spawn. Coho adapted to another river such as the Klamath could not live in the San Lorenzo because they would not know when to enter the river or how to react to the condition of the river. This is why a particular "run" of fish is like a different race or sub-species from those that come from another natal stream. When a run of fish goes extinct it is very difficult to restore them. The ESU that includes the San Lorenzo and the other spawning streams south of San Francisco Bay are on the edge of extinction. Despite this our Coho have not even been declared "endangered" under the Federal Endangered Species Act but only "threatened". Perhaps when they are all gone then we will then call them "endangered". Coho are disappearing across the entire Pacific Northwest. Steelhead Rainbow Trout are in a little better shape. Steelhead have more adaptable life cycles than Coho and can tolerate more degraded conditions in the watershed. Perhaps we can keep our steelhead from disappearing. Our Coho will need emergency help to survive. They need cleaner more abundant and colder water than we leave for them. Their migration must not be blocked by man made obstacles. It is possible. Will we do it?

Steelhead Rainbow Trout

Lompico Creek harbors these beautiful fish which were once the most famous "fresh" water game fish in California. Amazingly enough, it has so far been impossible for biologists to distinguish between land-locked rainbow trout and sea-run Steelhead rainbow trout. The differences are hidden deep in their genes and only a complete gene sequencing would be likely to show the differences.

There are however significant behavioral differences. Steelhead spawn in the fresh water stream of their birth, just as salmon do. Steelhead, however, can return to the ocean after spawning, unlike salmon which die after spawning once. In fact Steelhead can spawn two or three times in their lives if they are lucky enough to survive that long.
It is very hard to see an adult Steelhead in Lompico Creek because they are so rare, but if you were to spot one, it is a thrilling experience for those who love wildlife. It is hard to imagine a large fish making it up Lompico Creek, but Steelhead do this by using the high water of winter storms. Their reproductive strategy it to get as far up in a Creek drainage as they can so that after spawning, their fertilized eggs and fry are less likely to be flushed downstream and destroyed by the next big rain storm. Even this short description of their reproductive strategy makes it clear how precarious their lives are. Steelhead are listed under both the State and Federal Endangered Species Acts. It is a crime to molest them in our Creek.

To create a nest or "redd" the female fish looks for gravel at the tail of a pool in the stream. This is a shallow area of quick moving water called a riffle. She turns on her side and uses her powerful body to stir up the gravel and create a depression. Once this has been done, the male and female fish release eggs and sperm simultaneously. The female then buries the eggs with loose gravel to protect them. The gravel that these fish need to build nests is not easy to find and it is often ruined and buried by sand and silt from poorly maintained roads, logging operations and erosion from badly maintained or constructed housing sites. These are conditions that we are all responsible for. The fish also need structure in the Creek to build potential spawning habitat. This structure is often created by boulders and what is called "large woody debris", a scientific term for logs and other large pieces of wood which help provide habitat for the fish. What looks to us like a harmful log jam may actually be good for Steelhead. During high water, the wood is lifted by the water and large fish can squeeze through it. This large woody debris is now considered essential for the survival of these animals. Young fish shelter under it to avoid predators. Some log jams can block the passage of fish but others do not. It is sometimes necessary to build fish ladders around obstacles to the passage of fish. There are two such ladders between Lompico Creek and the ocean, both of which were built by Santa Cruz County with help from other agencies.

Young fish spend one to two years living in our Creek before they move downstream, acclimate to salt water in the San Lorenzo Lagoon, and then enter the Pacific Ocean. Once in the ocean, Steelhead roam widely over the continental shelf before returning to Lompico Creek to spawn. Current theory on the migration of salmonids suggests that the fish use the stars to navigate the vast reaches of ocean over which they roam. Some very complex method must be in play to allow these animals to find their natal streams after 3 years in the ocean during which they may travel far north of the Monterey Bay. When the fish reach the bay they find their home stream by scent.

The two year old fish look just like a beautiful rainbow trout with a green back, pink and silver sides and a white stomach. Steelhead need cold, clean, abundant water to survive. They are very sensitive to chemical contamination of the Creek. It is very important for all of us to be careful with oil, paints, lawn chemicals, chlorine and any other harmful substances which we might use around our houses or businesses. Everything that lands on the ground in a mountain canyon is carried by the rain into the Creek.

Over forty percent of the salmon and Steelhead runs on the Pacific Coast from here to Washington are now extinct.
The Conservancy is awaiting approval of a grant application to Fish and Game. The purpose of this grant request is to improve adult fish passage across the Lompico Pool area where concrete was laid on the stream bed.