The MBSTP hatchery is in Santa Cruz County on Big Creek (Tributary to Scotts Creek) at a site historically known as Kingfisher Flats. The setting and scale of the facility are well suited to the mission of recovering the local coho salmon and steelhead. By using our native captive coho brood-stock and the few wild fish that return, the hatchery staff and volunteers can produce about 35,000 hatchery-reared coho for planting as smolts that are ready to out-migrate to the ocean. If marine survival is good (~ 2%) then the spawning run on Scotts Creek would be about 700 fish. This is about the maximum that the small watershed can accommodate. The NMFS Coho Recovery Plan specifies that the run would be considered “recovered” if a 500 fish self-sustaining spawning run can be established. Returns in recent years have indicated that the 2% marine survival is not being achieved. A study by NOAA Fisheries scientists is underway to determine if planting the smolts later in the season will result in a greater marine survival rate.
The hatchery rears three year-classes of captive brood-stock. Brood-fish are selected for captive rearing on the basis of genetic diversity. The intention is to maximize the genetic diversity of the coho produced. The captive coho are reared on a diet of fresh-frozen krill and exercised by water currents generated in the rearing pools. Once mature, the coho are spawned according to a spawning matrix developed on the basis of genetic differences. In this way the local native gene-pool can be conserved and used to recover the local coho.
The hatchery can produce up to about 45,000 steelhead smolts for supplementing the populations of the San Lorenzo River and Scotts Creek. 40,000 for the San Lorenzo and 5,000 for Scotts Creek. These fish are managed as two distinct populations and are not mixed. There is no captive brood-stock. The brood-fish are trapped by our volunteers on the San Lorenzo River, and by NOAA Fisheries on Scotts Creek. The brood fish are “sub-spawned” at the hatchery. This means that only about half of the eggs and milt are taken. The fish are returned to their creek or river to complete spawning in the wild. Radio tracking of steelhead has provided good evidence that the fish do successfully spawn after their release. The sub-spawning technique is used to help avoid influencing the genetic composition of the wild population. The hatchery-reared steelhead are considered to be part of the “wild” population because only “wild” fish are used for the hatchery captive spawning and rearing. The hatchery-reared fish are all marked by an adipose fin-clip. The fin does not grow back, and the loss of the fin does not seem to influence the fish success. No clipped fish are used for spawning at the hatchery. Large healthy MBSTP hatchery-produced steelhead return from the sea and mix-in and spawn with the “wild” fish. In this way the MBSTP avoids creating a domesticated, or “hatchery” fish. The intention is to boost the numbers of steelhead and keep the wild population from declining further.
The hatchery operates with two paid staff (Hatchery Manager Mark Galloway, and Fish Culturist Seth Bowman). A substantial corps of experienced volunteers are needed to make the mission possible. The MBSTP operates in close partnership with the NOAA Fisheries Southwest Science Center in Santa Cruz. This partnership facilitates the development of increasingly more effective recovery techniques.