Trout Farming in California

Currently, there is relatively little commercial aquaculture being done in California. This may be due to a number of reasons: the high cost of living in the state, the environmental awareness and activism of its residents, etc. One of the most notable aquaculture companies in California is Kent Sea Tech, located in San Diego, but even they have switched their focus from a fairly-large striped bass operation to algae production, both for feed and biofuel.
 

However, one aspect of the industry that seems to be thriving is the government sector: the main player here is, of course, the California Department of Fish and Game. These state-run farms and hatcheries breed and raise rainbow trout to restock sport fishery waters throughout the state. These operations are funded directly from the revenue generated when fishermen purchase their annual fishing licenses from the state (a resident license cost $41.20 in 2009).

I had the opportunity to work at one such farm two summers ago; the farm was in Fillmore, California, within driving distance of Los Angeles. Even though the facility was called the “Fillmore Trout Hatchery”, the actual hatchery operations had been suspended for some time; we received fry from another state-hatchery and then simply grew the fish up to the legal limit (10 inches in length). Once a fry entered our facility, the entire grow-out process took approximately 12 months, at which point that fish would be taken by truck and “planted” in local fishing waters.

This was a low-density system designed to produce quality over quantity. Density is an important issue to consider when farming salmonids: if the density is too low, the fish will establish territories and pecking orders, leading to increased aggression and stress. However, if the density is too high, the fish experience fin abrasions and are more prone to disease. Because this facility was focused on producing quality fish that fishermen would be proud to catch, the densities were kept on the low end of this spectrum.

This was also a flow-through system, meaning that the total inflow of water was equal to the total outflow. The farm used groundwater as their source, with six wells supplying somewhere around 1000 gallons per minute. The facility utilized raceways, as opposed to circular tanks or ponds, for the grow-out process. The water would enter the raceways at the top, flow 1000 feet down the length of the channel, and then be deposited into a wetlands area at the far end. With 4 such channels in parallel, the farm consisted of a total of 4000 linear feet of grow-out space.

Each 1000-foot raceway was broken up into ten 100-foot sections separated by a screen and a series of two baffles. The first baffle was open along the bottom, forcing water through at a high rate of flow. This would cause the water to fill the space between the baffles and flow over the top of the second baffle very quickly, in turn oxygenating the water. Additionally, the water level got progressively lower in each section, creating oxygenating waterfalls after each baffle.

These baffles were also movable, allowing fish to be herded upstream or downstream in the raceways; this was useful in moving fish of different sizes: the smallest fish were housed in the first sections, where oxygen levels were highest. As the fish grew, the farmers moved them progressively downstream until they reached the final section 12 months later, where they were removed and sent out to be planted.

The daily operations on the farm were more mundane and less mentally-stimulating than I initially anticipated. Farm workers (or “technicians” as they are referred to) spend their days doing all forms of manual labor, the greatest task of which is cleaning. Dead fish that accumulate on the screens need to be removed and recorded. Algae buildup needs to be removed from the screens and the sides of the raceways to maximize water flow. The solids that collect on the bottom of the raceways needs to be swept downstream and out of the systems to avoid excess buildup, keep oxygen levels high, and prevent the outbreak of disease. Not to mention the feeding schedules that need to be kept, as well as the general service and maintenance of the mechanical engines that were used (forklifts, pick-up trucks, and tanker trucks).

However, there were several elements of fun in the job, the most notable of which was the opportunity to go out on plants. After loading a tank full of legal-size fish from the downstream sections, we drove the truck to sport-fishing waters that needed to be stocked and delivered these fish. If we were stocking a river or stream, we would net out several buckets of fish and toss them in along the entire length of the waterway. If we were stocking a lake, we would simply back the truck up to the edge of the water and “pull the plug” on the tank, resulting in anywhere from 500 to 2000 pounds of rainbow trout to come rushing out. Needless to say, it was a pretty cool process to watch!

All in all, the experience that I had while working at this facility was very positive. I learned quite a bit about rainbow trout production, as well as made several great industry contacts…all the while getting a fantastic tan!

Aquaculture: The Future of an Industry

With the near exponential growth of the human population, the global demand for fish protein is the highest it has ever been. This leads to increased fishing pressure on wild fisheries, which when coupled with anthropogenic pollution and habitat destruction, results in the collapse of these fisheries. Yet the global demand is relentless: if we can no longer obtain wild fish from our oceans, the market demands that we obtain fish from some other source.

The ONLY answer to this growing crisis is aquaculture, or fish farming as it is commonly known. Just as agriculture is concerned with growing plants and animals on land, aquaculture is the practice of farming species in the water. Virtually every commercially-valuable species is farmed, from salmon and tilapia to urchins, mussels, and even seaweeds. These farms also take many forms, such as sea cages in the open ocean, earthen ponds near the shore, and recirculating systems in-land.

While all of the commercial aquaculture practices and systems used today are lucrative and economically-successful, most of them create a substantial environmental impact. From a commercial perspective the entire industry is relative young and the long-term environmental effects of these systems are still unclear. However, most academics agree that many fish farms in use today are detrimental to the surrounding environment to some degree.

The secret here is sustainability. While most current farming practices are economically-sustainable, they are FAR from environmentally-sustainable. In order to protect our planet for future generations, an immediate and drastic change needs to made in aquaculture policy and practice.

That change is manifested in two ways: recirculation and polyculture. One of the main environmental impacts of a fish farm is the effluent discharge from the system, which is loaded with nutrients stemming from excess feed and feces. Recirculating systems are essentially zero-discharge: the water is filtered and sterilized before being pumped back into the start of the system. In this way, a farm could run with a set amount of water almost indefinitely (a major bonus when examining the current shortage of usable water on the planet).

The other solution is polyculture: growing many different species in the same environment. For example, effluent from salmon cages could be pumped into ponds containing sea cucumbers, a scavenging species that would reduce particulate organic matter levels. The water could then be pumped past mussel beds, which would further filter the water of particulates. Finally, the water could be passed through ponds containing algae, which would help to filter the water of any remaining dissolved nutrients. The water can then be passed through a series of biological filters, which helps to ensure that the effluent released from a farm does not contaminate the surrounding environment. Plus, if all the species used are economically-valuable, the farm is able to turn a greater profit.

Only through the utilization of one or both of these solutions can aquaculture become truly sustainable, both economically and environmentally.