“Closing the cycle” is how farming began. It was what turned us from hunters and gatherers to farmers. It began with terrestrial farming thousands of years ago and has only recently, relatively speaking, become possible in the water environment thanks to the relentless endeavors of aquaculture pioneers.
Salmon have been raised at stock enhancement hatcheries around the world since the late 1800’s, but these hatcheries have historically and currently relied on annual capture and spawning of adult salmon returning to rivers to produce the next generation. It wasn’t until the 1960’s that Norwegian and Scottish salmon farmers managed to raise salmon in a contained space for their entire lifecycle and, while most captive salmon were harvested for profit, kept some fish back in order to produce the next generation.
Today Marine Harvest Canada annually produces approximately 25 million green eggs, in house, to meet its ongoing production requirements. In BC, there are no independent egg producers and importation of eggs to Canada is very rare and if allowed, is strictly regulated. It is therefore important that salmon farmers protect the genetic integrity of the stocks they have while making improvements to their performance.
“The egg production cycle takes considerable time and requires several years of planning,” says Dean Guest, MHC’s Freshwater Production Manager. “Each fall, brood stock are selected from saltwater sites and transported to a freshwater water brood site. For example, brood selected in the fall of 2011 will produce eggs in the fall of 2012, that will first feed as fry in 2013, smolt in the spring of 2014, reach market size in 2015, and brood again in 2016.”
The majority of MHC’s brood stock are currently reared in salt water, but at MHC’s Fresh Water Farms site in Duncan, BC, 10 million eggs are spawned per year from brood that never see salt water. “They are kept in fresh water to add another layer of protection for our brood stock,” adds Dean.
Two unique strains of brood stock, Mowi and McConnell, are used at MHC. To date they have been reared as separate brood lines and only crossed as production fish.
“In the past, 150 new families were created each year to continue the brood lines into the next generation,” explains Dean, “and a family is created by mating a single male with a single female.”
Starting this fall, MHC will be creating 600 families that include both pure strains and hybrid crosses. The families will be mixed at the eyed egg stage to produce smaller groups of 2500 smolt, and grown to harvest size at sea. By taking tissue samples at the time of harvest, each fish can be identified by stock and family. Collecting information on these fish at the processing plant, such as weight and maturation, allow MHC to select families for the next generation, with a focus on improving performance.