The age of sexual maturity is determined by heredity as well as by the farming conditions (e.g., feeding strategy, temperature, light conditions). We could only strip eggs once a year and our brood stock took up lots of pond … Consequently, nine different populations of steelhead (sea-run rainbow trout) have been added to the federal endangered species list. The male fertilises them with milt (sperm). We kept our own brood stock up to a number of years ago but found it much more convenient to buy them in 6-8 times a year as learnt that it’s better for our farm management. Eggs take 20–100 days to hatch, depending on water temperature. However, males often are mature in their second year. The Rainbow Trout is a species of fish in the Salmonidae family. 3.0 LIFE CYCLE OF RAINBOW TROUT 3.1 Brood stock and breeding The brood stock fish (Figure 2) in Danish trout farms normally are sexually mature at the age of 3 years. Brood Stock. The maximum recorded lifespan for a rainbow trout is 11 years. Small trout generally create smaller redds in finer gravel, and big sea trout can create redds the size of a kitchen table top with much bigger stones. We buy our eggs from a specialised hatchery in the USA and the Isle of Man. Rainbow trout is economically the most important cultivated fish in Finland. How many eggs are laid also depends on the size of the hen trout – a 500g trout will typically deposit around 800 eggs. Rainbow trout, including steelhead forms, generally spawn in early to late spring (January to June in the Northern Hemisphere and September to November in the Southern Hemisphere) when water temperatures reach at least 42 to 44 °F (6 to 7 °C). In addition, construction of dams, road crossings, and other structures impede the ability of rainbow trout to migrate upstream and downstream, which is critical to successful completion of their life cycles. In this study, new knowledge on the energy consumption, emissions and environmental impacts caused by the production of rainbow trout in Finland was generated. The Lifecycle of Goatsbridge Rainbow Trout . Life cycle. Other members of the family include other trout species, salmon, char, grayling, whitefish, and more. The female digs a redd (nest) and deposits her eggs. Freshwater life cycle. Some of the closest relatives of this species include the cutthroat trout, pink salmon, dog salmon, coho salmon, sockeye salmon, and Chinook salmon.Read on to learn about the Rainbow Trout. The life cycle of rainbow trout is similar to that of brown trout and Chinook salmon. Once hatched the alevins (fry with yolk sacs attached) stay in the gravel for two to three weeks and feed off their yolk sacs.