FEATURE
Key factors in the successful production of rainbow trout
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by Martin Smith, Hatchery Manager, Bibury Trout Farm, UK
uccessful production of rainbow trout relies heavily on high gamete quality and progeny performance. Fecundity, egg size, high egg survival and hatch rates are all attributes considered important when quantifying brood stock performance. To achieve success it is necessary then to provide the brood fish with optimal conditions throughout the maturation period as well as a high quality feed and good husbandry techniques. Failure to provide these essentials will result in poor quality brood fish and subsequently poor quality ova and underperforming fry. Brood stock selection is also an important part of commercial farming but not all farms are looking for the same traits. Restocking farms may be looking for good body shape and patterning and table producers may be more inclined to select for growth rates, fillet yield etc. As an egg producer I have to take into consideration what all my customers require but high fecundity is desirable, not to the extent where egg size is compromised however. It is believed by many farmers that the larger the egg the better the fry, although this is not the case in my personal experience nor in studies
conducted by others. However, higher fecundity does reduce the number of brood required, which in turn will help reduce the food bill, provide better rearing conditions through lower densities and reduce labour due to less stripping time. Ultimately a good quality egg with high survival and hatch rates takes priority and this is achieved by giving the brood fish the best diet, care and environment I can. Now unless we have a purpose built, state of the art production site where all water quality parameters can be closely monitored and optimised appropriately, then this becomes difficult. Those of us on river/ spring fed farms are continually at the mercy of the weather and whatever else mother nature throws at us, therefore providing these ’optimal’ conditions becomes very challenging and sometimes impossible. What we have to do then is give them the best we can given the circumstances. A well trained, conscientious farmer will understand the importance of good husbandry technique, keeping handling to a minimum is highly important as well as implementing effective bio-security measures, this will significantly help to limit stress by minimising disease/ parasite challenges and the requirement for expensive treatments and the use of antibiotics. Stress in brood fish at different stages of egg development has
34 | November | December 2016 - International Aquafeed