Vaccinating rainbow trout can be very effective in the prevention of diseases and minimizing environmental risks and challenges. In this chapter, we review different methodologies to provide vaccines to our stock
Vaccinating rainbow trout can be very effective in the prevention of diseases and minimizing environmental risks and challenges. Fish populations that are reared in hatcheries or controlled environments will generally not have any natural immunity to many of the pathogens that are found in the wild. The purpose of vaccines is to expose the animals to inactivated forms of natural diseases, while posing no danger to consumers. There are three ways of administering vaccinations:
1. Oral Generally top coated on commercial feed and fed to stock. This method can be challenging as it is sometimes difficult to ensure proper dosage. If signs of illness are already showing in the population, fish may be lethargic and unwilling to consume the treated feed. The palatability of the feed may also be affected, furthering the difficulty of getting the entire population to ingest the diet and vaccine.
2. Immersion Commonly known as a “dip” or “bath” treatment and generally performed when the fish are smaller in size. Fish are immersed in a vaccine solution for a set period-of-time, and then placed back into fresh water immediately after. This method is useful for treating large populations quickly and effectively.
3. Injection This is considered to be the most effective method of introducing vaccines. Fish are individually administered a dose of vaccine through injection. This method can be very time consuming and has an inherent risk of accidental injection to staff.
Troutlodge uses vaccines as one of the many tools to keep our trout stocks healthy. The current vaccination program includes an immersion treatment, when fish are less than 10 grams in size, and a booster injection, at approximately 18 months of age. All stock are vaccinated for Yersinia Ruckeri, the bacterial pathogen causing enteric red mouth disease (ERM), as well as Aeromonas salmonicida. These vaccine treatments are effective in raising a protective immune response against these common diseases.
