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Rainbow Trout Incubation on Recirculation and Flow-Through System

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Eyed StageEyed Stage

The recirculation and flow-thru incubation systems were compared on the basis of temperature. In this aspect, the recirculation system provided several advantages. It should be noted that every facility is different and thus provides alternative advantages and disadvantages for both incubation systems dependant on the resources available.

- Recirculation systems can be heated or chilled artificially (via heaters or chillers)- Recirculation systems accumulate heat and maintain a higher average temperature- Flow-thru systems adopt ambient temperature and cannot be heated or chilled effectively- Warmer average temperatures in recirculation systems produce a faster development of eggs

*It should be noted that every facility is different and thus provides alternative advantages and disadvantages for both incubation systems dependant on the resources available.

“Golden” Rainbow Survival:- “Golden” rainbow trout exist as a genetic variant that has altered their natural colour to appear gold-Golden Rainbows had the highest average survival (80.1%) which was not expected for several reasons:- Golden eggs are smaller than regular rainbow eggs which increases their surface area allowing for greater permeability of toxins and waste elements- Golden eggs in both systems were located in the fourth heath tray. This is significant as the incubation system used cascades water down from the first tray to the last. This creates a concentration of waste and possible infectious elements in the lower trays. - Saprolegnia, in particular, accumulates in lower trays despite the addition of ozone to the system- Oxygen tends to decrease while CO2 increases in consecutively lower trays

Survival Results to Eyed Stage:-Of 24,866 initial eggs, 9,289 survived (37.3%)- Of 12,464 initial eggs in flow-thru, 3,824 survived (30.7%)- Of 12,402 initial eggs in recirculation, 5,465 survived (44.0%)- Of the 9,289 surviving eggs, 5,060 (54.5%) were golden while 4,229 (45.5%) were wild type rainbow trout - The recirculation system produced the greatest survival of the two systems

Fry

Juvenile (1-2 years old)

Brood Stock (3-5 years old)

Eggs (eyed and hatched)

Cost Savings of Recirculation System:-The following is a breakdown of cost between the flow thru system and the re-circulation system at Vancouver Island University for eggs incubated to the eyed stage- The flow thru system cost in total $233.30 to get our eggs to the eyed stage and the recirculation cost $62.21. Calculation example as follows for $0.72 m3:

VIU Project In Husbandry: Rainbow Trout Group

Project duties include:• Husbandry of rainbow trout (Oncorhynchus mykiss)• Spawning and incubation• Calculating feed rates and feeding • Treating for disease• Maintenance of system

• Conducting incubation experiment

The Incubation Experiment:• Comparison of flow-thru and recirculation incubation systems• Comparison of survival between incubation systems• Recirculation system consists of eight heath trays supplied with water from a 320L resevoir• Flow through system requires a constant flow of city water

Please visit our channel on YouTube: http://www.youtube.com/user/FishAquaMalaspin

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Presented by: Aaron Norberg, James Scott, Nan “Mark” Ma, Miles Lee, Peter Allen, Shaun Spenard

- There were other expenditures involved in the recirculation system such as cost to run a heater to heat the water when temperatures dropped to unwanted levels and the cost of excess flow thru water added to the recirculation system after hatch to flush excess wastes away