Historical early delivery of rainbow trout eggs

The season’s first rainbow trout eggs from the AquaGen strain was delivered to Hofseth Aqua in Tafjord, Norway on November 19th, 2019, two months earlier than normal. With access to these early eggs, the smolt can be put to sea in spring, benefit from good growth through the summer and be harvested the following spring after 10 months in the sea.

Rainbow trout in transport box.

Rainbow trout production in the sea is mainly seasonal. The bottleneck has been availability of smolt to ensure good utilisation of the plant capacity and be able to harvest year round. Historically, the first eggs have been delivered in the midle of January, and there has long been a strong desire from farmers to get the eggs earlier.

Research project on extension of the egg delivery season

Ingvild Flesjå Grønfur and Helge Kjartansson at Hofseth Aqua dep. Tafjord receiving rainbow trout ova, November 19th, 2019.

The parent fish of the recently delivered eggs have been part of an internal R&D project with the goal of expanding the rainbow trout delivery season.

Around 3,000 fish of 250 grams were moved from AquaGen Hemne to Nofima’s land based plant at Sunndalsøra in May 2018. The fish group was divided in two, one being managed to mature early and the other to mature late. The brood fish were regularly examined with ultrasound every three months for the last year prior to scheduled maturation.

– We have used the knowledge that has been built up on salmon to control the timing of sexual maturation of rainbow trout, says Researcher at AquaGen, Ingun Næve. She is working on a doctorate on the use of ultrasound to monitor salmon maturation. Two scientific articles from this work have been published.

Although the salmon is receiving the greatest attention in the breeding work, today the same advanced technologies are used to identify the best brood fish. DNA information is used to find resistance to both IPN and flavobacteriosis in the rainbow trout.

First early delivery to Hofseth Aqua

The project was carried out in close collaboration with Lerøy Sjøtroll dep. Jakta who received the early fish group in September 2019. The first stripping day was on Wednesday 23rd, October 2019 at an average weight of eight kgs.

– We consider the first part of the project to be successful as we have managed to control the brood fish to deliver eggs two months earlier than before, says Landbased Broodstock Production Manager at AquaGen, Tore Mjelde. In addition, we have fish groups that will deliver eggs far beyond summer 2020.

Rainbow trout eggs are ready for hatching.

The first egg delivery was delivered to the rainbow trout producer, Hofseth Aqua. They are dependent on having eggs delivered several times throughout the year in order to utilise production capacity in the freshwater- and seawater phase optimally.

– It means a lot to get eggs as early as November, since we can transfer 100 grams rainbow trout in early June and harvest the following spring. This means that we can harvest before the problem of lice and sex maturity come in to play, ”says Freshwater Production Manager at Hofseth Aqua dep. Tafjord, Henriette Nordstrand. She is looking forward to receiving more egg deliveries in the new freshwater facility that meets NS 9416 standard which includes escape technical regulations.

Freshwater Production Manager at Hofseth Aqua, Henriette Nordstrand and Landbased Broodstock Production Manager at AquaGen, Tore Mjelde stand in front of a picture of Storfjorden in Møre og Romsdal county, Norway where the rainbow trout is farmed until harvest.