Sande Settefisk delivered its first smolt group which consisted exclusively of female salmon to the Haneholmen site at Nordfjord Laks, Norway, on April 19 2020. These All Female salmon will reduce the problem of sexual maturation in the sea.
The eggs were delivered by AquaGen in January 2019 and were our first commercial All Female supply of salmon to the Norwegian aquaculture industry, says Lisbeth Ingebrigtsen, technical sales manager at AquaGen. The reason that Nordfjord Laks wanted to try All Female was the challenges related to sexual maturation in fast-growing smolt transferred to sea in early spring, says Leiv Slagstad, CEO of Nordfjord Laks.
Reduced sexual maturation with the use of female fish
In varying degrees, early sexual maturation can occur before the fish reaches slaughter size. Particularly at sea sites with fluctuating salinity and temperature, early sexual maturation can be seen, especially among male fish. This is an undesirable event as it leads to poor fish health, reduced quality, and growth. The use of lights can in many cases reduce sexual maturation, but it does not work under all conditions.
Compared to female fish, male fish are naturally at higher risk of developing early sexual maturation. One of the solutions to this problem is to transfer fish that are selected for reduced sexual maturation using gene markers and/or only produce female fish. This can be achieved through ultrasonic screening of sex at an early stage or the use of All Female fish.
Experience from the hatchery
The All Female eggs were selected for rapid growth (SHIELD) and virus resistance against IPN, PD, and CMS. Simultaneously ordinary eggs with both sexes (GAIN) which were selected for even better growth than the All Female and resistance against IPN, PD, CMS, and lice, were delivered. On the 3rd of January 2019, eggs from both groups were placed at Hyen Fisk. Then on the 1st of March, they were moved to Sande Settefisk. The hatching percent for All Female and GAIN was 98.6% and 98.5% respectively.
Considering that the All Female fish were compared to GAIN fish, which is AquaGen’s premium product, the growth was surprisingly good, says Ingrid Torvanger, department manager at Sande Settefisk (the video below shows the All Female fish).
Except from some differences in the development of the two smolt groups, we are very pleased, says Tom Wilke, CEO at Sande Settefisk. With some help from natural light, the All Female fish eventually achieved smolt status. We do not currently have the capacity to run seawater on these fish, but after some developments of the site this will be possible, he says.
Video of the All Female fish, weighing an average of 192 grams, in one of the tanks at Sande Settefisk, just before it was transported to Nordfjord Salmon.
Comparing two different groups of fish in the sea
Nordfjord Laks has two concessions, one location in Hyenfjord and one location in Nordfjord. They get their smolt from Hyen fisk and Sande Settefisk, which produces both rainbow trout and salmon. Nordfjord Laks was the first to take in All Female rainbow trout because of challenges with brackish water and early sexual maturation. As a result of the same problem, they wanted to do the same with salmon.
The All Female fish were transferred to the same location as the GAIN fish, so it will be exciting to follow the development for the groups until slaughter. The dream is to get All Female GAIN in the future, says Tom and Ingrid before heading back to the hatchery to feed the next generation of All Female salmon.