Atlantic Salmon Farming Quiz

Atlantic Salmon Farming

• Atlantic Salmon scientific name: Salmo salar
• Salar comes from the Latin word salio meaning "to leap"
• Atlantic salmon belong to the family Salmonidae
• In the wild, Atlantic salmon can live up to 13 years
• Juveniles feed on aquatic insects, molluscs, crustaceans, and fish, while adults consume larger fish and invertebrates
• The maximum length of an Atlantic Salmon is 150 centimeters and the maximum weight is 46 kilograms
• Atlantic salmon return to their birthplace to spawn between June and November
• Atlantic salmon spawn in the gravel areas of rivers upstream.
• Spawning occurs at 6-10°C
• Females lay 8,000 to 25,000 eggs
• Spawning lasts 1-2 weeks
• The majority of males die after spawning, while 10-40% of females survive and return to the sea
• Atlantic salmon eggs hatch in the spring after 70-160 days
• High mortality rates for young salmon (14-61%) occur during the first few months of life
• Atlantic salmon juveniles (parr) can remain in freshwater environments for 1-7 years
• Parr undergo smoltification (a physiological transformation that prepares them for saltwater)
• Decreasing day length triggers sexual maturation in Atlantic salmon
• During maturation, 90% of lipids and 50% of proteins from muscles move to growing ovaries

Atlantic Salmon Farming: Freshwater Phase

• Lasts 10-16 months
• Includes broodstock, hatchery, first feeding, and smolt production (in outdoor tanks)

Atlantic Salmon Farming: Seawater Phase

• Lasts 12-24 months
• Conducted within cages

Atlantic Salmon Farming: Broodstock and Fertilization

• Females in the same population ovulate at different times – breeding season lasts 2 months
• Eggs start to decay about one week after ovulation
• Anaesthesia and gentle handling are used for stripping (collecting eggs and sperm)
• Gametes (eggs and sperm) are not initially exposed to water
• Oocytes and milt are in contact for 1-2 minutes
• Freshwater covers eggs – this is important for spermatozoa motility
• Eggs are disinfected before incubation

Atlantic Salmon Farming: Production of Mono-sex Salmon

• Early maturation of males can be problematic
• Hormones, irradiation, and sterile populations are solutions to this challenge
• Triploidy (producing nonfunctional gametes) is another technique used to create sterile populations

Atlantic Salmon Farming: Hatchery and Incubation of Eggs

• High water temperature in the early stages of development increases mortality
• CO2 affects pH, which in turn affects the toxicity of some ions.

Atlantic Salmon Farming: Hatching, Alevins, Pre-feeding

• Eggs typically hatch after 480-520 degree days (a measure of temperature and time)
• Water parameters are critical, especially dark conditions
• Sub-optimal water conditions can affect alevins.

Atlantic Salmon Farming: First Feeding

• Starts about 370-440 degree days after hatching
• First feeding pellets should float on the surface before sinking gently with minimal fragmentation
• The amount and type of feeders are adjusted based on tank size and shape
• Stocking density is initially based on surface area then by volume

Atlantic Salmon Farming: Grading and Transporting Fish

• Fish are pumped through a system to be graded and sorted.

Atlantic Salmon Farming: Smolt Production

• Usually follows normal photoperiod
• It is possible to produce "autumn" smolts (early eggs, short days/12:12 L/D for some weeks then increase the L period, transfer in September but smaller fish)
• Seawater test (40‰) for 24 h (mortalities, blood ions)
• Before transferring to the sea, seawater is added – feeding stops some days before, when the temperature is greater than 7-8°C.

Atlantic Salmon Farming: Seawater Phase - Cages

• Cages are placed in appropriate locations with good water quality
• Cages have adequate mesh size and appropriate construction
• Cages can be up to 60m in diameter and 20-50m deep
• Fish density can reach 25 kg/m3

Atlantic Salmon Farming: Slaughtering of Salmon

• Fish are starved for a certain period of time
• Fish are transferred to a holding pen
• They are anesthetized before being slaughtered
• In Norway, they follow the Aquaculture Operations Regulations
• There are welfare concerns associated with crowding, pumping, poor water quality and time out of the water
• Stressed fish go into rigor mortis faster and develop a harder rigor mortis, which reduces the shelf life of the fresh product

Lumpfish (Cyclopterus lumpus)

• The name refers to the modified pelvic fins that form a suction disc
• Lumpfish belong to the family Cyclopteridae.
• They can reach a maximum length of 61 cm and 9.5 kg in weight
• Their maximum reported age is 13 years
• Lumpfish are mostly solitary and inhabit rocky bottoms
• During spawning season the males become reddish and females blue-green
• After an extended courtship, the female lays eggs which are fertilized by the male
• The male lumpfish cares for the eggs by aerating and guarding them against predators

Use of Cleaner Fish in Atlantic Salmon Production:

• Cleaner fish are used to control sea lice in salmon farms.
• The use of farmed and wild cleaner fish is decreasing due to health issues and welfare challenges

Cleaner Fish: Welfare Challenges

• Almost all Lumpfish are farmed, while the majority of wrasse are wild
• Different natural habitats (e.g. currents, temperatures)
• Stages of production: capture, recovery, weaning, slaughter
• Cleaners are slaughtered at 2.5-5 kg

Spotted Wolffish (Anarhichas minor)

• Belong to the family Anarhichadidae (Wolffishes)
• They are oceanodromous – making short migrations
• Maximum length is 180 cm and maximum weight is 28 kg
• The maximum age is 40 years
• Spotted Wolffish spawn between September and January at 250 m depth.
• Females lay eggs in nests built on the ground

Wolffish Farming

• First production in Norway around 2004
• Studies on farming Wolffish initially began in the mid 1980s
• Wolffish tolerate a wide range of salinities
• Wolffish are social fish and form large groups on the bottom of tanks
• Wolffish have low fecundity (about 1500-4000 eggs per kg female)
• Eggs are incubated at 4-6°C
• Yolk sacs are absorbed within 2 weeks and feeding starts with microparticulate diets

Challenges in Farming Cold-Water Species

• Non-standardized feeds are available
• Most cold-water fish reproduce easily in captivity (Cod is an exception)
• Disruption of male Wolffish behavior in captivity
• High mortality of eggs and sperm
• Limited genetic selection

Test your knowledge about Atlantic salmon farming and their life cycle. This quiz covers their scientific classification, feeding habits, spawning behaviors, and survival rates. Explore the fascinating world of Salmo salar and learn about their importance in aquaculture.