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Questions and Answers
What is the maximum age a spotted wolffish can reach?
During which months does spawning occur for the spotted wolffish?
At what depth does the spawning of spotted wolffish typically occur?
What is the typical fecundity range for female spotted wolffish?
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What is a significant challenge faced in the farming of spotted wolffish?
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What is the maximum length that Atlantic salmon can reach?
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Which phase of salmon farming takes place in freshwater?
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What triggers sexual maturation in Atlantic salmon?
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How many eggs does a female Atlantic salmon typically release during spawning?
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What is the primary diet of juvenile Atlantic salmon in the wild?
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During which months do Atlantic salmon typically return to spawn?
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What is the main reason for ensuring no contact of gametes with water during the stripping process?
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What percentage of lipids is transferred from muscles to growing ovaries during sexual maturation?
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What is the typical photoperiod for producing outdoor smolts?
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What role does freshwater play in the fertilization of oocytes and milt?
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What happens if fish are stressed before slaughter?
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What is the maximum reported age of a lumpfish?
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What is a key concern regarding the management of broodstock for mono-sex salmon production?
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What is a common method used to anesthetize fish before slaughter?
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Which method is used to ensure that sperm does not contribute to the genetic profile of the offspring?
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What is the purpose of the seawater test prior to fish transfer to the sea?
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How does high water temperature affect the incubation of fish eggs?
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What is one of the welfare concerns during the slaughtering of fish?
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What is the significance of the dark conditions during the hatching of fish eggs?
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What should be considered when determining stocking density for alevins?
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What is the primary role of male lumpfish during the spawning season?
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What diameter can fish cages reach for aquaculture use?
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What is the purpose of hand feeding alevins before switching to automated feeding systems?
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What should be done if the yolk sac of an alevin is cracked?
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Which species had the highest value in NOK in 2022?
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How many Berggylt/Ballan wrasse were recorded in 2021?
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What trend can be observed in the total value of cleaner fish from 2018 to 2022?
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Which species had the least total value over the entire time span listed?
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Which year saw the highest recorded number of total cleaner fish?
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What health issue is raising concerns regarding the use of cleaner fish?
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Which species has the highest recorded number of individuals in 2016?
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Which statement about the habitats of cleaner fish is correct?
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Study Notes
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
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Description
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.
