Nordlaks Oppdrett AS

Stokmarknes, Norway

Nordlaks Oppdrett AS

Stokmarknes, Norway

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Imsland A.K.,Akvaplan Niva | Imsland A.K.,University of Bergen | Reynolds P.,GIFAS AS | Eliassen G.,GIFAS AS | And 11 more authors.
Aquaculture | Year: 2016

To investigate the possible family influence on sea lice grazing of lumpfish on Atlantic salmon, nine families of lumpfish (N = 360) with a mean (±. SD) weight of 169.4 ± 8.3 g were distributed among nine sea cages (5 × 5 × 5 m) each stocked with 400 Atlantic salmon with a mean (±. SD) weight of 123.3 ± 12.3 g. For each family, 20 lumpfish were stocked into one of nine sea cages and 20 into another cage thus establishing duplicate treatments for each genetic family giving two families stocked per cage. There were significant differences in behaviour, feeding preferences and mortality between the nine families of lumpfish. Fish from family 2 were found to be more predisposed to exploiting natural food sources within the cage environment and showed a higher incidence of sea lice grazing from Atlantic salmon. Using mixed linear model to analyse the data revealed significant maternal and paternal effect on sea lice grazing. In contrast, fish from family 5 were observed choosing to compete with salmon and consume pellets more than the other eight families and were found to be less inclined in seeking out alternative food sources. Further, there were differences in the mortality rates between the nine families as a result of a Pasteurella spp. outbreak. This is probably the first study in fish aquaculture investigating the variation in a specific behavioral trait linked to different family background. Statement of relevance: The data presented here are highly relevant for aquaculture. © 2016 Elsevier B.V.


Imsland A.K.,Akvaplan Niva | Imsland A.K.,University of Bergen | Reynolds P.,GIFAS AS | Nytro A.V.,Akvaplan Niva | And 8 more authors.
Aquaculture | Year: 2016

To assess possible size effects of foraging of lumpfish and co-existence with Atlantic salmon with particular interest to the sea lice grazing efficiency, eight sea cages (5 × 5 × 5 m) were stocked with 150 Atlantic salmon with a mean (± SD) weight of 538 ± 14 g. Six of the cages were stocked with 15 lumpfish each (10% density), with two cages for each of three different size groups of lumpfish. Three duplicate groups of lumpfish with an initial mean (± SD) weight of 22.6 ± 0.7 g (small), 77.4 ± 3.6 g (medium) and 113.5 ± 2.1 g (large) were used in the study. Two cages without lumpfish acted as controls. Sea lice infestation levels were recorded at two to four week intervals for 159 days. To determine the diet preferences of lumpfish in the cages gastric lavage was performed at the same time intervals. Behaviour and growth of the lumpfish was assessed throughout the study period and mean weight of the Atlantic salmon measured at the start and end of the study period. From day 35 and onwards growth was higher for the small lumpfish group compared to the two other lumpfish size classes. Lumpfish from the smallest size class had a higher consumption of naturally occurring food items, including sea lice, compared to the other two size classes. Growth stimulation in salmon co-habiting the two smallest lumpfish size groups was observed. Signs of sexual maturation were found in the medium (13%) and the large (20%) size groups. Based on present data small lumpfish (initial size approx. 20 g) have a higher overall preference for natural food items compared to larger conspecifics. Although the sea lice infestation rate was low in the study (< 0.5 lice salmon− 1) final lice burden was 40% lower in salmon groups stocked with small lumpfish compared to the control group without lumpfish. Statement of relevance The data presented here are highly relevant for Aquaculture as the effective use of lumpfish for biological delousing of salmon is very important for commercial aquaculture of Atlantic salmon. © 2016 Elsevier B.V.


Imsland A.K.,Akvaplan Niva | Imsland A.K.,University of Bergen | Reynolds P.,GIFAS AS | Eliassen G.,GIFAS AS | And 6 more authors.
Aquaculture International | Year: 2016

A series of studies were undertaken to determine the behavioural interactions between three different size classes (110, 70 and 32 g) of lumpfish, Cyclopterus lumpus L., and one size class (30 g) of goldsinny wrasse, Ctenolabrus rupestris L. The study attempted to determine whether goldsinny wrasse could coexist with juvenile lumpfish in an attempt to enhance lice grazing potential of Atlantic salmon by using both species simultaneously. The results indicate that both lumpfish and goldsinny exhibit quite a limited and similar palette of behavioural traits. Size-dependent dominance behaviour of lumpfish against goldsinny wrasse was found. When large (110 g) lumpfish were reared together with small goldsinny wrasse (30 g), aggression towards goldsinny was seen in 15 % of the time, whilst for 70 and 32 g lumpfish, aggressive behaviour against goldsinny accounted for only 6 % of all observations. © 2016 Springer International Publishing Switzerland


Imsland A.K.,Akvaplan Niva | Imsland A.K.,University of Bergen | Reynolds P.,GIFAS AS | Eliassen G.,GIFAS AS | And 5 more authors.
Aquaculture | Year: 2015

Feeding preferences of juvenile lumpfish reared together with Atlantic salmon in sea pens were assessed. Juvenile lumpfish, initial mean (± SE) weight of 54.0±0.9g, were reared in small sea cages (125m3, 5×5×5m) together with Atlantic salmon with an initial mean (± SE) weight of 619±2.5g. Lumpfish were stocked at 10 and 15% density (12 and 18 lumpfish vs. 120 salmon, respectively) in replicate sea pens. To determine the feeding preferences of lumpfish in the cages gastric lavage was performed every two weeks and the feeding items were identified and categorized as: a) consumed sea lice, b) formulated feed fragments, c) crustacean species, d) hydrozoan species, e) Mytilus edulis, f) unidentified material or no contents found. The most common food item identified in the stomachs of lumpfish throughout the study period was fragments of salmon pellets. Results indicate that lumpfish in sea pens can be classified as strongly opportunistic and the fish do not restrict themselves or rely on a single food source if others are present. Lumpfish seemed to switch their preference towards which ever food item that was most readily available to them within their environment. The present data shows temporal changes in feed choice throughout the period, seemingly linked to food availability. © 2014 Elsevier B.V.


Imsland A.K.,University of Bergen | Reynolds P.,GIFAS AS | Eliassen G.,GIFAS AS | Hangstad T.A.,Akvaplan Niva | And 4 more authors.
Aquaculture | Year: 2014

Growth and performance of Atlantic salmon in the presence of lumpfish were assessed in two studies. In the first study, six sea cages (5. ×. 5. ×. 5. m) were each stocked with 120 Atlantic salmon with a mean (±. SD) weight of 619 (±. 49) g and reared for 159. days. Control cages were without lumpfish, while two of the cages were stocked with 12 lumpfish (10% density), and two with 18 lumpfish (15% density) with a mean (±. SD) weight of 54.0 (±. 7.2) g. The lumpfish were removed from the cages after 56. days, but feed consumption and growth of the salmon were monitored for another 12. weeks until 17 November 2012 to investigate possible long term effect from the presence of lumpfish on growth performance of the salmon. In the second study, six sea cages (5. ×. 5. ×. 5. m) were each stocked with 80 Atlantic salmon with a mean (±. SD) weight of 2400 (±. 220) g and reared for 60. days. Two of the cages were further stocked with 4 lumpfish (5% density), and two with 8 lumpfish (10% density) with a mean (±. SD) weight of 360 (±. 30) g. Two cages without lumpfish acted as controls. In both studies sea lice infestation levels were recorded every other week. In the study with small salmon and lumpfish, the presence of lumpfish did not have any negative short- or long-term effects on feed conversion ratio (FCR) or specific growth rate (SGR) in salmon. However, when large salmon were reared together with large lumpfish, FCR was lower and SGR higher in the control cages compared to the two lumpfish treatments. Significantly lower sea lice infection levels were seen on Atlantic salmon when reared together with small lumpfish compared to the control group without lumpfish, whereas this trend was not as clear when reared with larger lumpfish. © 2014 Elsevier B.V.


Imsland A.K.,Akvaplan Niva | Imsland A.K.,University of Bergen | Reynolds P.,GIFAS AS | Eliassen G.,GIFAS AS | And 4 more authors.
Aquaculture | Year: 2014

The salmon louse is an ectoparasitic copepod that causes major economic losses in the Atlantic salmon aquaculture industry. To assess the efficacy of lumpfish grazing on attached sea lice on Atlantic salmon, six sea cages (5. ×. 5. ×. 5. m) were each stocked with 120 Atlantic salmon with a mean. ±. SD weight of 619. ±. 49. g. Two of the cages were further stocked with 12 lumpfish (10% density) and two with 18 lumpfish (15% density) with a mean. ±. SD weight of 54.0. ±. 7.2. g. Two cages without lumpfish acted as controls. Sea lice infestation levels were recorded every other week for 54. days. To determine the diet preferences of lumpfish in the cages, gastric lavage was performed every 2. weeks. No differences in salmon or lumpfish growth between test groups and controls were observed. There were clear signs of lumpfish grazing on sea lice, with significantly lower average numbers of pre-adult, mature males and females stages of Lepeophtheirus salmonis per salmon. Lumpfish reduced the mature female stage of L. salmonis to levels equal to or lower than the counts recorded prior to the start of the study. There were no significant differences between the treatments (10% and 15% densities) in grazing efficacy. There was clear evidence of grazing from the results of gastric lavage, with 28% of all lumpfish found to have ingested sea lice on the last sampling day. Overall, the present results indicate that lumpfish is a suitable cold-water option for biological delousing of Atlantic salmon. © 2013 Elsevier B.V.


Imsland A.K.,Akvaplan Niva | Imsland A.K.,University of Bergen | Reynolds P.,GIFAS AS | Eliassen G.,GIFAS AS | And 5 more authors.
Journal of Ethology | Year: 2014

The behaviour of lumpfish, Cyclopterus lumpus L., in sea pens, with and without Atlantic salmon, Salmo salar L., present, was assessed by underwater camera technology. Behaviour was classified by recording the principal activity of individual fish for 30-s intervals. The majority of daylight time was spent actively foraging for food. Antagonistic behaviour between Atlantic salmon and lumpfish was not observed during the whole experimental period and no mortality was seen in either species. Cleaning behaviour, but at low frequency, was observed as lumpfish cleaned sea lice off Atlantic salmon. Significantly lower sea lice infection levels were seen on Atlantic salmon when reared together with lumpfish compared to the control group without lumpfish. Feeding behaviour can be classified as strongly opportunistic. © 2014 Japan Ethological Society and Springer Japan.


Nytro A.V.,Akvaplan Niva | Vikingstad E.,Akvaplan Niva | Foss A.,Akvaplan Niva | Hangstad T.A.,Akvaplan Niva | And 6 more authors.
Aquaculture | Year: 2014

The lumpfish (Cyclopterus lumpus L.) has recently become relevant for aquaculture due to its appetite for the ectoparasitic copepod, the sea louse (Lepeophtherius salmonis Krøyer). In order to determine the effect of temperature on growth properties of juvenile lumpfish, two size groups (6.2g, S.E.±0.1 and 26.5g, S.E.±0.6) were compared in terms of temperature- and size-related growth at 4, 7, 10, 13, 16°C and varying ambient temperature. The overall highest growth rates were observed for fish <120g at 13 and 16°C (3.65 and 3.60%day-1), and declined stepwise with decreasing temperature. Only a modest response to temperature was observed for large fish >120g. Size rank correlations increased with increasing body weight. The results presented in this study suggest that optimum temperatures for growth (ToptSGR) decreased with increasing fish size from 15.7°C for 11.0-20.0g fish, 16.1°C for 20.0-40.0g fish, 13.1°C for 100.0-110.0g fish, to 8.9°C for 120.0-200.0g fish. © 2014 Elsevier B.V.


Imsland A.K.,Akvaplan Niva | Imsland A.K.,University of Bergen | Reynolds P.,GIFAS AS | Eliassen G.,GIFAS AS | And 5 more authors.
Aquaculture International | Year: 2015

This study assessed the use of different types of substrates for lumpfish in sea pens. Observations were recorded in the early morning before first light, and the number of lumpfish attached to each surface type was recorded. The substrate was removed and another design was deployed if no lumpfish were attached to a substrate for more than 2 weeks. Lumpfish preferred flat and smooth vertical surfaces of plastic, as very few preferred to attach to stones and car tyres offered. Some lumpfish were also observed attaching to the floating seaweed placed into the cages, a more natural substrate used in the wild. It is concluded that lumpfish will easily adhere to artificial, smooth, plastic surfaces instead of natural surfaces such as kelp. Irrespective of the type of substrate offered, it is critical to the welfare of the fish that they have access to some form of substrate due to the need to rest and attach overnight. © 2014, Springer International Publishing Switzerland.

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