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Stokmarknes, Norway

Imsland A.K.,Akvaplan Niva | Imsland A.K.,University of Bergen | Reynolds P.,GIFAS | Eliassen G.,GIFAS | 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 Source


Imsland A.K.,University of Bergen | Reynolds P.,GIFAS | Eliassen G.,GIFAS | 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. Source


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. Source


Imsland A.K.,Akvaplan Niva | Imsland A.K.,University of Bergen | Reynolds P.,GIFAS | Eliassen G.,GIFAS | 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. Source


Imsland A.K.,Akvaplan Niva | Imsland A.K.,University of Bergen | Reynolds P.,GIFAS | Eliassen G.,GIFAS | 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. Source

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