Bergen, Norway
Bergen, Norway
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Hevroy E.M.,National Institute of Nutrition And Seafood Research | Hevroy E.M.,EWOS AS | Tipsmark C.K.,University of Arkansas | Remo S.C.,National Institute of Nutrition And Seafood Research | And 9 more authors.
Comparative Biochemistry and Physiology -Part A : Molecular and Integrative Physiology | Year: 2015

A comparative experiment with Atlantic salmon (Salmo salar) and rainbow trout (Oncorhynchus mykiss) postsmolts was conducted over 35. days to provide insight into how growth, respiration, energy metabolism and the growth hormone (GH) and insulin-like growth factor 1 (IGF-1) system are regulated at elevated sea temperatures. Rainbow trout grew better than Atlantic salmon, and did not show reduced growth at 19. °C. Rainbow trout kept at 19. °C had increased blood hemoglobin concentration compared to rainbow trout kept at 13. °C, while salmon did not show the same hemoglobin response due to increased temperature. Both species showed reduced length growth and decreased muscle glycogen stores at 19. °C. Circulating IGF-1 concentration was higher in rainbow trout than in Atlantic salmon, but was not affected by temperature in either species. Plasma IGF-binding protein 1b (IGFBP-1b) concentration was reduced in Atlantic salmon reared at 19. °C after 15. days but increased in rainbow trout at 19 °C after 35. days. The igfbp1b mRNA level in liver showed a positive correlation to plasma concentrations of glucose and IGFBP-1b, suggesting involvement of this binding protein in carbohydrate metabolism at 19. °C. At this temperature muscle igfbp1a mRNA was down-regulated in both species. The muscle expression of this binding protein correlated negatively with muscle igf1 and length growth. The plasma IGFBP-1b concentration and igfbp1b and igfbp1a expression suggests reduced muscle igf1 signaling at elevated temperature leading to glucose allostasis, and that time course is species specific due to higher thermal tolerance in rainbow trout. © 2015 Elsevier Inc.

Geffen A.J.,University of Bergen | Hoie H.,University of Bergen | Hoie H.,Norwegian Institute of Marine Research | Hoie H.,EWOS AS | And 6 more authors.
ICES Journal of Marine Science | Year: 2011

Cod (Gadus morhua) otoliths from archaeological sites in northern Norway were analysed to reconstruct the temperature regime and determine the age structure, growth, and population identity of the fish harvested. Otoliths were selected from late- and post-medieval sites (700300 years ago) to evaluate historical changes in the geographic region that matches the present-day stocks of Northeast Arctic cod (NEAC) and Norwegian coastal cod (NCC). Seasonal temperature cycles were reconstructed from stable isotope (δ 18O) measurements along transects representing fish ages 1.53 years old. Reconstructions of the size, age, and growth characteristics of individual fish were based on otolith growth increments. The geographical source and stock identity of the individuals were estimated based on otolith elemental composition and otolith growth features. Both NCC and NEAC fish were represented at Msøy and Vanna. The results indicate that fishing at Vanna exploited NEAC during their spawning migration, compared with fishing at Msøy, which was restricted to more coastal fish. Fish growth patterns appeared to be affected by changes in the temperature regimes as estimated from otolith δ18O and back-calculated fish length-at-age, with evident differences between pre- and post-1600 periods. © 2011 International Council for the Exploration of the Sea.

Millner R.S.,CEFAS - Center for Environment, Fisheries and Aquaculture Science | Pilling G.M.,CEFAS - Center for Environment, Fisheries and Aquaculture Science | Pilling G.M.,British Petroleum | McCully S.R.,CEFAS - Center for Environment, Fisheries and Aquaculture Science | And 3 more authors.
Marine Biology | Year: 2011

We examine the seasonal variation in otolith increment formation in southern North Sea cod as a means of monitoring how changes in sea temperature over the past 20 years have affected cod in the wild. Seasonal opaque zone formation was related to winter and early spring. Timing of opaque zone formation was not influenced by either temperature or fish length, but increasing age led to slightly earlier but slower opaque zone formation. In contrast, there was a clear shift in the timing of translucent zone formation with temperature. In warm years, translucent growth occurs up to 22 days earlier than in colder periods. Increasing age and smaller size-at-age resulted in an earlier transition from opaque to translucent edge formation. Translucent zone formation appears indicative of increasing metabolic stress, and the earlier onset provides direct evidence of the impact of increasing sea temperatures on wild North Sea cod stocks. © 2010 Crown copyright.

Limburg K.E.,New York University | Hoie H.,University of Bergen | Hoie H.,EWOS AS | Dale D.S.,Cornell University
Environmental Biology of Fishes | Year: 2010

Bromine was found to accumulate in otoliths of Norwegian coastal Cod Gadus morhua that were reared under known conditions. Despite the fact that the Cod were moved from one rearing environment to another, causing marked changes in some otolith elemental concentrations, bromine appeared to accumulate continuously along certain growth axes as revealed by 2-D elemental mapping. In contrast, North Sea and Baltic Sea Cod showed little to no patterning in Br. We suggest that Br uptake in otoliths may be under physiological and genetic control, and as such, may prove useful as a stock identification tool. © 2010 Springer Science+Business Media B.V.

Olsvik P.A.,National Institute of Nutrition And Seafood Research | Softeland L.,National Institute of Nutrition And Seafood Research | Hevroy E.M.,National Institute of Nutrition And Seafood Research | Hevroy E.M.,EWOS AS | And 2 more authors.
Journal of Thermal Biology | Year: 2016

An emerging focus in environmental toxicology is how climate change will alter bioavailability and uptake of contaminants in organisms. Ectothermic animals unable to adjust their temperature by local migration, such as farmed fish kept in net pens, may become more vulnerable to contaminants in warmer seas. The aim of this work was to study cadmium (Cd) toxicity in cells obtained from fish acclimated to sub-optimal growth temperature. Atlantic salmon hepatocytes, harvested from fish pre-acclimated either at 15 °C (optimal growth temperature) or 20 °C (heat-stressed), were exposed in vitro to two concentrations of Cd (control, 1 and 100 μM Cd) for 48 h. Cd-induced cytotoxicity, determined with the xCELLigence system, was more pronounced in cells from fish pre-acclimated to a high temperature than in cells from fish grown at optimal temperature. A feed spiked with antioxidants could not ameliorate the Cd-induced cytotoxicity in cells from temperature-stressed fish. At the transcriptional level, Cd exposure affected 11 out of 20 examined genes, of which most are linked to oxidative stress. The transcriptional levels of a majority of the altered genes were changed in cells harvested from fish grown at sub-optimal temperature. Interaction effects between Cd exposure and fish pre-acclimation temperature were seen for four transcripts, hmox1, mapk1, fth1 and mmp13. Overall, this study shows that cells from temperature-stressed fish are modestly more vulnerable to Cd stress, and indicate that mechanisms linked to oxidative stress may be differentially affected in temperature-stressed cells. © 2016 Elsevier Ltd.

Hatlen B.,Nofima | Jakobsen J.-V.,Innovation Norway | Crampton V.,Innovation Norway | Alm M.,EFPRA | And 7 more authors.
Aquaculture Nutrition | Year: 2015

The suitability of land animal by-products (ABPs) in feed for Atlantic salmon postsmolts (initial weight 372 g) in sea water was studied in a feeding experiment, using poultry by-product meal (PBM) and porcine blood meal (BM) as protein sources and poultry oil as fat source. Four extruded feeds were tested in a 2 * 2 factorial model, with or without ABP protein sources and with or without poultry oil. The control feed contained a mix of marine and plant ingredients. Initial feed intake was highest in the ABP protein-based diets, whereas poultry oil had a weak opposite effect. No differences were seen in growth rate or body weight. Addition of PBM and BM led to increased FCR, and lower retention of crude protein and energy. This could be explained by lower digestibility of amino acids and crude protein, and a slightly lower energy level in these diets. Reduced igf1 mRNA levels in liver and muscle were seen in fish fed dietary ABP protein and oil. Despite lower protein digestibility of ABP protein, this study confirms the suitability of ABP protein and lipid in combination with plant ingredients in feed for Atlantic salmon growers. © 2015 John Wiley & Sons Ltd.

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