scholarly journals Salmon lice dispersion in a northern Norwegian fjord system and the impact of vertical movements

2016 ◽  
Vol 8 ◽  
pp. 99-116 ◽  
Author(s):  
IA Johnsen ◽  
LC Asplin ◽  
AD Sandvik ◽  
RM Serra-Llinares
Keyword(s):  
Vertical Movements ◽  
Fjord System ◽  
Salmon Lice ◽  
Norwegian Fjord ◽  
The Impact

scholarly journals Prediction of the salmon lice infestation pressure in a Norwegian fjord

2020 ◽  
Vol 77 (2) ◽  
pp. 746-756 ◽  
Author(s):  
Anne D Sandvik ◽  
Ingrid A Johnsen ◽  
Mari S Myksvoll ◽  
Pål N Sævik ◽  
Morten D Skogen
Keyword(s):  
Laboratory Experiments ◽  
Test Area ◽  
Environmentally Sustainable ◽  
Salmon Lice ◽  
Direct Measurements ◽  
New Findings ◽  
Aquaculture Industry ◽  
Norwegian Fjord ◽  
The Impact

Abstract A further growth in the Norwegian aquaculture industry might potentially be hampered by the conclusion that it is not environmentally sustainable. As direct measurements of the lice induced mortality on wild salmonids are impossible, the management is based on a set of high-quality and well-documented sustainability indicators. These indicators combine observations from the national Norwegian salmon lice monitoring programme with salmon lice models. Here, we have documented the quality of one of these models used to identify areas where the impact from farmed to wild salmonids is over the prescribed limit. The Hardangerfjord area has been used as a test area, but the model is general and, therefore, suitable for the rest of the coast. It is shown that the model system is robust and also can be used to test whether new knowledge gained from laboratory experiments improves the model. New findings on salmon lice behaviour at low salinities have been incorporated and the new model, consisting of a high-resolution hydrodynamic model coupled with an individual-based salmon lice model and forced with realistic input of salmon lice larvae from aquaculture farms, represents the best realization of the local potential infestation pressure on wild fish.

scholarly journals Vertical movements of “escaped” farmed Atlantic salmon (Salmo salar L.)—a simulation study in a western Norwegian fjord

2009 ◽  
Vol 66 (2) ◽  
pp. 278-288 ◽  
Author(s):  
Ove T. Skilbrei ◽  
Jens Christian Holst ◽  
Lars Asplin ◽  
Marianne Holm
Keyword(s):  
Atlantic Salmon ◽  
Vertical Distribution ◽  
Salmo Salar ◽  
Simulation Study ◽  
Vertical Movements ◽  
Atlantic Salmon Salmo Salar ◽  
Wide Range ◽  
Norwegian Fjord ◽  
Farmed Atlantic Salmon ◽  
The Vertical Distribution

Abstract Skilbrei, O. T., Holst, J. C., Asplin, L., and Holm, M. 2009. Vertical movements of “escaped” farmed Atlantic salmon (Salmo salar L.)—a simulation study in a western Norwegian fjord. – ICES Journal of Marine Science, 66: 278–288. To study the vertical distribution of fish that had been allowed to escape, farmed Atlantic salmon were tagged with acoustic tags equipped with depth sensors, and then released on five different dates in the course of a year from two fish farms in the Hardanger Fjord in western Norway. Release stimulated the fish to dive to deeper than 15 m during the first hours or days post-release, often down to 50–80 m. However, during the following 4 weeks, most of the escapees spent most of their time above the pycnocline at depths of 0–4 m. The fish were more widely distributed in the water column after release during winter, but still spent most of the time in the cold surface layers. There was a wide range in the vertical distribution of individual fish, and the proportion of detections below 14-m depth ranged from 0 to 90%. There was a significant diurnal cycle in all seasons except midsummer, when the fish were less abundant in the upper layer during daylight, especially on brighter days. The results suggest that salmon diving activity following escape may complicate the recapture of escaped fish at the farm site but that the subsequent tendency of most fish to stay near the surface, virtually irrespective of the time of year, may facilitate recapture.

scholarly journals Experience of application of the measuring complex «Measurement System for testing permanent bridges» to determine the possibility of passing on permanent bridges of superheavy loads

2019 ◽  
Vol 6 (3) ◽  
Author(s):  
Evgeny Lugovtsev ◽  
Michael Erofeev
Keyword(s):  
Bearing Capacity ◽  
Measurement System ◽  
Load Capacity ◽  
Measuring System ◽  
Technical Diagnostics ◽  
Vertical Movements ◽  
Test Load ◽  
Measuring Complex ◽  
Mobile Test ◽  
The Impact

The article presents the experience of using the measuring complex SI-PPM 15N1955 to determine the possibility of passing on permanent bridges of superheavy loads used by military engineers. The first part of the article substantiates the need to examine a large number of bridges of various designs on the routes of exit and maneuver of the troops, which in turn puts before the engineering service of associations and connections serious tasks to determine the load capacity of artificial structures on roads. In the 2000s, specialists of the Military engineering Academy and the Moscow Institute of heat engineering developed a unified method for determining the bearing capacity of reinforced concrete beam bridges, which was implemented by STC «Technical diagnostics and precision measurements» in a portable measurement system to check the permanent bridges SI-PPM 15N1955. The basis for the creation of SI-PPM is the calculation and experimental method of operational (on-site testing) determination of the state of the load-bearing structures of permanent bridges, using multi-channel measurements of angular and corresponding vertical movements of various sections of the main beams of superstructures from the impact of mobile test load. Unlike traditional methods of measuring deflections unacceptable in complexity and time of the survey of permanent bridges for the passage of modern missile systems. The main part of the article describes the measurement system. The bearing capacity of a particular bridge span is determined in the calculation program «Bridge» (the structure is presented in the article), which is part of the system. To determine the possibility of skipping the unit for a specific span of the bridge, the calculation program uses the angles of rotation of the main beams of the bridge near the supports from the impact of the mobile test load on the span, the arrangement of the wheels and the weight on the axes for the test load and the unit as the initial data. To learn how to operate the measuring system SI-MRP developed program simulator.

scholarly journals Impact of variable physical conditions and future increased aquaculture production on lice infestation pressure and its sustainability in Norway

2020 ◽  
Vol 12 ◽  
pp. 193-204
Author(s):  
MS Myksvoll ◽  
AD Sandvik ◽  
IA Johnsen ◽  
J Skarðhamar ◽  
J Albretsen
Keyword(s):  
Interannual Variability ◽  
Ocean Circulation ◽  
Ocean Model ◽  
Migration Route ◽  
Traffic Light ◽  
Physical Conditions ◽  
Salmon Lice ◽  
The Impact ◽  
Production Zone ◽  
Lice Infestations

Salmon lice infestation is a challenge for wild post-smolt salmon during migration from their natal river to the sea in several regions of Norway. The traffic-light management system regulates growth in the aquaculture industry, where growth in production (6%) is only allowed if the impact of salmon lice on wild fish can be kept at a minimum and up to 10% mortality of wild salmonids are considered within the sustainability goal. We used a numerical ocean model, combined with an individual-based model for salmon lice, to evaluate the interannual variability in salmon lice concentrations in Production Zone 7, which was granted permission for production growth in 2017. Salmon lice releases were kept constant for 3 yr, while the physical conditions, e.g. wind and ocean circulation, varied. The total area of elevated lice infestations varied between 3.2 and 8.4% of the area within 5 km from the coast, due only to interannual physical variability mainly caused by variable wind patterns. Modeled post-smolts migrating out from the Namsen River (64.5°N, central Norway) towards the open ocean experienced mortality between 5 and 9%. Since Production Zone 7 was granted growth, we have simulated increased production and corresponding increases in lice releases. After 5 to 8 increments of 6% increase in production, the increase in salmon post-smolt mortality was of the same order of magnitude as the interannual variability. Information regarding migration route and time is crucial input to the model calculating post-smolt mortality, and inadequate information can affect the results significantly. These 2 methods (determining area of elevated lice infestations and estimating post-smolt mortality) provide complementary information and should be used in combination when the overall assessment of a production zone is made.

scholarly journals Detailed site survey examining the postglacial sediment succession and depositional processes within a Norwegian fjord system, Bjørnafjorden (West Norway)

2017 ◽  
Author(s):  
Kenneth Solli ◽  
Jarle André Vikebø ◽  
Elise Søyland ◽  
Berit Oline Hjelstuen ◽  
Heidi Kjennbakken ◽  
...  
Keyword(s):  
Fjord System ◽  
Depositional Processes ◽  
Site Survey ◽  
Norwegian Fjord

scholarly journals THE NEPSKY-1 IMPACT CRATER AND ITS FILL DEPOSITS ON THE BASEMENT ROOF OF THE SIBERIAN PLATFORM

2020 ◽  
Vol 11 (4) ◽  
pp. 710-721
Author(s):  
M. I. Gyokche ◽  
A. V. Plyusnin
Keyword(s):  
Sea Level ◽  
Survey Data ◽  
Siberian Platform ◽  
Impact Crater ◽  
Seismic Survey ◽  
Study Region ◽  
Vertical Movements ◽  
Geological Conditions ◽  
Geophysical Surveys ◽  
The Impact

In the Earth studies, discoveries and investigations of impact craters buried beneath thick sediments are sporadic so far and may still remain inefficient, unless geophysical surveys of the areas of interest are initiated. Such studies can provide useful data to develop the knowledge about cosmic events of the past geological eras, as well as contribute to industrial development of the areas. It is known that an impact crater is filled with layered deposits that create specific sequences and are generally thicker that deposits outside the crater. We have investigated a Precambrian crater located in the southern part of the Nepa-Botuoba anteclise of the Siberian platform. This impact crater called Nepsky-1 was discovered by seismic surveys using the common depth point method (CDPM). In our study, we used the geological and geophysical deep-drilling data of three wells, including gamma-ray and neutron logs and lithological core descriptions. With reference to the concepts of regional geological conditions, we reconstructed the conditions of sedimentation in the study area based on a comprehensive analysis of the structural and textural features of the rocks, and logging and seismic survey data. By processing and interpretation of the CDPM 3D seismic survey data, we obtained the structural images and cross-sections of the impact crater and analysed the thickness of its fill deposits. The Nepsky-1 crater is a bowl-shaped structure with a rim composed of allogenic breccia. In the area around the crater, fault systems are detected. Based on the core sample analysis, we identified the lithological members of the crater and its rim and described them in detail. Active compensation with lacustrine-delta sediments took place in the Nepa period of the late Vendian. By the end of the Tira time, the crater was completely leveled up. In our study, we obtained the first data on the structure of the crater section of the Vendian deposits. Sedimentation in the study area was controlled by the sea level changes. The main terrigenous productive horizons are confined to sandstones that accumulated during the sea level low stand, and found at the bottoms of the lower and upper Nepa subsuites, as well as at the bottoms of the lower and upper Tira subsuites. It is established that the study area was tectonically active in the late Tira time. As a result, the sediments filling the crater were removed to subaerial conditions, and the edges of the allogenic breccia rim were partially destroyed and formed granite breccia outgrowths observed in the rim’s cross-section. We conclude that in the Nepa and Tira times, tectonic vertical movements initiated relatively fast weathering and transportation of the terrigenous material from the adjacent hills into the sedimentation basin. The Nepsky-1 crater gives evidence of meteorite bombing of the Siberian paleocontinent in Precambrian. Finding similar crater structures can be reasonably expected in the study region. Considering the increased thicknesses of crater fill deposits, buried craters are promising potential for discovering oil-source and overlying seal rocks, which is important for petroleum industry.

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