scholarly journals Feeding strategy of mackerel in the Norwegian Sea relative to currents, temperature, and prey

2015 ◽  
Vol 73 (4) ◽  
pp. 1127-1137 ◽  
Author(s):  
Leif Nøttestad ◽  
Justine Diaz ◽  
Hector Penã ◽  
Henrik Søiland ◽  
Geir Huse ◽  
...  
Keyword(s):  
Swimming Speed ◽  
Swimming Performance ◽  
Feeding Strategy ◽  
Near Field ◽  
Norwegian Sea ◽  
Swimming Direction ◽  
Atlantic Mackerel ◽  
The North ◽  
Foraging Rate ◽  
Feeding Resources

Abstract High abundance of Northeast Atlantic mackerel (Scomber scombrus L.), combined with limited food resources, may now force mackerel to enter new and productive regions in the northern Norwegian Sea. However, it is not known how mackerel exploit the spatially varying feeding resources, and their vertical distribution and swimming behaviour are also largely unknown. During an ecosystem survey in the Norwegian Sea during the summer feeding season, swimming direction, and speed of mackerel schools were recorded with high-frequency omnidirectional sonar in four different regions relative to currents, ambient temperature, and zooplankton. A total of 251 schools were tracked, and fish and zooplankton were sampled with pelagic trawl and WP-2 plankton net. Except for the southwest region, swimming direction of the tracked schools coincided with the prevailing northerly Atlantic current direction in the Norwegian Sea. Swimming with the current saves energy, and the current also provides a directional cue towards the most productive areas in the northern Norwegian Sea. Average mean swimming speed in all regions combined was ∼3.8 body lengths s−1. However, fish did not swim in a straight course, but often changed direction, suggesting active feeding in the near field. Fish were largest and swimming speed lowest in the northwest region which had the highest plankton concentrations and lowest temperature. Mackerel swam close to the surface at a depth of 8–39 m, with all schools staying above the thermocline in waters of at least 6°C. In surface waters, mackerel encounter improved foraging rate and swimming performance. Going with the flow until temperature is too low, based on an expectation of increasing foraging rate towards the north while utilizing available prey under way, could be a simple and robust feeding strategy for mackerel in the Norwegian Sea.

scholarly journals Fish Specialize Their Metabolic Performance to Maximize Bioenergetic Efficiency in Their Local Environment: Conspecific Comparison Between Two Stocks of Pacific Chub Mackerel (Scomber japonicus)

2021 ◽  
Vol 8 ◽  
Author(s):  
Chenying Guo ◽  
Shin-ichi Ito ◽  
Michio Yoneda ◽  
Hajime Kitano ◽  
Hitoshi Kaneko ◽  
...  
Keyword(s):  
Swimming Speed ◽  
Swimming Performance ◽  
Local Environment ◽  
Scomber Japonicus ◽  
Chub Mackerel ◽  
The North ◽  
Significant Difference ◽  
In The Wild ◽  
Metabolic Performance ◽  
Species Specific

Species-specific ecological traits in fishes are likely to vary between populations or stocks due to differences in regional oceanic conditions, such as latitudinal temperature. We examined potential intraspecific differences in the swimming performance and metabolism of Pacific chub mackerel (Scomber japonicus) from the Northwest and Northeast Pacific stocks, which are distributed on opposite sides of the North Pacific at similar latitudes, but where the temperature contrast is large. Swimming bioenergetics and metabolic data of Northwest stock mackerel were measured at 14, 18, and 24°C using variable-speed swim-tunnel respirometers, and then the resulting bioenergetic parameters were compared with previous findings from the Northeast stock. At a given size, the maximum sustainable swimming speed (Umax) of the Northwest stock showed no significant difference compared to the Northeast stock at 18 and 24°C, but was lower at 14°C. In addition, the oxygen consumption rate (MO2) of the Northwest stock showed lower mass dependence and different temperature dependence at a given swimming speed than in the Northeast stock. Combined with stock-specific data on growth and experienced temperatures in the wild, these bioenergetic differences indicate that the swimming performance and metabolism of the two stocks are specific to their local environment to maximize bioenergetic efficiency.

Impact of Diet on Metabolism and Swimming Performance in Juvenile Lake Trout, Salvelinus namaycush

1989 ◽  
Vol 46 (3) ◽  
pp. 384-388 ◽  
Author(s):  
F. W. H. Beamish ◽  
J. C. Howlett ◽  
T. E. Medland
Keyword(s):  
Oxygen Consumption ◽  
Swimming Speed ◽  
Lake Trout ◽  
Swimming Performance ◽  
Salvelinus Namaycush ◽  
Feeding Trial ◽  
Direct Association ◽  
Feeding Trials ◽  
Velocity Increments ◽  
Isocaloric Diets

Juvenile lake trout, Salvelinus namaycush, of similar size were fed one of three isocaloric diets, each differing in protein and lipid content. Oxygen consumption and swimming performance were measured in a recirculating water flume at intervals throughout the 70-d feeding trials (10 °C). Swimming speed was increased by stepwise velocity increments (5 cm∙s−1) and oxygen consumption was measured at each velocity between 20 and 45 cm∙s−1. Oxygen consumption for a given speed did not differ significantly throughout the feeding trial nor among the diets implying a similarity in the quality and quantity of substrate catabolized for energy. Basal metabolism (0 cm∙s−1) was also independent of diet and feeding interval. Critical swimming speed increased with dietary and carcass protein content to suggest a direct association with muscle mass and number of myofilaments.

THE EFFECT OF SOLID AND POROUS CHANNEL WALLS ON STEADY SWIMMING OF STEELHEAD TROUT ONCORHYNCHUS MYKISS

1993 ◽  
Vol 178 (1) ◽  
pp. 97-108 ◽  
Author(s):  
P. W. Webb
Keyword(s):  
Swimming Speed ◽  
Swimming Performance ◽  
Beat Frequency ◽  
Regression Coefficients ◽  
Steelhead Trout ◽  
Wall Effects ◽  
Fish Swimming ◽  
Wide Channel ◽  
Solid Walls ◽  
Tail Beat

Kinematics and steady swimming performance were recorded for steelhead trout (approximately 12.2 cm in total length) swimming in channels 4.5, 3 and 1.6 cm wide in the centre of a flume 15 cm wide. Channel walls were solid or porous. Tail-beat depth and the length of the propulsive wave were not affected by spacing of either solid or porous walls. The product of tail-beat frequency, F, and amplitude, H, was related to swimming speed, u, and to harmonic mean distance of the tail from the wall, z. For solid walls: FH = 1.01(+/−0.31)u0.67(+/−0.09)z(0.12+/−0.02) and for grid walls: FH = 0.873(+/−0.302)u0.74(+/−0.08)z0.064(+/−0.024), where +/−2 s.e. are shown for regression coefficients. Thus, rates of working were smaller for fish swimming between solid walls, but the reduction due to wall effects decreased with increasing swimming speed. Porous grid walls had less effect on kinematics, except at low swimming speeds. Spacing of solid walls did not affect maximum tail-beat frequency, but maximum tail-beat amplitude decreased with smaller wall widths. Maximum tail-beat amplitude similarly decreased with spacing between grid walls, but maximum tail-beat frequency increased. Walls also reduced maximum swimming speed. Wall effects have not been adequately taken into account in most studies of fish swimming in flumes and fish wheels.

New Faunal and Isotopic Evidence on the Late Weichselian—Holocene Oceanographic Changes in the Norwegian Sea

1984 ◽  
Vol 21 (1) ◽  
pp. 74-84 ◽  
Author(s):  
Hans Petter Sejrup ◽  
Eystein Jansen ◽  
Helmut Erlenkeuser ◽  
Hans Holtedahl
Keyword(s):  
Deep Water ◽  
Circulation Pattern ◽  
Oceanic Circulation ◽  
Surface Cooling ◽  
Norwegian Sea ◽  
Neogloboquadrina Pachyderma ◽  
The North ◽  
Lower Oxygen ◽  
Late Weichselian ◽  
Stage 1

Downcore studies of planktonic and benthonic foraminifera and δ18O and δ13C in the planktonic foraminifer Neogloboquadrina pachyderma (sin.) in two piston cores from the southern part of the Norwegian Sea suggest large changes in the oceanic circulation pattern at the end of oxygenisotope stage 2 and in the early part of stage 1. Prior to oxygen-isotope Termination IA (16,000–13,000 yr B.P.), an isolated watermass with lower oxygen content and temperature warmer than today existed below a low salinity ice-covered surface layer in the Norwegian Sea. Close to Termination IA, well-oxygenated deep water, probably with positive temperatures, was introduced. This deep water, which must have had physical and/or chemical parameters different from those of present deep water in the Norwegian Sea, could have been introduced from the North Atlantic or been formed within the basin by another mechanism than that which forms the present deep water of the Norwegian Sea. A seasonal ice cover in the southern part of the Norwegian Sea is proposed for the period between Termination IA and the beginning of IB (close to 10,000 yr B.P.). The present situation, with strong influx of warm Atlantic surface-water and deep-water formation by surface cooling, was established at Termination IB.

scholarly journals The Maximal Lactate Steady State Workload Determines Individual Swimming Performance

2021 ◽  
Vol 12 ◽  
Author(s):  
Gernot O. Hering ◽  
Jens Stepan
Keyword(s):  
Steady State ◽  
Blood Lactate ◽  
Swimming Speed ◽  
Lactate Threshold ◽  
Swimming Performance ◽  
Endurance Capacity ◽  
Sudden Increase ◽  
Maximal Lactate Steady State ◽  
Custom Made ◽  
Major Interest

The lactate threshold (LT) and the strongly related maximal lactate steady state workload (MLSSW) are critical for physical endurance capacity and therefore of major interest in numerous sports. However, their relevance to individual swimming performance is not well understood. We used a custom-made visual light pacer for real-time speed modulation during front crawl to determine the LT and MLSSW in a single-exercise test. When approaching the LT, we found that minute variations in swimming speed had considerable effects on blood lactate concentration ([La−]). The LT was characterized by a sudden increase in [La−], while the MLSSW occurred after a subsequent workload reduction, as indicated by a rapid cessation of blood lactate accumulation. Determination of the MLSSW by this so-called “individual lactate threshold” (ILT)-test was highly reproducible and valid in a constant speed test. Mean swimming speed in 800 and 1,500 m competition (S-Comp) was 3.4% above MLSSW level and S-Comp, and the difference between S-Comp and the MLSSW (Δ S-Comp/MLSSW) were higher for long-distance swimmers (800–1,500 m) than for short- and middle-distance swimmers (50–400 m). Moreover, Δ S-Comp/MLSSW varied significantly between subjects and had a strong influence on overall swimming performance. Our results demonstrate that the MLSSW determines individual swimming performance, reflects endurance capacity in the sub- to supra-threshold range, and is therefore appropriate to adjust training intensity in moderate to severe domains of exercise.

scholarly journals Norwegian hindcast archive (NORA3) – A validation of offshore wind resources in the North Sea and Norwegian Sea

2021 ◽  
Author(s):  
Ida Marie Solbrekke ◽  
Asgeir Sorteberg ◽  
Hilde Haakenstad
Keyword(s):  
Wind Power ◽  
Power Production ◽  
Offshore Wind ◽  
Norwegian Sea ◽  
Offshore Wind Power ◽  
Wind Speeds ◽  
The North ◽  
The North Sea ◽  
Wind Events ◽  
Simulated Wind

Abstract. A new high-resolution (3 km) numerical mesoscale weather simulation spanning the period 2004–2018 is validated for offshore wind power purposes for the North Sea and Norwegian Sea. The NORwegian hindcast Archive (NORA3) was created by dynamical downscaling, forced with state-of-the-art hourly atmospheric reanalysis as boundary conditions. A validation of the simulated wind climatology has been carried out to determine the ability of NORA3 to act as a tool for planning future offshore wind power installations. Special emphasis is placed on evaluating offshore wind power-related metrics and the impact of simulated wind speed deviations on the estimated wind power and the related variability. The general conclusion of the validation is that the NORA3 data is rather well suited for wind power estimates, but gives slightly conservative estimates on the offshore wind metrics. Wind speeds are typically 5 % (0.5 ms−1) lower than observed wind speeds, giving an underestimation of offshore wind power of 10 %–20 % (equivalent to an underestimation of 3 percentage point in the capacity factor), for a selected turbine type and hub height. The model is biased towards lower wind power estimates because of overestimation of the frequency of low-speed wind events (< 10 ms−1) and underestimation of high-speed wind events (> 10 ms−1). The hourly wind speed and wind power variability are slightly underestimated in NORA3. However, the number of hours with zero power production (around 12 % of the time) is fairly well captured, while the duration of each of these events is slightly overestimated, leading to 25-year return values for zero-power duration being too high for four of the six sites. The model is relatively good at capturing spatial co-variability in hourly wind power production among the sites. However, the observed decorrelation length was estimated to be 432 km, whereas the model-based length was 19 % longer.

Effect of Morphological Fin-Curl on the Swimming Performance and Station-Holding Ability of Juvenile Shovelnose Sturgeon

2016 ◽  
Vol 7 (1) ◽  
pp. 198-204 ◽  
Author(s):  
David Deslauriers ◽  
Ryan Johnston ◽  
Steven R. Chipps
Keyword(s):  
Swimming Speed ◽  
Early Onset ◽  
Positive Relationship ◽  
Swimming Performance ◽  
Fork Length ◽  
Critical Swimming Speed ◽  
Pectoral Fin ◽  
Speed Test ◽  
Shovelnose Sturgeon ◽  
Pectoral Fins

Abstract We assessed the effect of fin-curl on the swimming and station-holding ability of juvenile shovelnose sturgeon Scaphirhynchus platorynchus (mean fork length = 17 cm; mean weight = 16 g; n = 21) using a critical swimming speed test performed in a small swim chamber (90 L) at 20°C. We quantified fin-curl severity using the pectoral fin index. Results showed a positive relationship between pectoral fin index and critical swimming speed indicative of reduced swimming performance displayed by fish afflicted with a pectoral fin index &lt; 8%. Fin-curl severity, however, did not affect the station-holding ability of individual fish. Rather, fish affected with severe fin-curl were likely unable to use their pectoral fins to position their body adequately in the water column, which led to the early onset of fatigue. Results generated from this study should serve as an important consideration for future stocking practices.

scholarly journals Evaluating acoustic-trawl survey strategies using an end-to-end ecosystem model

2020 ◽  
Author(s):  
Arne Johannes Holmin ◽  
Erik A Mousing ◽  
Solfrid S Hjøllo ◽  
Morten D Skogen ◽  
Geir Huse ◽  
...  
Keyword(s):  
Simulated Data ◽  
Ecosystem Model ◽  
Trawl Survey ◽  
Sampling Variance ◽  
Simulation Framework ◽  
Norwegian Sea ◽  
Atlantic Mackerel ◽  
Fish Migrations ◽  
Survey Estimates ◽  
Trawl Surveys

Abstract Fisheries independent surveys support science and fisheries assessments but are costly. Evaluating the efficacy of a survey before initiating it could save costs. We used the NORWECOM.E2E model to simulate Northeast Atlantic mackerel and Norwegian spring spawning herring distributions in the Norwegian Sea, and we ran vessel transects in silico to simulate acoustic-trawl surveys. The simulated data were processed using standard survey estimation software and compared to the stock abundances in the ecosystem model. Three existing real surveys were manipulated to demonstrate how the simulation framework can be used to investigate effects of changes in survey timing, direction, and coverage on survey estimates. The method picked up general sources of biases and variance, i.e. that surveys conducted during fish migrations are more vulnerable in terms of bias to timing and changes in survey direction than during more stationary situations and that increased effort reduced the sampling variance.

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