Influence of decreased biomass on the ogive of sex change of northern shrimp (Pandalus borealis)

2017 ◽  
Vol 75 (3) ◽  
pp. 1054-1062 ◽  
Author(s):  
Ingibjörg G Jónsdóttir ◽  
Gudrún G Thórarinsdóttir ◽  
Jónas P Jonasson
Keyword(s):  
Time Series ◽  
Change Process ◽  
Sex Change ◽  
Test Case ◽  
Pandalus Borealis ◽  
The Third ◽  
Northern Shrimp ◽  
Stock Biomass ◽  
Low Levels ◽  
Lower Size

Abstract Northern shrimp (Pandalus borealis) are protandrous hermaphrodites that reproduce first as males, go through a transition phase and transform to females, and then spawn as such for the rest of their lives. No clear consensus exists as to which factors influence the activation of the sex change process, but one possible factor is population density. Here, we investigate whether changes in stock size can influence the ogive of sex change, and use a 26-year time series (i.e. 1990–2015) of survey data on shrimp biomass from three different stocks in Iceland as a test case. Two of the stocks experienced periods of high biomass during the 1990 s, with a pronounced and prolonged depletion observed after 2000. In contrast, stock biomass of the third stock decreased only slightly during the time series. We found that the ogives of sex change of the two stocks where the biomass decreased to very low levels have changed significantly, and that shrimp now change sex at a lower size compared to earlier. Furthermore, Lmax has decreased significantly.

scholarly journals Influence of fleet renewal and trawl development on landings per unit effort of the Danish northern shrimp (Pandalus borealis) fishery

2010 ◽  
Vol 68 (1) ◽  
pp. 26-31 ◽  
Author(s):  
Ole Ritzau Eigaard ◽  
Sten Munch-Petersen
Keyword(s):  
Time Series ◽  
Pandalus Borealis ◽  
Northern Shrimp ◽  
Unit Effort ◽  
Generalized Linear Modelling ◽  
Stock Assessments ◽  
Order Books ◽  
The Relationship ◽  
Logbook Data ◽  
Engine Power

Abstract Eigaard, O. R., and Munch-Petersen, S. 2011. Influence of fleet renewal and trawl development on landings per unit effort of the Danish northern shrimp (Pandalus borealis) fishery. – ICES Journal of Marine Science, 68: 26–31. Recent stock assessments of the Pandalus stock in the Skagerrak (ICES Division IIIa) and the Norwegian Deep (Division IVa east) have relied largely on a time-series of landings per unit effort (lpue) calculated from Danish logbook data. Because of fleet renewal and trawl-size changes, the relationship between nominal effort data as recorded in logbooks (days fishing) and effective effort is likely to have changed, so to standardize the nominal lpue time-series, trawl-size development has been taken into account using generalized linear modelling. As logbooks do not provide trawl-size information, this standardization was made possible by retrieving technical trawl and vessel data from industry order books. These data demonstrated an approximately linear relationship between vessel engine power and Pandalus trawl size, so validated the use of vessel horsepower from the logbooks as a proxy for an unknown trawl size. Standardized lpue time-series for the past 20 years indicated a lesser increase in stock size than nominal lpue, the modelling results demonstrating that vessel lpue increased by 9.5% with each 100 hp of engine power.

ADRENOCORTICAL FUNCTION IN PATIENTS WITH ACUTE SEVERE BRAIN AND PITUITARY LESION

1962 ◽  
Vol 40 (2) ◽  
pp. 254-262 ◽  
Author(s):  
H. H. Bassøe ◽  
R. Emberland ◽  
E. Glück ◽  
K. F. Støa
Keyword(s):  
Pituitary Gland ◽  
Adrenal Cortex ◽  
Artificial Ventilation ◽  
Practical Significance ◽  
Adrenocortical Function ◽  
The Third ◽  
Low Levels ◽  
Pituitary Lesion ◽  
Steroid Excretion ◽  
The Brain

ABSTRACT The steroid excretion and the plasma corticosteroids were investigated in three patients with necrosis of the brain and of the pituitary gland. The patients were kept alive by artificial ventilation. In two of the patients the neutral 17-ketosteroids and the 17-hydrocorticosteroids fell to extremely low levels. At the same time, the number of eosinophil cells showed a tendency to increase. Corticotrophin administered intravenously twice to the third patient had a stimulating effect on the adrenal cortex. The theoretical and practical significance of these findings is discussed.

scholarly journals System for Forecasting COVID-19 Cases Using Time-Series and Neural Networks Models

2021 ◽  
Vol 5 (1) ◽  
pp. 46
Author(s):  
Mostafa Abotaleb ◽  
Tatiana Makarovskikh
Keyword(s):  
Neural Network ◽  
Neural Networks ◽  
Time Series ◽  
Time Series Models ◽  
Third Wave ◽  
The Third ◽  
Modeling And Forecasting ◽  
Auto Regressive ◽  
The Russian Federation ◽  
R Programming

COVID-19 is one of the biggest challenges that countries face at the present time, as infections and deaths change daily and because this pandemic has a dynamic spread. Our paper considers two tasks. The first one is to develop a system for modeling COVID-19 based on time-series models due to their accuracy in forecasting COVID-19 cases. We developed an “Epidemic. TA” system using R programming for modeling and forecasting COVID-19 cases. This system contains linear (ARIMA and Holt’s model) and non-linear (BATS, TBATS, and SIR) time-series models and neural network auto-regressive models (NNAR), which allows us to obtain the most accurate forecasts of infections, deaths, and vaccination cases. The second task is the implementation of our system to forecast the risk of the third wave of infections in the Russian Federation.

URANS Studies of Effect of Eccentricity on Ship–Lock Interactions

2016 ◽  
Vol 13 (04) ◽  
pp. 1641012
Author(s):  
Qingjie Meng ◽  
Decheng Wan
Keyword(s):  
Viscous Flow ◽  
Hydrodynamic Interaction ◽  
Vertical Displacement ◽  
Navier Stokes ◽  
Test Case ◽  
The Third ◽  
Surface Pressure Distribution ◽  
Sst Turbulence Model ◽  
Unsteady Viscous Flow ◽  
Ship Lock

The unsteady viscous flow around a 12000TEU ship model entering the Third Set of Panama Locks with different eccentricity is simulated by solving the unsteady Reynolds averaged Navier–Stokes (RANS) equations in combination with the [Formula: see text]SST turbulence model. Overset grid technology is utilized to maintain grid orthogonality and the effects of the free surface are taken into account. The hydrodynamic forces, vertical displacement as well as surface pressure distribution are predicted and analyzed. First, a benchmark test case is designed to validate the capability of the present methods in the prediction of the viscous flow around the ship when maneuvering into the lock. The accumulation of water in front of the ship during entry into a lock is noticed. A set of systematic computations with different eccentricity are then carried out to examine the effect of eccentricity on the ship–lock hydrodynamic interaction.

HISTORY OF THE STUDY AND FEATURES OF THE NORTHERN SHRIMP PANDALUS BOREALIS FISHERY IN THE NORTHERN PART OF THE SEA OF OKHOTSK

Fisheries ◽  
2021 ◽  
Vol 2021 (3) ◽  
pp. 62-67
Author(s):  
Yulia Shcherbakova ◽  
Yuri Semenov ◽  
Julia Elatinceva ◽  
Andrey Smirnov
Keyword(s):  
Sea Of Okhotsk ◽  
Industrial Development ◽  
Pandalus Borealis ◽  
The Sea Of Okhotsk ◽  
Northern Shrimp ◽  
History Of

The article deals with the history of the study of the northern shrimp, which lives in the northern part of the Sea of Okhotsk. Based on the materials collected in 2020, in comparison with 2018-2019, the course of fishing and catching of this object is analyzed. It is shown that the prospects of industrial development of this valuable object in the coming years do not cause concerns.

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