Spawning Stock Size and Resultant Production for Skeena Sockeye

1958 ◽  
Vol 15 (5) ◽  
pp. 1007-1025 ◽  
Author(s):  
M. P. Shepard ◽  
F. C. Withler
Keyword(s):  
Optimum Number ◽  
Total Production ◽  
Average Yield ◽  
Stock Size ◽  
The Past ◽  
Reproduction Curve ◽  
Exploitation Rate ◽  
Environmental Fluctuations ◽  
Spawning Stock ◽  
Maximum Sustained Yield

For age 4 and 5 Skeena sockeye, plots of total production of adults from individual brood years against number of parent spawners gave a reproduction curve with an almost linear ascending limb and a very precipitous descending limb. Maximum reproduction (2.4 million sockeye) was achieved at spawning levels of slightly over 0.9 million; the maximum sustained yield (1.4 million) was provided by spawnings of 0.9 million. The stock is very sensitive both to small changes in fishing intensity, and to random variations in survival caused by density-independent environmental fluctuations. Therefore the attainment of high sustained yields by application of a constant optimum exploitation rate is not practical. Regulation to provide the optimum number of spawners each year would more likely provide the highest average yield. Observed fluctuations in commercial catches over the past 50-odd years can be accounted for by changes in annual rates of exploitation. Still higher yields might be attained if individual components of the composite stock studied could be managed separately.

scholarly journals A two-stage biomass model to assess the English Channel cuttlefish (Sepia officinalis L.) stock

2014 ◽  
Vol 71 (9) ◽  
pp. 2457-2468 ◽  
Author(s):  
Michaël Gras ◽  
Beatriz A. Roel ◽  
Franck Coppin ◽  
Eric Foucher ◽  
Jean-Paul Robin
Keyword(s):  
Reference Points ◽  
Sea Surface ◽  
Sepia Officinalis ◽  
Sustainable Utilization ◽  
English Channel ◽  
Two Stage ◽  
Stock Biomass ◽  
Exploitation Rate ◽  
Spawning Stock ◽  
Age Structured

Abstract The English Channel cuttlefish (Sepia officinalis) is the most abundant cephalopod resource in the Northeast Atlantic and one of the three most valuable resources for English Channel fishers. Depletion methods and age-structured models have been used to assess the stock, though they have shown limitations related to the model assumptions and data demand. A two-stage biomass model is, therefore, proposed here using, as input data, four abundance indices derived from survey and commercial trawl data collected by Ifremer and Cefas. The model suggests great interannual variability in abundance during the 17 years of the period considered and a decreasing trend in recent years. Model results suggest that recruitment strength is independent of spawning–stock biomass, but appears to be influenced by environmental conditions such as sea surface temperature at the start of the life cycle. Trends in exploitation rate do not reveal evidence of overexploitation. Reference points are proposed and suggestions for management of the sustainable utilization of cuttlefish in the English Channel are advanced.

THE STATE AND TRENDS IN THE PRODUCTION OF MEAT OF DOMESTIC ANIMALS IN THE WORLD AND RUSSIA

2021 ◽  
pp. 20-22
Author(s):  
A.I. EROKHIN ◽  
Keyword(s):  
Domestic Animals ◽  
The State ◽  
Poultry Meat ◽  
Meat Production ◽  
Total Production ◽  
The Past ◽  
The World

The analysis of the dynamics of meat production of diff erent types of domestic animals in the world and in Russia over the past 20 years is given. It is noted that in the total production of meat of all types, the share of beef, pork and lamb is decreasing, and poultry meat is signifi cantly increasing.

Equality—an American Dilemma

Worldview ◽  
1976 ◽  
Vol 19 (4) ◽  
pp. 35-38
Author(s):  
Joseph P. DeMarco ◽  
Samuel A. Richmond
Keyword(s):  
The Other ◽  
Court Decisions ◽  
Total Production ◽  
Practical Realization ◽  
Political Equality ◽  
Economic Equality ◽  
Social Equality ◽  
The Past ◽  
The Poor ◽  
Economic Improvement

Americans are committed by Constitutional ideals to political equality. On the other hand, our economic ideals are libertarian and permit inequalities. Court decisions and federal legislation in the 1950's and '60's created a strong commitment to the practical realization of political and social equality. Yet we have come to see in the 1970's that economic inequalities make this achievement very difficult. The pressures for economic equality are relatively recent, because both poor and rich in Amerjca have in the past assumed the plight of the poor can be relieved most quickly through increases in total production rather than through a change in the distribution of what is produced. The prospect of limited economic growth in the future, or even no growth, dramatically shifts the pressures for economic improvement of the poor away from increased production toward greater equality in distribution.

scholarly journals An explicit solution for calculating optimum spawning stock size from Ricker’s stock recruitment model

PeerJ ◽  
2016 ◽  
Vol 4 ◽  
pp. e1623 ◽  
Author(s):  
Mark D. Scheuerell
Keyword(s):  
Explicit Solution ◽  
Model Fitting ◽  
Maximum Sustainable Yield ◽  
Reference Points ◽  
Stock Size ◽  
Points Of Interest ◽  
Spawning Stock ◽  
Stock Recruitment ◽  
Explicit Formulae ◽  
Recruitment Model

Stock-recruitment models have been used for decades in fisheries management as a means of formalizing the expected number of offspring that recruit to a fishery based on the number of parents. In particular, Ricker’s stock recruitment model is widely used due to its flexibility and ease with which the parameters can be estimated. After model fitting, the spawning stock size that produces the maximum sustainable yield (SMSY) to a fishery, and the harvest corresponding to it (UMSY), are two of the most common biological reference points of interest to fisheries managers. However, to date there has been no explicit solution for either reference point because of the transcendental nature of the equation needed to solve for them. Therefore, numerical or statistical approximations have been used for more than 30 years. Here I provide explicit formulae for calculating bothSMSYandUMSYin terms of the productivity and density-dependent parameters of Ricker’s model.

Swedish employers

1978 ◽  
Vol 10 (1) ◽  
pp. 4-10
Author(s):  
TOM GORE
Keyword(s):  
Poor Country ◽  
Industrial Relations ◽  
75Th Birthday ◽  
Balance Of Payments ◽  
Total Production ◽  
Working Population ◽  
Sound System ◽  
Industrial Economy ◽  
Goods And Services ◽  
The Past

The Swedish Employers' Federation (SAF), which reached its 75th birthday in September 1977, today operates in a highly developed economy. In 1902 Sweden was relatively a poor country, where 55 per cent of the working population was employed in agriculture and forestry, and only 27 per cent in industry and mining. Today, six per cent of the working population is concerned with agriculture and forestry, whilst industry, mining and construction account for 36 per cent. And there are 30 per cent in public administration and other services and fifteen per cent in trade. The rise of this industrial economy in some seventy years has been achieved largely by private enterprise and initiative, inventive genius, the development of foreign trade, and a sound system of industrial relations. Some forty per cent of the industrial production is exported which is equivalent to twenty‐four per cent of the total production of goods and services measured in monetary terms. The recent devaluation of the Krona has been designed to boost exports in order to overcome the balance of payments deficit which has increased considerably in the past year. Sweden, like Britain, has been affected by the slow economic recovery of Europe and other areas in the world.

scholarly journals Evaluation of the absolute levels of acoustic estimates of the 1983 year class of Norwegian spring-spawning herring

2003 ◽  
Vol 60 (3) ◽  
pp. 480-485 ◽  
Author(s):  
Ingolf Røttingen ◽  
Sigurd Tjelmeland
Keyword(s):  
Working Group ◽  
Assessment Model ◽  
Stock Size ◽  
Blue Whiting ◽  
Realistic Picture ◽  
Absolute Sense ◽  
Spawning Stock ◽  
The Absolute

Abstract The 1983 year class of Norwegian spring-spawning herring was large and, in retrospect, increased the spawning stock by more than two million tons when it recruited in 1987–1988. This paper summarizes and evaluates the acoustic estimates of the 1983 year class in the period 1983–2001. The key to the evaluation is a minimum stock based on the number of the 1983 year class caught in the international fishery and the year-class estimates made by the ICES Northern Pelagic and Blue Whiting Fisheries Working Group in 2002 using the SeaStar assessment model. The period of analysis covers a change in instrumentation, around 1990, from the SIMRAD EK400/Nord integrator to the EK500/BEI integrator system. The application of the acoustic estimates in the assessment and management of this herring stock is reviewed. It is concluded that the stock size was underestimated when the acoustic estimates were used in an absolute sense in the 1980s. In the 1990s the acoustic estimates were tuned to stock-size indices obtained from other methodologies and this approach seems to have given a realistic picture of the development of the 1983 year class.

CENTESIL: A Pilot Plant for R&D in Polysilicon

2009 ◽  
Vol 1210 ◽  
Author(s):  
Carlos del Cañizo ◽  
Araceli Rodríguez ◽  
Gabriel Ovejero ◽  
Antonio Luque
Keyword(s):  
Pilot Plant ◽  
Semiconductor Industry ◽  
New Ventures ◽  
Production Capacity ◽  
Industry Structure ◽  
Research Centre ◽  
Total Production ◽  
Independent Research ◽  
The Past ◽  
Solar Cell Technology

AbstractThe tremendous expansion and the relative avidity for silicon of the solar cell technology has resulted in a dramatic change of the polysilicon industry structure. While in the past the polysilicon was manufactured almost exclusively for the semiconductor industry, in 2008 around 67% of the total production was consumed by the solar industry. The consequence is that while in 2000 virtually only 7 companies supplied all the polysilicon consumed worldwide, in 2008 there were 11 major suppliers and numerous new ventures entering this market. Based on this in 2006 CENTESIL was founded as a new private-public partnership venture to deal with the polysilicon research. For it, a pilot plant is in advanced state of construction that has been preceded of some laboratory-size implementations. The pilot plant is designed for a production capacity of 60 kmol of trichlorosilane per day and 2 t of purified silicon per batch at the CVD reactor. The purpose is to allow the photovoltaic companies worldwide to count with an independent research centre to help them to establish their own polysilicon plant. The R&D activities already carried out by CENTESIL and the present status of the project are discussed in the paper.

Differential impacts of exploitation rate and juvenile exploitation on NE Atlantic fish stock dynamics over the past half century

2012 ◽  
Vol 134-136 ◽  
pp. 21-28 ◽  
Author(s):  
P. Vasilakopoulos ◽  
F.G. O’Neill ◽  
C.T. Marshall
Keyword(s):  
Fish Stock ◽  
Ne Atlantic ◽  
Half Century ◽  
The Past ◽  
Past Half Century ◽  
Exploitation Rate ◽  
Past Half

Further Information on Spawning Stock Size and Resultant Production for Skeena Sockeye

1964 ◽  
Vol 21 (5) ◽  
pp. 1329-1331 ◽  
Author(s):  
M. P. Shepard ◽  
F. C. Withler ◽  
J. McDonald ◽  
K. V. Aro
Keyword(s):  
Stock Size ◽  
Spawning Stock

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