scholarly journals Productivity and Management of Renewable Resources: Why More Efficient Fishing Fleets Should Fish Less

2022 ◽  
Author(s):  
Eric Nævdal
Keyword(s):  
Steady State ◽  
Fisheries Management ◽  
Renewable Resources ◽  
State Level ◽  
Harvest Rate ◽  
Stock Size ◽  
Optimal Harvest ◽  
Productivity Increase ◽  
Resource Stock ◽  
Fishing Fleets

AbstractThis article analyses the effect of productivity improvements on optimal fisheries management. It is shown that when harvest costs are independent of resource stock and the stock is below its steady state level, then for any given stock it is optimal to reduce harvest levels in response to a productivity increase unless optimal harvest rate is already zero. If harvest costs are stock dependent this result is modified; for stock dependent harvest costs there exists an interval of stock sizes below the steady state where it is optimal to reduce the harvest rate for any given stock size whereas if the harvest rate is close to an economically optimal steady state it is optimal to increase the harvest rate.

Optimal Stock Size and Harvest Rate in Multistage Life History Models

1986 ◽  
Vol 43 (1) ◽  
pp. 135-141 ◽  
Author(s):  
Elie Moussalli ◽  
Ray Hilborn
Keyword(s):  
Life History ◽  
Survival Rates ◽  
Harvest Rate ◽  
Recruitment Curve ◽  
Stock Size ◽  
Entire Life ◽  
Density Dependent ◽  
Optimal Harvest ◽  
History Of ◽  
The Relationship

If the life history of a population consists of a sequence of density-dependent stages linked by density-independent survival rates, and if the density-dependent stages take the form of the Beverton–Holt stock and recruitment curve, then a single Beverton–Holt curve will describe the entire life history. The relationship between the parameters of any stage in the life history and the optimal harvest rate and optimal stock size is analyzed. Increasing survival rates will always increase the optimal harvest rate, but may increase or decrease the optimal stock size. Increasing the habitat capacity will increase the optimal stock size and leave the optimal harvest rate unaffected. An example of changing freshwater survival rates by Salmonid Enhancement is shown, as is an example of changing ocean survival rate. As we acquire a better understanding of the determinants of survival and habitat capacity, we should adjust harvest rates and stock size as the environment changes.

Problems Confronting Fishing Industries Relative to Management Policies Adopted by Governments

1973 ◽  
Vol 30 (12) ◽  
pp. 2486-2489
Author(s):  
G. H. Elliot
Keyword(s):  
Fisheries Management ◽  
International Level ◽  
Full Understanding ◽  
Alternative Management ◽  
Fishery Resources ◽  
International Action ◽  
The Future ◽  
Future Viability ◽  
Management Policies ◽  
Fishing Fleets

With increase in numbers, size, and effectiveness, fishing fleets have depleted important stocks of fish, and strong international action by governments is imperative for the future viability of fishery resources. The author favors a system of an overall quota of fish, with individual quotas for boats and plants, and predicts that this will become "the accepted method of running fisheries" in 20 years. He discusses how best to organize such a system, with full consultation between governments and their national fishing industries as well as at the international level. For efficient handling of the complex issues involved and a full understanding of them, he suggests that governments should appoint to their fisheries ministries officers who have specialized in fisheries management and are able to analyze the situation in depth and advise the administrators on the implications of alternative management policies. The controls over fishing that he advocates are essential because "free fish means eventually no fish."

Tacrolimus initial steady state level in post-transplant cyclophosphamide-based GvHD prophylaxis regimens

2021 ◽  
Author(s):  
Janny M. Yao ◽  
Dongyun Yang ◽  
Mary C. Clark ◽  
Salman Otoukesh ◽  
Thai Cao ◽  
...  
Keyword(s):  
Steady State ◽  
State Level ◽  
Steady State Level ◽  
Post Transplant ◽  
Gvhd Prophylaxis

Ascorbate and glutathione homeostasis in vascular smooth muscle cells: cooperation with endothelial cells

1998 ◽  
Vol 275 (4) ◽  
pp. C1031-C1039 ◽  
Author(s):  
Ilia Voskoboinik ◽  
Karin Söderholm ◽  
Ian A. Cotgreave
Keyword(s):  
Endothelial Cells ◽  
Smooth Muscle ◽  
Steady State ◽  
Smooth Muscle Cells ◽  
Umbilical Vein ◽  
State Level ◽  
Muscle Cells ◽  
Free Access ◽  
Steady State Level ◽  
Human Umbilical Vein

Human umbilical vein smooth muscle cells (HUVSMCs) utilize extracellular cystine, glutathione (GSH), and N-acetylcysteine (NAC) to synthesize cellular GSH. Extracellular cystine was effective from 5 μM, whereas GSH and NAC were required at 100 μM for comparable effects. The efficacy of extracellular GSH was dependent on de novo GSH synthesis, indicating a dependence on cellular γ-glutamyltransferase (glutamyl transpeptidase). Coculture of syngenetic HUVSMCs and corresponding human umbilical vein endothelial cells (HUVECs) on porous supports restricted cystine- or GSH-stimulated synthesis of HUVSMC GSH when supplied on the “luminal” endothelial side. Thus HUVSMC GSH rapidly attained a steady-state level below that achieved in the absence of interposed HUVECs. HUVSMCs also readily utilize both reduced ascorbate (AA) and oxidized dehydroascorbate (DHAA) over the range 50–500 μM. Phloretin effectively blocked both AA- and DHAA-stimulated assimilation of intracellular AA, indicating a role for a glucose transporter in their transport. Uptake of extracellular AA was also sensitive to extracellular, but not intracellular, thiol depletion. When AA was applied to the endothelial side of the coculture model, assimilation of intracellular AA in HUVSMCs was restricted to a steady-state level below that achieved by free access.

scholarly journals The steady-state level of Mg-protoporphyrin IX is not a determinant of plastid-to-nucleus signaling in Arabidopsis

2008 ◽  
Vol 105 (39) ◽  
pp. 15184-15189 ◽  
Author(s):  
N. Mochizuki ◽  
R. Tanaka ◽  
A. Tanaka ◽  
T. Masuda ◽  
A. Nagatani
Keyword(s):  
Steady State ◽  
Protoporphyrin Ix ◽  
State Level ◽  
Steady State Level

scholarly journals Expression of human beta-secretase in the mouse brain increases the steady-state level of beta-amyloid

2002 ◽  
Vol 80 (5) ◽  
pp. 799-806 ◽  
Author(s):  
Ursula Bodendorf ◽  
Simone Danner ◽  
Frauke Fischer ◽  
Muriel Stefani ◽  
Christine Sturchler-Pierrat ◽  
...  
Keyword(s):  
Steady State ◽  
Mouse Brain ◽  
State Level ◽  
Beta Amyloid ◽  
Steady State Level ◽  
Beta Secretase

Expression of a gene for mouse eucaryotic elongation factor Tu during murine erythroleukemic cell differentiation

1987 ◽  
Vol 7 (11) ◽  
pp. 3929-3936
Author(s):  
W W Roth ◽  
P W Bragg ◽  
M V Corrias ◽  
N S Reddy ◽  
J N Dholakia ◽  
...  
Keyword(s):  
Steady State ◽  
Genomic Library ◽  
Elongation Factor ◽  
State Level ◽  
Genomic Clone ◽  
Elongation Factor Tu ◽  
Steady State Level ◽  
Similar Reduction ◽  
S1 Nuclease ◽  
Murine Erythroleukemia

The eucaryotic elongation factor Tu (eEF-Tu) is a single polypeptide with an approximate Mr of 53,000. During protein synthesis eEF-Tu promotes the binding of aminoacyl-tRNA to the ribosome. To study the expression of the gene(s) for this factor, a genomic clone was isolated that contains a mouse eEF-Tu gene. We screened a phage genomic library with a synthetic oligonucleotide probe complementary to a region of the Saccharomyces cerevisiae and Artemia sp. eEF-Tu genes which codes for an area that is highly conserved between both yeast and Artemia sp. eEF-Tu. From approximately 75,000 phage plaques we obtained five isolates with apparently identical inserts. All five clones contained a 3.8-kilobase EcoRI fragment that hybridized to additional oligonucleotide probes corresponding to different conserved regions of eEF-Tu. We sequenced the 5' end of one genomic clone and determined the length of the cloned fragment that was protected by eEF-Tu mRNA in S1 nuclease protection assays. A quantitative S1 nuclease protection assay was used to compare the relative steady-state levels of eEF-Tu mRNA in total mRNA in total RNA isolated from hexamethylene-bisacetamide-induced murine erythroleukemia cells. The results show a dramatic reduction in the steady-state level of eEF-Tu mRNA as differentiation proceeds. A similar reduction in transcription of eEF-Tu mRNA was observed in isolated nuclei. Finally, we examined the in vivo synthesis of eEF-Tu during differentiation and found that it declined in a manner parallel to the decline in the steady-state level of eEF-Tu mRNA. In addition, we have isolated and sequenced a cDNA clone for mouse eEF-Tu. The derived amino acid sequence is compared with sequences from other eucaryotes.

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