Price Volatility in Seafood Markets: Farmed vs. Wild Fish     

Frank Asche  Roy Endré Dahl  Marie Steen 《Aquaculture Economics & Management (Blackwell Science)》2015,19(3):316-335

Price volatility has an important impact on seafood markets and the aquaculture industry. This article investigates price volatility regimes along three dimensions; technology, species and product form. We identify regimes using the Iterated Cumulative Sum of Squares (ICSS), which allow us to compare the volatility found in aquaculture products, as well as comparing against fish-meal and soybeans. The results help identify the level of price risk found within the aquaculture industry across species and products. In addition, we differentiate between technologies comparing wild-caught fish with aquaculture products. The results also help us consider the relative riskiness of aquaculture compared to other industries. The results indicate that in aggregate, price volatility for aquacultured products is substantially lower than for wild. However, this varies substantially between species.  相似文献   

Host range and symptomatology of Pepino mosaic virus strains occurring in Europe     

Dag-Ragnar Blystad  René van der Vlugt  Ana Alfaro-Fernández  María del Carmen Córdoba  Gábor Bese  Dimitrinka Hristova  Henryk Pospieszny  Nataša Mehle  Maja Ravnikar  Laura Tomassoli  Christina Varveri  Steen Lykke Nielsen 《European journal of plant pathology / European Foundation for Plant Pathology》2015,143(1):43-56

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Stand-level wind damage can be assessed using diachronic photogrammetric canopy height models     

Jean-Pierre Renaud  Cédric Vega  Sylvie Durrieu  Jonathan Lisein  Steen Magnussen  Philippe Lejeune  Mériem Fournier 《Annals of Forest Science》2017,74(4):74

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Goshawk breeding densities in relation to mature forest in southeastern Norway     

Vidar Sels  Odd Frydenlund Steen  Jon Trygve Johnsen 《Forest Ecology and Management》2008,256(3):446

Forest harvesting practices have been assumed to be the main reason for the decrease in Goshawk Accipiter gentilis populations in Fennoscandia during the late 1900s, by reducing prey density, especially grouse and Red Squirrel (Sciurus vulgaris), and preferred hunting habitats (mature forest). In Norway, the highest breeding densities are now found in areas with a high proportion of farmland and urban areas where corvids and pigeons are important prey. To assess the importance of mature forest for Goshawk populations in southeastern Norway, we compared breeding densities from 20 municipalities with different percentages of farmland and mature forest. In multiple regression models, regional breeding densities were positively related to both the percentage of mature forest, and the percentage of farmland and urban areas. We conclude that the recommendation of establishing buffer zones around nest sites will not be sufficient to maintain Goshawk populations if the proportion of mature forest is reduced at a landscape level.  相似文献   

The status of marine biodiversity in the Eastern Central Atlantic (West and Central Africa)          下载免费PDF全文

Beth A. Polidoro  Gina M. Ralph  Kyle Strongin  Michael Harvey  Kent E. Carpenter  Rachel Arnold  Jack R. Buchanan  Khairdine Mohamed Abdallahi Camara  Bruce B. Collette  Mia T. Comeros‐Raynal  Godefroy De Bruyne  Ofer Gon  Antony S. Harold  Heather Harwell  Percival A. Hulley  Tomio Iwamoto  Steen W. Knudsen  Jean de Dieu Lewembe  Christi Linardich  Kenyon C. Lindeman  Vanda Monteiro  Thomas Munroe  Francis K.E. Nunoo  Caroline M. Pollock  Stuart Poss  Barry Russell  Catherine Sayer  Aboubacar Sidibe  William Smith‐Vaniz  Emilie Stump  Mor Sylla  Luis Tito De Morais  Jean‐Christophe Vié  Akanbi Williams 《水产资源保护:海洋与淡水生态系统》2017,27(5):1021-1034

Forest inventory inference with spatial model strata     

Steen Magnussen  Thomas Nord-Larsen 《Scandinavian Journal of Forest Research》2021,36(1):43-54

ABSTRACT

In design-based model assisted inference from data gathered in a large area forest inventory under a probability sampling design, one should anticipate spatial heterogeneity in the regression coefficients of an assisting model. The consequence of such heterogeneity is that a global estimate of a root mean squared error (RMSE) becomes unsuited for local predictions. With data from the Danish National Forest Inventory, we demonstrate how to: obtain an assisting model with the lasso method; test for spatial stationarity in regression coefficients of the assisting model; and identify spatial model strata for a post-stratification with either a finite mixture modeling or a lasso spatial clustered coefficients method. Spatial model strata apply to any domain and small area estimation problem without the need for complex modeling when domains or small area changes with shifting user needs. One should not à priori expect a spatial model stratification to improve design-based population and strata estimates of precision, but the reliability of domain and small area RMSEs will improve in presence of statistically significant spatial model strata.  相似文献   

Transgenic sugar beet tolerant to glyphosate   总被引：4，自引：0，他引：4  

Marie Mannerlöf  Stig Tuvesson  Per Steen  Paul Tenning 《Euphytica》1997,94(1):83-91

Phenology (i.e. the influence of environment on ontogeny) is the most important single factor influencing crop adaptation. The timing of flowering is particularly important since it largely determines when annual cereal, pulse and oilseed crops will subsequently be ripe for harvest. Two environmental factors are of overriding importance in the induction of flowering – photoperiod (daylength) and temperature. In seeking to predict times from sowing to flowering, f, it has proved profitable to analyse photothermal responses in terms of the rate of progress from sowing to flowering, 1/f. This paper summarises the advantages of a model based on rates rather than the traditional approach based on f. Over a wide range of photothermal regimes, the model involves just six coefficients, all of which (and their derivatives) have clearly defined biological meaning. Of paramount importance too is that the coefficients are not affected by the environment; they are genetic characters which determine phenotypic responses to the environment in a quantitative and predictable way.  相似文献   

Quantitative genotyping to estimate genetic contributions to pooled samples and genetic merit of the contributing entities     

B. P. Kinghorn  J. W. M. Bastiaansen  D. C. Ciobanu  H. A. M. van der Steen 《Acta Agriculturae Scandinavica, Section A - Animal Sciences》2013,63(1):3-12

Abstract

Genotyping required to track family membership in aquaculture breeding programs is reduced dramatically by estimating the contributions of different families to pooled samples of tissue. This approach is relevant to widely differing scenarios involving animals, plants, and microbes. For the family membership scenario, SNP markers are genotyped for the contributing families' parents, and quantitatively genotyped to estimate allele frequencies within the mixed-family pooled tissue. Results are used to infer proportional contributions of the different families to the pool. Different computational strategies were tested for bias and sampling error. A correlation of 99% between estimated and true genetic contributions was achieved using 20 (50) randomly chosen SNPs at a standard error of allele frequency estimates of 0.01 (0.02). Optimal grouping of families and choice of markers further increases performance markedly. Trait means and distributions of families can be quite accurately estimated by tissue sampling across the range of trait values.  相似文献   

Biofilm production of Pseudomonas spp. isolates from canine otitis in three different enrichment broths     

Victoria H. Robinson  Sue Paterson  Cheryl Bennett  Stephen I. Steen 《Veterinary dermatology》2019,30(3):218-e67

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A monitoring study to assess the acute mortality effects of indoxacarb on honey bees (Apis mellifera L.) in flowering apple orchards     

van der Steen JJ  Dinter A 《Pest management science》2007,63(11):1095-1099

To evaluate the effect of the indoxacarb 300 g kg(-1) WG, Steward 30WDG, on the honey bee (Apis mellifera L.) in apple orchards, a monitoring study was conducted in Dutch apple orchards in April/May 2004. Before apple flowering began, two honey bee colonies were placed in each orchard to investigate honey bee mortality. Each hive was provided with a Münster dead bee trap to collect dead honey bees. The numbers of dead bees found in these Münster dead traps were counted every 3-4 days for about 2 weeks before and after the period of the insecticide treatment. In nine flowering orchards no indoxacarb was applied during the flowering period, which served as control sites. In 30 flowering orchards indoxacarb was sprayed by the fruit growers according to local practice at 170-260 g formulated product ha(-1) (51-78 g AI ha(-1)). In the control orchards the average mortality was 8 honey bees colony(-1) day(-1). The average daily honey bee mortality before and after indoxacarb application was 8 and 10 honey bees colony(-1) day(-1) respectively. At one test site, indoxacarb was mixed with other plant protection products plus plant nutrients, and in this orchard a slight but biologically non-significant increase in acute honey bee mortality was recorded. It was concluded that the application of indoxacarb caused no effects on honey bee mortality, and that the number of dead honey bees counted in the Münster traps in the orchard treated with indoxacarb was comparable with those determined in control orchards.  相似文献