INPUT FACTOR SUBSTITUTABILITY IN SALMON AQUACULTURE

The salmon aquaculture industry has experienced substantial expansion during the last two decades. This expansion is largely the result of increased productivity, with a complementary decrease in costs. A general reduction in production costs has been accompanied by substantial shifts in the shares of inputs. Hence, one may question whether the technology has changed so much that some input factors are no longer substitutes in production. In this study, we investigate this by estimating a translog cost function focusing on the difference between full and partial static equilibrium specifications. The results from the different specifications provide evidence of limited or zero substitution possibilities in salmon production. This implies that salmon farming today can be thought of as a converter or refinement industry where less valuable fish (the feed) are converted into higher-valued product.Resource /Energy Economics and Policy,

Faustmann in the Sea: Optimal Rotation in Aquaculture

In this article an extended version of the well-known Faustmann model is developed for solving the rotation problem in fish farming. Two particularly important aspects of the problem are emphasized: First, the possibilities for cycles in relative price relationships and second, restrictions in release time for certain species. An illustration of the model based on assumptions from salmon farming shows that the inclusion of these two features has major influences on rotation time, and hence harvest weight.Aquaculture, optimal rotation, dynamic programming, relative prices., Research Methods/ Statistical Methods, Q22,

PATTERNS IN THE RELATIVE PRICE FOR DIFFERENT SIZES OF FARMED FISH

Fish farming is a biological production process dependent upon biological and environmental conditions. These constraints imply that different fish farmers are likely to have a similar distribution of different sizes of fish over time. If there are no perfect substitutes for the different sizes of fish in the shortrun, this production cycle can cause different relative prices between the different sizes over the year. By studying prices for different sizes of salmon for the period 1992–98, we show that such patterns exist. This can have important implications when studying aquaculture industries and markets. We look closer at two issues — optimal harvesting decisions and aggregation.Resource /Energy Economics and Policy,

The Value of Information in Salmon Farming: Harvesting the Right Fish to the Right Time

Research regarding management practice in fish farming has traditionally focused on two topics: production planning and forecasting of prices. This article combine these two areas of research, and illustrate how information of price patterns can change production plans, and hence increase the value of the farm enterprise. We present a model farm and illustrate with different levels of price information how information of future prices alter the original production plan and hence create extra value for the farmer. The phrasing of the paper and the empirical application are on salmon and salmon farming, but the ideas and general results should be applicable to all farmed species.Resource /Energy Economics and Policy,

Aquaculture—Opportunities and Challenges: Special Issue Introduction

Production Economics,

Modelling Production Risk in Small Scale Subsistence Agriculture

In this paper we are investigating how production risk may influence the way a risk averse producer like a subsistence farmer chooses optimal input levels. Risk averse producers will take into account both the mean and the variance of output, and therefore we expect them to choose input levels which differ form the optimal input level of risk neutral producers. Production risk is of particular importance in developing countries, since variance in production here may have grave consequences for the farmer and his family. To model the production decision problem under such circumstances we have made use of the fact that production risk can be treated as heteroskedasticity. Our analysis is based on a dataset obtained from a survey on smallholders in the Kilimanjaro region in Tanzania. Since evidence of output risk in inputs is found, we reestimate the mean and variance function using a maximum likelihood estimator, and correct the standard errors to provide valid inference.Farm Management,

CONSUMERS' WILLINGNESS TO PAY FOR THE COLOR OF SALMON:A CHOICE EXPERIMENT WITH REAL ECONOMIC INCENTIVES

We designed an experimental market with posted prices to investigate consumers' willingness to pay for the color of salmon. Salmon fillets varying in color and price were displayed in 20 choice scenarios. In each scenario, the participants chose which of two salmon fillets they wanted to buy. To induce real economic incentives, each participant drew one unique binding scenario; the participants then had to buy the salmon fillet they had chosen in their binding scenario.Consumer/Household Economics,

Level densities and γ\gamma-ray strength functions in 170,171,172^{170,171,172}Yb

Level densities and radiative strength functions in $^{171}$Yb and $^{170}$Yb nuclei have been measured using the $^{171}$Yb($^3$He,$^3$He$^\prime\gamma$)$^{171}$Yb and $^{171}$Yb($^3$He,$\alpha\gamma$)$^{170}$Yb reactions. New data on $^{171}$Yb are compared to a previous measurement for $^{171}$Yb from the $^{172}$Yb($^3$He,$\alpha\gamma$)$^{171}$Yb reaction. Systematics of level densities and radiative strength functions in $^{170,171,172}$Yb are established. The entropy excess in $^{171}$Yb relative to the even-even nuclei $^{170,172}$Yb due to the unpaired neutron quasiparticle is found to be approximately 2$k_B$. Results for the radiative strength function from the two reactions lead to consistent parameters characterizing the ``pygmy'' resonances. Pygmy resonances in the $^{170,172}$Yb populated by the ($^3$He,$\alpha$) reaction appear to be split into two components for both of which a complete set of resonance parameters are obtained.Comment: 8 pages, 7 figure

Import Demand Estimation and the Generalized Composite Commodity Theorem

A frequently encountered problem in import demand estimation is how to account for competition between imports and domestic production. Traditionally, use of the Armington model has been a way to handle this problem. This is a disaggregate model which distinguishes commodities by country of origin with import demand determined in a separable two-step procedure. The model appears frequently in analysis of international agricultural markets. However, the Armington model relies on a set of weak separability assumptions, which several authors have shown to be highly questionable. In this paper, a new aggregation theorem, the Generalized Composite Commodity Theorem (GCCT), is applied to test whether imports can be treated as a separate group. An advantage with the GCCT is that only import data is required to conduct the test. The application is to the imports of swordfish to the U.S. with implications for U.S. and international swordfish management policies.Armington, separability, GCCT, demand system, sword fish, International Relations/Trade, F18, Q11, Q22,