Optimal Partial Harvesting Schedule for Aquaculture Operations

Abstract When growth is density dependent, partial harvest of the standing stock of cultured species (fish or shrimp) over the course of the growing season (i.e., partial harvesting) would decrease competition and thereby increase individual growth rates and total yield. Existing studies in optimal harvest management of aquaculture operations, however, have not provided a rigorous framework for determining "discrete" partial harvesting (i.e., partially harvest the cultured species at several discrete points until the final harvest). In this paper, we develop a partial harvesting model that is capable of addressing discrete partial harvesting and other partial harvesting using impulsive control theory. We derive necessary conditions of the efficient partial harvesting scheme for a single production cycle. We also present a numerical example to illustrate how partial harvesting can improve the profitability of an aquaculture enterprise compared to single-batch harvesting and gradual thinning. The study results indicate that well-designed partial harvesting schemes can enhance the profitability of aquaculture operations.Partial harvesting, impulsive control theory, aquaculture., Livestock Production/Industries, C61, Q22,

Do Fishermen Have Different Attitudes Toward Risk? An Application of Prospect Theory to the Study of Vietnamese Fishermen

Field experiment and household survey data are combined to investigate whether working in a risky occupation such as fishing makes fishermen have different risk preferences than individuals in other occupations. Prospect theory is utilized as the main analytical framework and a structural model approach is developed to simultaneously correlate the parameters of the utility function under prospect theory with other socioeconomic variables. The key finding is that working in fishing makes economic agents less risk averse than others. Fishermen also tend to be less sensitive to probability weighting changes in the experiment. It is possible that fishermen have adapted to their unique environment by using specific heuristics for decision making under conditions of uncertainty.experimental economics, prospect theory, risk behavior, Vietnamese fishermen, Resource /Energy Economics and Policy, Risk and Uncertainty,

Choice of Remuneration Regime in Fisheries: The Case of Hawaii’s Longline Fisheries

One of the most prominent features of remuneration in Hawaii’s longline fisheries industry has been the norm of share contract regimes. This paper investigates whether the use of the share contract regime is positively correlated to increased economic returns. The principal-agent framework is applied to develop a theoretical model for the remuneration choice. Empirical estimation is conducted using a switching regression model that accounts for the effects of certain vessel characteristics on revenue, depending on remuneration regime used (i.e., share contract or flat wage), as well as the potential selection bias in the vessels’ contractual choice. Key findings from counterfactual simulations indicate: (a) a negative selection related to choosing share contracts, and (b) flat wage vessels would experience significantly higher revenues if they switched to share contracts. Thus, even though the labor market in Hawaii’s longline fisheries relies upon foreign crew members, the results suggest that owners of flat wage vessels would benefit by applying share contracts to increase their revenues.commercial fisheries, crew shares, Hawaii, incentive systems, labor contracts, lay system, longline fisheries, remuneration regime, Resource /Energy Economics and Policy,

Impacts of Institutional Arrangements on the Profitability and Profit Efficiency of Organic Rice in Thailand

This study assesses the performance of organic small farmers in Thailand under different institutional arrangements and over time. It was found that while organic farmers were significantly more profitable and profit efficient than conventional farmers, the level of profitability varies under different intermediaries. Farmers organized by NGOs on degraded marginal land showed a pattern of increasing profit and profit efficiency over time, after the transition period. On the other hand, farmers organized by a private sector firm on newly opened forest land exhibited a pattern of stable profit and increasing yields over time. The results showed that farmers under non-profit NGOs received the highest level of profit, followed by farmers under the private firm and finally the for-profit NGO. These findings suggest that while organic agriculture can increase the economic performance of small farmers, institutional arrangement is an important factor in realizing the broader benefits of organic agriculture for poverty reduction

REGIONAL ECONOMIC IMPACTS OF REDUCTIONS IN FISHERIES PRODUCTION: A SUPPLY-DRIVEN APPROACH

Much debate and subsequent confusion have recently been generated regarding the economic importance of the longline fisheries for tuna and swordfish in Hawaii. Depending on the methodology employed, the measures of the economic importance of these fisheries to Hawaii can vary significantly. This paper attempts to provide an assessment of the alternative measures and their implications for fishery policy. In assessing the economic impact of the reduction in longline activities due to season and area closures as mandated by a recent court order, we suggest that the supply-driven approach is more appropriate. An empirical application using the supply-driven approach is used to estimate the economy-wide impacts of a 100% reduction in Hawaii-based longline activities. In addition, a set of supply-driven multipliers is derived for the other sectors of Hawaii's economy to allow comparison with the fishery sectors.Resource /Energy Economics and Policy,

ANALYZING THE EFFECT OF CHANGING FEED-BEEF PRICE RELATIONSHIPS ON BEEF PRODUCTION MANAGEMENT STRATEGIES IN HAWAII: A DYNAMIC PROGRAMMING APPROACH

A dynamic programming approach was used to evaluate the effect of changing the feed input to product price relationship on the beef production management decision process. The dynamic programming model consists of nine submodels describing and analyzing the time-dependent beef production management decision process. The model incorporates biological functions and economic principles. Results clearly showed the importance of the feed-beef price relationships in management decision making. Optimal beef production management strategies were generally consistent with beef production management practices followed in Hawaii under those feed-beef price relationships.Livestock Production/Industries,

TECHNICAL EFFICIENCY OF THE LONGLINE FISHERY IN HAWAII: AN APPLICATION OF A STOCHASTIC PRODUCTION FRONTIER

This paper examines the level and determinants of technical efficiency for a sample of domestic longline fishing vessels operating in Hawaii in 1993. The data on per-trip costs and revenues, fishing targets, vessel ownership, experience and education level of fishermen, vessel size, and vessel age are analyzed using a translog stochastic production frontier, including a model for vessel-specific technical inefficiencies. Output elasticities, marginal productivities of inputs, and returns to scale are also examined. The technical inefficiency effects are found to be highly significant in explaining the levels of and variation in vessel revenues. The mean technical efficiency for the sample vessels is estimated to be 84%. Vessels that target swordfish, and those varying target by season, set, or trip, tend to be less efficient than those vessels targeting tuna and those mixing targets in all trips. Owner-operated vessels seem to be more efficient than those operated by hired captains. The experience of fishermen has a strong positive influence on technical efficiency. Although insignificant, vessel size and fishermen's education level have a positive influence, and vessel age has a negative influence on vessel efficiency.Resource /Energy Economics and Policy,

Profitability of Organic Agriculture in a Transition Economy: the Case of Organic Contract Rice Farming in Lao PDR

Poverty is prevalent among smallholder farmers in transition economies where market failures prevail and where the capacity of the public sector is limited. This study assesses the potential of organic contract farming as a private sector institutional arrangement to reduce rural poverty. Contract farming appears to facilitate market linkages for smallholder farmers to produce organic rice for export markets while providing necessary technical supports. Using an endogenous switching regression model to assess the profitability of organic contract farms and conventional farms in Lao PDR, it was found that organic farmers under contract earn significantly higher profit than conventional farms. The findings also showed that organic contract farming tends to provide the greatest increase in income to farmers with below average performance. These findings suggest that contract farming can be an effective mechanism to facilitate the development of organic agriculture and an effective tool to improve the profitability and raise incomes of small farmers, thereby reducing poverty in rural areas with limited market development

Tourism's Forward and Backward Linkages

This paper proposes “linkage analysis” as a complement to the traditional “tourism impact analysis” to examine tourism’s economic imprints on a destination’s economy. Although related, the two methods are not the same. The starting point of tourism “impact analysis” is “final demand”; impact analysis measures the direct and indirect impacts of tourist spending on the local economy. By contrast, the starting point of “linkage analysis” is the tourism sector; the analysis examines the strengths of the inter-sectoral forward (FL) and backward (BL) relationships between the tourism sector and the non-tourism industries in the rest of the economy. The FL measures the relative importance of the tourism sector as supplier to the other (non-tourism) industries in the economy whereas the BL measures its relative importance as demander. Directly applying conventional linkage analysis to tourism is not straightforward because tourism is not a defined industry. Thus we develop a methodology to calculate tourism’s forward and backward linkages using information from national, regional, or local input-output tables and demonstrate its utility by applying it to Hawaii.