Ola Flaaten

Harvest Functions: The Norwegian Bottom Trawl Cod Fisheries

A detailed and comprehensive set of catch and effort data for the cod fisheries of 18 Norwegian bottom trawlers have been obtained for the period 1971 85, a period with few binding quota restrictions on vessel operations. Harvest functions have been designed and estimated. The independent variables are hours of trawling per vessel day and biomass of the cod stock (3+). Daily biomass estimates have been calculated by polynomial interpolation of the annual estimates of the International Council for the Exploration of the Sea (ICES). By maximizing the log-likelihood function using numerical methods, parameter estimates and performance indicators of the different models were obtained. The best result was obtained for a harvest model allowing for seasonal changes and with an autocorrelated error term. For this model, the stock-output elasticity is estimated at 0.424, the effort-output elasticity at 1.232, and the technological change at about a 2% annual increase in productivity. The seasonal changes in catchability are significant, with the lowest intra-annual catchability being less than 30% of the annual maximum.

Bioeconomics of sustainable harvest of competing species

Abstract The concept of maximum sustainable yield frontier (MSF) is applied to a Gause model of competing species. Maximizing the present value of economic rent under costless harvesting with positive discount rate implies optimal stock levels below the locus of MSF stocks. Maximizing economic rent with positive harvesting costs and zero discount rate implies optimal stock levels above the locus of MSF stocks. It is shown how the optimal steady state stock levels are altered by changes in the exogenous discount rate, harvest prices, and harvest costs. Optimal harvesting might imply harvesting of one of the two species at a loss.

The Invisible Resource Rent in Limited Entry and Quota Managed Fisheries: The Case of Norwegian Purse Seine Fisheries

This paper tests empirically to what extent the rent in a limited entry and quota managed fishery is capitalized in the value of a vessel license. This is done by comparing the profitability of Norwegian purse seine vessels which received their licenses for free, to the profitability of vessels whose licenses were purchased along with the vessel. In a sample of forty-three vessels, thirty-one had obtained their licenses for free when the licensing system was introduced in 1973, whereas twelve owners had bought licensed vessels later on. Costs and earnings data for 1983 and 1984 show that those vessels which received free licenses have a significantly higher profitabilty than the other vessel group. The main reason for this is that the owners who bought licensed vessels had the highest capital costs. Policy implications of these findings are indicated.

On the bioeconomics of predator and prey fishing

Abstract A brief review of biological, bioeconomic and non-use objectives in fisheries management is given. It is shown that management strategies, with respect to optimal long run effort levels and stock sizes, might differ considerably with the choice of objective, and of a single-species or multispecies framework. Within a deterministic two-species predator–prey biomass model, equilibrium catch and resource rent of the predator are positively affected by an increased prey stock level. The effects on the equilibrium harvest and resource rent of the prey of a change in the predator stock level are ambiguous, although a negative relationship is most likely. In a simplified model with a linear equilibrium relationship between the two stocks this negative effect is always present. Such a simplified approach is applied to the case of northeast Arctic cods consumption of its commercially most important prey species: capelin, herring, shrimp and small cod, i.e. cannibalism. It is shown that on average for the years 1984–92 capelin constituted about 75% of the feed, on the basis of weight, of age-specific cod of age 2 and older. Shrimp is the second most important prey, constituting about 10–20% of the feed; the higher figure occurs for 2-year old cod and the lower for the 7+ age group. Using Norwegian data on prices of fish and cost of effort for the years 1991–92, and data on stomach content 1984–92, it is shown that shrimp constitute 40–80% of the feed costs for all age groups of 2 years and older, whereas capelin constitutes only 15–20%. For the 7+ age group cannibalism is just above half the feed costs. This, despite the fact that capelin is by far the major feed in weight. The assumption of the specific functional forms in biological multispecies models are of importance for the management implications derived. It might be that the inclusion of economic factors will weaken the relative importance of some biological factors for management strategies. The partial bioeconomic analyses in this paper strongly indicate that biological and economic factors should be considered simultaneously in management analyses.

The Optimal Management of a Transboundary Fish Resource: The Arcto-Norwegian Cod Stock

This is an applied analysis of two parties’ cooperative harvesting of a migratory renewable natural resource. The Arcto-Norwegian cod (Gadus morhua) is a resource shared by Norway and the USSR. Spawning takes place mainly in Lofoten, on the Norwegian coast, in March-April. The eggs are pelagic, and the eggs and larvae drift with the coastal currents to the north-eastern part of the Norwegian Sea and the Barents Sea. At the age of 3–7 years the cod migrate in to the coast to prey upon capelin (Mallotus villosus). The ArctoNorwegian cod reaches maturity after 5–8 years.

Management of and Economic Returns from Selected Fisheries in the Nordic Countries

Abstract There is potential to increase the economic returns in many fisheries by improving fisheries management. In this article, maximum and estimated current resource rents are analyzed using a standardized methodology for five case studies of fisheries with different management regimes: individual quotas (Norway), individual transferable quotas (Iceland), co-management (Denmark), vessel catch limits (Sweden), and tradable days-at-sea regulation (Faroe Islands). The Danish co-managed fishery had the highest estimated current rent, corresponding to 51% of landing value compared to a maximum rent of 62%. The Danish case was followed by the Icelandic ITQ fishery (estimated current 30%, maximum 66%), Faroese tradable days-at-sea (current 28%, maximum 55%), Swedish vessel catch limits (current 3%, maximum 74%), and Norwegian individual quotas (estimated current −22%, maximum 43%). Fishery characteristics other than management might influence the estimated resource rent, and the results are discussed in relation to biological sustainability. The method used across fisheries and countries for the estimation of the current economic rent, based on standardized opportunity costs of labor and capital, exaggerates the current positive rent for the ITQ fishery and the negative rent for the individual quota fishery. JEL Classification Codes: Q22, Q27

The economic costs of biological predation

This paper developes a bioeconomic model to analyse the economic losses from the reduced harvesting of prey species resulting from an increase in the stock of a natural predator. Examples of large mammals creating economic damage are whales and African elephants. The economic losses depend critically on the actual management of the prey stock, although the three measures we develop are equal when the stock is managed so as to maximize the sustained economic rent from the prey species. Predation losses are illustrated by the case of the Northeastern Atlantic Minke whale, where the estimate of the average predation cost per whale in 1991–1992 is between

Challenges and Successes in the Management of a Shared Fish Stock – The Case of the Russian–Norwegian Barents Sea Cod Fishery

US 1780 and

Bioeconomic Multispecies Models of the Barents Sea Fisheries

US 2370, using Norwegian cost and earnings data. A ten percent stock increase is estimated to cause a loss of almost

The Economics of Predator-Prey Harvesting

US 19 million to the fishers of the prey species. If half of this cost were assigned to Norway it would be equivalent to 2.8 and 6.7 percent of the gross profits of the Norwegian cod and herring fisheries, respectively.