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Resource Management

Proceedings of the Second Ralf Yorque Workshop held in Ashland, Oregon, July 23–25, 1984

herausgegeben von: Marc Mangel

Verlag: Springer Berlin Heidelberg

Buchreihe : Lecture Notes in Biomathematics

Enthalten in: Professional Book Archive

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These are the proceedings of the Second R. Yorque Workshop on Resource Management which took place in Ashland, Oregon on July 23-25, 1984. The purpose of the workshop is to provide an informal atmosphere for the discussion of resource assessment and management problems. Each participant presented a one hour morning talk; afternoons were reserved for informal chatting. The workshop was successful in stimulating ideas and interaction. The papers by R. Deriso, R. Hilborn and C. Walters all address the same basic issue, so they are lumped together. Other than that, the order to the papers in this volume was determined in the same fashion as the order of speakers during the workshop -- by random draw. Marc Mangel Department of Mathematics University of California Davis, California June 1985 TABLE OF CONTENTS A General Theory for Fishery Modeling Jon Schnute Data Transformations in Regression Analysis with Applications to Stock-Recruitment Relationships David Ruppert and Raymond J. Carroll ••••••. ••. ••. . •••••••••••••••. • 29 A Conceptual Model for Multispecies, Multifleet Fisheries Wayne M. Getz, Gordon L. Swartzman, and Robert C. Francis . ••. •••. ••• 49 Risk Adverse Harvesting Strategies Richard Der iso . . •. . ••••. . •. . . . . . . . ••••••. •. . . . . •. ••. •••••••••. •. ••• 65 A Comparison of Harvest Policies for Mixed Stock Fisheries Ray Hilborn . . •••••••. ••. ••. ••••••. ••••••••••••. . ••••••. . . . . ••••••. . • 75 Pathological Behavior of Managed Populations When Production Relationships are Assessed from Natural Experiments Carl J. Walters ••••••. ••••••••••. •. ••. ••••••. •. ••••••••••. •••••. . .

Inhaltsverzeichnis

Frontmatter

A General Theory for Fishery Modeling

Abstract

Is fisheries management a science? Here is one answer, given by Larkin (1972): “In brief, our fisheries literature is largely unscientific in the strict sense of the word, and our fisheries management is unscientific in almost every sense of the word.” In this paper I describe a mathematical theory which, I believe, significantly improves the possibilities for scientific management. To explain my basis for this claim, I must begin with a discussion of science itself, and I have chosen a historical example from a completely different field.

Jon Schnute

Data Transformations in Regression Analysis with Applications to Stock—Recruitment Relationships

Abstract

We propose a methodology for fitting theoretical models to data. The dependent variable (or response) and the model are transformed in the same way. Two types of transformations, power transformation and weighting, are used together to remove skewness and to induce constant variance. Our method is applied to the stock-recruitment data of four fish stocks. Also discussed are estimates of the conditional mean and the conditional quantiles of the original response.

David Ruppert, Raymond J. Carroll

A Conceptual Model for Multispecies, Multifleet Fisheries

Abstract

Marine fisheries scientists and managers are becoming more cognizant of the need to regard the exploitation of many single species stocks as part of a larger multispecies system (see, for example, Mercer 1982 and the 26 papers published therein). A problem in the analysis and management of any ecological and/or economic system is demarcating its boundary: there will always be components external to the bounded system that strongly influence its behavior and yet are dealt with in a simple manner often as a time varying input function. The approach that needs to be taken, especially with regard to managment problems, is to be pragmatic, to strike a balance between complexity and utility and to be goal oriented. If the goal is to understand the biological mechanisms that determine larval survival rates and hence recruitment levels, then comprehensive ecologically based models are required (cf. Laevastu, Favorite and Larkins 1982). If the primary goal is to assess stock and yield levels from catch and effort data, then a less biologically detailed approach is appropriate (cf. Murawski 1984, Ursin 1982).

Wayne M. Getz, Gordon L. Swartzman, Robert C. Francis

Risk Adverse Harvesting Strategies

Abstract

Results are presented on harvest strategies that optimize a risk adverse management objective. Risk in this paper refers to a reluctance on the part of managers to freely gamble with current quotas in an attempt to increase the odds for a higher future catch. Harvest policies that maximize a logarithmic utility function, one type of risk adverse objective, are shown to differ substantially from the fixed escapement policies that maximize average catch. In particular, a constant harvest rate policy maximizes log-catch in one model. A number of advantages to constant harvest rate strategies are discussed.

Richard Deriso

A Comparison of Harvest Policies for Mixed Stock Fisheries

Abstract

Existing theory on optimal harvesting policies for exploited populations deals almost exclusively with single stocks of known productivity managed for maximization of discounted average catch. This paper examines alternative harvest policies for mixed stock fisheries in which the manager cannot distinguish between abundances of separate stocks and can deal with total abundance only. Numerical methods are used to show that if the stocks have uncorrelated natural variation, the best harvest policy will be very much like a constant harvest rate rather than a constant escapement. When natural variation is correlated between stocks, even if productivities of stocks are different, a fixed escapement policy appears to maximize average catch. When the objective is not maximization of average catch, but rather the sum of logarithms of the catch, the best policy appears to be quite similar to constant harvest rate.

Ray Hilborn

Pathological Behavior of Managed Populations when Production Relationships are Assessed from Natural Experiments

Abstract

The assessment of fish production rates as a function of stock size is central to fisheries management, and this assessment obviously requires observations from a range of stock sizes. When stock size variation is due mainly to natural, random disturbances that are treated as “natural experiments”, the resulting sample may give a very distorted (biased) picture of the average production relationship. The bias will be especially bad when the natural disturbances occur in autocorrelated sequences over time. These results suggest that there is no safe substitute for deliberate, controlled experimentation with stock size.

Carl J. Walters

Search Models in Fisheries and Agriculture

Abstract

Various stochastic models associated with search problems in fisheries and agriculture are developed. This includes a discussion of binomial, Poisson, and negative binomial distributions and an introduction to diffusion processes. Random search models are discussed, followed by discussion of exhaustive search models. Two applications are presented. The first is a study of the relationship between catch per unit effort and stock abundance in fisheries. The second is a problem in trap spacing for the detection of an invading agricultural pest.

Marc Mangel

Backmatter

Titel: Resource Management
herausgegeben von: Marc Mangel
Verlag: Springer Berlin Heidelberg
Electronic ISBN: 978-3-642-46562-8
Print ISBN: 978-3-540-15982-7
DOI: https://doi.org/10.1007/978-3-642-46562-8

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Inhaltsverzeichnis

Frontmatter

A General Theory for Fishery Modeling

Data Transformations in Regression Analysis with Applications to Stock—Recruitment Relationships

A Conceptual Model for Multispecies, Multifleet Fisheries

Risk Adverse Harvesting Strategies

A Comparison of Harvest Policies for Mixed Stock Fisheries

Pathological Behavior of Managed Populations when Production Relationships are Assessed from Natural Experiments

Search Models in Fisheries and Agriculture

Backmatter