Cybernetic Approach to Fisheries Management
Abstract
The management of the living marine resources (stocks) exploitation entails the pursuit of a science-based policy in order to preserve the reproductive capacity of the stocks and their sustainable development in the course of time i.e. maintaining the stocks biomass levels within safe biological limits [27,28].
The excessive increase in catches (fishing effort) due to unscrupulous exploitation can result in irreversibly collapsed biological basis for their existence [19,27,28]. The situation thus created is further exacerbated by the incomplete or poorquality information about the development of the stocks potential. The present paper advances the adoption of cybernetic approach to the analysis of the management and exploitation of the living marine resources. Proposed also is a block diagram of the stock management system in a context of uncertainty and the use of the precautionary approach and step algorithm for the collection, analysis, processing of information and evaluation of the parameters and the reference biological indicators of the respective biological objects, on the basis of which the target (the target management indicator) is to be set.
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Introduction
A great number of researchers have made remarkable efforts to create valid management technologies for efficient exploitation of the resources [3,4,6,7,14,15,18]. That policy is additionally complemented by the introduction of internationally agreed normative documents, appropriate process control and management organizations, ensuring maximum sustainable yields (MSYs) and/or total allowable catches (TACs) within the context of uncertainty. On the whole, it is at the heart of the management strategies to secure maximum yields, while maintaining the optimal reproductive capacity of the stocks. The most recent status of the stocks necessitates the formation of management strategies and strict definition of the levels of exploitation in a highly uncertain environment with a view of minimizing the possibilities of risk being incurred upon the relevant resources and their living environment, the which, in turn, calls for drastic changes to be implemented in the field of the science and technology applied for their proper management. An integral part of that change is the requirement for the development of a precautionary approach in the management and exploitation of BO stocks. The concept of precautionary approach aims at improving the immediate environment and protecting the living (life-sustaining) renewable resources as a result of reduced risks of losses of their biological diversity and reproductive capacities [1,6,7,10,15,19,21,22].
The current paper will examine the required technology and algorithm for successful application of the precautionary approach in order to make an appropriate assessment of the possibility for attaining maximum total allowable catches that has been adapted to suit the relevant exploitation of stocks (biological objects).
Conclusion
7.1 Proposed are:
block diagram of stock management with the use the precautionary approach under conditions of uncertainty;
step algorithm for the collection, analysis, processing of information and evaluation of the parameters and the reference biological indicators for BO, on the basis of which the assignment is formed (target indicator of management);
A software system for the management of BO has been developed to enable the calculation of the growth parameters, the mortality parameters BO, examination of the law of distribution and verification of statistical hypotheses– assumptions of normal distribution of the sample data; stock-recruitment and biomass - recruitment curve analysis and calculation of reference points for the stock biological indicators, which are target indicators of the management of BO stocks in the context of uncertainty. The performance of the system thereof has been tested with experimental, simulation data and examples of numerical solutions as provided in [24].
The results delivered lead to the following conclusions:
1) The developed software system allows the precise calculation of the growth parameters, parameters of BOs mortality, examination of the law of distribution and verification of statistical hypotheses– assumptions of normal distribution of the sample data; stock-recruitment and biomass - recruitment curve analysis and calculation of reference points for the stock biological indicators, which are target indicators of the management of BO stocks in the context of uncertainty.
2) The input data may be current or historical information (observations/measurements) about BO, which opens up the opportunity for the software system to be applied for a retrospective and current analysis of the BOs stock status.
3) When implementing methods related to statistical evaluation of parameters, envisaged is a statistical analysis of the significance of the results (application of the Fischer’s criterion and/or analysis of the studentized residuals) with the relevant conclusion regarding the performance specifications of the models obtained.
4) The methods can be performed repeatedly, depending on the user's needs– with the same or new input data. If there is sufficient data for the implementation of different methods that evaluate the same parameters, then, for purposes of the analysis, the results may be compared and the accuracy of the modelling parameters assessments evaluated.
5) The developed system is functionally efficient as a standalone application which does not necessarily require installation and knowledge of the MATLAB software environment in order to run.
6) The results of the implementation of a given method are kept in text files, which, if necessary, can be processed with other software applications.