Implementing ecosystem approach to fishery management: advances and new tools
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2013
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30-07-2013
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Abstract
Since ancient times, fishing has been a major source of food for humanity and a provider of employment and economic benefits to those engaged in this activity. However, with increased knowledge and the dynamic development of fisheries it was realized that aquatic resources, although renewable, were not infinite and needed to be properly managed if their contribution to the nutritional, economic and social well-being of the growing world's population was to be sustained. In recent years, world fisheries have become a dynamically developing sector of the food industry, and coastal states have striven to take advantage of their new opportunities by investing in modern fishing fleets and processing factories in response to growing international demand for fish and fishery products. It became clear, however, that many fishery resources could not sustain an often uncontrolled increase in exploitation.
Concerns have been expressed about the contribution of fisheries to sustainable development and about overfishing, excess catching capacity, the depletion of some stocks, human-induced changes in ecosystems, as well as the increase and globalization of the fish trade
with its potential impact on local supplies and equity.
In order to address these problems, the United Nations Food and Agriculture Organization (FAO) has called for the application of an Ecosystem Approach to Fisheries Management (EAFM), which aims to achieve a sustainable exploitation of commercial fisheries, providing specific consideration of the interactions between fishing gears and marine ecosystems.
EAFM takes into account that fisheries are embedded into the environment and cannot be managed in isolation. It has to be considered as the application of sustainable development principles to the fishing sector, combining ecological sustainability, economic viability and social fairness.
Nevertheless, while it is widely recognized that fishing is important to sustainable development and that its contribution could be improved, the amount of objective scientific information about fishing is limited and what exists is difficult to access.
The reliability of scientific advice for the management of natural resources is highly dependent on the quantity and quality of data that are available for scientific assessment and interpretation.
Although large amounts of certain types of data about marine ecosystems are readily available, as in the case of satellite-derived remote sensing data or observations based on automatic telemetry, it is far more common to have to deal with limited and irregularly spaced data (e.g. on fish and other marine fauna), and the data may not always be strictly comparable due to variations in environmental conditions between sampling periods.
The main reason is that in fishery research the collection of data is both time-consuming and expensive.
Data are difficult to obtain, and the problems increase when the goal of the research is to study long time series on a macro-scale, with the purpose of examining changes in the dynamics of a whole ecosystem.
In all these cases that require large databases, with an adequate coverage in space and time of a variety of variables, information is almost non-existent.
In addition, information about the status of fisheries can be derived from different sources such as fishery-independent surveys, fishery-dependent surveys (skipper logbooks and/or observers) and FAO official landings.
Each of these sources provides different types of information with additional details, and must be carefully selected according to the type of study and the objectives pursued.
Fishery-independent surveys rely mostly on expensive research campaigns performed over relatively short periods of time. Survey data are considered to be of superior quality because they are independent of management measures, standardized fishing procedures are used, and both sampling statistics and the biological information on target species are taken into consideration during survey design. However, they generally have a limited coverage in space and time (both in terms of seasonality and the number of years of data), which could lead to biased and imprecise estimations. In brief, there are two main issues regarding fishery-independent surveys: the one of timing in relation to the seasonal cycle and location of the target species (leading to unrepresentative sampling, i.e. bias) and the fact that only a limited amount of data can be collected.
Fishery-dependent surveys can provide a long time series, wide spatial coverage all year round, and information on a large variety of target species, gear types, landing sites and distribution channels. Data of this kind sometimes lack particular details such as the location of fishing grounds and species identity (catches are mostly identified to a higher taxonomic level), and then there are issues of bias due to constraints imposed by management and the deliberate misreporting of catches. Some of the disadvantages of fishery-dependent surveys can by overcome by using on-board observers but inevitably only a small fraction of fishing activity can be covered in this way.
FAO official landings are often the only source of data available due to their connection to the economy and business.
The main issue in this source of information is that in many fisheries (official) landings and the actual catch are not necessarily the same. Large amounts of unreported or underreported catches, discards and illegal catches are not recorded in landing data, and not all landings enter official statistics (e.g. black landings, sales by small-scale fisheres directly to consumers, etc.). Furthermore, while previous data sources imply a spatial reference where species have been captured, the FAO official landings have no georeferencing.
However, the data collected by on-board observers and that from research surveys have relatively recent time series, while official landing data have been available for most FAO countries since 1950 (www.fao.org).
The quantity and quality of information varies depending on the country of the fisheries studied. In most countries, detailed information is available and management processes are in place for some important fisheries, while others are poorly documented and hardly managed at all.
In particular, but not exclusively, developing countries reflect these data-poor situations, given that the resources and infrastructure needed to collect relevant data, assess system status and implement management requirements have not increased at the same time as the recent rise international trade in fishery products.
Moreover, the need to move towards an EAFM has resulted in an increase in the need for data at different spatio-temporal scales and many areas are currently in a data-poor situation for the purposes of implementing it.
The problems increase when the goal is to study long time series on a macro-scale, with the purpose of examining changes in the dynamics of a whole ecosystem. In all these cases, where sophisticated ecosystem models cannot be applied due to the lack of detailed data, the first step towards applying the EAFM should be to set more realistic goals and use flexible tools that can work effectively despite uncertainty and limited information.
Within this context, the main aim of this thesis is to analyze the different available sources of information on fishery resources, in order to propose new methodologies for efficient fishery management both in terms of data-poor situations, macro-scale/long time series studies, and micro-meso-scale detailed studies.
Several scenarios have been addressed depending on the source of fisheries data used and the objective pursued. For each one of them, a specific methodology has either been developed (when there was no available method) or described (when there was), showing its strengths and limitations, and discussing its implications for the fishery management.