Fisheries have traditionally been managed using species-specific regulations for commercially important stocks and by protecting sites of biological, social, or economic interest. Although species-specific planning has been limited by factors such as a lack of assessment of indirect effects and a poor understanding of socioeconomic processes , scientists have recently sought to develop new holistic management approaches for fisheries management. However, ecological factors too considered in traditional fisheries management process.
Holistic does not only correspond to "more than one species" or "the entire ecosystem". It attempts to incorporate all the drivers that affect the system that we call fisheries, i.e. the species targetted, the other species of the ecosystem and their environment and even the social and economic drivers that shape the exploitation patterns. Hence, the modern "Ecosystem Approach to Fisheries Management" (usually found under the acronyms EAFM or EAF) tries to examine the fishery as an entity incorporating as best possible all the relevant elements that may affect it.
Yes, a holistic or ecosystem-based approach implies that other life history factors potentially impacting the health and abundance of the target species are to be considered.
That is about as clear as mud.
In order to give management a more workable and direct "holistic/EbA" focus, one needs to start with quantifiable goals (desired size/age structure, abundance and range/distribution) for the species to be managed. These metrics should use data that represent a fairly recent period when the species health/abundance was considered healthy by the managers and the public. Once the goal is adopted and understood by all, reaching and/or maintaining the goalshould be followed by annual quantifiable reviews. When problems come up, all potential human caused stresses (harvest, bi-catch, habitat loss, etc) need to be reviewed and those identified as causing some of the problems will need to be strictly addressed. And, progress needs to be measured and followed. Also, see some of my reports on this subject.
The main difference consists in that the traditional fisheries management is dealing only with single species population dynamics, while ignoring the well documented through history independent of fishing crucial influence of climatic and oceanic processes and fluctuations on fish populations which are the key controlling factor in fishing yields for about half of the world's large marine ecosystems. When climatic, biological and oceanographic conditions are just right, fish can respond with an extremely strong year class, or a series of them, and vice-versa
. Species that sustain only in narrow temperature range, are affected by thermal anomalies that delay or hasten spawning and hatching, displacing spawning and feeding grounds. Survival of larvae and juveniles depends, apart from hydrographic conditions, also on availability of the right food, at the right place and time, as well as on the predation rate. Changes in rivers' flow raise or reduce salinity in estuaries, and displace fish and aquatic plant species. Apart from the above, fishery ecosystems are strongly affected by human and nature caused changes in the coastlines and, thus, on spawning and grow-out grounds of many commercial marine species, as well as the "health" of inshore and coastal waters increasingly affected by upstream and beach-borne pollution sources, often to a degree of creation of "death-zones", either anoxic and/or enriched by influx of nutrients - carrying population-explosions of poisonous algae.
The traditional management also ignores the fact that like other predators, fishing people have been a part and parcel of marine ecosystems from times immemorial. Hence, the sustainability of fishermen's families and their communities is inseparable from that of ocean resources. Economic drivers, such as market access, prices and demand, availability of (cheap or expensive) credit, availability of appropriate technology, control over and monitoring of fishing operations, etc., also affect fish yields. Therefore the traditional management system based on rather simplified mathematical formulas fed with highly inaccurate and even speculative figures, cannot serve as a basis for anything like holistic management. The approach, in view of lack of methodology for quantifying most of the above drivers, and in view of unpredictability of nature's vagaries, must also be based on qualitative thinking. As Einstein once said, "not everything that can be quantified is imprtant, and not every thing important can be quantified".
MB-Y
En zonas de variabilidad ambiental muy alta, como las de surgencia costera. Hay menor diversidad y alta dominancia. Estas pocas especies tienen una gran biomasa. En cambio, en zonas más tropicales hay menor variabilidad ambiental, mayor diversidad y menos dominancia. La biomasa está más distribuida en distintas especies. Aquí toma mayor importancia la visión Holística.
I largely agree with Wolf-Dieters answer although in practice it is pretty difficult. to implement. In Europe we are currently doing a lot of arguing about what the targets should be and specifically how to deal with the problem of changing targets under environmental change.
Even moving from single species to multi-species harvest strategies is proving very challenging although some progress is being made for mixed fisheries e.g. in the North Sea.
However, EBFM is a worthy aspiration and I do not mean to imply we should just fall-back entirely to the more traditional approaches although I think they will continue to play an important role for some time to come.
To my view EBFM is still an aspiration and it has not been possible to really implement it because we still do not understand how environmental changes affect recruitment nor how changes in species composition affect recruitment - I'd be very interested if anyone has some good examples where they think it has or is being achieved and whether we can achieve EBFM with our current understanding of environmental-early life history linkages.
Agreed, Clive, but do you make the sea-borne research necessary to "understand how environmental changes affect recruitment nor how changes in species composition affect recruitment" ? ...And growth and survival - I'd add.A truly EBF Research?
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