This is the 17th article since we started our contributions to FNI. It is also the end of the introductory section on fisheries management. Up to now we have tried to establish the foundations upon which modern fisheries management philosophy is based, and to provide a flavor of the kind of issues that are considered in developing management plans. This is however the easy part. The real challenge is to translate all this insight about population dynamics, biology and economics into TACs, TAEs and regulations for minimum size limits, fishing seasons and gear types.
Before becoming “hard core”, we would like to list and summarise the main points raised in previous articles. This has been done by subject rather than in chronological order, although the subject sequence is very similar to the sequence in which the articles were published. Starting next month, our focus will be on a variety of techniques which are commonly (and less commonly) used to decide what can be harvested from fish resources, and under what associated conditions.
- Most marine species have complex and diverse habitat requirements at different stages of their early life history. These are often very different to the needs of the adult stock.
- All marine species interact via a complex food web, from primary producers to top predators. This web cannot be fully quantified or understood, but fisheries management cannot completely ignore it, because it implies that fishing may lead to undesirable ecological consequences.
- The mortality of commercially exploited species can be ascribed either to natural causes or to fishing. When natural mortality is high, then fishing mortality should also be high to compete effectively with natural predators. Conversely, resources with a low natural mortality are best harvested with a low fishing mortality.
- Most marine resources are r-selected (large number of offspring with high natural mortality), and can withstand adverse environmental conditions, and a substantial fishing mortality, without going extinct.
2 Production processes in renewable resources
- Surplus production is excess production which a living renewable resource generates in order to grow back to its carrying capacity.
- Surplus production can be harvested as sustainable yield - this will continually keep the population at some level below its carrying capacity.
- Maximum sustainable yield (MSY) is the maximum surplus production that can be generated by the resource, and to achieve it the resource must be reduced substantially below its carrying capacity.
- It is possible to keep an overexploited resource far below its MSY level by comparatively small catches - this can be called sustainable exploitation of the resource, but it would obviously be an undesirable way to utilise the resource.
- There is no reason why there should be any clear link between the maximum historic catch obtained from a resource, and the MSY. The MSY could for example be very much smaller than this maximum catch.
- Unproductive resources that have been overexploited will take a very long time to recover compared to more productive resources, even under a complete fishing moratorium.
- There is some optimal age and size for exploiting a renewable resource. This size or age depends on the growth rate and natural mortality of the species.
- Most fisheries data suggests that commercial recruitment is roughly constant above some critical spawning biomass level while below this level recruitment decreases.
- Fisheries are inherently variable, and this causes year to year changes in catches and catch rate, and these phenomenon are very difficult to predict.
- Catch per unit effort (CPUE) is the most commonly used parameter to estimate the state of marine resources, and is a critical parameter in determining total allowable catch (TAC) levels in many fisheries.
- In the short term, catch will increase as fishing effort increases. However in the medium to long term, this causes a decline in resource biomass and catch.
- There is a special relationship between the long term catch, or sustainable yield, and fishing effort, viz. sustainable yield increases with increasing fishing effort up to a point (MSY), and then starts to decline.
- The critical fishing effort level (a theoretical concept) which drives the resource to extinction is roughly double the fishing effort needed for achieving maximum sustainable yield. If fishing effort is larger than this critical level then the resource will always eventually be fished out. If fishing is smaller than this critical level then it will eventually reach some stable condition.
- Fishing will in most cases become uneconomical before a resource is fished out.
- Harvesting costs are roughly proportional to fishing effort.
- Economic rent is the value of the catch minus the harvesting costs. The point of maximum economic rent is achieved at a resource biomass which is larger than that which generates maximum sustainable yield.
- Neither maximum sustainable yield, nor maximum economic rent are necessarily the optimal way of exploiting marine resources, since both may ignore important economic and social factors.
- The tragedy of the commons in fisheries means that the free-for-all option inevitably leads to a ruin-for-all situation in which the resource is biologically threatened, and economically valueless.
- From purely financial considerations, it might be beneficial to fish a resource unsustainably, and to use the capital gain for more lucrative economic ventures. This would i) put employees in the fishery at risk, and more importantly ii) deprive future generations of important sustainable economic options. This approach to resource exploitation is considered to be totally unacceptable.
- It would be wrong to conclude from the above that fisheries only collapse because of the tragedy of the commons scenario sketched above. Many fisheries which have experienced collapse have done so while being managed by limited entry. Fishery collapses occur when the catch exceeds the amount that the resource can sustain. The reasons for this may be i) poor scientific advice, ii) political decisions which have ignored valid scientific advice, or iii) unregulated open access fishing (i.e. tragedy of the commons). In many cases, environmental change is a contributing factor to resource collapse.
- For historic reasons, in many fisheries the fishing effort actually deployed is much larger than the optimal fishing effort level. To achieve the optimal fishing effort condition often requires unacceptable short and medium term economic (e.g. employment levels) sacrifices.
- A further complication is that investment in fishing fleets and processing infrastructure during the development phase of a fishery has often been based on unrealistic expectations, so that more fishing capacity than necessary is owned by participants. This causes a loss of potential revenue to the industry and ultimately the nation, and leads to continuous lobbying for TAC increases.
- Even if a fishery is controlled by a limitation on the total catch, the need for participants to compete with each other can make harvesting costs so large that the resource has no net economic value. To avoid this, it is essential that participants are given a guaranteed access right, such as a fishing quota.
4 Overfishing and risk
- The general view of an overfished resource is one that has been driven to near extinction. In reality, there are different types of overfishing, with precise definitions. Some of them can occur in a resource that is still biologically sound.
- Fisheries cannot be conducted economically if the management objective is to attain a negligible biological risk. The principle that a reasonable compromise between biological and economic risk must be reached has to be accepted. A better way to address biological risk would be to set up a careful monitoring and control system for the resource, so that corrective action can be taken when necessary.
- Because of the limitation on production in marine resources, increased efficiency usually implies less employment. This may however be compensated for if the increased revenue from this efficiency advantage is directed at investment in new economic ventures.
- Fishers are not the only participants in the fishing sector, and their wage expectations cannot validly be pegged to the value of the end product, since this ignores downstream costs and wage earners.
- Fishers and other members of coastal communities have the right to benefit from the exploitation of marine resources. Their participation in the fishery could take many forms (entrenched fishing rights, quota, corporate share holdings, wages) which will give them economic and social security in proportion to the value of the fishery in their region. At the same time social considerations should not be allowed to override basic bioeconomic principles in fisheries management.
- In most cases it is undesirable to increase fishing capacity for the development of new resources (new species and/or new habitats). A much more responsible approach should be to divert effort and capital from overexploited resources to new fisheries, thereby giving “old resources” time to recover without suffering an overall unacceptable socioeconomic loss. This option is of course not always feasible because different fisheries may sometimes require the deployment of completely new and/or different technology.
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