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FISHERY AND RESOURCE USE CONFLICTS

Panel IV was concerned with conflicts between recreational fisheries and other users of water. The magnitude of the subject made it necessary to subdivide it in subgroups as follows:

  1. Fishing and other recreational uses; land use and fish resources;

  2. Effects of thermal and radioactive effluents and water pollution on fisheries;

  3. Streambeds and fish population; streamflow and fish population;

  4. Specific salmon problems.

Fishing and Other Recreational Uses

It is recognized that there is competition for most desirable commodities and that society has mechanisms to prevent outright confrontations. Sometimes this operates through a pricing structure or some protective device such as regulation or legislation. There are clearly instances in water recreation, of which angling forms a part, where conflicts arise by virtue of competition for the use of the water space; but not all such recreational use depends upon the biology of this resource, as does angling. It is found that many types of recreational users are insensitive to their effects upon the biology of the water, and have no incentive to safeguard it. Fishing can suffer where the biological capacity of the resource to produce fish is damaged or where fishermen are discouraged from making optimum use of the fishery resource. Fishermen often consider peace and relaxation as the most important factors of their enjoyment. Anglers tend to experience a high level of conflict compared with other users, and more frequently express dissatisfaction with overcrowding.

So far, however, there is little indication that conflicts which occur between angling and other recreational users of the water are responsible for a serious decline in the fishery exploitation. Resolution of conflicts can be expedited in many ways:

  1. more effective management where this is possible

  2. building upon existing preferences to guide management strategy

  3. building upon goodwill where this exists

  4. using time-zoning and space-zoning techniques if possible

  5. improvement of communication and understanding between user groups

  6. education and persuasion.

While the above methods of reducing conflicts may be useful in areas of increasing water use, they can never restore the element of solitude which many anglers cherish. Furthermore, in most cases there is no overall authority with the statutory powers needed to enforce reconciliation expedients.

Land Use and Fish Resources

Land use practices may result in acute and chronic effects on the fishery resources. Acute effects such as fish bills following an industrial accident may be very obvious; however, chronic effects may not be obvious but just as serious.

Among chronic effects noteworthy are those generated by changes in the vegetal or forest cover. Such changes can affect water quantity, flood regime, and water temperature, or siltation. All of these can have an immediate impact on the aquatic resources. Fertilizers, insecticides, or even concentrated residue from silage or pastures can be toxic to fish or affect them indirectly through the food chain.

Although progress has been made to protect fishery resources, particularly with respect to forestry exploitation, an overall programme for protection of the aquatic system is rarely seen. Lack of resources for adequate impact studies during the planning process is the main limiting factor. It can be concluded that, unless the public learns to modify economic activities for conservation purposes, whatever else we do in the management of fish and wildlife resources is in the long run irrelevant.

Summary of the Discussion on Other Recreational Uses and Land Uses

The use of outboard motors ranging from 50 to 200 hp is increasing rapidly in the USA and can conflict with fishermen and the fish resources. Noise, damage to fish stocks and the destructive effect of waves on the banks of lakes and rivers are particularly noted. Limitation on horsepower and zoning of motorized traffic are used to reduce conflicts.

Sail boards are reported to be in conflict with fishermen in France and The Netherlands where this sport is particularly popular. Regulation of this sport is becoming essential.

The planting of coniferous trees near rivers increases the acidity of the soil and reduces productivity of streams and rivers in Belgium and France. Regulation now requires a distance of 6 m between such plantations and river banks in Belgium. It was noted that surface water runoff from agricultural lands treated with lime could improve stream quality. Hybrid corn cultures are said to cause rapid land erosion which increases suspended solids in neighbouring streams.

Conflicts caused by agricultural practices will be studied at an international level in 1981 at a meeting sponsored by FAO and the European Community.

Effects of Thermal and Radioactive Effluents and Water Pollution on Fisheries

Reference on biological structure of a given aquatic ecosystem can be used to control thermal pollution and evaluate objectively the effects of human activities and determine the need for impact studies. Impact studies must be complete and analyse both sides of the question. The cumulative effect of successive thermal changes is also to be studied.

The environment has always contained natural radioactivity but, since the second world war, significant amounts of man-made radioactivity have been added to the aquatic environment. This has occurred primarily through fallout from nuclear explosions. Of more importance, however, are the very large amounts of radioactive material found in waste storage, nuclear weapons and nuclear reactors which could be harmful to man and aquatic organisms if released to the environment. Since there is always a possibility of release, there is need to know the amounts of radionuclides that can be accumulated by aquatic organisms and returned to man in fishery products and the levels of radioactivity that will result in significant radiation effects on aquatic organisms.

Radionuclides cycle in the aquatic environment and are accumulated by aquatic organisms in a similar manner to non-radioactive elements. Also their occurrence in different tissues within an organism depends upon metabolic needs. Many radionuclides are not concentrated to high levels in fish muscle and thus are of importance to man only in cases where the entire fish is eaten.

Aquatic organisms differ greatly in their sensitivity to radiation with large, complex organisms generally being more sensitive than small, simple organisms. Radiation effects, have been investigated in laboratory experiments and by observations in the environment where controlled releases of radioactive waste have occurred, such as in the Columbia River (United States) and at Windscale (England).

The release of radioactivity to the environment has been the best controlled of the pollutants. Results of extensive research have resulted in extremely tight restrictions governing all use and release of radionuclides into the environment (International Atomic Energy Agency and International Commission on Radiation Protection). As a result, peaceful uses of radioactivity have not interfered with commercial and recreational harvest of fishery resources with the growing number of nuclear power generating facilities and accompanying wastes; such situations could occur if we do not maintain strict vigilance.

The importance of realistic water quality criteria in helping resolve the conflicts between water pollution and the maintenance and improvement of freshwater fisheries was stressed in the synthesis paper on this subject and the achievements of EIFAC in the preparation of such criteria were noted. EIFAC has, in addition, recently reviewed the literature on the joint effect of toxicants on freshwater fish and fisheries. The few (unpublished) data available for the long-term lethal joint effect on fish of toxicants in mixtures suggest that they may be markedly more than additive, a phenomenon that needs confirmation and further investigation. The importance of realistic water criteria cannot be overemphasized because of the large cost penalty resulting from the adoption of too stringent standards. If desired, pollution abatement costs can be set against the value of benefits that may accrue including those from fisheries. The case of the heavily urbanized River Trent catchment area was quoted as an example. The estimated capital value of the fishery benefits arising from maintenance and improvement of water quality in the face of increasing demands of water resources was only 6–7 percent of the capital cost of waste-water treatment plants, but clearly the proportion will vary according to the particular situation and methods of evaluation adopted.

Summary of the Discussion on Thermal and Radioactive Effluents and Water Pollution on Fisheries

In discussing the effects on fisheries of discharges of heated effluents from electricity generating stations, it was pointed out that, as with chemical pollution, much depended upon the relative flows of the discharge and the receiving stream and also upon the increase in temperature across the condensers which was often greater in nuclear plants than those fired with fossil fuels; these affected the extent to which heated water would remain in the surface layers so allowing the passage of migratory fish through the cooler water below. Even with the use of cooling towers problems could arise from the evaporative loss of water at times of low river flow.

It was pointed out that in some salmon rivers an increase in temperature of 1.5°C would ruin the fishery and that in others there could be a cumulative effect of successive discharges along the length of a river. It was considered there was scope for detailed ecological studies of thermal and other forms of pollution.

Although there was conflicting evidence that radioactivity had damaged fisheries, it was pointed out that fish downstream of nuclear power plants contained radioactivity distributed through their tissues and that continued monitoring and vigilance were required. The “critical path” method of assessing environmental risk from contaminants was relevant to nuclear and other substances such as heavy metals and organo-chlorine compounds. Representatives of French fishermen consider that nuclear thermal stations are less harmful to fisheries in relation to the amount of electricity produced than the multiplication of micro hydro-electric stations on mountain streams.

The importance of developing methodologies for dealing with localized sources of pollution was stressed but attention was also drawn to massive pollution problems arising from more diffuse sources from far afield, as exemplified by acid rainfall in Scandinavia where thousands of lakes were now described as “dead”.

Effect of Streambed and Streamflow on Fish Population

The importance of the physico-chemical composition of water on fish stocks of rivers is well known and the subject well documented. Such is not yet the case for the streambed and streamflow of rivers.

With respect to streambed one must note the diversity of the streambed and fish population, the various causes of streambed deterioration, the types of streambed management, the restoration methods, the effects of cleaning up the streambed and river banks and the problems caused by gravel extraction from the streambed.

Channelization of rivers will have an immediate and long-term negative effect on fish fauna, i.e., on the number of species and the level of population. Extraction of gravel from river beds, a practice forbidden in many countries, still exists in France. It gives rise to serious problems such as the stability of the streambed, the pollution created by suspended solids and the destruction of spawning areas. Economic repercussions are numerous such as the crumbling of river banks, the lowering of the water table and collapsing of bridges. The construction of sills to stop streambed degradation is often disastrous on migrating fish stocks. Although the direct cost of gravel extraction is fairly low, indirect costs are very high if we take into consideration harmful lasting effects on the environment and aquatic resources.

Traditionally fishery managers have dealt with the fisherman and the fish stocks, and have not been directly involved with the management of water in the sense of quantity of flow. The allocation of streamflow to out-of-stream uses is presented as critical to fishery management interests and as often being irreversible.

Recent reviews of the literature on effects upon fisheries of water abstraction and alteration of flow regimes were cited.

Methods for evaluating instreamflow requirements were summarized and categorized as to data source and utility in water allocation decision-making. General allocation decisions, when the seasonal timing is not important, are generated from a hydrologic data base such as the annual mean daily flow. When flow is controlled by storage and diversion of a large portion of the streamflow, a microhabitat analysis is usually focusing upon “critical” life history stages and “critical” reaches of the stream environment to identify “minimum” flow levels below which maintenance of the fish population is not possible. When streamflow is managed to maximize the fishery habitat potential, an analysis of the total physical habitat through stratified sampling and cross-section analyses is becoming an accepted approach. This utilizes standard criteria for describing fish species habitat suitability by life stage.

Long-term biological measurements of standing crop and annual production are useful for calibration and validation of the hydraulic-based microhabitat models.

The microhabitat as niche space for fish species is shown as an important new area for research endeavour.

Lastly, the need for proper display of fish habitat and streamflow data in forms comprehensible to the general public, the engineering-hydrology profession and the administrator decision-maker was explained as being the responsibility of the fishery manager.

Summary of the Discussion on Streambed and Streamflow

In France, since river bank trees are no longer exploited as fuel, the increasing number of trees causes excessive shade and obstructions. Fishermen organizations are now taking upon themselves to clean the river banks. It was noted, however, that the correction of obstruction or excessive shade problems by abrupt measures such as channelization cause immediate and long-term negative effects every time. In those cases where gravel extractions are allowed strict controls in quantity and time are essential.

With respect to stream flow it was noted that minimum levels differ widely. In France levels of minimum flow have been established by the Compagnie nationale de production d'électricité (EDF) without consideration for fish stocks. Recently, however, studies have been commissioned by the Ministère de l'Environnement et du Cadre de Vie on the maintenance of flow at the low-water mark and the spreading-out of high water flow. It was also said that rapid changes in water flow from, for example, 30 to 300 m3/s or vice versa could have disastrous effects on fry survival and fish production.

Specific Salmon Problems

The Atlantic salmon exemplifies the opportunities and the problems besetting inland and marine fisheries of the world. As a species it is very valuable to both recreational and commercial fishermen, in marine and fresh water, and easily overexploited. It is very sensitive to various types of pollution and in many countries is now the subject of important and successful restoration and enhancement programmes.

Due to the precise homing of salmon, the stocks of these long-distance migrators are well individualized. They are, therefore, very vulnerable to overexploitation. The various salmon stocks are decreasing because of overexploitation and habitat deterioration due to ceaseless industrial and urban extension made without sufficient precautions to safeguard the environment.

In order to stop the decrease of salmon stocks, terminate costly exploitation at sea and take advantage of the new possibilities of “sea ranching”, two initiatives can be foreseen:

  1. The establishment of regional bodies, such as the International Pacific Salmon Commission, which include elected representatives of the Member States with power of decision. This would put an and to the multiplicity of regulations on the salmon fishery at sea.

  2. Gradual reduction, and then cessation of fishing at sea, to be replaced by river harvest. The latter could then be performed in a rational way with installation of counting dams as far downstream as possible, on the important salmon rivers. The quota of authorized captures could then be established by difference between the strength of upstream migrations and the optimum salmon stock needed to safeguard reproduction.

Summary of the Discussion of Salmon Problems

It was explained that discussions on the Law of the Sea referred specifically to the international aspects of the salmon problems and the need for an international convention to control salmon fisheries within and outside Exclusive Economic Zones. It was pointed out also that in Europe the Community and not individual governments had the authority to negotiate international agreements on salmon.

It was mentioned that engineers with a strong fishery background are increasingly required to help in the management of fisheries in rivers.


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