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Fisheries Management and Ecology, 2004, 11, 145–151 The effects of fisheries management practises on freshwater ecosystems I. G. COWX University of Hull, International Fisheries Institute, Hull, UK D. GERDEAUX Station d Õhydrobiologie lacustre, INRA, Thonon cedex, France Abstract The contributions presented at the European Inland Fisheries Advisory Commission Symposium on The Effects of Fisheries Management Practises on Freshwater Ecosystems in 2002 are reviewed. The principal mechanisms of inland fisheries management concentrate on four categories: fish stock enhancement (stocking and introductions); rehabilitation and habitat manipulation for fisheries purposes, including biomanipulation; fisheries regulations; and conservation and protection of fish and fisheries. The negative and beneficial impacts of these activities are summarised and options for improving the outputs of fisheries management practices to accrue wider benefits to society are discussed. Wider stakeholder participation and a shift from traditional fisheries towards ecosystem-based management approaches are the main mechanism proposed. This calls for new management tools to cater for legitimate human demand for water abstraction, hydropower generation and effluent disposal, as well as alternative commercial use of water bodies such as bathing, boating and tourism, in addition to fisheries exploitation and conservation needs. biomanipulation, fish conservation, fish stock enhancement, fishery rehabilitation, inland fisheries management. KEYWORDS: Introduction Inland fisheries are of high socio-economic and sociocultural importance, and provide Ôa myriad of benefits to societyÕ (Weithman 1999; Welcomme & Naeve 2001; Arlinghaus, Mehner & Cowx 2002). However, multipurpose use patterns, especially in industrialised countries, have created a distinct climate for change within the inland fisheries sector. Activities such as agriculture, impoundment, channelisation, deforestation, navigation, wetland reclamation, urbanisation, hydropower generation, water abstraction and transfer, and waste disposal have altered freshwater ecosystems profoundly, probably more than terrestrial ecosystems (Cowx 2002). As a result, the majority of freshwater ecosystems in industrialised countries are impacted and the fisheries heavily modified or degraded. Recent trends in inland fisheries management have attempted to address the problems created by societal development to improve the aquatic environment for biodiversity and allow for sustainable exploitation of the resources (Arlinghaus et al. 2002). The principal mechanisms of fisheries management concentrate on four categories of action, each with distinct objectives. These are: fish stock enhancement (stocking and introductions); rehabilitation and habitat manipulation for fisheries purposes, including biomanipulation; fisheries regulations; and conservation and protection of fish and fisheries. Despite these interventions little attention has been paid to their overall impact on the aquatic ecosystem in which they are enacted. This is a major knowledge gap, particular with the shift in emphasis towards ecosystem-based approaches to management of inland waters (FAO 2003), where all stakeholders and resources users should be involved in the decisionmaking processes so development in one sector does not impact negatively on others. The problem is exacerbated within Europe, because of the growing Correspondence: Ian G. Cowx, University of Hull, International Fisheries Institute, Hull, HU6 7RX, UK (e-mail: [email protected]) 2004 Blackwell Publishing Ltd 145 146 I. G. COWX & D. GERDEAUX pressure on European Union countries to improve the status of rivers and lakes to meet their obligations under the Water Framework Directive 2000/60/EC, as well as the need to contribute towards protection of biodiversity under the Habitats Directive 92/43/EEC. Consequently, any activities that could potentially have a detrimental impact on the ecosystem should be avoided or mitigated against. In this context, the European Inland Fisheries Advisory Commission (EIFAC) recognised the need to improve understanding of the impacts of inland fisheries management activities on the environment to meet the obligations of the sector in a wider ecosystem-based approach to management. To address this limitation the EIFAC held a symposium entitled The effects of fisheries management practises on freshwater ecosystems in Windermere, UK, between 12 and 15 June 2002 with the following objectives: • to bring together inland fisheries experts to exchange knowledge among countries and to appraise fisheries management activities and their impact on the environment, constraints on their application, issues and options regarding their use, and the benefits and problems associated with these activities; • to identify constraints and gaps in knowledge that affect the application of fisheries management activities in inland fisheries; • to recommend and promote action to improve the management of inland fisheries to the benefit of the aquatic environment; and • to provide guidelines for the policy formulation, planning methodology and evaluation of future fisheries management activities. This paper reviews the output of the EIFAC symposium in the four principal areas of management activities identified above and consolidates the information held within the proceedings that comprise this issue of Fisheries Management and Ecology. Further details of the output of the symposium can be found on http://www.fao.org/docrep/005/y4261e/y4261e00.htm. Impact of stocking and introductions on the environment Stocking and introduction of non-native species are widespread management techniques used to improve the quality and diversity of fisheries and enhance the angling experience (Cowx 1994, 1998). They are also used to manipulate population structures to influence food webs with the ultimate goal of improving water quality and ecosystem health (i.e. biomanipulation, see later). However, these activities are achieved at considerable cost. Some introductions and stocking programmes are made illegally because recreational angling demand is high and commercial benefits override the small fiscal penalties incurred (Hickley & Chare 2004). It appears that species-poor fish communities favour the establishment of non-native populations and are more vulnerable to invaders because alien species are less liable to be out-competed or predated upon by indigenous species. Direct assessment of the impact of introductions and stocking activities is seldom possible but local increases in species richness and abundance are likely to increase niche overlap, and therefore inter- and intra-specific relationships are more likely to be prevalent (van Zyll de Jong, Gibson & Cowx 2004). Interactions could result from competition with indigenous fishes or direct predation on native populations (Hickley & Chare 2004; van Zyll de Jong et al. 2004; Winfield & Durie 2004). The genetic effects of introductions and stocking are also considerable, and co-introduction of parasites has enabled some diseases to become widespread in Europe (Almodóvar & Nicola 2004; Hickley & Chare 2004; van Zyll de Jong et al. 2004). Despite these negative aspects, introductions and stocking can also be successful because in some cases the stocked species now support sustainable fisheries with no detectable detrimental effects (Hickley & Chare 2004). Consequently, fish introductions and stocking should not be systematically assumed to be negative, but risks appear to be higher with exotic species than species translocated within an ecoregion or the stocking of indigenous species. Unfortunately, there is often insufficient information on impacts of introductions and stocking programmes, particularly because there is no systematic monitoring and dissemination of information on the outcomes. Causal relationships are, therefore, difficult to distinguish from indirect correlation with environmental parameters. It was recognised that managers have a dual role in that they have to maintain, improve and develop fishing at the same time as having to protect the environment. Such a situation can lead to conflicts. Nevertheless, the threats posed by fish stock enhancement programmes, especially introductions, are particularly insidious because recovery management tools to overcome any adverse effects are not available. It is therefore recommended that the precautionary approach should be adopted with regard to the introduction of species, particularly in the case of non-native fishes. It is also recommended that international codes of practice are updated (e.g. ICES 1988 or EIFAC 1988) and followed to the letter to ensure the risks associated with introducing fish or other 2004 Blackwell Publishing Ltd, Fisheries Management and Ecology, 2004, 11, 145–151 EFFECTS OF FISHERIES MANAGEMENT ON FRESH WATERS aquatic organisms are evaluated and the correct decision to protect the extant biota is made. If insufficient information is available to make a decision on introducing a species, the precautionary principle should be adopted and the enhancement exercise curtailed. It was also recognised that increasing scientific understanding of fish and their habitat is required to support legislation in this respect. Consequently, more research is needed on the behaviour and mechanisms involved in the spread of non-native species. There is also a need for more information on the ecological impacts of stocking, the economic valuation of inland fisheries and the impact of introduced pathogens on fish stocks. In this respect, the relative merits and cost effectiveness of stocking rivers with different life stages and at different times of the year could be useful in determining if stocking contributes to improved stock status (Aprahamian, Barnard & Farooqi 2004). For example, when stocking rivers with fed salmon, Salmo salar L., fry a net gain can be realised when natural survival rates from egg to smolt are in the region of 1% or less. At high survival rates in the wild, the advantage of rearing and stocking fish is diminished. For coarse fish, e.g. chub, Leuciscus cephalus (L.), dace, Leuciscus leuciscus (L.) and roach, Rutilus rutilus (L.), stocking either 1- or 2-year-old fish is unlikely to make a significant difference to catches. In river rehabilitation situations, where no population exists, stocking older fish of >2 years old is likely to be more cost effective and lead to faster establishment of self-sustaining population, although knowledge of survival rates is still lacking. Rehabilitation of inland fisheries Restoration of aquatic habitats towards pristine conditions is a utopian view (Cowx 2004). In most cases, the watersheds have experienced extensive land-use changes. The most dramatic impacts result from deforestation, land use change, intensification of agricultural and industrial activity, and the modification of river channels to control floods and provide for navigation. More recently, demands for water resources and electricity have created new impacts. All these changes have been superimposed upon environmental changes caused by recent global climatic variations. The aim of rehabilitation for fisheries should therefore be to recreate functional habitats and connectivity between these habitats, and the target should be a quality of environment that achieves a compromise between maximum biodiversity and maximum productivity of fish. In this context, a functional unit includes spawning, feeding, nursery (growth) and resting (self protection) areas, each of which is linked in various ways with environmental features. Rehabilitation of rivers for fish focuses mainly on reinstating lateral and longitudinal connectivity, recreating habitat diversity and channel morphology, improving flow regimes for fisheries purposes and improving water quality problems (Cowx & Welcomme 1998). In lowland floodplain areas, reconnection of backwaters and ponds, or connection of adjacent gravel and borrow pits, which represent valuable spawning and nursery habitats, have been shown to increase species richness and relative abundance of fishes, especially if coupled with controlled flooding of the floodplain habitat (Jurajda, Ondračková & Reichard 2004). However, it appears that rehabilitation activities often do not always meet their desired objectives, partly because of lack of understanding of the biotic and abiotic factors influencing the target fish populations (Cowx 2004). Also, rehabilitation schemes often fail to address wider catchment problems and issues affecting fish communities, and/or manager’s expectations are too high. There is thus a need to have an overview of the entire catchment when establishing programmes for rehabilitation. Base line studies are needed to understand the relative importance of imbalances in individual river channels and tributary catchments relative to the overall catchment. Such studies will identify bottlenecks to viable fish populations in the whole catchment, allowing the generation of habitat enhancement procedures that will aid rehabilitation of a natural balance. Unfortunately, activities that reduce the impacts of development activities and resource extraction, which are an integral part of rehabilitation measures, cannot be achieved by government intervention alone. Consequently, agency partnerships, as well as legislation enforcement and compliance, are necessary if rehabilitation exercises are to successful, and greater emphasis must be given to providing advice to clients, public education and outreach activities to engender stakeholder participation in conserving habitat (Goodchild 2004). Finally, it was recognised that improvements achieved did not always warrant the expense of the scheme, and better costbenefit analysis is required, including post-project monitoring of rehabilitation works, if unsuccessful schemes are not to be duplicated. Rehabilitation of lakes largely focuses on shoreline habitat improvements, reducing nutrient input and overcoming the problems associated with eutrophication, including hypolimnic anoxia. Deep-water salmonid habitat can be expanded in lakes suffering from 2004 Blackwell Publishing Ltd, Fisheries Management and Ecology, 2004, 11, 145–151 147 148 I. G. COWX & D. GERDEAUX depleted summer oxygen levels by artificial mixing and raising hypolimnic dissolved oxygen levels by oxygenation to at least 4–5 mg L)1, although the effects on fisheries production are varied (Müller & Stadelmann 2004). This is largely because anoxic conditions, linked to eutrophication, still persist if nutrient input to the lake is not curtailed. In such cases the risk of fish kills from toxic algae production persists, and sediments continue to be anoxic causing mortality of whitefish (Coregonus spp.) eggs (Müller & Stadelmann 2004). Recruitment of fish populations can also be improved through reinstatement of shoreline habitat diversity and riparian and littoral zone vegetation (Jurajda et al. 2004). However, one tool that is being increasingly used to overcome the problems with eutrophication and to control algal blooms is biomanipulation. Biomanipulation has been used in several regions of Europe to control algal blooms, but with varying degrees of success (Mehner, Arlinghaus, Berg, Dörner, Jacobsen, Kasprzak, Koschel, Schulze, Skov, Wolter & Wysujack 2004). Two main approaches are used: (a) the traditional approach to biomanipulation by enhancement of predators and reduction of planktivorous fishes without participation of local stakeholders and (b) approaches that consider the socio-economic demands of anglers and commercial fishermen, and biomanipulation conducted mainly by means of the fishery. Traditional approaches through manipulation of density of piscivorous fish density and reduction of planktivorous fishes are considered valuable tools for reconciling fisheries and water quality problems on lakes, although care is need to ensure that stocking density of predators is adequate and appropriate (Mehner et al. 2004). To assist in appropriate application of biomanipulation for lake rehabilitation, Mehner et al. (2004) proposed step-by-step guidelines that integrate all stakeholdersÕ interests. The guidelines provide advice for water quality management but need to be tested in practice, and the technological parameters have to be completed. The power of the approach adopted within the guidelines lies in the integration of traditional fisheries management measures, such as stocking of piscivorous fishes, with ecosystem-based management. Unfortunately, continuity of interventions still remains paramount for the long-term success of biomanipulation activities. In this respect, anglers and fishermen are an appropriate way of maintaining continuous fishing pressure and should be used, especially in countries with major commercial fisheries. The use of experienced carp anglers in biomanipulation projects is recommended in cases where dense carp stocks lead to a resurgence of eutrophication. In these circumstances, catch and release should be avoided (Mehner et al. 2004). One source of nutrient input in fresh waters that needs to be evaluated is anglersÕ groundbait. Bait seems to be a substantial source of phosphorus in some fisheries (Neisar, Arlinghaus, Rennart & Mehner 2004), although more experienced anglers are able to maintain high catch rates without increasing the amount of groundbait used. To alleviate this problem, further investigations on phosphorus-reduced baits are necessary and anglers should adopt methods that reduce the amount of bait used. Furthermore, specific management guidelines for ground- and pre-baiting are needed because groundbaiting is generally common among coarse fish anglers. Fisheries regulations and stakeholder involvement Traditional fisheries management, through regulation of fishing activities, can have positive benefits for fish stocks. For example, in Lake Peipsi-Pihkva, problems arise from differences in the species targeted by the fisheries of Estonia and the Russian Federation, and traditional technical measures to increase the selectivity and lower the efficiency fishing gears through larger mesh-sizes, and imposing annual catch quotas have successfully raised the catch potential of the stock to cater for higher demand (Vetemaa, Vaino, Saat & Kuldin 2001). Similarly, problems have been encountered with the overexploitation of the sturgeon fisheries in the Lower Danube River, which are in a sate of collapse and extinction of the species is a real threat (Navodaru, Staras & Cernisencu 2001). The current situation calls for classical remedies, including a decrease of fishing effort, catch control and protection of spawning areas, and enforcement of the regulations. It is now recognised, however, that such traditional approaches must be coupled with stakeholder involvement (Goodchild 2004). This is largely because there is usually a lack of incentives when imposing traditional fisheries management regulations, although the scientific knowledge for implementation of such management tools is available. For example, in Finland, regulations restricting the movements of the alien signal crayfish, Pacifactacus leniusculus Dana, to conserve the native crayfishes are often ignored because the signal crayfish is resistant to crayfish plague, Aphanomyces astaci Shikora, and has better growth and reproduction potential than the native noble crayfish, Astacus astacus L. (Kirjavainen & Sipponen 2004). Similarly, Irz, Arguillier & Proteau (2004) showed that the practice of introducing non-native 2004 Blackwell Publishing Ltd, Fisheries Management and Ecology, 2004, 11, 145–151 EFFECTS OF FISHERIES MANAGEMENT ON FRESH WATERS species in French reservoirs leads to lower species richness and a reduction in species-biodiversity, but the activity still persists. There is thus a need to change the underlying thinking towards one that states that native species per se are of higher value to society than introduced or stocked non-native species. Similar changes in philosophy against other fisheries management practices that have potentially negative effects are also needed. To this end, the democratic processes necessary to protect and rehabilitate aquatic ecosystems, or fund research programmes for protection of aquatic biodiversity, call for regulations that the fisheries sector accept and follow. This goal will only be reached if the incentives are either positive self-interest or a feeling of collective moral and social obligations. Such an approach was successfully applied in Finland, where institutional changes have induced changes in fisheries governance closely related to changes in society. Here, the attitude towards the Saimaa ringed seal has changed from that of a competitor to the fishermen to one where the seals are perceived as part of a diverse fauna in need of conservation (Tonder & Salmi 2004). Effective fisheries management must therefore depend on public support and very often the perception of personal as against collective value trade-offs. This change in perception of the importance of natural, as well as artificial, water bodies, is slowly changing traditional fisheries towards ecosystem-based management approaches. Ecosystem-based management systems represent a paradigm shift and may best be described as adaptive management. This calls for new management tools to cater for legitimate human demand for water abstraction, hydropower generation and effluent disposal, as well as alternative commercial use of water bodies, such as bathing, boating and tourism, in addition to fisheries exploitation and conservation needs. Role of fish conservation in environmental management Fresh waters have suffered the most intense intervention of all ecosystems over the past 100 years. As a consequence, freshwater fishes have become threatened by a wide array of factors, but anthropogenic disturbance, especially species introductions and translocations, impoundment of rivers, pollution, habitat degradation and overexploitation, seems to underlie the decline and extinction of many species (Cowx 2002). This has resulted in many fish species becoming extinct, rare or endangered. Although actions have been taken to address some precarious situations, traditional methods of conservation management (e.g. regulation of exploitation, designation of nature reserves, captive breeding programmes for stock enhancement) do not seem to be as effective for freshwater fishes as for other animal groups (see Collares-Pereira, Cowx & Coelho 2002 for examples). This appears to be largely because fish populations and communities are treated in isolation and do not adopt a wider ecosystem-approach to conservation management. Traditional methods tend to concentrate on protecting or enhancing localised populations and do not necessarily address the bottlenecks contributing to the population’s demise. In this context, the bottlenecks to recruitment and survival need identifying, and mechanisms that overcome them should be put into place if fish conservation management is to be successful (Cowx & Collares-Pereira 2002). Strategies for fish conservation management must therefore adopt a more holistic approach accounting for other stakeholder activities and actions within the catchment and identify compromise scenarios that allow the preservation of the targeted fish species, whilst allowing development of activities in other sectors. This approach requires knowledge of biological, environmental, social and economic issues that affect the fish and fisheries as well as other stakeholders. Only then can compromise situations be formulated that benefit all parts of society. Such an approach was illustrated by Collares-Pereira & Cowx (2004), who reviewed the present threats to freshwater fishes, identified the underlying issues and reviewed the problems relating to current management practices. They illustrated the approach using a case study from a highly endangered Iberian cyprinid fish – Anaecypris hispanica (Steindachner) – to highlight the options for action to protect the freshwater fish natural heritage for future generations. They concluded that if conducted in a comprehensive manner, involving the wider public and all stakeholders, fish conservation management will confer wider environmental benefits, and protect biodiversity for future generations. Ultimately, it appears that fish conservation and improvement actions can accrue wider environmental benefits and help protect freshwater ecosystems from further degradation. This was illustrated by Noble, Harvey & Cowx (2004), who showed that habitat management activities to enhance fish population abundance can have positive benefits for other biota. In this case, rehabilitation of reedbeds to enhance fish population structure and abundance was considered a major factor enhancing the conservation status of the bitterns, Botaurus stellaris (L.), an extremely rare fisheating bird in the UK. 2004 Blackwell Publishing Ltd, Fisheries Management and Ecology, 2004, 11, 145–151 149 150 I. G. COWX & D. GERDEAUX Conclusions and recommendations References The Symposium highlighted that traditional inland fisheries management has clear benefits to river and lake ecosystems and to stakeholders over and above benefits to the fishery itself, but it is not always implemented successfully in European inland fisheries. Furthermore, activities such as stocking and introduction of fish can have negative impacts. Recent paradigm shifts suggest there is a trend away from traditional management of fisheries resources towards integrated management of the ecosystem, which necessitates the development of new participatory approaches. The unwillingness of elements of the public to respect fisheries regulations was illustrated. It was recommended that improved communication and education programmes on protection and conservation be developed for inland waters. In this respect, it was recognised that there is a general need for guidelines that are readily understandable by stakeholders and fisheries administrators alike. It was recommended that new guidelines be developed for biomanipulation, and that existing guidelines for stocking and introductions be updated and incorporated into national and local level policy. It was also recommended that all stakeholders be included in the consultative and decision-making processes for management and conservation of inland fisheries resources. Ideally this should develop into a full participatory management process. When contemplating rehabilitation works or enhancement activities, it was recommended that the catchment basin be evaluated in its entirety to identify other factors that may affect the project and what problems may still persist. In this respect the goals for rehabilitation projects should be evaluated fully and realistic targets set that project managers and the public find acceptable. It is further recommended that post-project monitoring of rehabilitation projects is a component of the evaluation procedure and the effectiveness thereof, and that the results should receive wide dissemination. It was recommended that a risk assessment-based approach be adopted for all fisheries management activities and the strength of legislation and regulation should relate to the potential risk of the management interventions. Finally, it was recommended that mechanisms be established for the common management of international water bodies where these do not already exist: where international mechanisms already exist, these need to be reinforced to concentrate better on fisheries and environmental issues. Almodóvar A. & Nicola G.G. (2004) Angling impact on conservation of Spanish stream-dwelling brown trout Salmo trutta. Fisheries Management and Ecology 11, 173–182. 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Hubert (eds) Inland Fisheries Management in North America, 2nd edn. Bethesda, MD, USA: American Fisheries Society, pp. 193–213. Welcomme R.L. & Naeve H. (eds) (2001) An international symposium on Fisheries and Society, Budapest, Hungary, 1–3 June 2000. Fisheries Management and Ecology 8, 283– 462. Winfield I.J. & Durie C. (2004) Fish introductions and their management in the English Lake District. Fisheries Management and Ecology 11, 195–201. van Zyll de Jong M.C., Gibson R.J. & Cowx I.G. (2004) Impacts of stocking and introductions on freshwater fisheries of Newfoundland and Labrador, Canada. Fisheries Management and Ecology 11, 183–193. 2004 Blackwell Publishing Ltd, Fisheries Management and Ecology, 2004, 11, 145–151 151