Restoration of native Atlantic salmon runs in northern Spain: do costs outweigh benefits?

Atlantic salmon stocks in northern Spain are at the southern range of the species distribution. As such they are likely more vulnerable to environmental change and human disturbance. The Nalon-Narcea River salmon is one such population in Asturias, Spain. The river is dammed throughout the watershed with few fish passage facilities. However, angling data show that salmon returns are consistent although the population is relatively small. We have employed one tributary as a model, the River Trubia. Although some problems of agriculture and industrial pollution have been detected downstream, an upstream habitat evaluation suggests that adequate spawning and juvenile habitat exists. The regional Government has proposed to construct fishways for allowing upstream passage of salmon. This would potentially increase salmon production, but there are also some concerns like increased hybridization of salmon and trout which is already evident downriver and which previous work suggests will increase as salmon colonize new habitat, and potential changes in fishing regulations as salmon distributions shift upriver and away from traditional angling areas. Here, we present an overview of ecological and social aspects of salmon habitat restoration in the River Nalon-Narcea that we hope will provide solutions that balance costs and benefits and may be applicable to other anadromous populations

Restoration of native Atlantic salmon runs in northern Spain: do cost outweigh benefits

ABSTRACT Atlantic salmon stocks in northern Spain are at the southern range of the species distribution. As such they are likely more vulnerable to environmental change and human disturbance. The Nalon-Narcea River salmon is one such population in Asturias, Spain. The river is dammed throughout the watershed with few fish passage facilities. However, angling data show that salmon returns are consistent although the population is relatively small. We have employed one tributary as a model, the River Trubia. Although some problems of agriculture and industrial pollution have been detected downstream, an upstream habitat evaluation suggests that adequate spawning and juvenile habitat exists. The regional Government has proposed to construct fishways for allowing upstream passage of salmon. This would potentially increase salmon production, but there are also some concerns like increased hybridization of salmon and trout which is already evident downriver and which previous work suggests will increase as salmon colonize new habitat, and potential changes in fishing regulations as salmon distributions shift upriver and away from traditional angling areas. Here, we present an overview of ecological and social aspects of salmon habitat restoration in the River Nalon-Narcea that we hope will provide solutions that balance costs and benefits and may be applicable to other anadromous populations. RÉSUMÉ La restauration du saumon de l'Atlantique natif fonctionne dans le nord de l'Espagne : les coûts dépassent-ils les avantages ? Les stocks de saumon atlantique dans le nord de l'Espagne sont à la limite sud de la distribution de l'espèce. Comme tels, ils sont probablement plus vulnérables aux changements environnementaux et aux perturbations humaines. Le saumon de la rivière Nalon-Narcea est une de ces populations dans les Asturies, en Espagne. La rivière est endiguée, avec quelques passes à poissons. Toutefois, les données de pêche montrent que les retours de saumon sont bons bien que la population soit relativement faible. Nous avons employé un affluent comme modèle, la rivière Trubia. Bien que certains problèmes de pollution agricole e

An Overview of the Program to Restore Atlantic Salmon and other Diadromous Fishes to the Connecticut River with Notes on the Current Status of these Species in the River

A federal and multi-state cooperative program to restore American shad Alosa sapidissima and Atlantic salmon Salmo salar to the Connecticut River basin was begun in 1967 and has evolved to include many other species. The program began in the last years of the Connecticut River Ecological Study, but most of its activities have occurred since the study ended. The Connecticut River Atlantic Salmon Commission manages the program. Emphasis has been placed on the provision of fish passage at barrier dams. Early fishways were justified on the basis of existing American shad runs, and later upriver fishways were built to support future salmon runs. Fishways existed at five mainstem dams and eight tributary dams, with facilities for downstream fish passage provided at many additional dams. Salmon restoration has been pursued with stocking of hatchery-reared fry and smolts, catch prohibitions, kelt reconditioning, fish health management, and various genetic management and marking schemes. Annual runs typically have numbered in the hundreds but recently have declined to less than 100 at the same time runs elsewhere through the species\u27 range have also declined. Annual runs of American shad, blueback herring A. aestivalis, and alewife A. pseudoharengus increased but recently experienced declines, for which stock recovery of the striped bass Morone saxatilis is thought to be at least partially responsible. Gizzard shad Dorosoma cepedianum and hickory shad A. mediocris experienced significant range extensions in the Connecticut River basin since the 1990s, and the number of nonspawning striped bass that enter the river annually has increased dramatically during the same time period. Brief reviews of the status in the Connecticut River basin of these anadromous species as well as of the shortnose sturgeon Acipenser brevirostrum, Atlantic sturgeon A. oxyrinchus, white perch Morone americana, rainbow smelt Asmerus mordax, sea lamprey Petromyzon marinus, and sea-run brown trout Salmo trutta and the catadromous American eel Anguilla rostrata are provided

Long-term changes in migration timing of adult Atlantic salmon (Salmo salar) at the southern edge of the species distribution

ADAPTATION,adult,adult migration,age,ATLANTIC,Atlantic salmon,Canada,capture,Climate,CLIMATE-CHANGE,Connecticut,Connecticut River,DAM,Dam Construction,DIFFERENCE,Distribution,Flow,life history,LIFE-HISTORIES,life-history,Maine,migration,migration timing,native,pattern,PATTERNS,Penobscot River,population,POPULATIONS,range,restoration,river,Rivers,SALAR,Salmo,Salmo salar,salmon,species,stock,Stocks,structure,SYSTEM,temperature,timing,work

Diadromous Fish Enhancement and Restoration: 2004 Annual Performance Report

From executive summary: The purpose of this project is to restore and enhance diadromous fish runs to the streams of Connecticut through the provision of effective fish passage and the reintroduction of fish into selected watercourses. The scope of this project was expanded in 2003 to include jobs for American eel and sea-run trout. Other jobs were also re-organized. The goals of this project are: (1) To restore Atlantic salmon to three tributaries of the Connecticut River in Connecticut. (2) To restore and enhance runs of American shad in ten streams in Connecticut. (3) To restore and enhance runs of river herring in 30 streams in Connecticut. (4) To restore and enhance runs of American eel in 20 streams in Connecticut. (5) To develop and enhance runs of sea-run trout in eight streams in Connecticut. (6) To provide effective fish passage at 30 existing fish passage facilities. (7) To provide effective fish passage at 30 existing barriers to fish migration. (8) To expand public knowledge of the success of diadromous fish restoration and its importance to the health of Connecticut\u27s ecological resources

Effects of multiple low-head dams on fish, macroinvertebrates, habitat, and water quality in the Fox River, Illinois

We examined the effects of low-head dams on aquatic biota, habitat, and water qualityin a 171-km reach of a midwestern warmwater river that was fragmented by 15 dams into a seriesof free-flowing and impounded habitats. Dams impounded 55% of the river\u27s surface area withinthe study reach and influenced distributions of 30 species of fish by restricting upstreammovements. Values for the Illinois index of biotic integrity (IBI) were higher in free-flowing areas(mean IBI = 46 out of a possible 60 at below-dam and midsegment free-flowing locations) thanimpounded areas (mean IBI \u3c 31 for above-dam and midsegment impounded locations).Likewise, scores from a macroinvertebrate condition index (MCI) were higher at stations in freeflowingreaches (mean MCI \u3e 415 out of a possible 700) than in nearshore areas of impoundedreaches (mean MCI \u3c 210). Ponar dredge samples taken only from open-water impounded areasshowed an offshore invertebrate community that consisted almost entirely of tolerant oligochaetesand chironomid larvae. Qualitative habitat evaluation index (QHEI) scores indicated good-qualityhabitat in free-flowing areas (mean QHEI \u3e 70 out of a possible 100) and severely degradedhabitat at impounded sites (mean QHEI \u3c 45). In impounded reaches, dissolved oxygen and pHshowed wide daily fluctuations (2.5û18.0 mg/L and 7.0û9.4 units) and often failed to meet Illinoiswater quality standards. In free-flowing portions of river, fluctuations in these parameters wereless extreme and water quality standards typically were met. We found little evidence ofcumulative effects of dams; however, our data suggest that low-head dams adversely affectwarmwater stream fish and macroinvertebrate communities by degrading habitat and waterquality and fragmenting the river landscape. These results should aid river managers andstakeholders in determining appropriate restoration practices (i.e., dam removal versus fishpassage structures) for warmwater rivers and streams that contain low-head dams

Diadromous Fish Enhancement and Restoration: 2006 Performance Report

From executive summary: The purpose of this project is to restore and enhance diadromous fish runs to the streams of Connecticut through the provision of effective fish passage and the reintroduction of fish into selected watercourses. The scope of this project was expanded in 2003 to include jobs for American eel and sea-run trout. Other jobs were also re-organized. The goals of this project are: (1) To restore Atlantic salmon to three tributaries of the Connecticut River in Connecticut. (2) To restore and enhance runs of American shad in ten streams in Connecticut. (3) To restore and enhance runs of river herring in 30 streams in Connecticut. (4) To restore and enhance runs of American eel in 20 streams in Connecticut. (5) To develop and enhance runs of sea-run trout in eight streams in Connecticut. (6) To provide effective fish passage at 30 existing fish passage facilities. (7) To provide effective fish passage at 30 existing barriers to fish migration. (8) To expand public knowledge of the success of diadromous fish restoration and its importance to the health of Connecticut\u27s ecological resources

Diadromous Fish Enhancement and Restoration: 2005 Performance Report

From executive summary: The purpose of this project is to restore and enhance diadromous fish runs to the streams of Connecticut through the provision of effective fish passage and the reintroduction of fish into selected watercourses. The scope of this project was expanded in 2003 to include jobs for American eel and sea-run trout. Other jobs were also re-organized. The goals of this project are: (1) To restore Atlantic salmon to three tributaries of the Connecticut River in Connecticut. (2) To restore and enhance runs of American shad in ten streams in Connecticut. (3) To restore and enhance runs of river herring in 30 streams in Connecticut. (4) To restore and enhance runs of American eel in 20 streams in Connecticut. (5) To develop and enhance runs of sea-run trout in eight streams in Connecticut. (6) To provide effective fish passage at 30 existing fish passage facilities. (7) To provide effective fish passage at 30 existing barriers to fish migration. (8) To expand public knowledge of the success of diadromous fish restoration and its importance to the health of Connecticut\u27s ecological resources