ON THE WILLINGNESS-TO-PAY FOR RECREATIONAL FISHING—ESCAPED FARMED VERSUS WILD ATLANTIC SALMON

This article explores to what extent escaped farmed salmon from fish farms affect the willingness-to-pay for recreational fishing of Atlantic salmon in Norwegian rivers. This is a first attempt to explore the economic consequences of escaped farmed species in terms of the anglers’ willingness-to-pay for fishing permits working through the relationship between the price of fishing permits and the share of escaped farmed salmon. The empirical analysis is based on the results from a contingent valuation survey conducted in Norway. It is found that the presence of escaped farmed salmon in Norwegian rivers may have severe economic consequences on the willingness-to-pay for recreational fishing with a reduction of up to 85% compared to a situation with a ‘pure’ wild salmon stock.     

Catchability of Atlantic salmon at high water temperatures: Implications for river closure temperature thresholds to catch and release angling

Warming water temperatures, combined with increased mortality following catch and release, could have synergistic consequences if rivers remain open to catch and release at high water temperatures, and catchability of fish remains similar across water temperatures. Here archived data for Atlantic salmon, Salmo salar L., were used to (a) quantify the influence of water temperature on catchability and (b) refine estimates of absolute catch and release mortality to incorporate the relationship between temperature and catchability. A significant decline in the number of Atlantic salmon caught at warmer water temperatures was found after accounting for the effects of river water height, fishing effort, run duration and year-to-year differences in fish abundance. Overall, absolute catch and release mortalities were predicted to be infrequent at cool river temperatures. At river temperatures sometimes associated with fishing closures, mortality due to the catch and release ranged from 6% to 14%. Although post-release mortality increases with water temperature, it is somewhat compensated by the reduced catchability of Atlantic salmon. Thus, the catchability component of catch and release is an integral consideration when evaluating the effectiveness of river closure temperature thresholds when managing catch and release angling.     

The straying of Icelandic ranched Atlantic salmon, Salmo salar L.: release and recapture techniques

The straying rate of ranched Atlantic salmon, Salmo salar L., into rivers in Iceland was estimated on the basis of coded wire tag recoveries. Out of a total of 15 158 recaptured tagged salmon from the releases between 1987 and 1992, 189 fish (1.3%) strayed into 25 out of the 79 salmon rivers observed. Most of the strayers were found in neighbouring rivers to the ranching stations. There were no significant differences in straying rate between different age classes of salmon returning from the same smolt year class. Generally, there was a delay of 26-27 days in running time between strayers in rivers and salmon returning to the ranching station. Higher straying rates were observed for ranching stations using riverine traps than for stations using estuary traps. By close inspection of seven key rivers in Iceland and assuming a 50% exploitation rate (fishing effort) in the rivers, on average, 2.1% of the returning salmon in ranching were estimated to stray to native salmon rivers over the years. A limitation of using these numbers to estimate geneflow between ranching stocks and wild populations is discussed.     

Behaviour of juvenile Atlantic salmon, Salmo salar L., in rapid- and slow-flowing sections of a small Norwegian stream

Abstract. Through ultrasonic tagging, fish living in running water and in slow-flowing water in man-made weir basins were tracked over a period of 3–6 days. Results showed that the fish living in the weir basins changed position more frequently and moved over larger areas than fish living in running water. As a consequence of the different behavioural patterns of fish in rapids and in weirbasins, densities of salmon are lower in the weir basins than in the rapids. Therefore, weirs creating large areas of slow-flowing water should not be established in rivers where an optimal production of Atlantic salmon is the goal.     

Straying of Atlantic salmon, Salmo salar, from delayed and coastal releases in the Baltic Sea, with special focus on the Swedish west coast

Abstract  Atlantic salmon, Salmo salar L., reared from two Baltic strains were released around the islands Bornholm and Møn in the Baltic Sea between 1995 and 1999. A total 600 000 reared salmon were released from net pens using the delayed release technique, keeping the salmon in net pens for approximately 3 months after smolting, and 208 000 were released directly from the hatchery. Of these, 15 958 were tagged with Carlin tags. Additionally, 65 300 coded wire tagged salmon were released as delayed release salmon close to Bornholm in 2000. Recaptures from the five years of Carlin tagged releases varied between 2.8% and 21.2% (average 13.1%). Most recaptures were from within the Baltic Sea (average 98%), but some were recaptured outside the Baltic Sea, either in the sea (1%) or in fresh water (1%). Recaptures outside the Baltic Sea and in fresh water were higher for releases at Møn in the western part of the Baltic, than releases at Bornholm. Straying rates from the releases into six rivers on the Swedish west coast were estimated using information from capture in traps and sport and broodstock fisheries. The proportion of straying salmon in rivers on the Swedish west coast was about 3.8% of the salmon run, but with large variations between rivers. Releases were discontinued because of possible deleterious effect on the local wild salmon populations.     

Atlantic Salmon (Salmo salar L.) in Brittany and Lower-Normandy: Preliminary Observations on the General Characteristics of Adults

This paper presents some characteristics (length, weight and age) of adult Atlantic salmon in rivers of Brittany. The data were derived from 1,578 fish caught mainly by rod and line; the remainder being from net catches in estuaries and small samples taken outside the fishing season. The bulk of the fish spent 1 or 2 years in freshwater before smoltifying. Those fish becoming smolts at the end of 1 year were the most numerous (54%). The majority of the fish sampled were spring fish (82.4%). Very few summer fish were identified and those found were mainly grilse. The high proportion of spring fish in the sample is due to the high proportion of rod-caught fish. Probably a complete census over the year would show a larger proportion of grilse and summer fish as these are not subject to heavy rod-fishing the season being closed at the beginning of June. The relationship between sea age and river age and the influence of freshwater life upon the sea life were tested in four rivers. It seems probable that sea life depends chiefly on the river and the year of smoltification rather than on the freshwater stage. The biometric characteristics of Brittany salmon were compared with data from some foreign rivers. The angling exploitation of the spring Atlantic salmon in Brittany and the lack of data about summer migrations are discussed in regard to the future of this stock.     

Importance of recreational fisheries in the Guadiana River Basin in Portugal

The rapid expansion of recreational fishing in Portugal over the last 20 years, along with the multiplicity of pressures affecting inland fisheries, demands the urgent recognition of the social and economic values. Sport-angling information is still inadequate to formulate management actions. To address this issue, a regional survey on freshwater recreational fishing in all the municipalities of the Guadiana River Basin was carried out in 1999. The survey, based on 1998 data, provided information on the profile of anglers, preferences as regards reservoirs and sections of rivers fished, frequency of fishing trips, motivation, expenditure, fish species caught, an estimation of total catch and its destination, interest in competitions, enforcement and personal opinions. The results recommended improved communication and feedback between users, and mechanisms for future regional development and management of recreational fisheries.     

Influence of gear switching on recapture of Atlantic salmon (Salmo salar) in catch‐and‐release fisheries

Anglers that release Atlantic salmon (Salmo salar) in recreational fisheries do so with the intention that the fish will survive and contribute to succeeding generations. In some instances, salmon that are released may be recaptured, but mechanisms associated with recapture are unclear. To test whether gear avoidance influences recapture rates, we analysed data from tagging programmes in major Norwegian Atlantic salmon fishing rivers to determine how frequently salmon were recaptured by different gear than that by which they were initially captured (i.e. gear switch). Among 339 salmon captured, externally tagged and released in 2012 and 2013, 46 (14%) were recaptured; 70% of these recaptured salmon exhibited gear switch. To test whether this gear switch percentage could be expected in the absence of gear avoidance, a simulation was conducted, which accounted for variation in catch probability among rivers and across time with different gear types based on comprehensive catch data. Each simulation step provided a simulated rate of gear switch under the null hypothesis of no gear avoidance. A distribution was generated, which described the probability that we would observe 70% gear switch. The simulated results indicated that this rate of gear switch was highly unlikely (P = 0.003) if recapture gear is assumed to be independent of initial capture gear, suggesting that salmon avoided familiar gear types. Changes to behaviour after release, including learned hook avoidance, may explain our observation of gear avoidance by recaptured salmon.     

Effects of the Faroese long-line fishery, other oceanic fisheries and oceanic variations on age at maturity of Icelandic north-coast stocks of Atlantic salmon (Salmo salar)

Investigations were conducted on the effects of oceanic variations (as indicated by sea temperatures) and catches of the Faroese, Norwegian Sea and West Greenland salmon fisheries on the sea-age composition of Atlantic salmon (Salmo salar L.) from 22 Icelandic north-coast rivers. Catches of grilse in rivers were strongly correlated among the 22 rivers, as were the ratios of grilse caught to two-sea winter (2SW) salmon caught the next year. Four of the 22 rivers showed increasing ratios over time and three of these rivers, all in the northeast, had significantly higher mean ratios after the expansion of the Faroese fishery than before (P < 0.05). No evidence was found from ratios for the other 18 rivers to suggest that Faroese fishing was significantly depleting those stocks, even though 13 micro-tagged north-coast salmon had been recovered in the fishery in the 1988–1989 season. No evidence was found that Norwegian Sea or West Greenland fisheries affected stock composition. The mean April–May sea temperature prior to when the smolts enter the sea was significantly and positively related to ratios in eight of the 22 rivers. This result, along with frequent significant correlations in ratios among rivers, indicated that more rapid growth of smolts in their first summer may have increased grilse to 2SW salmon ratios on several rivers.     

An examination of the use of angling data to estimate total returns of Atlantic salmon, Salmo salar, to two rivers in Newfoundland, Canada

Conservation spawning requirements (limits) for Atlantic salmon, Salmo salar L., have been developed for a number of rivers in Newfoundland. Status of stocks is evaluated against these limits and scientific advice and recommendations on levels of recreational catch provided to resource managers. A critical factor in this process is the determination of total returns. This has been accomplished for 30–40% of the rivers in question over the years through the use of fish counting fences and traps installed in fishways. In Newfoundland, it is not logistically or financially possible to operate fish counting facilities in all of the approximately 200 Atlantic salmon rivers. Thus angling catch data have been used as an alternative means of estimating total returns to rivers without counting facilities. Estimates of total returns were three to four times higher than the actual values for one of the two rivers studied and deviated from the actual by as much as 60% for the other. Management implications of the approach are discussed.     

Recreational sector is the dominant source of fishing mortality for oceanic fishes in the Southeast United States Atlantic Ocean

Recreational fishing is increasingly recognised as an important source of mortality for marine fish populations. In the United States, estimates of marine recreational catch and effort were recently revised for the time period 1981 and beyond, and for many species, the revised estimates were substantially higher than the original values. Here, the proportion of total landings that came from the recreational sector in the Southeast US Atlantic was quantified. The proportions for 22 oceanic species and for all species combined were computed, using a full time series of landings (1981–2016) and a more recent time series (1999–2016). For the full and recent time series, landings of most species (15/22 and 17/22, respectively) were dominated by the recreational sector. For all species combined, 71% of landings in the full time series were from the recreational sector, and 76% in the recent time series. Trend analysis indicated that most species had a stable or increasing proportion of landings from the recreational sector. In addition, stock assessments were conducted on four species, and the catch revisions increased the estimated scale of abundance and, in some cases, affected stock or fishery status. This work underscores the importance of recreational fishing for marine resource management.     

The Recreational value of Atlantic salmon angling under different fishing regulations

Atlantic salmon, Salmo salar L., stocks worldwide have dwindled, and stricter recreational fishing regulations have been implemented. This study estimates the recreational value of salmon fishing under different regulatory schemes and identifies factors explaining changes in net economic value of sport fishing. A Contingent Valuation mail survey in the Verdal River, Norway, asked anglers their willingness-to-pay for increased fishing expenditures or willingness-to-accept compensation in reduced fishing expenditures, to estimate recreational value. The average annual recreational value per angler decreased under stricter regulations from about €420 (in 2007–2009) to €280 (2010–2012) to €180 for the future scenario (2013–2015). Although an overall net decline in recreational value was found with stricter regulations, anglers have heterogeneous preferences. Anglers with non-catch motives or high place attachment have higher recreational value with stricter regulations than others. If stricter regulations remain over time, younger, less consumptive-oriented anglers would probably dominate the fishery.     

Stocking of sea trout, Salmo trutta, in Lake Veere, south-west Netherlands

Lake Veere (1750–2050 ha), a brackish water lake in south‐west Netherlands, is a former branch of the Oosterschelde. The lake was closed off by the construction of two dams in 1961. Since the early 1970s Lake Veere has been regularly stocked for recreational and commercial fisheries with rainbow trout, Oncorhynchus mykiss (Walbaum), brown trout, Salmo trutta L., and glass eel, Anguilla anguilla (L.). Between May and September 1996 an experimental stocking of 18 054 trout of sea trout parentage (15–16 cm; 776 kg) was carried out to study their potential for recreational fisheries. The growth and mortality of the stocked trout were estimated from recaptures in eel fyke nets. The production and consumption of the stocked trout were estimated with a bioenergetics model. After 3.5 years (May 1996–November 1999) the stocked trout measured between 50 and 70 cm. The estimated annual total mortality was 84%. During the winter of 1996–1997, the biomass of the stocked trout reached a maximum of about 1800 kg. By November 1999 the biomass was estimated to be 100 kg. The maximum daily consumption by the trout population was 60 g ha^?1 in October 1996 and in June 1997. The total consumption of the stocked trout population over the 3.5‐year period was estimated as 54 244 kg. The analysis suggested that the stocked trout used about 0.2% of the average annual primary production of the lake system. Although the growth and initial production of the population are attractive from the perspective of a recreational fishery, the high mortality and infestation with the salmon louse, Lepeophtheirus salmonis (Krøyer), are serious drawbacks for a future stocking programme with trout in Lake Veere.     

Effects of recreational fishing on zooplankton communities of drainage system reservoirs at an open‐pit mine

The use of artificial water bodies for angling is a popular practice, especially in industrial and urbanised areas where natural water bodies are lost. In this study, the zooplankton structure dynamics and water quality at three strip mine drainage system reservoirs were assessed with different types of recreational fishery exploitation: K1—intensive angling using the catch‐and‐release model, K2—lowest angling pressure and higher share of predatory fishes and K3—moderate fishing, that is limiting groundbait quantities and eliminating non‐predatory fishes by anglers. The null hypothesis tested was that recreational fishing does not affect the biotic and abiotic conditions of reservoirs. The significance of each environmental variable was tested using redundancy analysis (RDA). The highest nutrients and chlorophyll a concentration, turbidity level and organic matter content occurred in K1. Zooplankton diversity was the lowest under these conditions; protozoa and larval stages of copepods dominated. In reservoirs where sustainable fishing was implemented (K2, K3), trophic parameters of water were lower, on average, by 25%, turbidity by 30%, and productivity by 35–70%. Zooplankton diversity was significantly higher; rotifers and small cladocerans dominated. The choice of recreational fishing model determines the functionality and biological potential of the reservoir.     

Distribution of Atlantic salmon, Salmo salar L., in freshwater bodies of Europe

Data are presented on the current geographic distribution of Atlantic salmon, Salmo salar L., in freshwater bodies of Europe. They dwell in 14 hydrological systems, including basins of U lakes and three rivers. Nine of the lakes (Ladoga, Onega, Kuito and others) arc located in Russia, one in Finland (Saimaa) and one in Sweden (Vänern). All the rivers inhabited by freshwater salmon flow within Norwegian borders. Most of the lakes and rivers have good connection with the Baltic, White or Norwegian Seas. Over the past 20 years the freshwater salmon stock in Lake Imandra (the Kola Peninsula) has completely disappeared as a result of heavy human impact. The situation with such non-migratory salmon, which used to be important to fishing and trade, is also critical in all other water bodies. It is necessary, therefore, to elaborate effective measures for protecting and restoring freshwater salmon in the lakes and rivers of Europe.     

Increased abundance of European eel (Anguilla anguilla) in acidified Norwegian rivers after liming

The prevalence and abundance (density 100 m^?2) of European eel (Anguilla anguilla) were studied by means of electrofishing in 13 acidified rivers in Norway that had been limed to restore acceptable water quality for Atlantic salmon (Salmo salar). Status of Atlantic salmon in these rivers varied prior to liming, from being entirely lost in six highly acidified rivers and in different stages of decline in seven less acidified rivers. Four of the rivers are heavily affected by hydropower development. The abundance and prevalence of European eel increased significantly during the study period. The best model for predicting eel abundance was that with four explanatory variables: time after liming, time after liming squared, status of salmon stocks and hydropower regulation. The eel density was expected to increase by a factor of almost 5 after 10 years of liming. The model also predicts that a river with a formerly reduced Atlantic salmon stock has a 2.8 times higher density of eel than rivers with formerly lost salmon stocks. Before liming, European eel were on average recorded at 15 and 41% of the sampling stations in rivers with formerly lost and reduced Atlantic salmon populations, respectively, increasing to 49 and 68% in individual rivers, respectively, after 10 years of liming. The recovery of European eel in these formerly acidified rivers by means of liming took place during the same period as their abundance declined in other parts of their distribution area in Norway and elsewhere in Europe.     

The risk of individual fish being captured multiple times in a catch and release fishery

The proportion of angled Atlantic salmon Salmo salar L. being caught and released has increased. If individuals are repeatedly captured, this may have fish welfare consequences. Of 995 Atlantic salmon tagged during catch and release in eight Norwegian rivers, 10% were captured twice, while 3% were captured three times within the same fishing season. The probability that released salmon were captured again decreased with decreasing time left of the fishing season, decreased for larger‐sized fish and varied among rivers/years. Increased exploitation rates within the river, indicating an increased fishing pressure, strongly increased the probability that fish would be recaptured. However, the proportion of salmon caught a second time was much lower than the total exploitation rates in the same rivers (which was on average 46%). For fish tagged in the sea, the likelihood of being angled decreased with time since entering the river, which may explain why the recapture rates of caught and released fish were lower than the total exploitation rates.     

Modelling the impacts of removing seal predation from Atlantic salmon, Salmo salar, rivers in Scotland: a tool for targeting conflict resolution

Abstract  Bioenergetics were used to model the potential impacts on adult Atlantic salmon, Salmo salar L., stocks and rod fisheries of removing harbour seals, Phoca vitulina L., from three rivers of different scales in the Moray Firth, Scotland, viz: the Spey (large), Conon (medium) and Moriston (small). Overall, seals had the greatest impact on the Moriston, where removal of a single animal could increase cumulative catch by 17% during the fishing season. On the Conon and Spey the impacts were negligible, and resulted in increased catches of <1% annually. On all rivers eliminating seal predation had the greatest impact during the spring due to the smaller size of spring salmon sub-stocks. A generalised model of seal removal illustrated that stocks and catches increased by >33% in rivers with monthly rod catches ≤10 fish, but declined to <10% for rivers with catches >34 fish. The outputs of the models are qualitative, but provide a management tool for targeting action to resolve seal-salmon fishery conflict. Smaller salmon population units, and spring salmon sub-stocks and fisheries in particular, are most vulnerable to predation. The merit of this approach is discussed regarding the management of Special Areas of Conservation for salmon and seals.     

Migratory behaviour of adult wild and escaped farmed Atlantic salmon, Salmo salar L., before, during and after spawning in a Norwegian river

The migratory behaviour of adult wild and escaped farmed Atlantic salmon, Salmo salar L., before, during after spawning in the River Namsen, Norway, was analysed using radio telemetry. The fish were caught, radio tagged and released into the fjord between 7 and 25 km from the river mouth. A significantly higher proportion of wild (74%) than farmed (43%) salmon was subsequently recorded in the river. Wild salmon (33%) were more frequently captured in the sea and in rivers than farmed salmon (14%). The migration speed from release to passing a data logger 11 km upstream from the river mouth was not significantly different between wild (20.6 km day^?1) and farmed (19.8 km day^?1) salmon. Wild salmon tagged when water flow in the river was increasing had a significantly higher migration speed than wild salmon tagged when water flow was decreasing. This was not true for farmed salmon. Farmed salmon were distributed significantly higher up the river than wild salmon during spawning, although both types of fish were found together in spawning areas. Thus, there was no geographical isolation to prevent spawning between wild and escaped farmed salmon. Farmed salmon had significantly more and longer up- and downstream movements than wild salmon during the spawning period. Unlike farmed salmon, the number of riverine movements by wild salmon increased significantly when variation in water flow increased. A smaller proportion of wild (9%) than farmed (77%) salmon survived through the winter after spawning.     

Fishing effort redistribution in response to area closures

Spatial fishery closures will induce fishing effort to either move to open areas or to cease to fish. When designing a short- or long-term closed area management regime, the expected impact of that closure will depend upon how that effort is redistributed. We present a redistribution model based upon Ideal Free Distributions (IFDs) which is intermediate in complexity between analyses in which effort is distributed uniformly over open areas and models of full fleet dynamics. The IFD models incorporate the fundamentals of the decision process invoked by fishers facing relocation and the ensuing catch rates that result from the addition or removal of effort. Two classes of models were tested: an Availability model where catch rate declines were proportional to abundance; and an Abundance model where abundance declines at an exponential rate with the entry of displaced effort into an area. Results of these models were compared with uniform and proportional redistribution methods. The IFD-based methods included relative cost of relocation, thereby illustrating the importance of both catch rates and movement costs in designing closed area regulations. To demonstrate the methods, hypothetical area closures to United States pelagic longliners in the western Atlantic were examined and the impact of those closures on bycatch rates was evaluated. Guidance for selecting an appropriate model structure for a particular closed area problem is given.