Presque partout sur la planรจte, la pรชche rรฉcrรฉative reprรฉsente une activitรฉ sociale et รฉconomique importante (Arlinghaus et al. 2002; Post et al. 2002; Cooke & Cowx 2004; Allan et al. 2005; Lewin et al. 2006). Les pรชcheurs pratiquent ce sport d’abord pour le plaisir, mais รฉgalement ร des fins de consommation, contribuant ainsi par leurs dรฉpenses ร lโรฉconomie locale et nationale (Arlinghaus et al. 2002). Au Canada, plus de 3 millions de personnes pratiquent la pรชche au moins une fois par annรฉe, en eau douce ou en eau salรฉe. Les dรฉpenses totales annuelles reprรฉsentent 8,3 G $, dont 2,5 G $ correspondent ร des dรฉpenses directes (Pรชches et Ocรฉans Canada 2012). Ce chiffre se situe largement au-dessus de la valeur totale des dรฉbarquements de la pรชche commerciale canadienne pour l’annรฉe 2008, qui a รฉtรฉ estimรฉe ร 1,9 G $ (Pรชches et Ocรฉans Canada 2011). Au Quรฉbec, on compte plus de 700 000 adeptes de pรชche sportive, soit prรจs du quart de tous les pรชcheurs sportifs du Canada (Pรชches et Ocรฉans Canada 2012). Au total, les adeptes quรฉbรฉcois cumulent 10 millions de jours de pรชche et capturent 40 millions de poissons par annรฉe (Pรชches et Ocรฉans Canada 2012). Ces activitรฉs rรฉcrรฉatives amรจnent des dรฉpenses totales annuelles sโรฉlevant ร plus de 1,5 G $ (Pรชches et Ocรฉans Canada 2012).
Globalement, les populations de poissons sportifs sont soumises aux impacts nรฉgatifs des activitรฉs anthropiques telles que lโagriculture, la fragmentation des habitats, lโintroduction dโespรจces exotiques, le rรฉchauffement climatique et la surexploitation par la pรชche (Chu et al. 2003; Dextrase & Mandrak 2006; Lewin et al. 2006). Il en rรฉsulte un dรฉclin des populations de poissons dโintรฉrรชt sportif et de la qualitรฉ de pรชche ร plusieurs endroits dans le monde (McPhee et al. 2002; Post et al. 2002, Coleman et al. 2004). McPhee et al. (2002) ont affirmรฉ quโen Australie, lโimpact de lโexploitation de la pรชche sportive sur les populations de poissons est souvent plus important que celui de la pรชche commerciale. Ils mentionnent รฉgalement que sans changement dans la gestion et le suivi de la ressource, lโactivitรฉ sera non viable ร long terme. En Espagne, Almodรณvar et Nicola (2004) ont indiquรฉ que lโexploitation par la pรชche a rรฉduit lโabondance, la taille et lโรขge moyen de la truite brune Salmo trutta. En France, lโabondance de lโanguille europรฉenne Anguilla anguilla et de la truite brune dans les riviรจres a รฉtรฉ rรฉduite au cours des prรฉcรฉdentes dรฉcennies (Poulet et al. 2011). Aux รtats-Unis, les pรชcheries sportives et commerciales ont contribuรฉ au dรฉclin des poissons cรดtiers tels que lโombrine ocellรฉe Sciaenops ocellatus et le vivaneau rouge Lutjanus campechanus (Coleman et al. 2004). Dans lโรฉtat du Minnesota, Olson et Cunningham (1989) ont observรฉ une diminution du nombre de gros spรฉcimens, notamment pour le maskinongรฉ Esox masquinongy, le grand brochet Esox lucius, le dorรฉ jaune Sander vitreus, lโachigan ร grande bouche Micropterus salmoides et le crapet arlequin Lepomis macrochirus. Par ailleurs, une autre รฉtude au Minnesota a montrรฉ que les populations exploitรฉes de marigane noire Pomoxis nigromaculatus ont dรฉclinรฉ tandis que lโabondance du dorรฉ jaune a augmentรฉ entre 1983 et 1997 (Grant et al. 2004). Au Wisconsin, un suivi des populations exploitรฉes de crapet arlequin et de perchaude ร partir de filets expรฉrimentaux a rรฉvรฉlรฉ que la taille moyenne ainsi que la proportion dโindividus de grande taille ont รฉtรฉ rรฉduites de 1967 ร 1991 (Beard & Kampa 1999). En plus, des donnรฉes de pรชche sportive de 1991 ร 2002 ont rรฉvรฉlรฉ que la longueur des crapets a diminuรฉ alors que le succรจs de pรชche au dorรฉ jaune est restรฉ le mรชme (Deroba et al. 2007). Donc, considรฉrant le dรฉclin de plusieurs espรจces de poissons dโintรฉrรชt sportif, il apparait maintenant nรฉcessaire dโeffectuer de meilleurs suivis ร long terme des populations de poissons, afin de prรฉvenir lโeffondrement des pรชcheries rรฉcrรฉatives (Radomski et al. 2001; Cooke & Cowx 2006; Dauwalter et al. 2009; McClelland et al. 2012).
LONG-TERM TRENDS OF THE BROOK TROUT RECREATIONAL FISHERY IN CONTROLLED WILDLIFE
Recreational fishing is an important cultural, economic, and social activity in many parts of the world (Arlinghaus et al. 2002; Post et al. 2002; Cooke & Cowx 2004; Allan et al. 2005; Lewin et al. 2006). However, the cumulative effects of habitat modification, invasion by exotic species, improved access to lakes, and increased fishing pressure have caused the decline of many recreational fisheries (McPhee et al. 2002; Post et al. 2002; Chu et al. 2003; Coleman et al. 2004; Dextrase & Mandrak 2006). Several studies have shown that the abundance and size of freshwater game fish have decreased over time (Olson & Cunningham 1989; Cook & Younk 1998; Beard & Kampa 1999;Young et al. 1999; Almodรณvar & Nicola 2004; Grant et al. 2004; Deroba et al. 2007; Lehtonen et al. 2009; Poulet et al. 2011). Because many recreational fisheries have declined, there has been a need for more large-scale spatial and temporal analyses of fish populations (Radomski et al. 2001; Lester et al. 2003; Cooke & Cowx 2006; Mosindy & Duffy 2007; McClelland et al. 2012). In Canada, there has been no attempt to evaluate the status of recreational fisheries since Pearse (1988). Nonetheless, Post et al. (2002) identified four high-profile Canadian fisheries that showed evidence of strong declines attributable to recreational angling. They stated that these declines were largely unnoticed by fisheries scientists and managers, as well as the public, and described this phenomenon as an โinvisible collapse.โ Fish stocking, the poor intergenerational memory of anglers, temporal and spatial variability in fish populations and the lack of data have contributed to masking the decline of angling quality (Post et al. 2002).
Study area and database
In the province of Quรฉbec, a substantial proportion of brook trout exploitation occurs in small lakes of three types of wildlife areas: national parks, wildlife reserves, and controlled harvest zones (also called zec; Pearse & Wilson 1999). These territories cover approximately 50 % of the southern half of the province. Since the 1970s, fishing in these areas has been carefully controlled by governmental agencies and sometime in association with voluntary organizations. Access is controlled in each area for each lake, and fishing results must be reported daily by anglers to fishery officers who record the number and, if available, the total biomass of harvested fish. Moreover, in national parks and wildlife reserves, anglers can be randomly allocated among lakes by lottery to disperse fishing effort. Fishery managers try to maintain the maximum sustainable fishing yield (MSY) of these lakes by controlling fishing pressure through the imposition of annual exploitation quotas that are reviewed periodically (Ricker 1980). As a result, the Quรฉbec Ministry of Forests, Wildlife and Parks (MFWP) has maintained, since 1970, a database for more than 10,000 lakes containing the number and weight of all harvested brook trout in addition to the total fishing effort for each lake and each year. All the fishery data used in this study were extracted from this database.
Lake selection
In the present study, we only used data from lakes because data from rivers were incomplete and represent a very small proportion of the database. To ensure that the measured fishing effort was not for species other than brook trout, all lakes containing other species targeted by sport anglers (e.g., lake trout Salvelinus namaycush, landlocked Atlantic salmon Salmo salar, northern pike Esox Lucius, rainbow trout Oncorhynchus mykiss, smallmouth bass Micropterus dolomieu and walleye Sander vitreus) were excluded. To increase the chance of detecting temporal trends, we selected lakes for which at least ten years of data were available and for which the data series were at least 75 % complete (e.g., a minimum of 15 years of data available for a data series that cover the period between 1990 and 2010). A total of 4155 lakes met those criteria and were selected for the analysis (Fig. 1), corresponding to approximately 65 million brook trout harvested and 16 million angler-days between 1963 and 2011. Selected lakes had 25 years of data on average, and most of them cover the entire period from 1980 to 2009. To the best of our knowledge, this is the most extensive angling database ever studied. Since 1963, there have been some changes in fishing regulations, such as a reduction in daily creel limits and annual exploitation quotas. The length of the fishing season varied between lakes and years, but fishing occurred during summer only in most lakes. The use of baitfish was prohibited, and there was no size limits for any lakes. Lakes were located on the Canadian Shield and the Appalachians. There was no agriculture activities in the catchment area of these lakes (La Financiรจre Agricole du Quรฉbec 2013).
Fishery data
The fishery data used in the analysis were fishing success, mean weight, fishing yield, and fishing pressure. Fishing success was estimated as the number of fish harvested per unit effort (HPUE). HPUE was estimated as a total ratio estimator, representing the total number of fish harvested in a year divided by the total number of angler-days (Malvestuto 1994). Mean weight (g) was calculated by dividing the total harvested biomass by the number of fish harvested. Fishing yield is the total weight of fish captured per hectare of lake area (kgโขha-1 ). Because fish weight was not recorded for all lakes, the two last estimators could not be calculated for 64 lakes. Fishing pressure, i.e., the number of angler-days per hectare of lake area (A-Dโขha-1 ), was also used in the study but not in all analyses. Each variable was calculated for each lake and for each year.
Independent variables
To determine which factors influence the temporal trends seen in the fishery data, several independent variables reported in the literature to have an impact on brook trout populations were included in the analyses. Since measurements of independent variables were not available for all lakes, the number of data included in the analysis differed among factors. When two independent variables were highly correlated (Pearson correlation coefficient r > 0.8), only one was kept in the analysis. Some variables were rejected because of their small range of values or because of their imprecision at the lake scale (i.e., annual precipitation, annual temperature, basin permanence index, forest cover of catchment area, lake acidity, maximum lake depth, and lake perimeter). The first independent variable analyzed was stocking frequency (%), which was calculated as the number of years stocked divided by the total number of years that data were collected for that lake. For example, a lake that was stocked once every two years has a stocking frequency of 50 %. Stocking frequency was grouped into five categories: never stocked 0 %, ]0-25 %], ]25-50 %], ]50-75 %] and ]75-100 %]. The second independent variable was interspecific competition, either allopatric or sympatric brook trout populations. This information, available for about half of the lakes, resulted from experimental fishing conducted by different governmental agencies since 1960. Electric fishing and gillnets were the primary sample methods, but, trap nets and seines were also used. The information concerning the lake and landscape variables used (latitude, longitude, altitude, areas, mean depth, and shoreline development) are from Lacs et Cours dโEau database of the Quรฉbec Ministry of Sustainable Development, Environment and Fight against Climate Change or were determined using digital maps (ArcGIS 10.1). For physical landscape characteristics (area, slope, number of culverts, river density, and road density) we used data from many databases (National Hydro Network, Rรฉseau de transport terrestre du Quรฉbec, Cadre de rรฉfรฉrence hydrologique du Quรฉbec and Canada digital elevation database) and ArcGIS software.
CONCLUSION GรNรRALE
Puisque lโomble de fontaine est le poisson dโintรฉrรชt sportif le plus exploitรฉ de la province, il รฉtait nรฉcessaire dโรฉvaluer lโรฉtat des pรชcheries rรฉcrรฉatives et รฉgalement de dรฉcrire leurs changements durant les 30 derniรจres annรฉes. En outre, lโobjectif de ce projet consistait ร รฉvaluer lโimpact de plusieurs variables biologiques, gรฉographiques et anthropiques sur les changements temporels des populations lacustres dโomble de fontaine dans les territoires fauniques structurรฉs. De plus, plusieurs aspects appliquรฉs concernant la gestion de lโomble de fontaine dans ces territoires ont รฉtรฉ examinรฉs.
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Table des matiรจres
INTRODUCTION GรNรRALEย
1.1 OBJECTIFS
LONG-TERM TRENDS OF THE BROOK TROUT RECREATIONAL FISHERY IN CONTROLLED WILDLIFE AREAS OF QUรBEC
2.1 INTRODUCTION
2.2 MATERIALS AND METHODS
2.2.1 Study area and database
2.2.2 Lake selection
2.2.3 Fishery data
2.2.4 Independent variables
2.2.5 Data analysis
2.3 RESULTS
2.4 DISCUSSION
2.4.1 Broad-scale trends
2.4.2 Factors influencing trends in fishery data
2.4.3 Usefulness of recreational catch data
2.4.4 Implications for brook trout management in controlled wildlife areas of Quรฉbec
SYNTHรSE DES DONNรES RELATIVES ร LA GESTION DE LโOMBLE DE FONTAINE DANS LES TERRITOIRES FAUNIQUES STRUCTURรS DU QUรBEC
3.1 MISE EN CONTEXTE
3.2 RรSULTATS ET DISCUSSION
3.2.1 Est-ce que la rรฉcolte dโomble de fontaine a diminuรฉ dans les territoires fauniques
structurรฉs depuis 1980 ?
3.2.2 La rรฉduction des limites de prise et de possession peut-elle expliquer la diminution du succรจs de pรชche entre 1980 et 2009?
3.2.3 Est-ce que lโรฉtat des populations diffรจre selon le type de territoire faunique ?
3.2.4 Est-ce que les tendances temporelles diffรจrent entre les rรฉgions administratives ?
3.2.5 Les quotas annuels dโexploitation sont-ils efficaces ?
3.2.6 Le nombre moyen dโheures pรชchรฉes par journรฉe a-t-il diminuรฉ depuis 1980 ?
3.2.7 Est-ce que les lโรฉtat des populations est bien reprรฉsentรฉ par donnรฉes de pรชche sportive?
CONCLUSION GรNรRALE
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