Impacts of road access on lake trout (Salvelinus namaycush) populations: regional scale effects of overexploitation and the introduction of smallmouth bass (Micropterus dolomieu)

Abstract

In lake trout (Salvelinus namaycush) lakes of northeastern Ontario, Canada, aerial surveys of fishing activity on individual lakes (N = 589) and quantitative gillnet surveys (N = 65) were used to assess the effects of road access on angling effort and the presence of introduced smallmouth bass (Micropterus dolomieu). Angling effort, particularly during the open-water season, was highest and often exceeded estimated sustainable levels on lakes with good road access. Approximately 25% of the remote lakes also received excessive pressure during the winter season. Angler numerical responses to lake trout abundance were detected in remote lakes, but not in road-accessible lakes. Smallmouth bass were more prevalent in lakes with road access and human settlement (either cottages or lodges), supporting the theory that they were introduced into these lakes. Lake trout populations were depleted throughout much of the study range. Even without road access or smallmouth bass, lake trout abundance was still 47% lower than in unexploited reference lakes. When bass and (or) road access were present, lake trout abundance decreased by 77%. Remote lake trout populations in this area are clearly vulnerable to the negative impacts of improved access, a vector for both overexploitation and species introductions.Résumé : Des inventaires aériens de l'activité de pêche sur des lacs individus (N = 589) et des inventaires quantitatifs au filet maillant (N = 65) nous ont servi à évaluer les effets de l'accès routier sur l'effort de pêche sportive et sur la présence d'achigans à petite bouche (Micropterus dolomieu) introduits dans des lacs à touladis (Salvelinus namaycush) du nord-est de l'Ontario, Canada. L'effort de pêche, particulièrement durant la période d'eau libre, est le plus élevé dans les lacs facilement accessibles par la route et il dépasse souvent le niveau admissible estimé. Environ 25 % des lacs éloignés subissent aussi une pression excessive durant la saison d'hiver. On remarque une relation entre le nombre de pêcheurs et l'abondance des touladis dans les lacs éloignés, mais pas dans les lacs accessibles par la route. Les achigans à petite bouche sont plus présents dans les lacs à accès routier et à présence humaine (chalets ou auberges), ce qui laisse croire qu'ils ont été introduits dans ces lacs. Les populations de touladis sont réduites dans presque toute la région d'étude. Même en l'absence d'accès routier et d'achigans à petite bouche, l'abondance des touladis est tout de même de 47 % inférieure à celle des lacs témoins non exploités. Quand il y un accès routier et (ou) présence d'achigans, l'abondance des touladis est réduite de 77 %. Les populations éloignées de touladis sont visiblement vulnérables aux impacts négatifs de l'amélioration de l'accès routier, un vecteur représentatif à la fois de la surexploitation et de l'introduction d'espèces.[Traduit par la Rédaction]

Temporal and spatial patterns of angler effort across lake districts and policy options to sustain recreational fisheries

“…Therefore, policies that are successful in one context may not maintain quality fishing and ensure long-term sustainability across a landscape where effort varies. Since many recreational fisheries are embedded in lake districts, equivalent to multistock, spatially structured fisheries (Post et al 2008;Hunt and Lester 2009;Kaufman et al 2009), we expect to see variation in effort across space and therefore variable success of common harvest policies.…”

Relative demand by double-crested cormorants and anglers for fish production from lakes on Manitoulin Island, Lake Huron

“…Aerial surveys were used to collect midday activity count (MAC) data to estimate angler effort following standard protocols developed for provincial fisheries monitoring programs (Kaufman et al, 2009;Lester et al, 1991;McGuiness et al, 2000). Aerial surveys of anglers were distinct from aerial surveys of cormorants.…”

“…The midday activity bias factor values (K m ) ranged from 1.1 to 1.3 and were selected for each lake from values presented in Parker et al (2006) based on fish community (lake trout, walleye or multi-species targeted) and day-type (weekend vs weekday; Kaufman et al, 2009). For the ice-fishing season, parameter values used were: N = 90 (64 weekdays; 26 weekend days); T = 10 h; p = 2; K m ranged from 1.0 to 1.2.…”

Modelling Landscape-level Effects of Reduced Herbicide Use in Two Forests in Northern Ontario

“…Roads are essential for forest management and also provide access for recreation, but there is concern about potential undesirable effects on wildlife and remote fisheries (e.g., Rempel et al 1997, Kaufman et al 2009, Bowman et al 2010. Rempel et al (1997) showed that the small, dispersed harvest blocks recommended to produce habitat for moose in northwestern Ontario actually resulted in a lower density of moose than areas with larger harvest blocks, likely because the relatively dense road network needed for small blocks increased hunter access.…”