Summary
- Research has identified numerous conservation benefits attributed to the use of marine protected areas (MPAs), yet comparatively less is known about the effectiveness of freshwater protected areas (FPAs).
- This study assessed multiple long‐standing (>70 years active) intra‐lake FPAs in three lakes in eastern Ontario, Canada, to evaluate their potential conservation benefits. These FPAs were intended initially to protect exploited populations of largemouth bass (Micropterus salmoides (Lacépède, 1802)), but since their establishment no empirical data have been collected to evaluate the effectiveness of FPAs for protecting bass or the broader fish community.
- A comparative biological census of fish species abundance, biomass and species richness was conducted using snorkelling surveys within FPAs, along the bordering transition zones, and in more distant non‐protected areas of the lake that had similar habitats to the FPAs.
- In general, the FPAs yielded benefits that were most obvious (in terms of abundance and biomass) for the focal protected species (i.e. largemouth bass) as well as several shiner species. Largemouth bass and shiner abundance and biomass were highest in the FPA, lowest in the distant non‐protected areas, and intermediate in the transition zone. Species richness was also highest in the FPAs in two of the three lakes.
- Collectively, these results support the use of FPAs as a viable and effective conservation strategy that extends beyond simply limiting the exploitation of a target species. Beyond the benefits afforded to fish within the FPA, evidence of spillover in adjacent areas was also observed, which is promising. Additional research is needed on the effectiveness of FPAs in a variety of regions and water‐body types facing various threats in an effort to understand when, where and how to best use FPAs to benefit aquatic biodiversity.
Methodology
Study sites
Three interconnected lakes throughout the Rideau Lakes system, Ontario, Canada, were used for this study: Lake Opinicon, Newboro Lake and Big Rideau Lake. Each of these lakes has one or more long‐standing (i.e. >70 year) intra‐lake FPAs that provides year‐round protection from fishing activity (Figure 1). The placement of the FPAs within each of the study lakes was based on historical knowledge of spawning locations for largemouth bass, provided from anecdotal observations by local fishing guides and resource managers (Ontario Department of Game and Fisheries, 1946). All lakes have active recreational fisheries (both catch‐and‐release and catch‐and‐harvest) for a variety of species of fishes including, but not limited to, black basses (a collective term for both smallmouth bass and largemouth bass), northern pike (Esox lucius (Linnaeus, 1758)), bluegill (Lepomis macrochirus (Rafinesque, 1810)) and yellow perch (Perca flavescens (Mitchill, 1814)). These lakes are also subject to intermittent small‐scale commercial fishing activity that targets mainly ‘pan‐fish’, e.g. bluegill and pumpkinseed (Lepomis gibbosus (Linnaeus, 1758)), yellow perch, black crappie (Pomoxis nigromaculatus (Lesueur, 1829)) and brown bullhead (Ameiurus nebulosus (Lesueur, 1819); Hogg, Lester, & Ball, 2010; Larocque et al., 2012) – all such fishing activities, both commercial and recreational, are prohibited inside the FPAs, and have been since their inception. Lake Opinicon (~8.66 km2) houses two separate FPAs with an approximate combined protection area of 1.0 km2. Newboro Lake (~17.01 km2) also has two separate FPAs with an approximate combined protection area of 3.33 km2. Big Rideau Lake (~45.36 km2) has one designated FPA with an approximate protection area of 0.57 km2 (Figure 1). These long‐standing protected areas are easily identifiable from the water (i.e. well‐maintained signage posted at each entrance way and along the bordering transition zones between the FPAs and neighbouring waters, as defined below), as well as from navigation and fishing maps. Furthermore, these FPAs are actively patrolled and enforced by the Ontario Ministry of Natural Resources and Forestry with assistance in reporting of infractions by the public to ensure that fishing activity does not occur within their boundaries.
Visual censuses
Fish species richness, abundance and size (estimated to within a ± 2 cm error) were recorded by snorkellers conducting visual surveys along standardized transects within the littoral regions of each study lake. Transects were established within three zones of each lake. The three lake zones were designated as (1) entirely within the FPAs, (2) within the bordering transition zone immediately adjacent to the FPA boundaries, which we defined as the area of water/habitat extending outwards up to 2 km from an FPA border and (3) outside in fished areas, which we defined as the lake area that extended beyond the transition zone (i.e. >2 km from FPAs). Establishing the transition zones as 2 km lake/habitat areas enabled the home range size of largemouth bass to be accounted for (i.e. <1 km2; Lewis & Flickinger, 1967; Ahrenstorff, Sass, & Helmus, 2009), reducing the potential confound of quantifying transient fish that may be long‐term inhabitants of either the FPA or the outside fished lake zone. Establishing three distinct lake zones to survey in this manner allows informative evaluations of the effectiveness of these FPAs as a conservation tool, through the assessment of ecological spillover and/or changes in fish community structure between lake zones.