Summary
The continued popularity of angling for largemouth bass Micropterus salmoides and smallmouth bass M. dolomieu has led to concerns about the effects it may have on fish populations, including the realized fitness of individuals. Although catch‐and‐release angling and its effects on nest abandonment have been well documented, very little research has examined the effect that competitive angling practices may have on nest abandonment. We subjected nest‐guarding male largemouth bass in one lake and smallmouth bass in four lakes to various competitive angling practices (i.e., livewell retention, release after displacement from the nest, and a combination of these practices) and assessed subsequent nest abandonment. We also examined the importance of nest predation on the nest abandonment decisions of male bass by protecting some of the nests from predation after the angling event. Nest abandonment by largemouth bass was affected by angling treatment, the water depth at the nest site, and brood size but was not affected by male size. Angling treatment and lake influenced abandonment by smallmouth bass guarding eggs, whereas angling treatment, lake, and the presence of a protective nest cover influenced nest abandonment by smallmouth bass guarding fry. The only factor that influenced abandonment for both species and all stages was angling treatment, with abandonment being highest for all treatments that involved prolonged removal and displacement (i.e., the complete tournament simulation). These findings could be important to bass populations if year‐class size is related to the number of successful nests. The effects of angling, both catch and release and competitive, on individual nesting success in largemouth bass and smallmouth bass are now well understood, although additional work is needed to determine whether disruption of nesting at the individual level translates to population‐level effects.
Methodology
Largemouth bass nests were located by means of snorkel surveys in Lake Opinicon, southeastern Ontario, whereas smallmouth bass nests were located in Lake Opinicon, Sand Lake, Charleston Lake, and Wolfe Lake. Lakes were selected based on the abundance of study fish inhabiting the waters, and all lakes contained a variety of known brood predators (e.g., bluegill Lepomis macrochirus, pumpkinseed L. gibbosus, rock bass Ambloplites rupestris, black crappie Pomoxis nigromaculatus, and yellow perch Perca flavescens ). Nests were marked underwater with a numbered polyvinyl chloride tag, and their locations were mapped on a plastic slate. Snorkelers also recorded nest depth, brood size (a ranking system from 1 to 5, with 1 representing a nest with few eggs and 5 representing a nest containing a large number of eggs; Kubacki 1992), and developmental stage of the offspring (i.e., egg or fry in nest; Kramer and Smith 1962; Kieffer et al. 1995). Study groups consisting of male largemouth bass (360 ± 4 mm total length [TL], mean ± SE) guarding eggs and male smallmouth bass guarding either eggs (381 ± 4 mm) or fry (386 ± 5 mm) were angled off nests from 23 May to 17 June 2002. After fish were successfully hooked and landed, they were measured (TL) and given a fin clip for later identification on the nest. A completely randomized design with nest abandonment as the binary response variable was used to assign males to one of the following treatments:
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Control: males were only exposed to measurement of nest data. Male sizes were estimated underwater by the snorkeler, and no angling treatment was applied to the fish.
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Catch and Release: males were removed from their nests by hook‐and‐line angling. Anglers used a Texas‐rigged, 10‐cm plastic worm and cast past the nest before working the bait into the nest. After anglers sensed a strike, they set the hook and quickly landed the fish (∼15 s). Fish were then subjected to a 120‐s period of air exposure (Cooke et al. 2002b), a length of time typically required to remove the hook and measure the fish's TL, before releasing the individual within 10 m of his nest.
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Distance: males were angled as above and subjected to a 120‐s period of air exposure during hook removal and measuring, and during that time each fish was moved 1 km from the nest site and released. Fish are often transported greater distances during actual competitive angling events (see Stang et al. 1996; Bunt et al. 2002; Wilde 2003); we chose displacement of 1 km for this study as a conservative but still common distance for tournaments in small lakes.
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Time: males were angled as above, subjected to 120 s of air exposure while the hook was removed and a TL measurement taken, and placed in a recirculating livewell (41 L with intermittent flow through; i.e., a timer provided fresh lake water for 1 min every 6 min). Fish densities never exceeded five fish per livewell. After 2 h, each fish was returned to the nest site and released within 10 m of the nest.
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Time + Distance: males were angled, subjected to a 120‐s period of air exposure, and placed in a recirculating livewell as described previously. After 2 h of confinement, the parental male was moved 1 km from the nest site and released.