Determinants of Angling Catch of Northern Pike (Esox Lucius) As

Fisheries Research 186 (2017) 648–657 Contents lists available at ScienceDirect Fisheries Research j ournal homepage: www.elsevier.com/locate/fishres Full length article Determinants of angling catch of northern pike (Esox lucius) as revealed by a controlled whole-lake catch-and-release angling experiment—The role of abiotic and biotic factors, spatial encounters and lure type a,b,∗ a,c a a,d Robert Arlinghaus , Josep Alós , Tonio Pieterek , Thomas Klefoth a Department of Biology and Ecology of Fishes, Leibniz-Institute of Freshwater Ecology and Inland Fisheries, Müggelseedamm 310, 12587 Berlin, Germany b Division of Integrative Fisheries Management, Faculty of Life Sciences & Integrative Research Institute for the Transformation of Human-Environment Systems (IRI THESys), Humboldt-Universität zu Berlin, Invalidenstrasse 42, 10115 Berlin, Germany c Instituto Mediterráneo de Estudios Avanzados, IMEDEA (CSIC-UIB), C/Miquel Marqués 21, 07190, Esporles, Illes Balears, Spain d Angling Association of Lower Saxony (Anglerverband Niedersachsen e.V.), Bürgermeister-Stümpel-Weg 1, 30457 Hannover, Germany a r a t i b s c l e i n f o t r a c t Article history: Studies on catches of anglers usually rely on observational data and are thus uncontrolled with respect Received 10 November 2015 to angler skill, bait/lure choice and site choice. We performed a controlled fishing experiment targeting Received in revised form 8 August 2016 northern pike (Esox lucius) in a small (25 ha), weakly eutrophic natural lake situated about 80 km northeast Accepted 10 September 2016 of Berlin (Germany) to understand abiotic, biotic and gear-related factors that relate to catch rates and size Handled by George A. Rose of pike captured by angling. The experiment was conducted over two one-week long fishing campaigns Available online 20 September 2016 where boat-based anglers randomly sampled across 30 pre-determined sites. Sites were systematically exposed to two standardized lure types (soft plastic shad or spoon). We found the catch rates of pike Keywords: Catchability per 15 min to be significantly higher in shallow water and when soft plastic lures were used compared to deeper water and when spoons were used. Catch rates significantly dropped over the course of seven Diel period Vulnerability days, suggesting either learning or other reasons moving pike from vulnerable to invulnerable pools Habitat choice (e.g., due to stress caused by capture, sampling and release). Catch rates also varied by season and across Avoidance learning anglers and sites as random effects. The variation in size of pike captured exhibited greater stochasticity than variation in catch rate. There was no lure effect on the size of the pike captured, but we found a seasonal effect and a day effect, suggesting larger fish were captured first. Pike captured in sublittoral areas were significantly smaller than those captured in other habitats. Overall, our study documented a novel effect of lure type on the catch rates of pike, but the explanatory power of the predictors was only moderate. Therefore, our results support the idea that the best fishing ingredients are investing time and maximizing encounter probabilities through habitat choice, with only moderate additional effects to be expected from attention to abiotic conditions, day time and choice of type of artificial lure. © 2016 Elsevier B.V. All rights reserved. 1. Introduction importance to anglers. Unsurprisingly, the angling media are filled with discussions about the best (i.e., most effective) lure type for Angler satisfaction is strongly determined by catch-related com- catching many and/or particularly large fishes. The lure industry ponents of the fishing experience, in particular size of fish and strategically taps into the intrinsic desire of anglers to optimize catch rates (Arlinghaus, 2006; Arlinghaus et al., 2014; Beardmore catches and constantly releases novel lure types, colors, shapes and et al., 2015). Therefore, private knowledge of determinants of catch attractants. However, from a robust scientific perspective surprins- rates and how to catch the largest individuals in a population is of ingly little is known whether the lure innovations actually have intented effects by boosting catch rates (but see Lennox et al., 2016; Rapp et al., 2008; Webster and Little, 1947 for notable exceptions). ∗ Northern pike (Esox lucius, hereafter referred to as pike) is a cir- Corresponding author at: Department of Biology and Ecology of Fishes, Leibniz- cumpolarly distributed aquatic top predator that lives in river and Institute of Freshwater Ecology and Inland Fisheries, Müggelseedamm 310, 12587 Berlin. lakes and low-salinity coastal waters (Craig, 1996; Raat, 1988). It E-mail address: [email protected] (R. Arlinghaus). http://dx.doi.org/10.1016/j.fishres.2016.09.009 0165-7836/© 2016 Elsevier B.V. All rights reserved. R. Arlinghaus et al. / Fisheries Research 186 (2017) 648–657 649 constitutes the prime target species of inland and some coastal In recent years, fishing for pike and other freshwater predators fishers in many countries in the northern hemisphere (Crane with variants of soft plastic lures has become fashionable, partic- et al., 2015; Paukert et al., 2001; Arlinghaus and Mehner, 2004; ularly among specialized angler groups (Arlinghaus et al., 2008b; Arlinghaus et al., 2008a). Pike is especially desired by recreational Raison et al., 2014; Stålhammar et al., 2014). Given the more natu- anglers. Due to its aggressive foraging behaviour and close associ- ral shape and texture, many specialized anglers are convinced that ation to underwater vegetation, pike habitats are easily identified soft plastics (lures made out of soft rubber baits, often mimicking by anglers, leading to pike being highly vulnerable to overexploita- the form of fishes) are more effective lures in pike angling com- tion diagnosed by severe size truncation (Pierce, 2010; Arlinghaus pared to traditional lures such as spoons (lures made out of metal et al., 2010; Pierce et al., 1995; Post et al., 2002). Pike popula- blades) and spinners (lures made out of rotating metal blades). tions are known to be composed of different behavioural types There is indeed evidence that pike ingest soft plastic lures of an (Kobler et al., 2009), and recent research by Pieterek (2014) has appropriate size more deeply than other artificial lures (Arlinghaus documented variation in individual vulnerability to angling as a et al., 2008b; but see Stålhammar et al., 2014), and several pisciv- function of behavioural and life-history traits. More active, explo- orous fish species have even been found with soft plastic lures in rative and faster-growing individuals were found to be particuarly their stomach, suggesting they confused such bait with natural prey vulnerable to angling, while slower growing individuals spending (Danner et al., 2009; Raison et al., 2014). Stålhammar et al. (2014) most of their life in refuges unaccessible to anglers were less readily showed that the average sizes of Baltic Sea pike captured on var- captured (Pieterek, 2014). Intensive angling might thus also con- ious lure types differed, and there was a trend for pike captured stitute an evolutionary force altering life-history and behaviour of on soft-plastics to be among the largest fishes captured. Unfor- exploited pike populations (Arlinghaus et al., 2009a; Arlinghaus tunately, no spoons were used in that study, which according to et al. in press). anectodal information are commonly used among less experienced The fact that pike cluster into vulnerable and invulnerable indi- pike anglers and are among the oldest and most traditional pike viduals agrees with foraging arena theory (Cox and Walters, 2002), lures. Arlinghaus et al. (2008b) reported that the average catch which assumes that not the entire fish population is available to rates of freshwater pike exposed to artificial lures were twice as anglers (or other predators) to capture in any moment in time high as those of natural bait, but the average size of pike captured (Matthias et al., 2014). Indeed, for behavioural and partly also on soft plastics and spoons did not differ. However, Arlinghaus et al. for underlying genetic reasons, some individuals might even be (2008b) did not control for the size of artificial lures, and neither entirely invulnerable to angling (Philipp et al., 2009), in turn never Arlinghaus et al. (2008b) nor Stålhammar et al. (2014) fully con- showing up in the vulnerable pool accessible to anglers. Moreoever, trolled site choices and gears of experimental anglers. Because of Kuparinen et al. (2010) showed that high pike angling effort two the potential co-variance of angler site choice and angler skill with days prior to a fishing event significantly reduced catch rates in a a particular lure type (Matthias et al., 2014), robust knowledge on total catch-and-release pike fishery, suggesting that the vulnerable the relative effectivness of lure types can only be generated in a fully pool of fishes can further change in response to previous exposure controlled setting where experimental anglers use exactly the same to fishing due to learning (Beukema, 1970). Klefoth et al. (2008, gear types at the same location in a random fashion. We completed 2011), Arlinghaus et al. (2008c) and Baktoft et al. (2013), however, such a study using two one-week long experimental angling ses- reported that recovery of normal behavioural patterns after catch- sions targeting pike in a small freshwater lake in Germany for which and-release was very

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