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

Studies on catches of anglers usually rely on observational data and are thus uncontrolled with respect to angler skill, bait/lure choice and site choice. We performed a controlled fishing experiment targeting northern pike (Esox lucius) in a small (25 ha), weakly eutrophic natural lake situated about 80 km northeastof Berlin (Germany) to understand abiotic, biotic and gear-related factors that relate to catch rates and size of pike captured by angling. The experiment was conducted over two one-week long fishing campaigns 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 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 days, suggesting either learning or other reasons moving pike from vulnerable to invulnerable pools (e.g., due to stress caused by capture, sampling and release). Catch rates also varied by season and across 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.