Quantitative Estimates of Nutrient Inputs From Angling Baits in Lakes Supporting Different Recreational Fisheries

Abstract

Recreational anglers use ground baiting to attract fish and increase catch inputs organic matter that can have important effects on water quality by increasing eutrophication. However, nutrient inputs from angling bait by recreational fisheries have not yet been estimated. We quantified nutrient inputs from angling baits in small lakes supporting specialized carp, put-and-take, and specialized roach recreational fisheries with a 2-year field survey of angling activity and in-person angler questionnaires. Angling activity was highly variable among recreational fisheries and averaged 82 (±74 SD) angler-day/ha/year in lakes with specialized carp fisheries, 145 (±80) in lakes with put-and-take fisheries, and 36 (±18) in lakes with specialized roach fisheries. Angling activity also differed temporally among recreational fisheries, with high angling activity in spring and summer for specialized carp and specialized roach fisheries, and in autumn and winter for put-and-take fisheries. The type and amount of baits used by anglers strongly differed among recreational fisheries, with specialized carp anglers using boilies (2.5 ± 1.5 SD kg/angler/day) and seeds (2.1 ± 1.9 kg/angler/day), put-and-take anglers using exclusively pellets (0.39 ± 0.15 kg/angler/day), and specialized roach anglers using ground baits (0.72 ± 0.36 kg/angler/day). Nutrient inputs from angling baits were highly variable among recreational fisheries and ranged from 0.5 (±0.2 SD) kg/ha/year of nitrogen and 0.1 (±0.0) kg/ha/year of phosphorus in specialized roach fisheries to 10.2 (±9.3) kg/ha/year of nitrogen and 1.6 (±1.5) kg/ha/year of phosphorus in specialized carp fisheries. Our findings revealed that ecological consequences of ground baiting differed among recreational fisheries, which should be useful for developing fishery-specific regulations to efficiently manage ground baiting.