Effects of landing net mesh type on injury and mortality in a freshwater recreational fishery

Landing nets used by recreational anglers can be constructed of a variety of different mesh materials. Anglers and fisheries managers have hypothesized that mesh type may affect injury rates and fish survival. To test this hypothesis, we used bluegill (Lepomis macrochirus) as a model species to examine the effects of different net mesh types (rubber, knotless nylon, fine knotted nylon, coarse knotted nylon) on injury and mortality following angling at 26 degreesC. A control group consisted of individuals that were angled and held out of the water but not netted. Retention in a landing net for 30 s resulted in increased pectoral and caudal fin abrasion relative to control fish. Furthermore, evidence of dermal disturbance (i.e. scale and/or mucous loss) was more prevalent in netted fish than in control individuals. No control fish died during a 168 h holding period, whereas mortality rates ranged from 4 to 14% for fish landed with nets, and the majority of mortality occurred between 48 and 96 h post-treatment. Fish that died exhibited impaired swimming behavior for approximately 24 h prior to death that was attributable to the extreme caudal fin erosion. Fish that died also had Saprolegnian lesions on the caudal peduncle that had begun to progress anteriorly toward the gills. Our results indicate that fish captured and landed by hand had lower injury rates than those fish landed using a net and experienced no mortality. Conversely, all net types resulted in heightened injury and mortality with the knotted mesh types being more injurious than the rubber or knotless mesh. This study supports the hypotheses that landing nets injure fish, and that mesh type alters the severity of injury. We urge further study using larger species of fish that are commonly landed using these gear types. (C) 2003 Elsevier Science B.V. All rights reserved.