Effects of Retention Gear on the Injury and Short-Term Mortality of Adult Smallmouth Bass

Abstract

Little is known about the effects of the different types of fish retention gear commonly used by recreational anglers, such as stringers, fish baskets, and keep nets. The injury and short-term mortality of 313 adult smallmouth bass Micropterus dolomieu were studied at Lake Erie over a range of water temperatures (10.6–21.8°C). Lure-caught fish were retained by one of the following six gear types or methods for 3–5 h: metal stringer through lip, metal stringer through gill arch, cord through lip, cord through gill arch, wire fish basket, and nylon keep net. Fish were then transferred to a holding pen and their survival estimated relative to control fish over a 48-h period. Control fish exhibited very little mortality (3%) and had negligible physical injury across all sampling periods. Most retained fish (95%) experienced some form of injury or mortality. In general, increased injury and mortality coincided with higher water temperatures, particularly when water temperatures reached 21.8°C. Survival and injury varied among retention gears, but gill damage or fungal lesions associated with abrasion, along with the cumulative stress of angling and retention, appeared to be the precursors to most deaths. These results suggest that even at low water temperatures, significant injury can occur from retention gear; at higher temperatures, this injury seems to manifest itself in death. For this reason, these gears should only be used with fish that are to be harvested, not those that are to be temporarily retained before release.