Get it before it gets to my catch: misdirection traps to mitigate against socioeconomic impacts associated with crayfish invasion

Abstract

The threats posed by invasive freshwater crayfish species are one of the greatest concerns for freshwater ecologists, environmental managers, policy makers and local communities in the invaded regions. The invasive Australian redclaw crayfish Cherax quadricarinatus is rapidly spreading in southern Africa. Fishers in the Zambezi Basin have reported that crayfish affect their catch through partial consumption of fish caught on static gillnets. Owing to the immeasurable contributions of fishery to socioeconomic livelihoods in Africa, the catch losses that are due to crayfish are of concern. With this problem in Africa, it is imperative to continue researching on adaptive strategies to cope with the invasion. This study tested the effectiveness of “misdirection traps” to prevent fish spoilage and gear damage for gillnet catches by crayfish in Lake Kariba, Zimbabwe. The method involved placing baited traps along a gillnet to misdirect crayfish into the traps rather than fishing gear to prevent fish spoilage by scavenging. The misdirection traps significantly lowered the amount of catch spoilage. Gillnet damage by crayfish in general was minimal, although it was higher for gillnets without baited traps. The misdirection traps pose a pragmatic management initiative to reduce socioeconomic fishery costs from crayfish. We consider this method to be applicable in all the invaded regions where artisanal fishers are experiencing catch spoilage problems making a huge step towards preventing socioeconomic impacts associated with crayfish invasion.