Using underwater video to evaluate the performance of the Fukui trap as a mitigation tool for the invasive European green crab (Carcinus maenas) in Newfoundland, Canada

Abstract

The European green crab (Carcinus maenas) is a destructive marine invader that was first discovered in Newfoundland waters in 2007 and has since become established in nearshore ecosystems on the south and west coast of the island. Targeted fishing programs aimed at removing green crabs from invaded Newfoundland ecosystems use Fukui traps, but the capture efficiency of these traps has not been previously assessed. We assessed Fukui traps using in situ observation with underwater video cameras as they actively fished for green crabs. From these videos, we recorded the number of green crabs that approached the trap, the outcome of each entry attempt (success or failure), and the number of exits from the trap. Across eight videos, we observed 1,226 green crab entry attempts, with only a 16% rate of success from these attempts. Based on these observations we believe there is scope to improve the performance of the Fukui trap through modifications in order to achieve a higher catch per unit effort (CPUE), maximizing trap usage for mitigation. Ultimately, a more efficient Fukui trap will help to control green crab populations in order to preserve the function and integrity of ecosystems invaded by the green crab.

Application of Luminescent Netting in Traps to Improve the Catchability of the Snow Crab Chionoecetes opilio

“…; Bergshoeff et al. ). The attraction phase depends on a variety of factors such as the satiation level of the targeted species, type and amount of bait, water velocity, density of the targeted species, and environment (Cyr and Sainte‐Marie ; Grant and Hiscock ; Bergshoeff et al.…”

“…The duration of attraction can vary from minutes to hours depending on the targeted species (Bergshoeff et al. ; Meintzer et al. ).…”

“…Underwater camera observations have shown that animals typically swim or walk up-currrent to find the odor source that is being released from the bait (e.g., Winger and Walsh 2011;Jørgensen et al 2017;Bergshoeff et al 2018). The attraction phase depends on a variety of factors such as the satiation level of the targeted species, type and amount of bait, water velocity, density of the targeted species, and environment (Cyr and Sainte-Marie 1995;Grant and Hiscock 2009;Bergshoeff et al 2018). The duration of attraction can vary from minutes to hours depending on the targeted species (Bergshoeff et al 2018;Meintzer et al 2018).…”

“…For the fishing experiment, a generalized linear mixedeffect model (GLMM) was used to estimate the effect of trap treatment on the CPUE of snow crabs. Since the CPUE is count data, it was best modeled with a negative binomial distribution (Jørgensen et al 2017;Bergshoeff et al 2018;Meintzer et al 2018;Nguyen and Winger, in press). Analyses were conducted separately for each soak 298 time condition via the glmmadmb function based on the glmmADMB package in R statistical software (R Core Team, Vienna).…”

PopulationDynamics of Green Crabs (Carcinus maenas) -- A Review

“…It is estimated that only 80% of a green crab population can be caught at any one time using traps ( [1]). Underwater video used to evaluate the effectiveness of Fukui traps to catch green crabs revealed only a 16% success rate out of 1,226 entry attempts [140]. Passive nets are sometimes used but this method trusts to the currents and wandering crabs to enter the net so may be equally unreliable as a population density estimate.…”