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.
Remote cameras are an increasingly important tool in field-based biological research. Terrestrial researchers can purchase inexpensive off-the-shelf cameras, but aquatic researchers face challenges in adopting similar systems for underwater science. Although technology allows researchers to deploy cameras in any aquatic environment, high procurement costs are often a barrier, particularly for studies that require the collection of lengthy videos. In this note, we provide a detailed guide explaining how to assemble an underwater camera system for less than $425 USD. We focus especially on the construction of the underwater housing, which is typically the most expensive component of an underwater camera system. As described, this system can record 13 h full high-definition videos in depths up to 100 m. It can be constructed and assembled with limited technical background using tools available in most workshops. The guide includes a general overview of the system, a full list of components, detailed instructions on constructing the camera housing, and suggestions on how to mount and use the camera in fieldwork. Our goal for this note is to promote the wider use of remote underwater cameras in aquatic research by making them accessible to those with limited financial means.
The European green crab (Carcinus maenas) is a crustacean species native to European and North African coastlines that has become one of the world’s most successful marine invasive species. Targeted fishing programs aimed at removing green crabs from invaded ecosystems commonly use Fukui multi-species marine traps. Improving the efficiency of these traps would improve the ability to respond to green crab invasions. In this study, we developed four distinct trap modifications that were designed to facilitate the successful capture of green crabs, with the goal of improving the performance of the Fukui trap. We tested these modifications in situ during the summer of 2016 at two locations in Placentia Bay, Newfoundland. We discovered that three of our modified Fukui trap designs caught significantly more green crabs than the standard Fukui trap, increasing catch-per-unit-effort (CPUE) by as much as 81%. We conclude that our top-performing modifications have great potential for widespread use with existing Fukui traps that are being used for green crab removal efforts.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.