A Novel System for the Deployment and Retrieval of Trawl Gear from the Bow of a Small Research Vessel

Research vessel crews have increasingly applied trawling gear in a diversity of freshwater habitats, including river systems. Crews typically deploy and retrieve trawling gear by hand or with hydraulic winches. These methods are often labor intensive and require crews of three or more people to operate safely. Additionally, unless the research vessel has an inboard engine with power take-off capabilities, hydraulic winches will need to be powered by a generator, requiring additional maintenance and creating a loud work environment. We describe a new system for the deployment and retrieval of trawling gear that is suitable for smaller vessels where a hydraulic system may not be practical. This system utilizes electric line haulers mounted on davits at the bow of the boat. The line haulers are retrofitted with a novel mechanism for loading the trawl line into the line hauler pulley, allowing deployment and retrieval of many types of trawl gear by one deckhand and one boat operator. The electric trawl retrieval system is powered by a battery bank that charges from the boat motor, thereby reducing risk of hearing damage from generator noise. We have designed it to be interchangeable and portable amongst different research vessels, which increases sampling efficiency and reduces costs.