Boater Habits and the Potential Spread of the Clubbed tunicate, Styela clava Introduction To assess the role of boating activities and movements in dispersal of tunicates in the southern Gulf of St. Lawrence, interviews were conducted and samples were collected from recreational and commercial boats as they arrived in marinas in eastern Prince Edward Island (PEI). At the time of the study, the clubbed tunicate Styela clava was the only non- indigenous tunicate recorded from the area. The goal of these interviews and sampling was to determine (1) what activities might spread the species; (2) the predominant movement patterns of vessels; and (3) if tunicates were present on the boats. Methods During the summers of 2003 and 2004, 150 boater interviews were carried out in eastern PEI (Fig. 1). Boaters were questioned on how long their boat had been at the present location and where it was headed next, the primary use of the vessel, whether anchors, sounding equipment or fishing gear were used, whether any organisms were attached to these items when retrieved, and the fate of those organisms. Bilge water was collected using a turkey baster and the hull was sampled near the water line with a rubber squeegee; samples were preserved in 4% buffered formaldehyde and examined under a dissecting microscope. Results Boater Behaviours: Over 1/3 of the boaters participated in fishing activities and almost 1/4 of their vessels were equipped with live wells, tanks or similar devices which could transport invaders (Table 1). Any water in these devices was usually dumped at sea. This reduces the likelihood of spread of larval tunicates to estuaries, the typical habitat of clubbed tunicate. Over 2/3 of the commercial fishermen used some type of trap or net. Organisms attached to these devices could be moved to new locations. Most fishermen threw entangled organisms on nets or traps overboard at the location where they were found. This greatly reduces the likelihood of large, visible, organisms such as adult tunicates being accidentally transported to new locations on this type of fishing gear. Fouling of the anchor, sounding equipment and other associated structures also do not seem to be important for the dispersal of clubbed tunicate from PEI. Boat Movements: Fishermen docked more often in their home ports compared to recreational boaters who docked more often in other locations (Table 2). Recreational boaters traveled more often to areas that were uninfected by clubbed tunicates. Based on ‘next port’ responses, Pictou and Cape Breton, Nova Scotia as well as Charlottetown, PEI, are the next likely locations of spread of the clubbed tunicate from southeastern PEI. Lobster fishermen moved less from port to port compared to tuna or crab fishermen or mussel growers. Among recreational vessels, sailboats tended to move from port to port while motorized vessels returned to the same port more often. Bilge and Hull Sampling: Bilge water and hull scrapings collected from the vessels were found to contain 47 taxa and 71 taxa, respectively. The items found most often in the samples were copepods and copepod nauplii, fish eggs, bivalve veligers, barnacle nauplii, mites and nematodes. No tunicates were found in any of the samples. Darbyson, E., A. Locke*, J.M. Hanson* and J.H.M. Willison Dept. of Biology, Dalhousie University, Halifax, Nova Scotia * Gulf Fisheries Centre, Fisheries and Oceans Canada, P.O. Box 5030, Moncton, New Brunswick Figure 1. Locations of boater interviews. Conclusions For the most part, boaters appear to be handling their bait, entangled organisms, etc., in ways that should minimize the spread of tunicates. Based on boater movements, recreational boaters in PEI are more likely to act as vectors than commercial fishermen. Sailboats moved between ports more often than recreational power boats. However, some commercial groups, such as tuna fishermen, are even more far-ranging, moving between ports of southern Nova Scotia and eastern PEI. We did not detect any tunicates being transported on boats. In this study, our study of commercial boaters was the result of an opportunistic sampling schedule and future work should target the different fleets over the whole of the southern Gulf of St. Lawrence. Only a few aquaculture boats were sampled, as their industry association declined to participate in the survey, but the movements of this group should be part of future work. Interview questionPositive responses No. of vessels Percentage of total Used vessel for fishing Vessel equipped with live wells or tanks Used live wells or tanks in last 5 days Dumped water from live wells or tanks at sea Dumped water from live wells or tanks in port21.3 Used bait Used live bait138.7 Used salted bait21.3 Stored bait on ice Stored bait in a bucket21.3 Dumped bait water at sea Used a net or trap Found algae on net or trap Dumped algae at sea Dumped algae on land10.7 Dumped algae in port21.3 Used scientific or sounding equipment Found algae on equipment Dumped algae at sea10.7 Dumped algae in port53.3 Dumped algae on land149.3 Did not dump algae10.7 Cleaned off algae at the end of the season21.3 Used an anchor Found algae on the anchor85.3 Dumped algae at sea85.3 Traveled overland to next port of call64.0 Interview questionCommercial fishing vessels (N=53) Recreational vessels (N=85) NumberPercentage of total NumberPercentage of total Docked in home port Docked in home estuary (but not home port) Docked outside home estuary Will dock next in home port Will dock next in home estuary (but not home port) Will dock next outside home estuary Table 1. Boater behaviours in PEI, based on interviews. Table 2. Boater movement patterns deduced from interviews in PEI.