John Rothlisberger

Project Title:"Recreational boater risk assessments and individual-based modeling to limit spread of aquatic invasive species"

External Partnership: Lindsay Chadderton- Aquatic Invasive Species Director- The Nature Conservancy

Recreational boaters sometimes inadvertently transport aquatic organisms with them as they move from one body of water to another.  Organisms may be carried on boat hulls, fishing gear, and anchor lines and in live wells, bilge water, and bait buckets.  This inadvertent transport can result in the spread of aquatic invasive species (AIS) to previously uninvaded lakes and rivers.  The invasive spiny waterflea Bythotrephes longimanus, which disrupts food webs and fouls anglers’ gear, likely became established in Lake Gogebic, MI after being transported there from Lake Superior on fishing gear or in bilge water.  On a national scale, the recent establishment of quagga mussels in Lake Mead is likely linked to the movement of houseboats from the Midwest.  Quagga mussels are close relatives of the zebra mussels that have had enormous detrimental impacts in the Great Lakes. 

Boaters can make a difference and help to slow the spread of AIS by taking time to inspect and clean their watercraft before moving to a different waterway.  To encourage such responsible practices, public awareness campaigns have been and are being developed and implemented.  These campaigns, however, generally view small-craft boaters as a single category, and seem focused on anglers. In reality, there are many different types of boaters that move their vessels among waterways.  These include, in addition to anglers, charter boat operators, fishing guides, water skiers, cruisers, trailer yachters, house-boaters, pontoon boaters, small-boat commercial fisherman, and hunters.  The behavior and movement pattern of each boating group differs from the others, as does their probability of spreading AIS. Thus, generic AIS education campaigns that target the broadly construed group of recreational boaters may not be as effective as they could be in teaching the most important ‘spreaders’ to be more careful.

For his CAC Fellowship, John worked with Lindsay Chadderton, the The Nature Conservancy’s AIS Director, to produce boating activity-specific risk assessments.  These risk assessments identified the ways that various boating activities accumulate AIS hitchhikers. These risk assessments were used in computer simulations of boater movements among waterways, allowing researchers to make specific predictions about the importance of various boater types in promoting spread.

Risk assessments of diverse boater categories were and are used by managers and policymakers as they evaluate various options for reducing the spread of AIS.  Knowledge of which types of boaters are the most likely to spread organisms will help to better direct public awareness campaigns and AIS prevention and compliance intervention strategies.  John's research has made it possible to compare intervention strategies, including public awareness campaigns, compliance checks, and boat cleaning facilities, that target high-risk categories with more generic approaches.  This allows managers to see how various alternatives could affect the future of the landscape.

The Nature Conservancy, in partnership with The Center for Aquatic Conservation, has already obtained funding to implement boat inspection and cleaning stations at multiple sites in the Great Lakes region over the next several years.

Distinctive Outcomes: Since his involvement in CAC, John has received the Presidential Management Fellowship. He is currently performing a postdoctoral fellowship at Southwestern University where he is making changes in Wisconsin invasive species management.