Aquatic Hitchhikers: What Are They and Why You Should Care

By: Taylor Darnell, agronomy master’s student with UF/IFAS Center for Aquatic and Invasive Plants (CAIP)

Have you ever been waiting to launch at a boat ramp, ready for a day of fishing or leisure with friends and notice gobs of tangled mess hanging from the boat trailers that are pulling out in front of you? Unfortunately, this is a fairly common sight in most systems. Those tangled strands hanging from trailers are commonly referred to as aquatic hitchhikers, and they could be invasive plants such as hydrilla (Hydrilla verticillata), Eurasian water-milfoil (Myriophyllum spicatum), or giant salvinia (Salvinia molesta). While these plants may seem harmless, they can cause severe damage if introduced to another waterbody. It should be noted that most new aquatic species are introduced to water bodies around or at boat ramps because it is often the first entrance area into a system from foreign bodies.

Plants are often trapped between the boat hull and the trailer bunk, protecting them from water loss. This allows them to survive on the boat trailer for several hours or even days. For example, hydrilla can spread through small stem fragments that can survive out of water for several hours.

Aquatic hitchhikers attached to boat trailer
Aquatic hitchhikers attached to a boat trailer

Not only do invasive aquatic plants harm the environment, but they also have economic impacts. In Florida alone, hydrilla management has accounted for almost 10 million dollars of expenditures by the Florida Fish and Wildlife Conservation Commission’s invasive plant management operations for decades. These costs may have been avoided if plant material on vessels that were moving in and out of the canals in Tampa, Florida, in the late 1950s had been properly removed and disposed of.

Image of hydrilla being held over the side of a boat
Hydrilla mat from Orange Lake that could latch on boat or trailer and become an aquatic hitchhiker

Aquatic hitchhikers are not limited to plants. Muscles, barnacles, snails, and other organisms are classified as hitchhikers and are just as, if not more devastating to an aquatic environment and infrastructure.

One example of an economic impacts case study on invasive species introductions is the story of the invasive lionfish (Pterois volitans). Lionfish are invasive, predatory fish that have wreaked havoc on native fish populations, destroyed native coral reefs, and reduced trophy fishing populations along the Atlantic coast and Gulf coast cities in the panhandle of Florida. The exact mode of introduction is not known but is speculated to be related to improper disposal of fish-related materials. As with most invasive and nuisance species, their reproductive strategy involves producing as many offspring as possible and, in turn, those offspring can easily be transported between systems.

Be sure to follow these very simple steps to stop the spread of aquatic hitchhikers:

  1. Remove all visible aquatic plants, animals, and sediments from the boat, trailer, and prop before departure
  2. Drain all water holding devices before leaving the site
  3. Dry all parts and materials for at least five days between systems
  4. Properly dispose of unwanted items in the trash
  5. Never transport fish or plants between aquatic systems


For more information, explore the following links for further reading:

Stop Aquatic Hitchhikers

Protect Your Waters from Aquatic Invasive Species

Weeding Out Invasive Aquatic Plants

Stopping the Spread of Invasive Species


This blog post was written by Taylor Darnell, an agronomy master’s student with UF/IFAS CAIP. Questions or comments can be sent to the UF/IFAS CAIP communications manager at

Follow UF/IFAS CAIP on social media at @ufifascaip. Read more blogs like this one on the UF/IFAS CAIP blog.

UF/IFAS Center for Aquatic and Invasive Plants. Turning Science Into Solutions.



Posted: August 12, 2021

Category: Agriculture, Conservation, Invasive Species, Natural Resources, Pests & Disease, Recreation, Water
Tags: Aquatic Hitchhikers, Aquatic Invasive Plants, Aquatic Plant Management, Boat, Graduate Student, Invasive Plants, Turning Science Into Solutions, UF/IFAS CAIP

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