Don't be a vector
On land, some of these precautions are already evident. When you return to the U.S. mainland from Hawai'i, your luggage is inspected for fruit pests that could damage mainland crops. When you fly into certain countries, your airplane may be sprayed with insecticides. During the current hoof-and-mouth epidemic, even Prince Charles had to wipe his feet upon arrival in the U.S. On a smaller scale, we can implement our own preventive standards for the places we explore.

The simplest guideline is this: Don't be a vector. Invasive species get transmitted just like the flu does-by people. The same reason you stay home from work when you're ill (or at least, that's what you tell the boss as you pack up your dry bag) is the reason to leave other species at home when you travel. You are protecting the places you visit and the native species that live there. Both during and between trips, four simple tips can help reduce the risk of invasions.

On trips:
1. Report any unusual plants or animals in your local waters to your area fish and wildlife department, aquarium, or university. Study posters and other materials at marinas to recognize invaders in your area. By keeping an eye out for new arrivals, you can play an important role in invasion early warning.

2. Rinse off hulls and trailers at the take-out site to avoid moving pesky hitchhikers from one water body to the next (on any kind of boat).

3. Wash tents and other gear between trips to remove unwanted seeds and pollen grains. In the same way, rinse off your boots before exploring inland on your next trip. You can even wash off your car tires before visiting national parks and other protected areas.

4. Bring your unused bait home rather than dumping it: even if you can't see them, live non-native species may be present on baitshop bait.

(photo: Zebra mussels warning sign at lake Meniphremagog in Quebec.)