Safe Kayaking with Horseshoe Crabs

As Spring approaches, many beaches in Florida will be covered with mating horseshoe crabs. They are not harmful to humans, so you don’t need to worry about that. But we can be harmful to them, especially when launching and landing kayaks on the beach. There have been times on the Cedar Keys Kayak Trip when we had to gently move crabs out of the way so we could launch.  Landing is another challenge, especially if there is any wave action which makes it difficult to see them on the waters edge. The last thing we want is to land on them, so please keep an eye out and approach the beach slowly.

Horseshoe crabs have been performing this ritual for what scientists believe to be over 445 million years and are considered “living fossils”.  Like clockwork, every year between late February and early April, during a new or full moon and a high tide they will appear on Florida beaches. Probably the most interesting thing about horseshoe crabs is that they aren’t crabs at all and are more closely related to arachnids than crabs or lobsters!

These “crabs” are an important part of the ecology of coastal communities.  Their eggs are a major food source for shorebirds and fish and the adult horseshoes are preyed upon by sea turtles, alligators and sharks.

Horseshoe crabs are also extremely important to the biomedical industry because their unique, copper-based blue blood contains a substance called "Limulus Amebocyte Lysate", or "LAL". This compound coagulates or clumps up in the presence of small amounts of bacterial toxins and is used to test for sterility of medical equipment and virtually all injectable drugs. That way, when you get a vaccine you know it hasn’t been contaminated by any bacteria.  Anyone who has had an injection, vaccination, or surgery has benefited from horseshoe crabs!

Unfortunately, there has a noticeable decline in populations across their range and ironically, considering the amount of time they have been in existence, scientists realized that they didn’t know much about these “crabs” or what might be causing the decline. So, in 1998, The Atlantic States Marine Fisheries Commission developed a Horseshoe Crab Fishery Management Plan that requires all Atlantic coastal states to identify horseshoe crab nesting beaches. Currently, with the help of the public, biologists at the Fish and Wildlife Research Institute are documenting nesting sites of horseshoe crabs throughout the state.

“Citizen Scientists” (like the ones pictured above) are a very important part of this research. Volunteers walk a known section of beach at predetermined times and count the number of horseshoe crab mating groups observed. A subset of the crabs are collected, tagged with a small, numbered disc, and released back to the wild. Reports of tagged horseshoe crabs help to track crab movements and population numbers.

I have been lucky enough to watch this watch on several occasions in Cedar Key, Florida and it is an interesting process to watch. If you ever get the chance, do it! Better yet, if you are in the area during the spring and want to volunteer you can contact the Nature Coast Biological Station.
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In any case, keep an eye out for them as you launch and land on the beaches this spring.  We want them to be around for at least another 445 million years!

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