The blue blood of horseshoe crabs contains a special chemical limulus amebocyte lysate (LAL) that medical laboratories obtain from thousands of animals annually to detect bacterial infections in humans. The labs are only allowed to draw up to 30% of their blood once a year. Despite these precautions, researchers are becoming increasingly concerned that some animals may be injured during the process resulting in the death of animals after they are returned to the ocean. In fact, some researchers are pushing to add horseshoe crabs to the vulnerable list as populations decline in some countries.
In a new book, Changing Global Perspectives on Horseshoe Crab Biology, Conservation and Management (Springer, 2015) Thomas Novitsky (CEO of Associates of Cape Cod LAL company, MA) stated, “Evidence is accumulating that mortality of bled horseshoe crabs is higher than originally thought [29 percent versus 15 percent]; that females may have an impaired ability to spawn following bleeding and release; and that bled crabs become disoriented and debilitated for various lengths of time following capture, handling, bleeding and release.”
Scientists from Plymouth State University and University of New Hampshire published a study in 2014 in which they tested the effects of bleeding crabs and found that the animals showed abnormal behavioral and physiological effects for two weeks following the bleeding. A follow up study will examine the effects of blood volume drawn, the amount of time animals are out of water, as well as variations in temperatures. The team will observe the animals in the laboratory following a blood draw and will then release them into the ocean with a transmitter to track the animal's activity after release.