Horseshoe crabs are harvested annually in huge numbers to produce Limulus Amebocyte Lysate (LAL), used to test pharmaceutical products for bacterial contamination, raising serious welfare concerns.
Horseshoe crab bleeding raises welfare concerns at multiple levels. The bleeding procedure itself causes measurable physiological stress, and post-release mortality rates are significant. The broader ecological welfare impact - reduced horseshoe crab breeding success, and consequent starvation pressure on shorebirds like the red knot that depend on their eggs - extends the welfare harm to entire ecological communities. The existence of a validated synthetic alternative (rFC) makes continued large-scale bleeding difficult to justify on welfare grounds. The pharmaceutical industry's reluctance to switch is primarily financial and regulatory rather than scientific. This is a case where welfare, ecology, and innovation all point in the same direction - towards adoption of the synthetic alternative.