The Long-Term Effect of Bleeding for Limulus Amebocyte Lysate on Annual Survival and Recapture of Tagged Horseshoe Crabs

Abstract

In the U.S., 525,000 horseshoe crabs (Limulus polyphemus) per year have been captured during 2013–2017, brought to biomedical facilities, and bled to produce Limulus amebocyte lysate (LAL), then mostly released to the area of capture. The Atlantic States Marine Fisheries Commission estimates short-term bleeding-induced mortality to be 15% (4% to 30%), resulting in mortality of approximately 78,750 horseshoe crabs annually in recent years comprising a minor portion (<13%) of the up to one million annual coastwide landings dominated by harvest for bait. However, the long-term effect of bleeding for LAL on annual survival and spawning behavior is unknown; thus, results from short-term studies alone might underestimate bleeding effects at the population level. To address this knowledge gap, we analyzed data from the U.S. Fish and Wildlife horseshoe crab tagging database to estimate the differences in survival and recapture rates of bled and not bled horseshoe crabs tagged in the same years and geographic area. Contrary to expectation, survival was not lower for bled crabs compared to unbled crabs. Differences varied, but survival estimates tended to be higher for bled crabs than for unbled crabs. However, biomedical culling and selection for younger or healthier animals could have resulted in biomedically tagged individuals representing a healthier subset of the overall population with subsequent higher survival. Furthermore, the tagging analysis revealed a post-bleeding reduction in capture probability, which could indicate decreased spawning activity, evident in males more than females. Continued tagging of bled and unbled crabs in the same geographic area while recording age class and sex will contribute to the further resolution of LAL production’s effect on horseshoe crab populations.

Assessment of recovery potential for the American horseshoe crab (Limulus polyphemus): An application of the IUCN green status process

“…Moreover, haemocyanin declines while horseshoe crabs are held in captivity, such as in the South Carolina ponds cited above. However, tagging data studies have not found lower survival of bled horseshoe crabs compared with control animals (Butler, 2012; Smith et al, 2020b). Finally, those horseshoe crabs that survive the procedure and are released back into their natural habitat might spawn less often (Anderson, Watson & Chabot, 2013; Owings, Chabot & Watson, 2019; Smith et al, 2020b; Watson, Lemmon & Chabot, 2022), potentially reducing the reproductive output in areas where harvest coincides with the spawning season.…”

“…The US Food and Drug Administration (FDA) is evaluating the recombinant Factor C (rFC) assay in comparison with LAL for endotoxin testing (Botton et al, 2022). While collection and bleeding for LAL production has been shown to affect survival and behaviour (ASMFC, 2019; Smith et al, 2020b; Owings, Chabot & Watson, 2020; Watson, Lemmon & Chabot, 2022), the population‐level effect depends on the abundance of the population where the harvest is occurring. Where the population is small, even modest levels of harvest can lead to local extirpation (Widener & Barlow, 1999).…”

“…Where the population is small, even modest levels of harvest can lead to local extirpation (Widener & Barlow, 1999). However, evidence does not show that LAL production has impacted the large Delaware Bay population, which numbers in the tens of millions of adult horseshoe crabs (Smith et al, 2020b; ASMFC, 2022a; Anstead et al, 2023).…”

“…Harvest for LAL is monitored by ASMFC, and capture and handling of animals are guided by best practices developed by the US Food and Drug Administration (FDA) and ASMFC. At current levels, based on recent assessments (Smith et al, 2020b;ASMFC, 2022a) harvest for LAL in the Delaware Bay ecosystem affects the entire adult population but is not expected to cause declines or prevent reaching ecological functionality assuming adequate habitat. • Pollution: Because Delaware Bay is a corridor for oil transport, oil spills are possible.…”

Transition metal dichalcogenide-based Janus micromotors for on-the-fly Salmonella detection

“…Currently, the gold standard methods for bacterial contamination detection compromise culture-based methods, polymerase chain reaction (PCR) protocols, which are robust but require expensive and sophisticated instrumentation, qualified personnel, and long analysis times [ 8 ]. The Limulus amoebocyte lysate (LAL) allows for detection and quantification of endotoxins with excellent LODs ranging from 0.0005 to 5.0 ng/mL, yet such technique suffers from low recoveries and requires blood from the pericardium of horseshoe crabs [ 9 ].…”