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37-Year Chesapeake Study Finds Cannibalism Drives Juvenile Blue Crab Deaths

The findings will inform a new Chesapeake stock assessment this year.

Overview

  • Researchers at the Smithsonian Environmental Research Center ran tethering trials in the Rhode River from 1989 to 2025 and published the results in PNAS.
  • About 74% of tethered juveniles survived 24 hours, with roughly 42% showing injuries or remains consistent with attacks by other blue crabs.
  • No fish predation was detected in the mid-salinity study area, a result supported by high-resolution sonar observations of attacks by adult crabs.
  • Shallow nearshore zones offered strong refuge, with small juveniles far less likely to be eaten in the shallowest waters than in depths of 1.3–2.5 feet.
  • Coverage differs on the magnitude of cannibalism, with Scientific American citing 97% of killings or injuries and other reports emphasizing the ~42% cannibalism indicators, while authors also warn that shoreline hardening and invasive blue catfish threaten these refuges.