Unraveling the mystery of cannibalism in the larvae of the Chinese mitten crab (Eriocheir sinensis)

To prevent production losses due to larval cannibalism, the behaviour and mechanisms in Z2-M stage E. sinensis larvae were investigated. The findings revealed that cannibalism primarily occurred during the M stage, with M significantly preying on Z5. The claws that appear during the M stage play an important role in cannibalism. Although there were no significant differences in crude protein and lipid content between Z5 and M, Z5 had a crude protein content of 7.27% ± 0.20%, which was significantly higher than rotifers and Artemia. Z5's crude lipid content was 1.37% ± 0.03%, exceeding that of rotifers ( P < 0.05). The principal component analysis (PCA) of amino acid composition indicated that the amino acid profile of M was similar to that of Artemia, but differed significantly from those of Z5 and rotifers. Starvation also influenced cannibalism. M (fasting 12- and 24-h groups) ingested more Z5 larvae compared to controls ( P < 0.05). Cannibalistic behavior in starved M individuals was reduced when they were fed rotifers or Artemia. The effect of Artemia was greater than that of rotifers. M ingested 1.44 ± 0.16 Z5 in 24 h when fed with Artemia, compared to 2.11 ± 0.16 Z5 when fed with rotifers ( P < 0.05). In conclusion, starvation induced cannibalism in M. High-nutrient of Z5 also induced cannibalism in M. Feeding with Artemia effectively reduced the predation of Z5 by M.