Portal de Periódicos da CAPES

Incidence of Limb Loss and Bald Chelipeds in the Japanese Mitten Crab Eriocheir japonica (de Haan) in its Marine Phase

1997; Volume: 52; Issue: 1 Linguagem: Inglês

10.5179/benthos1996.52.1_61

2186-4535

Satoshi Kobayashi, Shuhei Matsuura,

Marine and fisheries research

The incidence of limb loss and bald chelipeds in the Japanese mitten crab Eriocheir japonica in the sea was investigated at Tsuyazaki, Fukuoka Prefecture, Japan, in 1990-1991. Frequency of crabs with missing limbs increased remarkably in males from the beginning (September-December) to the end (May-July) of the reproductive season (26.8% to 83.3%), but only slightly in females (26.5% to 53.1%). Cheliped loss increased in males, from 8.9% to 33.3%, but showed no apparent change in females (5.8% to 4.1%) over the same period. Similarly, the average number of missing limbs per crab among all the sampled specimens increased markedly in males (0.36 to 1.71), but not as much in females (0.45 to 0.86). The site of limb loss was significantly different between sexes, with a lower frequency of cheliped loss in females compared to males, but there was no significant site specificity of loss in either sex. Increases in frequencies of limb loss reflect the deterioration in physiological condition after migration and reproduction and no regeneration of limbs by moulting in the sea. Higher frequencies of limb loss in males, especially of chelipeds, reflect their more active use of their larger chelipeds in the sea. Occurrence of bald chelipeds increased in both sexes towards summer (3.7% to 66.7% in males and 2.9% to 53.1% in females), with no significant difference between sexes in each season. Thus, the causes of baldness may differ from those of limb loss which more clearly reflect the behavioural differences between sexes.