Abstract: The fishery ecology of jellyfish at Minjiang River estuary was studied from May to September 1993. The peaks of density and biomass of the jellyfish appeared in June 20 and July 10, respectively. The diameter of the umbrella part ranged from 18 mm to 546 mm, averaging328.8mm. The body weight ranged from 0.5g to 9540g, averaging2877.4 g. The sexual reproduction capability of individuals with the diameter of umbrella part ranged 345～485mm was 1120.6×10⁴～3754.8×10⁴ eggs, averaging 2444.7×10⁴ eggs, and the period of sexual reproduction continued from the beginning of August to November. The diameter growth of the umbrella part and the body weight of the jellyfish could be calculated respectively by the power equation and power exponential equation: Φ_t=12.1337 + 17.7048t + 3.1385 t²-0.2049t³+0.00302t⁴, log_eW_t=-0.5749+1.4818t-0.0771t²+0.00129t³. From the standpoint of biology and economics, the optimum date for starting fishing may be in July 20, with the optimum diameter of the umbrella part by 465.8mm. The optimum date and size of actual beginning fishing were also discussed, which would be important for the conservation and exploitation of the resources of jellyfish, and for the increasing economic effect.

Key words: Jellyfish, Ecological distribution, Growth, Sexual reproduction, Minjiang River estuary