Studies On The Fisheries Resources And Fish Stocking Model Of Wuhu Lake

Wuhu Lake is one of the shallow lakes along the middle reach of the Yangze River, covering an area of 20 square kilometers. In order to recognize the characteristics and the status of the fishery resources in Wuhu Lake, make full use of its resources and pursue continual development of fishery, aquatic living resources ,fish fauna, stocking, catch and age and growth of fish populations in different feeding habits were studied. The main results and conclusions summarized as:1,Wuhu Lake was a eutrophic lake. Water pH in Wuhu Lake was 8.24, presenting alkalescence, dissolved oxygen was 9.0 mg/L, total phosphorus was 0.076 mg/L, total nitrogen was 0.93 mg/L, chlorophyll-a was 0.0204 mg/L, alkalinity was 98.09 mg/L, chemical oxygen demand was 2.67 mg/L.2,There were mainly five aquatic vascular plants belonging to four families in Wuhu Lake. Submerged macrophyte included Myriophyllum spicatum, Vallisneria spiralis, Ceratophyllum demersum, and Potamogeton crispus. There was one floating-leaved macrophyte Trapa natans. According to the investigation of zoobenthos in Wuhu Lake, mollusks and insects constituted the most dominant group and oligchaetes were rare.3,There were fifty fish species in Wuhu Lake, belonging to six orders and fourteen families. Thirty-four fish species belonged to Cypriniformes, accounting for 68% of the total fish species; nine fish species belonged to Perciformes accounting for 18%; three fish species belonged to Siluriformes accounting for 6%; two fish species belonged to Clupeiformes accounting for 4%; one fish species belonged to Cyprinodontiformes accounting for 2%; one fish species belonged to Synbranchidae accounting for 2%. In the Cypriniformes, thirty-three fish species belonged to Cyprinidae, accounting for 97% of the total fish species in Cypriniformes .4,Bighead carp and silver carp were main stocked fish categories .They were stocked together with other fishes every year. In order to increase yield, organic and inorganic fertilizers were applied. The catch of Wuhu Lake was mainly composed of silver carp, bighead carp, common carp, crucian carp and culters. Their yield was equivalent to about 93% of the total yield. As the stocking density of siver carp and bighead carp increased from 2000 to 2006, the corresponding yield from the lake decreased.5,Silver carp had two age classes and were mainly 2 years old, accounting for 69.7%. Bighead carp had three age classes and were mainly 3 years old, accounting for 69.5%. The growth rate of bighead carp was high before 3-year-old fish. The growth rate of bighead carp in Wuhu Lake was lower than in other lakes. Common carp had seven age classes and were mainly 2-3 years old, accounting for 93.7%. The growth rate of common carp was high before 7 years old. Two-year-old common carp had the highest annual growth rate. Grayfin culter had six age classes and were mainly 2-4 years old , accounting for 89.8%. Two-year-old grayfin culter had the highest annual growth rate. Redfin culter had five age classes and were maily 2-3 years old, accounting for 85.9%. Redfin culter had high growth rates in 2-year-old and 4-year-old fish.