Length-frequency data of eight commercial fish species in the Beibu Gulf （Golf of Tonkin）, northern South China Sea, were collected during 2006-2007. Length-weight relationships and growth and mortality parameters w...Length-frequency data of eight commercial fish species in the Beibu Gulf （Golf of Tonkin）, northern South China Sea, were collected during 2006-2007. Length-weight relationships and growth and mortality parameters were analyzed using FiSAT II software. Five species had isometric growth, two species had negative allometric growth, and one species had positive allometric growth. Overall, the exploitation rates of the eight species were lower in 2006 2007 than in 1997-1999： for four species （Saurida tumbil, Saurida undosquamis, Argyrosomus macrocephalus, and Nemipterus virgatus） it was lower in 2006-2007 than in 1997 1999, for two species （Parargyrops edita and Trichiurus haumela） it remained the same, and for the other two species （Trachurus japonicus and Decapterus maruadsi） it was higher in 2006~007 than in 1997-1999. The exploitation rates might have declined because of the decline in fishing intensity caused by high crude oil prices. The optimum exploitation rate, estimated using Beverton-Holt dynamic pool models, indicated that although fishes in the Beibu Gulf could sustain high exploitation rates, the under-size fishes at first capture resulted in low yields. To increase the yield per recruitment, it is more effective to increase the size at first capture than to control fishing effort.展开更多
A mass-balanced model was constructed to determine the flow-energy in a community of fishes and invertebrates in the Beibu Gulf, northern South China Sea using Ecopath and Ecosim software. Input parameters were taken ...A mass-balanced model was constructed to determine the flow-energy in a community of fishes and invertebrates in the Beibu Gulf, northern South China Sea using Ecopath and Ecosim software. Input parameters were taken from the literature, except for the biomass of fish groups which was obtained from trawl surveys during October 1997 to May 1999 in the study area. The model consisted of 16 functional groups （boxes）, including one marine mammal and seabirds, each representing organisms with a similar role in the food web, and only covered the main trophic flow in the Beibu Gulf ecosystem. The results showed that the food web of Beibu Gulf was dominated by the detrital path and benthic invertebrates played a significant role in transferring energy from the detritus to higher trophic levels; phytoplankton was a primary producer and most utilized as a food source. Fractional trophic levels ranged from 1.0 to 4.08 with marine mammals occupying the highest trophic level. Using network analysis, the system network was mapped into a linear food chain and six discrete trophic levels were found with a mean transfer efficiency of 16.7% from the detritus, 16.2% from the primary producer within the ecosystem. The biomass density of the commercially utilized species estimated by the model is 8.46 t/km^2, only O. 48% of the net primary production.展开更多
The morphology, microstructure and demographic parameters of statolith of Sthenoteuthis oualaniensis were studied from 90 individuals captured in the central South China Sea in September and October, 2012. The marphol...The morphology, microstructure and demographic parameters of statolith of Sthenoteuthis oualaniensis were studied from 90 individuals captured in the central South China Sea in September and October, 2012. The marphologic results showed that the statolith has great lateral dome and wing dome, small dorsal dome, and long narrow rostrum dome. S. Oualaniensis could be divided into three populations by statolith morphology in the central South China Sea. Five most important featured parameters including total statolith length （TSL）, wing length （WL）, maximum width （MW） were described by logarithmic functions with mental length （ML） （P 〈 0.05 ） ; rostnnn length （ RSL）, dorsolateral length （DLL） were described by linear functions with ML（ P 〈 0.05 ）. With the squid growth, the size of statolith gradually develops, while the ratio of each featured parameter to ML slowly decreases, the ratio of DLL, LDL, RSL and WL to TSL almost remain the same level, corresponding to 48.05%, 60.05%, 35.44%, 67.59%, and the ratio of LDL and WL to SL show little higher.展开更多
Purpleback flying squid （Sthenoeuthis oualaniensis） is an important marine economic species, studying its biological characteristics is very important for the resource assessment and management. This paper summed up...Purpleback flying squid （Sthenoeuthis oualaniensis） is an important marine economic species, studying its biological characteristics is very important for the resource assessment and management. This paper summed up domestic and international information of squid biology, and showed some details on this subject. According to the squid life history ：egg, larvae, juveniles and adult fish stage, it summarized from the age of growth, population structure, migration, spawning, vertical distribution, habitat, and status of resources. There is little research on the squid larvae and the signs of juveniles period ended are not clear. Adult fish is divided into four main populations and two minor popular ons, the large group, medium-sized group, small group and mini-group, while medium-sized groups can be divided into medium uniaxial group and medium-sized biaxial according to the characteristics of the inner shell. The distribution of purpleback flying squid has the ＂island correlation＂, it usually ascend to the surface at night and drop to the deep-water during the daytime. Purpleback flying squid plays an important role in the ecosystem. It is the main food of many fish, and marine mammals ; also it is the predators of crustaceans and small fish. It has the self-feed characteristics. Purpleback flying squid widely distributes in the 38 °N to 40°S tropical and subtropical waters, especially in the South China Sea, the catchability is （130 -200）×10^4 tons in one year.展开更多
基金Supported by the Chinese Ministry of Agriculture under the Investigation of Fishery Stocks in China Seas Program (No. 070404)the Special Project of the Social Commonwealth Research National Institute (Nos.2009TS08, 2010YD10)
文摘Length-frequency data of eight commercial fish species in the Beibu Gulf （Golf of Tonkin）, northern South China Sea, were collected during 2006-2007. Length-weight relationships and growth and mortality parameters were analyzed using FiSAT II software. Five species had isometric growth, two species had negative allometric growth, and one species had positive allometric growth. Overall, the exploitation rates of the eight species were lower in 2006 2007 than in 1997-1999： for four species （Saurida tumbil, Saurida undosquamis, Argyrosomus macrocephalus, and Nemipterus virgatus） it was lower in 2006-2007 than in 1997 1999, for two species （Parargyrops edita and Trichiurus haumela） it remained the same, and for the other two species （Trachurus japonicus and Decapterus maruadsi） it was higher in 2006~007 than in 1997-1999. The exploitation rates might have declined because of the decline in fishing intensity caused by high crude oil prices. The optimum exploitation rate, estimated using Beverton-Holt dynamic pool models, indicated that although fishes in the Beibu Gulf could sustain high exploitation rates, the under-size fishes at first capture resulted in low yields. To increase the yield per recruitment, it is more effective to increase the size at first capture than to control fishing effort.
文摘A mass-balanced model was constructed to determine the flow-energy in a community of fishes and invertebrates in the Beibu Gulf, northern South China Sea using Ecopath and Ecosim software. Input parameters were taken from the literature, except for the biomass of fish groups which was obtained from trawl surveys during October 1997 to May 1999 in the study area. The model consisted of 16 functional groups （boxes）, including one marine mammal and seabirds, each representing organisms with a similar role in the food web, and only covered the main trophic flow in the Beibu Gulf ecosystem. The results showed that the food web of Beibu Gulf was dominated by the detrital path and benthic invertebrates played a significant role in transferring energy from the detritus to higher trophic levels; phytoplankton was a primary producer and most utilized as a food source. Fractional trophic levels ranged from 1.0 to 4.08 with marine mammals occupying the highest trophic level. Using network analysis, the system network was mapped into a linear food chain and six discrete trophic levels were found with a mean transfer efficiency of 16.7% from the detritus, 16.2% from the primary producer within the ecosystem. The biomass density of the commercially utilized species estimated by the model is 8.46 t/km^2, only O. 48% of the net primary production.
文摘The morphology, microstructure and demographic parameters of statolith of Sthenoteuthis oualaniensis were studied from 90 individuals captured in the central South China Sea in September and October, 2012. The marphologic results showed that the statolith has great lateral dome and wing dome, small dorsal dome, and long narrow rostrum dome. S. Oualaniensis could be divided into three populations by statolith morphology in the central South China Sea. Five most important featured parameters including total statolith length （TSL）, wing length （WL）, maximum width （MW） were described by logarithmic functions with mental length （ML） （P 〈 0.05 ） ; rostnnn length （ RSL）, dorsolateral length （DLL） were described by linear functions with ML（ P 〈 0.05 ）. With the squid growth, the size of statolith gradually develops, while the ratio of each featured parameter to ML slowly decreases, the ratio of DLL, LDL, RSL and WL to TSL almost remain the same level, corresponding to 48.05%, 60.05%, 35.44%, 67.59%, and the ratio of LDL and WL to SL show little higher.
基金Supported by National Science and Technology Support Project(2013BAD13B06)Basic Scientific Research Project of Nonprofit Central Research Institutions(2012TS11)Financial Major Projects of the Ministry of Agriculture(NFZX2013)
文摘Purpleback flying squid （Sthenoeuthis oualaniensis） is an important marine economic species, studying its biological characteristics is very important for the resource assessment and management. This paper summed up domestic and international information of squid biology, and showed some details on this subject. According to the squid life history ：egg, larvae, juveniles and adult fish stage, it summarized from the age of growth, population structure, migration, spawning, vertical distribution, habitat, and status of resources. There is little research on the squid larvae and the signs of juveniles period ended are not clear. Adult fish is divided into four main populations and two minor popular ons, the large group, medium-sized group, small group and mini-group, while medium-sized groups can be divided into medium uniaxial group and medium-sized biaxial according to the characteristics of the inner shell. The distribution of purpleback flying squid has the ＂island correlation＂, it usually ascend to the surface at night and drop to the deep-water during the daytime. Purpleback flying squid plays an important role in the ecosystem. It is the main food of many fish, and marine mammals ; also it is the predators of crustaceans and small fish. It has the self-feed characteristics. Purpleback flying squid widely distributes in the 38 °N to 40°S tropical and subtropical waters, especially in the South China Sea, the catchability is （130 -200）×10^4 tons in one year.
