东海和黄海主要鱼类的食物竞争

Feeding competition of the major fish in the East China Sea and the Yellow Sea

以2000年和2001年在东、黄海两次大面调查所收集的、占总生物量90%的重要生物种类中的鱼类为研究对象,通过分析胃含物获得各饵料成分的重量百分比,用Pianka(1973)提出的公式计算的饵料重叠系数分析了东、黄海主要鱼类之间的食物竞争状况,以了解食物竞争与种群变动和优势种交替之间的相互关系。结果表明:黄海主要鱼类的食物竞争对象主要为太平洋磷虾、脊腹褐虾和,东海主要鱼类的食物竞争对象主要为太平洋磷虾、细条天竺鱼、发光鲷、、七星底灯鱼和带鱼。东、黄海鱼类通过摄食种类、摄食食物大小、摄食时间和栖息地的分化来减少食物竞争,从而维持群落结构的动态平衡。渔业资源群落结构的变化将导致食物竞争状况发生改变;鱼类食物竞争状况也会影响种群动态。

According to the simplified version of food web, we defined fish of important resources species, which accounted for 90% of the total biomass of the resource populations, as the major fish species. Fifteen species in the Yellow Sea and 23 species in the East China Sea were collected from two surw.ys in 2000 and 2001. By analyzing stomach samples, the percentage weight of each prey species was obtained, and then the formula proposed by Pianka （1973） was used to calculate the dietary overlap coefficient between the major fish. The aim of the present study is, using dietary overlap between the major fish, to analyze feeding competition in the East China Sea and Yellow Sea and explore the relationship between feeding competition and the change of fish assemblage and the shift of dominant species. In the Yellow Sea, dietary overlap between 6 planktophagic species, i. e., hairfin anchovy Setipinna taty, madura anchovy Thrissa kammalensis, spotted velvefish Erisphex pottii, anchovy Engraulis japonicus, Trichiurus muticus and bighead croaker Collichthys niveatus was related to Euphausia pacifica, only anchovy feed much Copepoda and bighead croaker feed much Sagitta; dietary overlap between small yellow croaker Pseudosciaena polyactis, pointhead plaice Cleisthenes herzensteini, Pacific cod Gadus macrocephalus and Tanaka＇s snailfish Liparis tanakae was Crangon affinis and anchovy; dietary overlap between yellow goosefish Lophius litulon and largehead hairtail Trichiurus haumela was anchovy; because the other 3 species-brown croaker Miichthys miiuy, Chinese skate Raja chinensis and Bombay duck Harpodon nehereus feed different Macrura and fish species, dietary overlap with other fish was little. These results indicated that the main competition for food in the Yellow Sea occurred among Euphausia pacifica, Crangon affinis and Engraulis japonicus. Although there was feeding differentiation among the major fish, feeding competition for the main prey was serious. In the East China Sea, 3 benthophagic species-Thamnaconus hypargyreus, pinkgray goby Chaeturichthys heoranema and fin-striped goatfish Upeneus bensasi mainly feed on Ophiuroidea, Lamellibranchia, Cumacea,Gammaridea and different Macrura, so they feed independently of other major fish. Dietary overlap between cardinal fish Apogonictzthys lineatus, firefly-fish Acropoma japonicum and skinnycheek lanternfish Myctophum pterotum was related to Euphausia pacifica. At the same time, they depend heavily on other food （such as Copepoda and Macrura）. The other 17 species, include Pacific mackerel Pneumatophorus japonicus, small yellow croaker, gaper Champsodon capensis, red bigeye Priacanthus macrocanthus, brownspotted puffer Gastrophysus spadiceus, redwing searobin Lepidotrigla microptera, white croaker Argyrosomus argentatus, Japanese butterfish Psenopsis anomala, largehead hairtail, Bombay duck, brushtooth lizardfish Saurida undosquamis, crossmark lizardfish Synidus macrops, black chin conger Alloconger anagoides, Spanish mackerel Scomberomorus niphonius, yellowtail kingfish Seriola lalandi and snock Sphyraena japonica, comprised 45.29%-99.76% of the weight of fish prey, but because fish prey species were abundant （49 species） and those major fish feed on different species, food overlap was not serious. Only 8 pairs of fish species had serious dietary overlap. The main dietary overlaps between Pacific mackerel and small yellow croaker were cardinal fish and skinnycheek lanternfis, between Pacific mackerel and Bombay duck was cardinal fish, between small yellow croaker and gaper was skinnycheek lanternfis, between small yellow croaker and Bombay duck was cardinal fish, between Japanese butterfish and brushtooth lizardfish was firefly-fish, between Spanish mackerel and largehead hairtail were largehead hairtail and anchovy. Generally, major fish species in the East China Sea competed mainly for Euphausia pacifica , cardinal fish, skinnycheek lanternfis, firefly-fish, largehead hairtail and anchovy. However, whether predators would experience intense competition is difficult to determine because information is lacking both on prey production rates and food requirements of the fish, so it is also difficult to know. By feeding on different prey species, different size of prey and feeding time and microhabitat partitioning, the major fish in the East China Sea and Yellow Sea reduce feeding competition and maintain the dynamic balance of community structure. The change of fish assemblages can influence feeding competition between fish. In the Bohai Sea, the main competition changed from small demersal fish （ Chaeturichthys stigmatias and C. hexanerna ） in 1982-1983 to anchovy in 1992-1993. It was related to change in community structure of fishery resource, many large-sized species with high commercial values having been replaced by small pelagic species. In the Yellow Sea, the main competition prey didn＇t change between 1985-1986 and 2000-2001 , but feeding competition showed some differences. Because most major fish became lower trophic levels and the number of ichthyophagic species decreased, feeding stress on anchovy decreased and feeding stress on Euphausia pacifica and Crangon affinis increased. But because the main prey recourse was abundant, the change of feeding competition did not influence the main prey species. On the other hand, feeding competition also can change the fish assemblage. In the Yellow Sea, although the biomass of anchovy declined, decrease of feeding stress on anchovy could maintain the stability of fish assemblages. Because it is difficult to establish the degree of feeding competition, more study must be done to understand the effect of feeding competition on the change of fish assemblage [Acta Zoologica Sinica 51（4）： 616-623, 2005].