The Geographical Features And Fish Biodiversity Investigation In The Jiaozhou Bay And Its Neighboring Waters

Based on the catch data from setnet and bottom trawl surveys in the Jiaozhou Bay and its neighboring waters from October 2003 to December 2004, the fish biodiversity and resources status are examined. The catch composition of the two types of fishing gear is compared. Seasonal variations of biodiversity and dominant species are analyzed, and the biological features of main species are described. On this basis, the relationship between the features of the geography and hydrology and the fish biodiversity is also studied. The paper points out the biological and hydrological reasons that cause its present fish biodiversity in the Jiaozhou Bay. And it can be viewed as one of the scientific basis for the protection of fish biodiversity and for the sustainable utilization of fisheries. The most important results are as follows:(1) There are 111 species recorded in the Jiaozhou Bay and its neighboring waters, including 75 fish species, 31 crustacean species and 5 cephalopod species.(2) In this investigation, 75 fish species are caught, with warm temperature species, warm water species and cold temperature species accounting for 48.0%, 33.3% and 18.7%. The settling species, the migratory species and the estuarine species account for 50.7%, 48.0% and 1.3%. The pelagic species accounts for 16.0%, while the demersal species amounts to 84.0%. 31 crustacean species are caught, and the main species are Trachypenaeus curvirostris, Palaemon gravieri, Alpheus japonicus, Alpheus heterocarpus and charybdis bimaculata. 5 cephalopod species are caught, and the main species are Octopus ocellatus and Octopus variabilis.(3) The dominant species in the study area consist of small low-value fishes (such as Engraulis japanicus, Thryssa kammalensis, Ammodytes personatus, Enedrias fangi etc.) > commercial invertebrates (such as Trachypenaeus curvirostris, Palaemon gravieri, Octopus ocellatus, Octopus variabilis) and juveniles of commercial fishes (such as Pseudosciaena polyactis, Argyrosomus argentatus). These dominant species appear by turns. They make up the most catches in the fishing seasons.(4) The number of species are the largest in April, May, and September 2004, with the number of 39, while the number of species are the smallest in January 2004, with the number of 21. The species richness index {R) is highest in April 2004 (3.689) and lowest in January 2004 (2.512). When it comes to Shannon-Wiener index (Hr), the highest value appears in September 2004 (2.640), and the lowest value appears in January 2004 (1.980). When the species evenness index (J1) is concerned, it is highest in September 2004 (0.721) and lowest in May 2004 (0.556).(5) The length composition and weight composition of the catch are studied. The results show that the sizes of individuals of Pseudosciaena polyactis, Argyrosomus argentatus, Conger myriaster, Trachypenaeus curvirostris are very small, most of which are juveniles and small shrimps.(6) This study also records the presence of the Ophisurus macrorhynchus in the setnet the first time, which is rare in the coastal waters in the Yellow Sea. This adds new material to the fishery biodiversity study in the Jiaozhou Bay and its neighbouring waters.