Spatial Distribution Of Dominant Fish Species In Haizhou Bay And Their Relationships With Environmental Factors

Haizhou Bay is a typical open bay located at the coast of the central Yellow Sea.The ecosystem of Haizhou Bay serves as an excellent spawning and feeding groundfor fishes and other invertebrate animals, with high productivity and biodiversity.However, as a result of the high fishing activities, marine environmental changes, andthe effect of global warming, evident changes in fisheries resources have taken placein this area.In our study, survey data of fishery and environmental factors were collectedfrom seasonal bottom trawl surveys of five voyages in Haizhou Bay from March2011to December2011. Spatial distributions of three thermophilic groups (warm-waterspecies, warm-temperate species, cold-temperate species) and their dominant speciesin each voyage were analyzed. ArcGIS was used to draw the spatial distribution mapsof fish species. Generalized Additive Models (GAM) were employed to examine therelationships between fish biomass and the environmental factors, further the mostprincipal factors affecting fish distributions could be detected.The results showed that there were75fish species occured in this area, belongingto13orders,38families and59genera. There were47warm-temperate fish species(63%of the total species),21warm-water species (28%) and7cold-temperate species(9%). Amblychaeturichthys hexanema, Syngnathus acus and Enedrias fangi were thedominant species of these three groups respectively.After preliminary selection, seven environmental factors (month, longitude,latitude, BST, BSS, depth, BDO) were included into the model. The results showedthat month, BST, longitude, and BDO were the main environmental factors affectingwarm-temperate fishes distribution, and BST is the most dominant factors. Theirbiomass peaked at12℃and decreased at both sides. Environmental factorsaffecting the distribution of warm-water fishes were month, BST, the depth, thelongitude and latitude, and the dominant one was month. Biomass was the highest inDecember, and was little difference during the other months. The secondary factor was BST. At the range of12-20℃, there was an obvious upward trend in fish biomass,and near20℃it reached the maximum. Environmental factors that affected thecold-temperate fish distribution were the month, the depth, BDO, latitude and BST.The dominant one was depth, followed by BST. Within10-40m water depth biomassincreased gradually.Environmental factors affecting the spatial distribution of Amblychaeturichthyshexanema were month, longitude, BSS and latitude, and month is the most dominantfactor. Biomass was maximum in December, and was minimum in July. All the sevenfactor examined were chosen into the GAM for Syngnathus acus. Constribution rateof BST was the largest of all factors, followed by month and latitude. At the rangeof5-25℃, biomass of Syngnathus acus increased gradually., and the biomass wasmaximum in March and December while minimum in September. Biomass increasedwith the arising of latitude in the study area. Four environmental factors affecting thedistribution of Enedrias fangi were month, depth, BST and BSS. The most dominantone was depth. The biomass increased gradually within10-40m water depth.This study found that BST, month, depth were the three most importantenvironmental factors for spatial distributions of fish community in Haizhou Bay, ofwhich BST was the principal factor. Fish species were spread on their favorite livinghabitats in Haizhou Bay, and the spatial distribution changed with seasonal variation.