| 英文摘要 |
Species composition and occurrence of juvenile fish in trawl catches were examined surrounding waters of the Guei-San Island. Results indicated that bony fish comprised most of the catch, while crustacean and elasmobranches could also seasonally, count for more than 30% of the catch. Number of target species taken from sampling vessels ranged from 10 to 39 catalogues, while bycatch species recorded included 93 families and 228 species. Species diversity, richness and evenness, as well as % of juvenile fish were higher and more abundant in the summer and fall when compare to the spring. For the bycatch species, it was found that water depth seems play more important role than the season and substrate type, in structuring demersal fish assemblages in the region, such results were different from analyses based on the target species. Besides, basic biological information including size range, and BL-BW relationships for major bycatch species, which were not available in the region, were also examined and recorded in our study. In addition, mackerels are the major catch of danish net fishery. Since 2003, the CPUE of danish net fishery is dropped, and the proportions of each species catches, except mackerel, are dropped, too.
In this study, 4,107 individuals of larval fish were collected in June of 2007. From the result of species identification, in 2007, have 152 taxa belonging to 84 families in June. The cluster analysis indicated three groups under the 40%. In addition, this study was conducted by MTD net from surface to 250 m depth in the I-lan bay on 30-31 July 2007. A total of 591 larval fishes was collected and assigned to at least 13 families and 57 taxa. The dominant species was Benthosama pterotum(40.95%), Myctophidae Diaphus B(12.18%), Callionymidae(8.46%) and Gobiidae(6.60%), respectively. Based on the species composition lager than 5%, their vertical distribution was dominant in the diurnal nocturnal migration, as most of B. pterotum were aggregate at 50m deep at night-time and down into 200m at noon. For other species (e.g. Diaphus B and Gobiidae), their distribution model were also discussed in the text.
The fauna of the deep-sea hydrothermal vents off the Gueishan Island is very different from the adjacent fishing grounds in I-lan Bay. For large crustaceans, the different in species composition can be as high as 69.41%. Four newly discovered and endemic species, three crustaceans and one bivalve, have been found from the Guieshan Island deep-sea hydrothermal vents. The unique fauna of the deep-sea hydrothermal vents off the Guieshan Island should be protected.
This survey was conducted on the brachyuran fauna of the Lan-Yang Marshes feom July to November in 2007. A Total of 8 species of brchyuran crabs, via. Uca arcuata, Uca borealis, Uca crassipes, Uca lactea, Tmethypocoelis ceratophora, Chiromantes dehaani, Perisesarma biden, and Helice formosensis were recorded from the various interdal and semi-terrestrial habitats. Differnet and overlapping assemblages of crabs dominated in the various habitats. Species richness was low in Lan-Yang Marshes compared to other surveyed by other authors at the same sites is probably a result of the typhoon.
Otherwise, the species in the I-Lan bay ecosystem were classified to redtail scad, Japanese jack mackerel, largehead hairtail, dolphinfish, anchovy, mackerel, bullet tuna, scomber, shrimp, cephalopod, marine mammals, zooplankton, phytoplankton, other pelagic fishes and groundfishes based on the fishery statistics and information related to living food. The data and parameters, such as biomass, production per unit of biomass and consumption per unit of biomass, have been collected and preliminarily estimated for ecosystem modelling. However, the collection and discussion of some input data and the diet composition will be necessary for further analysis. |