FUNCTION OF SENSE ORGANS TO THE FEEDING BEHAVIOR OF JUVENILES CHINESE STURGEON CAPTURED FROM THE YANGTZE ESTUARY

Chinese sturgeon, A cip enser sinensis, is an endangered anadrom ous species that currently only remains in the main stream of the Yangtze River and the coastal China Seas. It spawns in the upper YangtzeR iver and grows in ocean, and it is one of the largest fish to enter fresh water, with them axmi um of 400 cm total length and 450 kg body w eight. As a result of habitat alteration and overfishing, population of this spec ies have greatly declined in abundance. Thus, this species has been listed as one of the Chinaps national protected wild anmials in category I in 1988, and listed in the IUCN s' Red List in 1997. The Yang tze Estuary is the only passage for Chinese sturgeon migrating between fresh water and ocean, and also the miportant feeding ground for the young Chinese sturgeon when they pass through the estuarine area from May to August every year. In order to protect this species,the Yangtze Estuarine Nature Reserve (area, 274km2) for young Chinese sturgeon was established in 2002, and this area has been listed as Important International Wetland by the Convention on Wetlands of International Importance Especially as Waterfow Habitat in 2008. How ever, most aspects of the early life history of Chinese sturgeon in the wild have not been invest igated. The objective of this study was to document the function of sense organs to feeding behavior of Chinese sturgeon juveniles, and to use this inform ation to provide guidance for the conservation of feeding ground of young Chinese sturgeon in the Yangtze estuarine area, and also to provide guidance for the miprovement of aquaculture techn iques of young Chinese sturgeon. 63 fishes (20.0±3.5cm of total length, 69±15.7g of body weight) for this expermient were collected using gill nets from the Yangtze Estuary from May to June, 2006. Collected fishes were accommodated in tanks for 2 weeks before expermi ent. By means of surgical sense excision of vision, smell touch, electricity, and latera l line, respectively, the function of specific sense organs to feeding behavior was studied. Six expermiental groups and one contral group were designed. Expermient lasted for 5 days, and water temperature of expermienta l tanks was contro lled between 24.5-27.0℃. The expermiental results showed that there was no significant difference in food intake rates between tested groups (respective excision of vision, lateral line and electrosensory) and control group (p>0.05). Food intake rate of tested group that sense of smellwas excised was only 34.76% of that of control group, and food intake rate of tested group that sense of touch was excised was 73.80% of that of control group Foodin take rate of tested group that sense of smell and chin barbell were excised in the same tmie was only 17.01% of that of control group. There fore, it is may conclude that sense organs of smell and touch of young Chinese sturgeon played an important role in feeding behavior.