Abstract:

Branchiostoma belcheri is a second class protected animal species in China, and is distributed mainly in Jiaozhou Bay and adjacent areas. Based on an ecological survey in November, 2009, the distribution of the lancelet and its relationship with bottom sediments were studied. We found that Beisha waters may be the predominant habitat of lancelet in autumn. Most individuals within three year classes fit in a body size range of 30-40 mm. The abundance and biomass of lancelets in Beisha were 162 ind./m² and 11.93 g/m², respectively. No obvious length classes were observed in Nansha waters. The abundance and biomass of lancelets were 17.33 ind./m² and 0.57 g/m² in Nansha, respectively. We found that the sediment type in Beisha waters was gravel and sand while it was sand and silty sand in Nansha waters. Lancelets generally were found in areas with sandy sediment where the range of mean grain-size was very large with a water depth of 10-20 m. To cope with declining lancelet populations, an adequate reserve should be established in Beisha waters.

Key words: Branchiostoma belcheri, distribution, sediment, protection zone