The fishing ground formation of sergestid shrimp (Sergia lucens) in the coastal waters of southwestern Taiwan

Abstract

The aggregation mechanism of sergestid shrimp (Sergia lucens) in the coastal waters of southwestern Taiwan was studies based on the eleven monthly cruises data including temperature, salinity, nutrients, phytoplankton and zooplankton, collected by research vessel Hai-Fu from August 1999 to June 2000. Mean while, the CPUE (kg/hour) of the shrimp were also estimated from 16 selected sampling vessels. The results indicated that the shrimp aggregates near two major fishing grounds Kaoping River estuary and Fangliao canyon in the coastal waters of southwestern Taiwan at the depth stratum from 100 to 200m, water temperature in the range of 15-22°C and salinity at 34. 3~34.7 psu, which are named by local fishermen as Kangkou and Sanlunwei fishing grounds, respectively. The formation of fishing ground was related to the mixed layer depth (MLD) as indicated by the monthly variation of environmental factors and daily CPUE which coincided with the peak season of nutrients and phytoplankton and zooplankton. The Kangkou fishing ground was formed at the coastal front mixed by the coastal water and South China Sea surface water during spring and summer, whereas Sanlunwei fishing ground was formed at the upwelling area, which was driven by strong prevailing offshore wind during autumn and winter.