Comparison of distribution of pelagic fish egg and larva between the Minjiang estuary and Xinghua bay

Abstract:

Based on the data from four oceanographic censuses in the Minjiang estuary and Xinghua bay of Fujian Province during April and September of 2008,this paper compared the spatial-temporal distribution of pelagic fish eggs and larva between the Minjiang estuary and Xinghua bay,including the location of spawning grounds,breeding seasons,species composition and density variation in the seas.The results showed that 8 species in 4 orders,7 families of pelagic fish eggs and larva occurred in Xinghua bay,while 10 species in 5 orders,9 families occurred in the Minjiang estuary.The spawning ground mainly lay in the southern waters of Minjiang estuary where high density of pelagic fish eggs and larva occurred.This is because the runoff mainly flowed down the river through the south branch of Minjiang estuary,furthermore,the runoff deflected to south under the influence of the Coriolis Force after going out of mouth,so the southern waters serve as the area where different currents mixed.The middle of Xinghua bay is responsible for the ideal spawning ground where the inner bay water mixed with incoming tidal water.The fishes breeding their offspring mainly were migratory species in the Minjiang estuary,for example Argyrosomus argentatus and Stolephorus chinensis,but resident fishes in the Xinghua bay such as Eleotridae and Gobiidae.For pelagic fish eggs and larva,the densities in the Xinghua bay were 5 ind./m₂ and 9.58 ind./m₂,being clearly lower than the densities (197.17 ind./m₂ and 20 ind./m₂ respectively) in the Minjiang estuary so that its importance as a spawning ground in the Minjiang estuary is greater than that in the Xinghua bay.