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Spatial and temporal variations in fish populations in the upper Thames estuary
Author(s) -
Araújo F. G.,
Bailey R. G.,
Williams W. P.
Publication year - 1999
Publication title -
journal of fish biology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.672
H-Index - 115
eISSN - 1095-8649
pISSN - 0022-1112
DOI - 10.1111/j.1095-8649.1999.tb00721.x
Subject(s) - rutilus , biology , perch , estuary , leuciscus , pomatoschistus , goby , fishery , gasterosteus , flounder , cottidae , three spined stickleback , mugil , salinity , stickleback , piscivore , ecology , sculpin , fish <actinopterygii> , predation , predator
Between February 1989 and August 1990, the upper Thames estuary contained 23 species of fish. Fish numbers were higher and relatively constant in the uppermost part of the estuary. Number of species was augmented in summer from fresh water and from downstream, coinciding with high temperature, low flow and high salinity. The eight most abundant species contributed to 98·5% of the total number. Flounder Pleuronectes flesus , dace Leuciscus leuciscus and perch Perca fluviatilis , recruited from May to August, and common goby Pomatoschistus microps , roach Rutilus rutilus and chub Leuciscus cephalus , from August to November. The upper estuary (salinity 0·34–2·96 p.s.u.) formed a species transition area between the freshwater but salinity‐resistant roach, chub, and gudgeon Gobio gobio upstream, and the estuarine eurhyhaline common goby and flounder downstream. The three‐spined stickleback Gasterosteus aculeatus and cyprinids were more abundant at upstream while perch was more abundant at downstream sites. High abundances of gudgeon, chub and roach were associated with high transparency and dissolved oxygen and low salinity, while high abundances of perch were associated with high salinity and low transparency. Dace and three‐spined stickleback were associated with high dissolved oxygen and low pH, and common goby with high pH. Flounder showed no clear preferences.