Spatial variability in the nekton of a canal estate in southern New South Wales, Australia, and its implications for estuarine management

1995 ◽  
Vol 46 (4) ◽  
pp. 715 ◽  
Author(s):  
MP Lincoln Smith ◽  
PMH Hawes ◽  
FJ Duque-Portugal

The nekton of a canal development in NSW, Australia, is described. Two sites each were sampled from the main canal and in end canals. The main canal had more species of fish than did the end canals, but the number of individuals was similar between locations. Abundance of particular species showed three patterns: species that were more abundant in either location, species that varied between locations and sites, and species that did not differ significantly in abundance. There was little evidence that the nekton from the end canals, which are presumably less well flushed, was depauperate compared with the main canal. Surveys of nekton in canal estates should incorporate spatial variability at two or more scales so that the effects of these human developments can be assessed properly.

1990 ◽  
Vol 41 (1) ◽  
pp. 13 ◽  
Author(s):  
CA Gray ◽  
VC McDonall ◽  
DD Reid

This study examined spatial and temporal variability in the composition, distribution and relative abundance of by-catch from prawn trawl sampling in the Hawkesbury River, New South Wales. It also determined whether there were differences in the fauna between sections of the river that are open and closed to prawn trawling. By-catch was sampled monthly between March 1986 and February 1988 in three areas along the river that differed in distance from the mouth of the estuary and in salinity. The total incidental catch comprised 75 species of fish, 13 species of crustaceans and 5 species of molluscs: 42 species were commercially and/or recreationally important. Classification and ordination analyses showed that the species composition of the by-catch differed between the area closest to the mouth of the estuary and that furthest upstream, and that this difference was relatively consistent throughout time. The number of species in the by-catch decreased with increasing distance upstream. Annual and seasonal changes in the number of species were similar in all areas along the river: more species were caught in 1987 than in 1986, and in autumn and winter each year. In contrast, the number of individuals caught differed among areas and these differences varied between years. Similarly, seasonal fluctuations in the numbers of individuals caught varied between years, but these variations were similar in all areas. In the area furthest upstream there were no apparent differences in the numbers of species and individuals caught by prawn trawl sampling in sections of the river open or closed to prawn trawling.


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