Restoring streams for freshwater fish Jody Richardson Ian Jowett NIWA Science & Technology Series No. 53 2005 Published by NIWA Wellington 2005 Edited and produced by Science Communication, NIWA Private Bag 14901, Wellington, New Zealand ISSN 1173-0382 ISBN 0-478-23272-1 © NIWA 2005 Citation: Richardson, J.; Jowett, I.G. (2005). Restoring streams for freshwater fish. NIWA Science and Technology Series No. 53. 55 p. Cover photograph: Restored section of Okeover Stream, Christchurch, by Bob Spigel. The National Institute of Water and Atmospheric Research is New Zealand’s leading provider of atmospheric, marine, and freshwater science Visit NIWA’s website at http://www.niwa.co.nz Contents Abstract.....................................................................................................................5 Introduction...............................................................................................................5 Types of fish communities........................................................................................7 Data selection and analysis ...................................................................................7 Results...................................................................................................................9 River morphology ...................................................................................................12 River classification..............................................................................................12 Gravel-bed.......................................................................................................12 Spring-/lake-fed ..............................................................................................13 Bush streams ...................................................................................................13 Low gradient ...................................................................................................13 Implications for restoration.................................................................................14 Community requirements........................................................................................14 Shortjaw kokopu community..............................................................................15 Location and physical attributes .....................................................................15 Water quality...................................................................................................15 Banded kokopu community ................................................................................17 Location and physical attributes .....................................................................17 Water quality...................................................................................................17 Redfin bully community .....................................................................................19 Location and physical attributes .....................................................................19 Water quality...................................................................................................19 Cran’s bully community .....................................................................................20 Location and physical attributes .....................................................................21 Water quality...................................................................................................21 Shortfin eel community.......................................................................................22 Location and physical attributes .....................................................................22 Water quality...................................................................................................24 Inanga community ..............................................................................................24 Location and physical attributes .....................................................................25 Water quality...................................................................................................25 Torrentfish community .......................................................................................26 Location and physical attributes .....................................................................26 Water quality...................................................................................................27 Upland bully community ....................................................................................29 Location and physical attributes .....................................................................29 Water quality...................................................................................................29 Brown trout community......................................................................................30 Location and physical attributes .....................................................................30 Water quality...................................................................................................32 Rainbow trout communities................................................................................32 Location and physical attributes .....................................................................32 Water quality...................................................................................................32 Koaro communities.............................................................................................34 Location and physical attributes .....................................................................34 Water quality...................................................................................................34 Longfin eel community.......................................................................................35 Location and physical attributes .....................................................................35 Water quality...................................................................................................37 Restoration activities...............................................................................................37 Physical attributes ...............................................................................................39 Location and morphology ...............................................................................39 Flow regime ................................................................................................40 Sediment supply..........................................................................................41 Gradient.......................................................................................................41 Bank and bed material.................................................................................42 Access .............................................................................................................42 Cover...............................................................................................................44 Catchment land use.........................................................................................46 Water quality.......................................................................................................46 Water temperature...........................................................................................47 Dissolved oxygen and pH ...............................................................................47 Suspended sediment........................................................................................47 Ammonia and other chemical pollutants ........................................................48 Lessons from an active project ...............................................................................48 Summary.................................................................................................................51 Acknowledgments...................................................................................................51 References...............................................................................................................51 Abstract Richardson, J.; Jowett, I.G. (2005). Restoring streams for freshwater fish. NIWA Science and Technology Series No. 53. 55 p. This document provides an overview of factors to consider when restoring streams for freshwater fish communities. The fish community present in a stream depends on the location and physical characteristics of that stream. In some streams, environmental values might be enhanced by increasing species diversity or by increasing fish numbers. This might be achieved by habitat improvement or by excluding unwanted species. Twelve commonly occurring fish communities were identified using selected records from the New Zealand freshwater fish database. The data selection criteria meant that the analysis applied only to communities that occur in flowing water habitats. Relationships between the fish communities and various environmental variables, e.g., the site location, were examined to determine which variables were associated with each community. This allowed us to build models that could be used to predict the fish community in a particular stream from the physical attributes of that stream. Our analysis showed that site location and stream morphology were two of the most important determinants of fish community composition.