In Headwater Streams of Otago, New Zealand. Lance
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Some aspects of the ecology of non-native Brook Charr (Salvelinus fontinalis) in headwater streams of Otago, New Zealand. Lance Wayne Dorsey Department of Zoology University of Otago Dunedin, New Zealand A thesis submitted for the degree of Doctor of Philosophy in Ecology 2016 ii Abstract Humans have been altering their environment for thousands of years both intentionally and unintentionally. The alteration of freshwater ecosystems has been extensive through the transfer of species across natural barriers and outside their native range. Salmonids were introduced into the Southern Hemisphere in the mid- 19th century during a worldwide frenzy of plant and animal introductions known as the Acclimatisation Movement. Seeking to populate the streams and rivers with useful species for food or sport, brook charr (Salvelinus fontinalis) were introduced to New Zealand during this time along with a number of other salmonids. The introductions were haphazard and not well documented, especially as sustained, repeated introductions from hatchery stock continued well into the 20th century. This thesis examines the introduction of brook charr to New Zealand in a historical perspective, then looks at the current distribution of brook charr and some of their life history, their diet and energetics, and also competitive interactions with native galaxiids in a laboratory experiment. The highland streams of Otago received brook charr introductions starting in the 1880s and sporadically through the 20th century. A fishery did not develop but many populations remain somewhat cryptically present in headwater streams, mostly upstream of brown trout (Salmo trutta). Some of these populations were confirmed and have a direct overlap with the native non-migratory galaxiid species complex which is threatened or endangered. Brook charr displayed a suite of life history traits in these streams including small adult size, early or delayed maturation, and short life span. The life histories were reflective of a combination of factors at each site and were mostly shaped by temperature, growth, and interspecific competition. Growth was influenced by water temperature and light. Fish in warmer water had good growth rates and early maturation. Fish that were sympatric with brown trout had poorer growth but still had early maturation that appears to be a resource allocation strategy. Fish in the cold, high altitude water had slower growth but lived longer and had delayed maturation. An examination of the energy available as invertebrate drift showed differences in the available energy available to fish and that was used to model growth and compare to observed growth. All sites were found to have sufficient invertebrate drift to support the populations. Diet was also examined and analyses indicate a significant overlap between charr and trout. Competitive interactions were measured between brook charr and galaxiids in the laboratory. Galaxiids changed their behaviour in the presence of brook charr in a way that would have negative implications for a population and would make cohabitation iii of a stream very unlikely. Given these conclusions brook charr will persist in Otago for decades or longer and will remain a threat to native fish. iv Acknowledgements I would like to thank my supervisor Gerry Closs for his guidance and unending enthusiasm. I would not have pursued this without his support. I would also like thank Richard Allibone for his discussions and knowledge during the development of this project. Special thanks to Pete Jones for his friendship as well as the months and months of help in the field and with Welsh pronunciations. Special thanks to Manna Warburton for his friendship and understanding as well as help in the field and office. Special thanks to Sourav Paul for his friendship and stories as well as help with statistics. Special thanks to Jay Piggott for the friendship, support, and for being the nicest person in New Zealand. Thanks to Rowan Moore and Josh Tabac for their repeated help in the field. Others were of help in many ways including Tanya Dann, Abbas Akbaripasand, Aurélien Vivancos, Katha Lange, and Christoph Matthaei. I am also grateful to Mohsen Dkhili for his positivity and help with statistics. A general thank you to Jack Jones for his eternal presence and periodic assistance. Thanks to Steve Sturgess and David Lamb for flexibility during the writing and revision process. Thanks to Matt Jarvis for his long distance assistance. Department of Zoology staff were of great assistance on a regular basis and I would like to thank Nicky McHugh for her good nature and help with my laboratory needs. I would like to thank Kim Garrett for his assistance with the fieldwork, equipment, aquarium room, inductions, and providing advice. I would like to thank Murray McKenzie for his workshop skills and help with vehicles and equipment. Vivienne McNaughton for her help purchasing and getting supplies. A big thanks to Ronda Keen and Wendy Shanks for their positive attitudes and help with all the paperwork. I was supported by a University of Otago Postgraduate Scholarship and many CELS191 hours thanks to Lisa Russell. Thanks to Bev Dickson, Albie Zhou, and especially Reuben Pooley at the Portobello Marine Laboratory who were great hosts and made the competition experiment possible. During the frequent repairs of the Zoology electrofishing machine, this project was kept on schedule by the borrowed electrofishing machines of Fish and Game Otago, Department of Conservation, and Clutha Fisheries Trust. This project was assisted by a number of local fisheries professionals in various organizations. The Fish and Game Otago office was of great help providing records, insight, advice, coffee, accommodation, a collection permit, and an electrofishing machine. This great group of people includes Sharon Milne, Morgan Trotter, Helen Trotter, Niall Watson, Ian Hadland, and Cliff Halford. Pete Ravenscroft and Daniel Jack from the Department of Conservation were helpful and full of information about both brook charr and galaxiids, especially in the upper Waipori, and an occasional v electrofishing machine. Aaron Horrell, of the Clutha Fisheries Trust, provided encouragement, information, and an electrofishing machine. Donald Scott, professor emeritus, provided an oral history of some of the Otago populations. John Hayes and Karen Shearer of the Cawthron Institute provided information and support on the Hayes growth model. Thanks to all the other professionals who provided information and are listed as references. I would like to thank the following for access: Wenita forestry for Munro’s Creek, James Scott for Pisgah Creek, Robert and Jock Scott for Boundary Creek, and Mary Lee and the managers of the Snow Farm for the upper Roaring Meg. Mary and Kim Heaney provided accommodation in the Ida Burn valley. A very special thanks to the repeated kind hospitality of Rose and Dave Greer whose farm in the Kye Burn valley provided an ideal base camp and a stomach full of the best lamb I have ever eaten. Thanks to my parents, Maryellen and Wayne, for giving me the love, support, outlook, and attitude necessary to do whatever interested me. Thanks to Carol and Satch for their love and support. Finally, I would like to thank my wife, Maria, for her patience and adventurous defiance as well as Jordan, Logan, and Grace for participating in this experimental journey whether they liked it or not. vi Contents Chapter 1 General Introduction .............................................................................. 1 1.1 Human expansion .......................................................................................... 1 1.2 Expansion of Salmonids ................................................................................. 2 1.3 Effect of Salmonids on native fish .................................................................. 2 1.4 Study species ................................................................................................. 3 1.5 Brook charr in New Zealand ........................................................................... 4 1.6 Aim ................................................................................................................ 5 1.7 Thesis structure ............................................................................................. 5 Chapter 2 The History of Brook Charr in New Zealand ............................................. 7 2.1 Introduction ................................................................................................... 7 2.1.1 Historical background of the settlement and Acclimatisation Movement in New Zealand .................................................................................................. 10 2.2 Methods ...................................................................................................... 13 2.3 Results ......................................................................................................... 15 2.3.1 Historical records .................................................................................. 15 2.3.2 New Zealand Freshwater Fish Database ................................................ 20 2.3.3 Literature .............................................................................................. 30 2.4 Discussion .................................................................................................... 31 2.5 Appendix ....................................................................................................