Determining the spatial distribution of spawning by anadromous and resident brown trout Salmo trutta L using strontium content of eggs collected from redds |
| |
| Authors: | Esben A Kristensen Gerard P Closs Ricky Olley Jonathan Kim Malcolm Reid Claudine Stirling |
| |
| Institution: | 1. Aarhus University, National Environmental Research Institute, Department of Freshwater Ecology, Vejls?vej, Silkeborg, Denmark;2. Department of Zoology, University of Otago, Dunedin, New Zealand;3. Nelson/Marlborough Fish and Game, Nelson, New Zealand;4. Department of Chemistry, University of Otago, Dunedin, New Zealand;5. Community Trust of Otago Centre for Trace Element Analysis, Department of Chemistry, University of Otago, Dunedin, New Zealand |
| |
| Abstract: | Abstract – Strontium (Sr) content of eggs collected from redds were used to determine the spawning contribution of resident and anadromous female brown trout in the Taieri River, New Zealand and were analysed on the catchment and tributary scale. At the catchment scale, analysis of Sr showed differences between eggs collected above and below the Taieri River Gorge. Samples collected above the gorge all had low‐Sr concentrations similar to levels found in an entirely resident brown trout population. Samples collected below the gorge exhibited a broad range in Sr concentrations, ranging from levels comparable to the known anadromous samples to levels comparable to the known freshwater‐resident samples. This suggests that the gorge prevents upstream migration by anadromous brown trout in the Taieri River. At the tributary scale, this pattern of anadromous brown trout spawning downstream of freshwater‐resident fish was repeated in one of the two tributaries located downstream of the gorge. Energetic cost of migration is the most likely explanation for the observed patterns in catchment and tributary scale distribution of spawning by resident and anadromous brown trout. It is concluded that the use of Sr concentrations in eggs collected from redds is a cost‐effective and reliable method to investigate the spawning contribution by anadromous brown trout. |
| |
| Keywords: | trace elements migration salmonids New Zealand |
|
|
