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Locating whitebait (Galaxias argenteus) eggs via canine scent detection

The New Zealand whitebait fishery consists of five species of Galaxiidae fish and constitutes a culturally important commercial and recreational resource for New Zealand. Despite efforts by the Department of Conservation and regional councils, there has been a significant decline in whitebait over the past several decades, with three of the five whitebait species (īnanga, giant kōkopu, kōaro) now classified as 'declining’ and one (shortjaw kōkopu) considered ‘threatened’. Adult fish spawn on riparian vegetation near river mouths during spring tides, the eggs then develop aerially until the following spring tide when they hatch, and the larvae disperse into coastal estuaries. Anthropogenic activities such as flood management, vegetation removal and reduced water quality have led to widespread loss of suitable spawning habitat. Identification of spawning habitat is a key aspect to conserving whitebait species. However, visual surveys for spawning sites are time consuming and spawning areas difficult to predict, as most species do not return to the same spawning site each year. Scent-detection dogs may provide an efficient and effective way of locating whitebait nests, allowing increased protection of spawning areas against disturbance. Four dogs were trained to reliably detect and discriminate giant kōkopu (Galaxias argenteus) eggs from garden snail (Cantareus aspersus) eggs, grass, and blank (no scent) samples within a laboratory-based line-up with a high level of accuracy (≥90% hit rate and ≤10% false alarm rate). Progressing from this, one dog worked on scent line-ups outdoors and demonstrated the ability to reliably detect giant kōkopu eggs (≥90% hit rate and ≤10% false alarm rate), with increasing environmental complexity, as a progression towards application of these dogs for whitebait egg detection in the field. This research provides an opportunity to further explore the use of dogs to detect whitebait spawning sites in the field, potentially providing a new tool for whitebait conservation in New Zealand.
Type of thesis
The University of Waikato
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