Thesis (M. For. Sc.)--University of Canterbury, 2006. / Typescript (photocopy). "June 2006." Includes bibliographical references (leaves 88-90). Also available via the World Wide Web.

Goldfish, an exotic originally from Asia, are frequently released into North American waters, causing unknown impacts on native fauna and flora. In the wild, diet overlap between feral goldfish (Carassius auratus) and native red-spotted newts (Notophthalmus v. viridescens) is high, leading to potential interspecific competition over food. In the laboratory, we manipulated densities of goldfish and red-spotted newts to test competition for benthic food organisms between these unrelated species. / No intraspecific interference was noted for either goldfish or newts at any density. However, as density increased food resources were more rapidly depleted by both species, suggesting scramble competition. Foraging strategies of the species differed. Goldfish shoaled more and abandoned food patches before they were depleted, whereas newts were solitary and exhausted a food patch before moving on to new sites. Both species found more food patches when with heterospecifics than with conspecifics, suggesting interspecific information transfer. In addition, goldfish found more food patches than newts in all trials, indicating scramble competition occurred.

Thesis (M.C.M.) -- Lincoln University, 2010. / Also available via the World Wide Web.

No description available.

Thesis (M. Sc.)--University of Canterbury, 2007. / Typescript (photocopy). Includes bibliographical references (leaves 80-90). Also available via the World Wide Web.

No description available.

The goldfish (Carassius auratus) is a hardy exotic species that have established sporadically distributed feral populations throughout North America. In one shallow seasonally anoxic pond goldfish formed a large stunted population of 15-17,000 ind ha$ sp{-1}$, with 53% being small young of the year. Goldfish were predominantly benthic herbivores with little diet overlap with resident red-spotted newts (Notapthalmus v. viredescens). Thus in relatively simple systems lacking fish predators goldfish can be very successful. However in systems with a complex native fish community, goldfish have had less success in colonizing. This could be related to an inability of goldfish to cope with native predators. / Tests for assortative shoaling between brown and gold coloured morphs showed that gold coloured fish exhibited no colour based assortive shoaling, while brown fish showed slight but significant colour preferences for like-coloured fish. This level of shoaling preference did not improve after visual exposure or interaction with native predators, indicating that goldfish showed limited behaviourial responses to predators, and that they were unable to modify their response to a predation threat. Further trials allowing goldfish to interact with either pike (Esox lucius) or bass (Ambloplites rupestris), in both single species groups of predator-naive goldfish, and mixed species conditions of goldfish with predator-experience minnows, showed that goldfish did not alter their behaviour in the presence of minnows (Pimephales notatus) when the predators were not present. However, with the predators present goldfish altered their activities to a more minnow-like pattern and showed a significant improvement in anti-predator behaviour. This improved behaviour continued by goldfish when they were retested on their own, indicating that the goldfish were reacting to the predator and not the minnows. Goldfish colonization may therefore be limited not so much by predation or competition from native cyprinids, but more by the absence/presence of a suitable, native, predator-experienced fish from which to copy the appropriate anti-predator behaviours.