Spawning related seasonal variation in fyke net catches of golden galaxias (Galaxias auratus): Implications for monitoring lacustrine galaxiid populations

Abstract

Fishes belonging to the family Galaxiidae are relatively small (usually <300 mm long), freshwaterdwelling teleosts that are found on several land masses in the southern hemisphere (McDowall & Fulton 1996). Many galaxiid species have nondiadromous life histories and the distribution of some of these consists of discrete lacustrine populations (McDowall 2000; Allen, Midgley & Allen 2002). As a result of restricted or fragmented distributions, along with other impacts (e.g. introduced fish species), many lacustrine galaxiid species are considered to be threatened; hence monitoring populations for conservation purposes is a common management practice. Fyke nets are known to be effective for capturing small-sized benthic or littoral fish in lakes (Fago 1998; Krueger & Hubert 1998), including galaxiids (Rowe & Chisnall 1997; Rowe, Konui & Christie 2002). Fyke net catches of Atlantic salmon, Salmo salar L., in lakes vary seasonally, suggesting relative abundance indices based on catch data often require correction for differences in catchability (Ryan 1984). Seasonal fluctuations in fyke net catches of European perch, Perca fluviatilis L., due to spawning-related habitat shifts were also reported by Kubeka (1992). Other studies showed that cover-orientated fish species tend to have increased catchability by fyke nets because fyke nets provide cover (Krueger & Hubert 1998; Rogers, Hansen & Beard 2003).