Fascinating studies of different New Zealand animals are being conducted at the Zoology Department of the University of Otago; Pavel Mikheev, a PhD student originating from Russia, is currently leading a research project on brown trout. The species was introduced in to New Zealand more than 150 years ago and nowadays is a significant component of freshwater and estuarine ecosystems across the country, with high economic and recreational significance as a popular sport fish.
In his study, Pavel is investigating brown trout populations of the Taieri River catchment (Otago Region), with the most intensive sampling taking place at the Silverstream - one of the main spawning tributaries of the Taieri river near Dunedin. The main aim of the project is to estimate competition between juvenile trout and resource use at habitats used intensively for spawning by the migratory sea-run form of trout. Pavel estimates the dynamics of migratory activity, density, biomass and growth rates of brown trout juveniles and their pressures on the stream invertebrate community during the first months of their life after hatching from “nests” in the gravel. The majority of the data is obtained using spotlighting at night; the most harmless method of intensive stream fish surveys. At night, fish are less active and it is much easier to see them using a powerful torch. Some of the fish are then captured by dip net, measured, weighed and released unharmed at the place of capture.
People walking near Pavel’s surveys at Silverstream took interest of his study, with many parents asking him to show the fish to the children. With University approval, Pavel displayed fish to the community at a weekend event using aquaria on the stream bank. Some brown trout juveniles and native fish were captured during the night survey, kept in cages in the river until the morning, when they were released into the aquaria.
Live fish in aquaria on the riverbank impressed both children and their parents! They were happy to learn so many new things about fish living in the stream nearby. The fountain of questions never stopped!!! And this fish lives here as well?.. How big can it grow?.. What do they eat?.. How do they spawn? What is whitebait?..
But the best part for many was seeing two longfin eels! It was the first time the children and their parents had been able to see real eels up so close. The story about their life cycle got a lot of interest and more questions… After being shown to the children, the fish were released back into the river with applause and after end of the display, parents were asking to repeat this event one more time, promising to invite their friends.
Following the interest of the community and the undoubted significance of environmental education of children (and their parents!), we plan to repeate similar public events on a regular basis. Stay tuned!