Growth, diet, movement, and abundance of adult banded kokopu (Galaxias fasciatus) in five Coromandel, New Zealand streams

Abstract

Banded kokopu populations were surveyed seasonally over 1 year in five Coromandel streams to determine the influence of food supply on diet, growth, abundance, and movement. Streams with high benthic invertebrate abundance and drift of aquatic origin had high fish abundance. However, terrestrial drift was the dominant food for adult banded kokopu over all seasons and streams, on average comprising 75% of their diet by number and 89% by weight. Annual growth rates of tagged individuals ranged from 3 mm to 16.5 mm, with smaller fish growing faster than large fish. Low growth rates of large fish were consistent with the recapture of a fish that had only grown from 195 mm to 215 mm in 7 years. Our observations confirmed the strong association between banded kokopu, pool habitat, and cover, and also indicated that high fish abundance restricted growth rates and movement and increased interaction.

Key words:

• banded kokopu
• Galaxias fasciatus
• growth
• diet
• density
• pool fidelity
• terrestrial invertebrates
• invertebrate drift