Ecological studies on two intertidal New Zealand fishes, Acanthoclinus fuscus and Forsterygion nigripenne robustum

Abstract

Population density, seasonal abundance fluctuations, and habitat preferences of Acanthoclinus fuscus and Forsterygion nigripenne robustum were studied in the rocky intertidal zone at Kaikoura, New Zjaland, from August 1988 to June 1989. Monthly recaptures of marked fishes showed that A. fuscus was common on rocky platforms with small shallow pools; F. n. robustum occurred under larger stones and in deeper channels or larger pools. Most captured A. fuscus were juveniles and adolescents; no seasonal fluctuation in abundance was recorded. The intertidal A. fuscus populations at Kaikoura and Auckland were similar in growth rate and condition factor but differed in age structure. The intertidal population of F. n. robustum was dominated by mature fish; the highest abundance was recorded during the winter spawning season. Each monthly sample of A. fuscus included 40% recaptures, significantly more than in F. n. robustum samples. 31% of displaced A. fuscus returned to their original pool within 1 day and 58% within 1 week.

Keywords:

• Acanthoclinidae
• Tripterygiidae
• intertidal environment
• rocky shore
• habitat selection
• population dynamics
• size distribution
• residence time