A quantitative sampling method for assessment of deep cryptobenthic ichthyofauna using trimix diving

Abstract

The first quantitative sampling method for deep cryptobenthic and epibenthic ichthyofauna using trimix diving was performed at about 60 m depth at two localities off the island of Hvar (eastern central Adriatic Sea) in October 2014. The safe, efficient, and relatively simple diving technique combined with the quantitative method for collecting fishes on studied depths is described and explained. A total of 16 fish specimens representing four species, i.e., three gobiid and one blenniid species, were collected using anaesthetic quinaldine at six bottom quadrats (squares) of 1 m². The cryptobenthic and small epibenthic ichthyofauna on these habitats at circalittoral depths could not be efficiently sampled by any other method. Two of the collected species, Thorogobius macrolepis (Kolombatović, 1891) and Vanneaugobius dollfusi Brownell, 1978, are considered rare with very few reported records. The deepest findings of species Parablennius rouxi (Cocco, 1833), Gobius auratus Risso, 1810, and T. macrolepis were recorded.