The Diel Behaviour of Small Demersal Fish on Soft Sediments on the West Coast of Scotland using a Variety of Techniques: with Special Reference to Lesueurigobius friesii (Pisces; Gobiidae)

Abstract. The diel behaviour of communities of small demersal fishes was studied in situ on the west coast of Scotland using trawling, diving, underwater television and underwater time-lapse photography techniques. Lumpenus lampretaeformis and Pomatoschistus norvegicus were shown to have crepuscular behaviour patterns. Lesueurigobius friesii was a day active fish, spending the night close to or within its burrow and feeding through the day. Disruptions to this behaviour pattern occurred at high abundances of gadoids and during the spawning season. The fish community as a whole showed a crepuscular periodicity. The various observational methods are discussed. There did not appear to be any close association between Lesueurigobius friesii and the decapod Nephrops norvegicus.