Aggression and territoriality in Stichaeus Punctatus (Pisces : Stichaeidae)

Brown, Joseph A. (1976) Aggression and territoriality in Stichaeus Punctatus (Pisces : Stichaeidae). Masters thesis, Memorial University of Newfoundland.

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Abstract

Laboratory experiments demonstrated that underyearling Stichaeus punctatus are territorial in tanks of 4050 cm² total bottom area or more for the periods September to January and July through August. In the field, territory holders won a significant number of encounters with intruding fish and were observed to occupy territories from August to November. In laboratory experiments, prior residency was found to be a factor in the territoriality of underyearlings. Older fish were never observed to establish territories in the laboratory or field during the study but appeared to show area affinities for a particular area of the substrate in the field. -- Underyearling aggressiveness was influenced by time of year, water temperature and photoperiod. Aggressive levels were low for the period January to June and high from July to December. Photoperiod affected the intensity of underyearling aggressiveness but not the seasonality of it. The aggressive level decreased sharply in August when the underyearlings completed their first year of benthic life. Older fish were less aggressive and no seasonal influences were noted. The rate of interaction between the two age groups was low and in all encounters between them the older fish were always dominant. -- Underyearlings preferred a rocky habitat when presented with a choice. The isolation and social aspects of aggression and territoriality were examined but the relative importance of these two factors in the territoriality of this species was not determined. -- The social organization operating between the two age groups and its ecological implications during their period of inshore life are discussed.

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