TERRITORIAL AND NONTERRITORIAL SPAWNING BEHAVIOR IN THE BREAM

The spawning behaviour of bream Abramis brama was studied in 1993, in a harbour on the River Meuse, Belgium. Fish spaced from 22 to 27 April and from 11 to 14 May, when the water temperature rose to 14.5 degree s C. The reproductive behaviour of the bream was studied within a 15 m long part of the harbour using a video camera. Territorial males with tubercles (33-43 cm total length; > 5 years old) defended bank areas of diameter 80-150 cm which included spawning substratum, i.e. roots o f alder and willow trees and aquatic plants. Water depth ranged from 2 5 to 50 cm. Non-territorial males without tubercles (24-33 cm; 3-4 yea rs old), remained 2-4 m away from the bank. Aggressive behaviour betwe en males was frequent and, occasionally, males with tubercles were una ble to defend a territory. Mature females (25-43 cm; > 3 years old), c oming from the deeper water of the surrounding area, were followed by non-territorial males before spawning in territories near the bank. (C ) 1996 The Fisheries Society of the British Isles