Growth variability in individually confined elvers, <i>Anguilla anguilla</i> (L.)

Abstract

Newly caught elvers Anguilla anguilla (L.) were individually confined, induced to feed and their survival and growth variability compared to those of similar elvers held communally in lowdensity populations. Similar trials were conducted with fast‐growing and slow‐growing older elvers that had been induced to feed while cultured communally. It was not difficult to induce feeding in newly caught elvers, nor did it appear necessary for elvers to be stimulated to feed by the presence of others. Isolation seemed to enhance growth variability in newly caught elvers. In older elvers growth was generally depressed by isolation. Following a period of stress, e.g. weighing, small fish tended to grow more slowly than larger fish in the individual groups. This suggested some permanency of stunting; however, some markedly stunted fish taken from large populations showed remarkable recovery when isolated and exhibited very high instantaneous growth rates, over 6.5% day −1 .