Growth, feeding, production, and consumption in 0-group bib (Trisopterus luscus l.) and whiting (merlangius merlangus l.) in a shallow coastal area of the south-west netherlands

Abstract

Hanierlynck, O., and Hostens. K. 1993. Growth, feeding, production, and consumption in 0-group bib l Trisopterus /useus L.) and whiting (Merlungius merlangus L.)in a shallow coastal area of the south-west Netherlands. - ICES J. mar. Sci., 50: 81-91. In 1988 juvenile bib (Trisopterus luscus) and whiling (Merlangius merlangus) were studied in a shallow coastal area by monthly sampling with fine-meshed nets. 0-group fish ofboth species are first caught in May. By the end of the first growth season bib reached about 150 mm SL (standard length), whiling about 170 mm SL. Maximal densities were recorded in June and by the end of the year most fish had left the area. The instantaneous mortality is estimated at 0.008 day"1 (0.77% day 1 for bib and 0.76% day-1for whiting) for both species. In May both species depended almost exclusively on calanoid eopepods. In June and July mysids and amphipods were the most important invertebrate prey, but small fishes such as gobies provided a substantial proportion of the energy requirements, especially in whiting. Front August onwards shrimp and fish dominated the diet in both species Using Jones' (1974) model, food consumption as per cent body weight day'1 varied between 4 and 6% during summer and declined to 2 to 3% in autumn. Total consumption per unit area of subtidal seafloor, by the 0-group fish ofboth species taken together, was estimated at 0.47 g ash-free dry weight (ADWj m-1year-1using Jones' (1974) model and at 0.57 g ADW m-1year-1using a conversion efficiency (P:C ratio) of 0.34. © 1993 Conseil International pour l’Exploration de la Mer.