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The ecology of 0‐ and 1‐group turbot was studied at Borth, Cardiganshire, during the years 1966–68. Newly‐metamorphosed turbot appeared in the surf zone from July to October, Abundance during the period September 1967 to May 1968 decreased at an average rate of 25% of the sampled population per month. Fish of the 1966 year‐class grew from a mean length of 4.5 cm in September 1966 to 14.4 cm in October 1967. Growth was fast in the spring and summer, slowing during the late autumn and winter. The most important food items of 0‐ and 1‐group turbot by percentage occurrence and dry weight were polychaetes and mysids. The daily food intake of 0‐group turbot in September 1967 was estimated as 2.5 % of the body weight per day.

Plate I, Data were collected during the period April 1967 to May 1970 from North Sea catches of commercial fishing vessels and research vessels. The gonad maturation cycle showed that turbot spawn during the summer months from May to August; 50% of females were mature at length 46 cm, weight 2 kg and age 4J years. The logarithmic relationship between weight and length in males and females was described by the equation inW = -3-012+ 2-269lnL. Fecundity estimates were examined with respect to weight and length. Fecundity was proportional to the body weight and to about the cube of the length. Growth curves of males and females diverged markedly from age 3 onwards, females growing larger than males. Parameters of the von Bertalanffy growth equation were for males L^ = 492 cm, W^ = 2-4 kg, K = 037 and for females L x = 648 cm, W x = 5-1 kg, K = 0-26. I N T R O D U C T I O NThe turbot Scophthalmus maximus L. is a large teleost flatfish of the family Bothidae. Its range extends from the Adriatic (Faber, 1883) and Mediterranean (Morgan, 1956) northwards to the Norwegian coast, and includes the Baltic Sea and waters surrounding the British Isles. It has been recorded as far north as the Lofoten Islands (Fulton, 1905), and is taken occasionally at Faroe, Iceland and Rockall.The turbot is important as a food fish, not for the size of its commercial catch, but for its value per kg, in which it ranks second to Dover sole {Solea solea L.) It is most abundant in the North Sea, this area supplying roughly 80 % of the total world catch, and is taken mainly as a by-catch by boats fishing for other demersal species. Because of its low abundance compared with other species, the turbot accounts for only 0 7 % of the total annual North Sea demersal catch by weight (Jones, 1970, Ph.D. Thesis, University of East Anglia). . The commercial catches were sampled on the fish market and the information recorded included sex, gonad maturation stage, length (to the nearest centimetre below) and gutted weight in grammes. Wherever possible otoliths were collected for age determination and ovaries for fecundity studies. The high market price commanded by turbot prevented the purchase of whole fish, but collection of otoliths and ovaries was made possible by arrangements with local fish merchants. One important source of material was from the purchase of

Methods are described for rearing turbot (Scophthalmus maximus L.) and brill (Scophthalmus rhombus L.) to late larval stages; the major part of the work was done on the former species. Turbot were reared to 16–0 mm and brill to 17–0 mm in length. Rearing tanks ranged in capacity from 8 to 60 1. Turbotlarvae hatched at 2–7–3–0 mm and successful first feeding was established on rotifers (Brachionus plicatilis) at a length of 3–6–3–8 mm; larvae were transferred to a diet of Artemia nauplii at 5–6—6–0 mm. Experiments on the effect of temperature on growth and yolkabsorption rates in yolksac turbot larvae showed optimal growth efficiency at 15–0 °C. Delayed initial feeding reduced subsequent survival. Drawings of larval development of turbot and brill were made as an aid to their identification in plankton samples.

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