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The spotted wolf®sh Anarhichas minor (Olafsen), with its rich and tasty ®llets, popular skin and high growth rates in captivity, is a promising candidate for cold-water aquaculture. We have established a production line for the wolf®sh during 5 years of active research on the biology of the species. Our broodstock, sampled from the Barents Sea, has mainly spawned during autumn. The females must be stripped as soon as possible after ovulation. The best egg batches have shown c. 100% fertilization and survival rates between 60% and 80% during the 800-to 960-daydegrees-long incubation period. Rearing temperatures of 6°C, 8°C, ambient and decreasing temperatures have turned out to be satisfactory for survival. Treatment with 150 p.p.m. glutardialdehyde twice a month is recommended to control microorganism growth on eggs. Premature hatching has been a problem in individual egg batches; the reasons are not fully understood. Normally hatched individuals are » 22 mm long and well developed, with a small yolk sac, which is completely resorbed after about 4 weeks at 6±8°C. The fry have been successfully start fed on formulated feed as well as Artemia. Highest early growth rates have been noted at 8°C, but overall survival was best at 6°C. On-growth of spotted wolf®sh juveniles fed formulated dry¯oating feed at low temperatures in shallow raceways has been promising. After 2, 3 and 4 years, the mean weights of the ®rst generation produced in aquaculture were 0.7, 2.7 and 5.1 kg respectively. These individuals now make up the broodstock at a recently established commercial production facility.

Growth rate of tagged juvenile turbot was significantly influenced by the interaction of temperature and fish size. The results suggest the optimum temperature for growth of juvenile turbot in the size range 25-75 g is between 16 and 19 C. Optimal temperature for growth decreased rapidly with increasing size, and is between 13 and 16 C for 100 g turbot. Although individual growth rates varied highly at all times within the temperature treatments, significant size rank correlations were maintained during the experimental period. The study confirms that turbot exhibit ontogenetic variation in temperature optimum, which might partly explain different spatial distribution of juvenile and adult turbot in ocean waters. 1996 The Fisheries Society of the British Isles

Escapes of cod (Gadus morhua) from sea cages represent an economic problem for farmers and a potential environmental problem. We estimate that 0^6% of cod held in sea-cage farms in Norway were reported to have escaped each year from 2000 to 2005, which is a high proportion compared with salmon.We interviewed employees at 19 coastal sea-cage cod farms in Norway to investigate both how and why cultured cod escape and to document cage handling and management strategies that were e¡ective in minimizing escapes. Based on the interviews, we describe ¢ve working hypotheses that may explain why a greater proportion of cod than salmon escape: (1) cod are more willing to escape than salmon; (2) cod bite the net cage and create wear and tear; (3) net cages have insu⁄cient technical standards for cod culture; (4) cod are placed in sea cages at considerably smaller sizes than salmon; and (5) cod are more popular feed for predators. Preliminary testing of the hypothesis that cod bite netting and create holes was done by placing pre-damaged net panels with cut twines and control panels inside sea cages. Holes in the pre-damaged net panels increased in size over a period of 3 months. The type of damage indicated that biting of netting twines was the likely cause. Escape of cod from sea-cage ¢sh farms H Moe et al. Aquaculture Research, 2007, 38, 91^99 Aquaculture Research, 2007, 38, 91^99 Escape of cod from sea-cage ¢sh farms H Moe et al.

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