Seasonal variation in growth and yield of the brown mussel Perna perna (L.) cultured in Ubatuba, Brazil

Seasonal variation in growth and yield of cultured brown mussels Perna pern a was studied in Ubatuba, south-east Brazilian coastline. Young mussels wer e transplanted (seeded) into four groups of 16 polyethylene net tubes 2 m l ong, suspended from a wooden raft (18 m(2)). The first group was set out in April (autumn), the next in July (winter), the next in October (spring) 19 84 and the final group in January (summer) 1985. One net tube of each group was sampled monthly and biometric data were collected. Growth was initiall y faster for the spring group, but at the end of the culture period length and weight were not statistically different between groups. L-proportional to and W-infinity were 73.9, 71.3, 72.7 and 73.8 mm and 26.3, 23.9, 25.7 an d 25.7 g for the autumn, winter, spring and summer groups, respectively. Ma ximum yield was attained 9 months after seeding for groups of autumn, winte r and spring (7.2, 5.2 and 6.3 kg x m(-1), respectively) and after 10 month s for the summer group (6.9 kg x m(-1)). The conclusion of this study is th at, growth and yield were unaffected by the season of seeding at the study site and that it is not commercially worthwhile to farm mussels more than 9 months, due to yield decrease. (C) 1998 Elsevier Science B.V. All rights r eserved.