Evaluation of
microalgae and industrial cheese whey as diets for Tapes decussatus
(L.) seed: effects on water quality, growth, survival, condition and
filtration rate
P. Enes, M.-T. Borges-2003
Aquaculture Research, 34(4): 299
Abstract :
As reference diets for bivalve molluscs
are missing, this study first evaluated the best mixed algal diet (Tetraselmis
suecica Butch/Phaeodactylum tricornutum Bohlin) concentration for
4-mm-length Tapes decussatus (L.) clams. It also assessed the
performance of an industrial by-product (cheese whey) as a single diet or
supplement for the best algal ration previously determined. Growth,
survival, condition index and filtration rate were used to compare the
different diets. Implications of rations tested on rearing water quality
were also investigated, especially ammonium and heterotrophic bacteria
levels. With a food concentration as algal dry weight per total seed live
weight of 0.7% day
-1,
seed for grow-out (7 mm) could be obtained within 1 month. A
mixture of 25% algal ration and 75% cheese whey gave the best performances.
Artificial diets resulted in lower growth rates than live food (20 % to 40%
of the best algal ration), but could be considered good maintenance rations
in energetic terms. Using cheese whey, and without any algae, hatchery
produced seed can be kept economically indoors for at least 30 days
without loss in condition.
(Departamento
de Zoologia e Antropologia, Faculdade de Ciências da Universidade do Porto,
4050-290 Porto, Portugal)