Veterinary Research Communications, 27 Suppl. 1 (2003) 695–698 © 2003 Kluwer Academic Publishers. Printed in the Netherlands
Farmed Fish Pathology: Quality Aspects M. Manera*, P. Visciano, P. Losito and A. Ianieri Dipartimento di Scienze degli Alimenti, Universita` degli Studi di T eramo, Piazza Aldo Moro 45, I-64100 T eramo, Italy *Correspondence: Dipartimento di Scienze degli Alimenti, Facolta` di Medicina Veterinaria, Universita` degli Studi di T eramo, Piazza Aldo Moro, 45, I-64100 T eramo, Italy E-mail:
[email protected] Keywords: gilthead sea bream, pathology, quality, rainbow trout, sea bass
INTRODUCTION The increase in fish demand has caused a proportional increase in the fishing effort but, because of over-fishing and the consequent decrease in fish stocks, annual world catches are actually diminishing. Aquaculture has therefore registered an exponential increase, in order to at least partially satisfy the supply deficit. Farmed fish can be harvested at will, enabling at least in theory, peak condition and the production of uniform and superior product (Roberts, 2001). Moreover, this implies the solving of many husbandry problems, one of which is fish pathology and its impact on fish quality. The aim of our survey was to evaluate the consequences on fish quality of several pathologies observed in farmed fish in the market.
MATERIALS AND METHODS Twenty-four gilthead sea bream (Sparus aurata, L.) – six lots, 24 sea bass (Dicentrarchus labrax, L.) – six lots, and 16 rainbow trout (Oncorhynchus mykiss, Walbaum) – four lots, were sampled from fish wholesalers. All sea bass and 20 sea bream came from Greece (floating cage fish farm); the remaining four sea bream and all trout came from Italy. Fish were measured and weighed and a complete necropsy was performed. Livers were also weighed, and both the condition factor (somatic weight×standard length−3×100) and hepatosomatic index (liver weight×somatic weight−1×100) were calculated. Lateral muscles of sea bream (four unaffected and four affected by winter syndrome) and sea bass (four uninfected, four infected with parasites) belonging to the same lot were homogenized and analysed for water, protein, lipid and ash content according to the following methods, respectively: A.O.A.C. 1975, CEE-ASPA, ISO/DP 6492, ISO-5984. Data obtained were statistically analysed (one-way Anova). 695
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RESULTS AND DISCUSSION The biometrical data, observed pathologies and the percentage composition of the lateral muscle are summarised in Tables I, II and III. The occurrence of disease varied according to the species; condition factor, hepatosomatic index and the percentage composition were affected in both sea bream (winter syndrome), and in sea bass (L ernanthropus sp. [Copepoda] and Cymothoid [Isopoda]). Crustacean parasite species are numerous and are distributed worldwide, in fresh, brackish and salt waters (Kabata, 1970). Local and general effects have been reported regarding damage to fish (Kabata, 1970). In our study the effect of crustacean parasites on weight, condition factor, muscle water and fat content was similar to that described by Kabata TABLE I Biometrical data (mean±standard error)
Standard length (cm) Somatic weight (g) Hepatic weight (g) Condition factora Hepatosomatic indexb
Sea bream
Sea bass
Trout
21.0±0.5 298.5±21.8 5.8±0.8 3.2±0.1 1.9±0.2
25.5±0.8 323.7±28.0 8.6±1.1 1.9±0.1 2.7±0.3
27.7±0.6 396.4±22.9 5.4±0.3 1.9±0.1 1.4±0.1
aUnaffected sea bream (3.11±0.07) vs sea bream affected by winter syndrome (2.27±0.28) (Anova, p
