Preprint volume - SIBM

Pre-print Volume – Posters
AQUACULTURE COMMITEE
G. MARICCHIOLO, T. CARUSO, G. CARUSO, L. GENOVESE, S. MIRTO
Institute for Coastal Marine Environment (IAMC), CNR, Spianata S. Raineri, 86 - 98122 Messina, Italia.
giulia.maricchiolo@iamc.cnr.it
REARING CONDITIONS AND WELFARE IN DICENTRARCHUS LABRAX:
A COMPARISON BETWEEN SUBMERGED AND SURFACE CAGES
VALUTAZIONE DEL BENESSERE IN SPIGOLE (DICENTRARCHUS LABRAX)
ALLEVATE IN GABBIE DI SUPERFICIE E SOMMERSE
Abstract – The aim of this study is to investigates growth, haematological, biochemical and immunological
parameters of European sea bass, Dicentrarchus labrax (Teleostei, Moronidae) farmed in submersible and
surface cages in order to compare physiological status under different rearing conditions. Results obtained
suggest mariculture in submerged cages a promising system that allows to minimize stress and that, hence,
promotes fish welfare.
Key-words: aquaculture, submergence, sea-cage, fish welfare.
Introduction – Offshore submersible cages play an important role for Mediterranean
aquaculture expansion solving several of the substantial operational challenges that
exist in surface-based fish farming such as those related to heavy storms, algal and
jellyfish blooms, sea lice infestations, unsuitable temperatures, and biofouling of net
cages. Moreover, the high concentration of fish confined in surface net cages causing
repeated attacks by predators (i.e., cormorants) determine death, injury and expose fish
to a stressful condition. Therefore, we expected submergence may have a positive
effect on fish welfare.
Subsurface technologies have been tested in several production experiments but the
growth and behaviour of fish in submerged cages relative to standard surface systems
is however largely unknown; objective comparisons of fish performance in
commercial-scale submerged cages vs. surface cages have only been undertaken for
short-term, shallow submergences (Dempster et al., 2008, 2009), or for long-term in
Atlantic salmon (Korsøen et al., 2009).
The aim of this study is to investigate haematological, biochemical and immunological
parameters of European sea bass (Dicentrarchus labrax) farmed in submersible and
surface cages in order to compare physiological status under different rearing
conditions and to validate the efficacy of submersible technology.
Materials and methods – The study was conducted from January to December 2008
in the Castellammare Gulf (NW-Mediterranean Sea) in four fish cages (two submerged
and two surface). The fish cages (2000 m 3 ) were filled, on January 2008, with 75.000
specimens of D. labrax (initial weight: 28.2±4.3 gr), for each cage. The fish were
manually fed with a commercial diet twice a day according to the estimated live weight
and water temperature.
During the trial, fish were randomly collected on a monthly basis, and total and
standard length and wet weight were immediately recorded for each specimen, to test
growth performance, by calculation of the daily specific growth rate (SGRW%) and the
relative condition factor (Kn, Le Cren, 1951). At three sampling time (February, June,
September), samples of fish (n=40) were taken to investigate haematological,
biochemical and immunological parameters. Individuals were taken from the cages and
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