SARDINE Sardina pilchardus AQUACULTURE PRODUCTION: ADAPTATION TO CAPTIVITY, NUTRITION AND SPAWNING

The southern Atlantic stock of European sardines (Sardina pilchardus) is exploited by Portugal and Spain, where the species has high cultural and gastronomic demand and is also absorbed by the canning industry of both countries. Present historical sardine low biomass levels led to strict catching/landing restrictions to the fishing sector, which raised the question on the viability of the production of the species in captivity. Culturing marine species depends on many factors from adapting wild broodstock to captivity, regular natural or induced spawning, to the domain of larval and fattening culture techniques. Sardine particularly constitutes a challenge for aquaculture mainly, because it is a pelagic species of small dimensions, lives in large schools, is a planktonic feeder and is more sensitive to husbandry (intensive scale loss). In 2016, EPPO adapted to captivity two wild sardine broodstock with different ages. The broodstock A (n=80) composed by animals with an initial mean weight of 21.2 ± 2.8 g and the broodstock B (n=300) by individuals with an initial mean weight of 16.4 ± 2.2 g. These breeders have adapted well to captivity, presenting a very low mortality and good growth rate (6.7g. month^-1 during the first 6 months of captivity), within an optimum wide thermal range (13-18 ºC). Both stocks have adapted well to artificial diet, in the case, sea bream commercial inert feeds 1 and 2mm, with a daily feeding rate of approximately 1.5 % of the total biomass. Currently, both broodstock lots are in the second year of natural spawns, last year spawning cycle began at the end of January 2018 until late June in a total of 563g; 14spawns (lot A) and 470g; 29 spawns (lot B) with an average viability of 84% and a hatching rate of 83.5±16.3%. After successfully breeding in captivity, the next focus was to understand what feeding protocol could be suited to rear sardine larvae. Therefore, we have attempted to fed larvae with the "traditionally" rotifers and Artemia used in marine hatcheries and other available plankton. With this is proved that it is possible to rear S. pilchardus larvae using the live feed commonly available for marine fish hatcheries, but other aspects, such as different live feeds, more applied feeding schedules and larval nutritional requirements, must be investigated.

Also, we have compared the nutritional profile of the edible part of adult sardines in attempt to understand the impact in the human nutrition when consuming the reared specimens. After 1 year in captivity these sardines showed a higher content of lipids in the muscle when compared with specimens captured in the wild (25 vs 14%). Fatty acid profile was also significantly different in the sardines from wild, with higher levels of 18:1 n-9 and lower 20:5n-3 and 22:6n-3. Lipids from the liver tissues were not significantly different.

All these results in larvae, juveniles and breeders, lead us to consider that sardines production in aquaculture might be promising in a near future as a new food source, for demand of fresh fish market and mainly to assure a constant supply for the canning industry while allowing a reduction in the exploitation of the wild declining stocks, with clear ecological advantages.      

This study had the support of the project DIVERSIAQUA (Mar2020 16-02-01-FMP-0066)