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Ecuador has a long tradition in aquaculture, mainly related to the cultivation of shrimp and tilapia in earthen ponds. Land-based production methods have a large environmental, economic and social impact due to the extensive use of land and its effects on the ecosystems. In order to increase the production of fish without further land use and with a lower environmental impact, a good alternative is the culture of fish in floating cages, adopting technologies used successfully in many other countries. This article analyses the current situation of offshore aquaculture (the production of fish and other aquatic organisms in the open sea) in Ecuador, and the prospects for the future of this sector in the country.

The use of two protein sources, krill meal (protein 62% dry matter) and soybean protein (protein 85.2% dry matter), and their effect on growth performance and feeding behavior of red sea bream, Pagrus major, during weaning and metamorphosis, was studied using microbound diets. High levels of dietary soybean protein (25% of the diet) resulted in a poor feeding response and marked anorexia, resulting in high mortalities and poor growth. Moderate levels of dietary soybean protein (17-19% of diet) resulted in higher growth. Krill meal contributed to an increase in food consumption. A possible reason for the reduced growth of fish fed soybean protein-based diets was the lower palatability of these diets. Alternative sources of protein could replace fish meal, if these sources are more palatable to the fish.

Three types of microparticulate diets for marine larval fish were tested to improve retention of added amino acids after immersion in water. These particle types included microbound, microcoated, and microencapsulated particles. Binding crystalline amino acids to alginate, carrageenan or zein microparticles gave poor results, with leaching of 80–90% of the crystalline amino acids within minutes after immersion in water. Coating microbound diets or crystalline amino acids with tripalmitin had little effect on the retention of crystalline amino acids. Microencapsulation of crystalline amino acids within protein-walled capsules gave better results, with capsules retaining up to 60% of some crystalline amino acids after 2 min in water. The best results were obtained by encapsulating crystalline amino acids within lipid-walled capsules. Retention was further improved by including 2% (w/w) Span 85, a surface-active agent, in the lipid wall of the capsules. With this technique, leaching was reduced to 1.4% when capsules were suspended for 2 min in buffered water (pH 8.5). Feeding studies with olive flounder ( Paralichthys olivaceus ) indicated that larvae older than 20 days could break tripalmitin-walled capsules. Lipid-walled capsules show promising potential for use in nutritional studies with marine fish larvae.

The effectiveness of live-algae replacement diets for the conditioning and spawning success of adult Manila clam, Tapes philippinarum (Adams and Reeve), was assessed. Two dried diets were tested: a diet of dried Tetrasetmis suecica (Kylin) Butch, and a mixed diet of dried T. suecica (70%) and dried Cyclotella cryptica Reimann et al. (30%). These diets were compared with three live diets: Skeletonema costatum (Grev.) Cleve, Dunaliella tertiolecta (Butcher) and T. suecica. An unfed group was used as a control. The same ration (dry weight) of food was supplied for all groups at 6% of the dry meat weight per day. The broodstock were conditioned for 7 weeks. After 4 weeks none of the animals was ready to spawn. After 6 weeks all the diets promoted spawning and after 7 weeks the unfed group also spawned. It seems that dried algal diets are effective for conditioning and spawning of Manila clams, as the dry meat weight, condition index and fecundity of broodstock fed these diets were significantly greater than for unfed animals. However, the fecundity and proportion of parental lipid released in the eggs of clams conditioned with dried diets was lower than for the clams conditioned with live algae.