Abstract

Marine aquaculture is a promising activity along the nutrient-rich coastal waters of the Pacific Ocean in Chile and Peru. Scallop is a commercially valuable species with a cultivation technology that was successfully tested in phase I of this project in Peru. While earlier attempts at commercial cultivation by small-scale producers came to a stop due to bottlenecks in the availability of natural seed, researchers successfully produced sufficient quantities (1.8 million per batch) of surviving larvae in laboratory experiments. This second phase project will attempt to establish a pilot production module using laboratory-produced seed. Some collaboration with artisanal fishermen is anticipated within the framework of another ongoing project "Artisanal Fisheries (Peru)" (88-0191). This activity will also be supported by the ongoing regional joint Fisheries/Communications Division project "Fisheries Technology Transfer" (88-0119) that will supply audiovisual material for extension work at the community level. Coordination with projects in Chile will be provided under the umbrella of the regional aquaculture network project "Aquaculture Development Thrust (Regional)" (89-0017).

Post-Project Summary

The first phase was funded under project 85-0272. In the second phase, researchers cultivated four species of algae under laboratory conditions as food for scallop larvae. These were: Pavlova lutheri, Isochrysis galbana var. tahitiensis (T-iso), Chaetoceros gracilis and Dunaliella tertiolecta. Maximum cellular concentrations were obtained with T-iso and C. gracilis, which reached more than 6 million cells per ml by the ninth day, after which they rapidly declined. Native species did not perform as well under laboratory conditions. The researchers achieved similar results raising algae in fishmeal, a less expensive alternative to the standard medium. The researchers compared the growthrate of larvae fed on microalgae from native and imported species, and observed that the former gave better results. Also, larvae fed on microalgae grown on fishmeal developed faster than those raised on the microalgae grown in the standard medium, reaching the attachment stage in 18 rather than 21 days. At 30 days, the first post-larvae appeared and at 2 months they were ready to be transferred to the ocean. The scallop, Argopecten purpuratus, was propagated in the laboratory and transferred to the pilot production module on a private concession owned by the firm, Mariexport S.A. The production module consisted of two longlines from which were suspended three nets of graduated mesh size to hold scallops of different sizes, at different depths and at three different stocking densities. Samples of scallops were taken from each net on a regular basis, and weighed, measured and monitored for mortality. At the initial stage of ocean cultivation, the optimal density and depth were 5 000 individuals per pearl net at 7 m deep. These showed a growthrate of 5 mm per month and a survival rate of 94.8%. The best growth (5 mm per month) and survival rate (96%) at the intermediate stage was obtained at a density of 800 individuals per net at 7 m deep. At the final stage, the largest increments in length and weight were obtained at a density of 20 individuals per net at 7 m deep. However, the best rate of survival was obtained at the same density, but at 17 m deep. A cost benefit analysis of integrated scallop production as described above gave a high rate of profitability: 47.15% economic internal return rate; and 45.68% financial internal return rate. The technology was transferred to various enterprises and universities. Approximately 30 students and professionals received training. The project results were disseminated at various meetings and workshops and in eight publications listed in the final report.

Recipient Institution(s)