Armando García-Ortega

Expression and activity of trypsin and pepsin during larval development of the spotted rose snapper Lutjanus guttatus

The present study aimed to describe and understand the development of the digestive system in spotted rose snapper (Lutjanus guttatus) larvae from hatching to 40 days post-hatch (dph). The mouth opened between 2 and 3 dph, at that moment the digestive tract was barely differentiated into the anterior and posterior intestine, although the liver and pancreas were already present. Gastric glands were observed until 20 dph, followed by the differentiation of the stomach between 20 and 25 dph. Trypsinogen expression and trypsin activity were detected at hatching, increasing concomitantly to larval development and the change in the type of food. Maximum levels of trypsinogen expression were observed at 25 dph, when animals were fed with Artemia nauplii, and maximum trypsin activity was detected at 35 dph, when larvae were fed with an artificial diet. On the other hand, pepsinogen gene expression was detected at 18 dph, two days before pepsin enzymatic activity and appearance of gastric glands. Maximum pepsin activity was also observed at 35 dph. These results suggest that in this species weaning could be initiated at an earlier age than is currently practiced (between 28 and 30 dph), since larvae of spotted rose snapper develop a functional stomach between days 20 and 25 post-hatch.

Nutrition and feeding research in the spotted rose snapper (Lutjanus guttatus) and bullseye puffer (Sphoeroides annulatus), new species for marine aquaculture

The spotted rose snapper (Lutjanus guttatus) and bullseye puffer (Sphoeroides annulatus) are fish species from the tropical Eastern Pacific for which controlled production of larvae and juveniles has been accomplished in recent years. Diverse topics relating to their biology and aquaculture production are currently under study, in particular the nutrition and feeding aspects required to formulate practical feeds and rearing protocols. Improvements in larval growth and survival are possible by feeding live food organisms with natural or enhanced essential fatty acids content and highly digestible artificial microdiets. The ontogeny of the digestive tract and the expression and activity of digestive enzymes have been described for S. annulatus larvae. The effect of various protein and lipid levels on growth and feed utilization has been studied in juvenile and on-growing fish. Both species have carnivorous feeding habits and require high levels of protein in their diets, from 40% to 45% (dry weight) in spotted rose snapper and above 50% in bullseye puffer, with the younger stages requiring the highest protein levels. Encouraging results have been obtained in feeding experiments with different sources of dietary protein from animal and plant origin to evaluate their suitability as feed ingredients in practical diets. Optimization of fish culture practices through feeding management has also been investigated. Trials with various fish densities and feeding frequencies in intensive culture systems are providing information to improve feed utilization and growth in on-growing fish. Further research is underway to evaluate factors in broodstock nutrition which have an impact on egg and larval quality, and into the use of various commercially available oil sources in on-growing diets. In this paper, the results on nutrition and feeding research with both species are reviewed and research needs to support their commercial production in the region are discussed.

Use of Copepods during Early Feeding Stages of Spotted Rose Snapper Larvae in a Scale-Up System

AbstractGrowth but not survival of Spotted Rose Snapper Lutjanus guttatus larvae was improved when calanoid copepods Pseudodiaptomus euryhalinus were included as early feed in a pilot-scale production system. Production of P. euryhalinus that were fed microalgae Nannochloropsis oculata was stable through the snapper spawning season (May–September; 21.4–29.5°C), providing 6,200–9,400 copepods/L with higher nutritional quality than rotifers Brachionus rotundiformis. To evaluate the influence of including P. euryhalinus as a first feed, three dietary treatments were administered to larvae from 3 to 15 d posthatch: (1) P. euryhalinus only, (2) a mix of both P. euryhalinus and B. rotundiformis, and (3) B. rotundiformis only. Use of P. euryhalinus as live feed produced significant differences in larval specific growth rate, which was 48.4% of body weight (BW)/d for treatment 1; 17.5% BW/d for treatment 2; and 7.3% BW/d for treatment 3. However, survival was significantly higher for Spotted Rose Snapper larvae t...