EFFECT OF FEED QUALITY DURING THE LARVAL STAGE IN THE GROW-OUT PERFORMANCE OF Totoaba macdonaldi JUVENILES

The totoaba (Totoaba macdonaldi) is the largest member of the Sciaenidae family and is consider an endangered endemic fish of the Gulf of California due to overfishing and habitat alteration. Totoaba has a fast growth rate (up to 3 kg in 12 months), an excellent meat quality and is considered a good candidate for aquaculture in the Baja region. The development of culture techniques for this and other marine species has been limited by the supply of healthy and high-quality larvae for grow-out, resulting in highly variable survival and growth performance during the juveniles stage, which becomes a limiting factor for profitable and sustainable industry. It is well know that long chain polyunsaturated fatty acids (LC-PUFAs) are important lipids during the larval period, but studies evaluating the effects of dietary LC-PUFAs during larval stage in the performance of the juvenile stage are scarce. Thus, the objectives of this study were to evaluate the effect of the live feed (rotifers and Artemia) quality (high and low LC-PUFAs content) during larval stage in the growth, survival, digestive capacity, muscle growth, skeletal deformities (SD), stress tolerance and nutrient utilization during the grow-out stage.

Two dietary LC-PUFAs levels were used as enrichments of Artemia from 18 to 30 days after hatching (DAH). The high LC-PUFAs (HL) treatment was achieved by enriching live prey with Ori-Green (OG; Skretting, Norway) diluted one-third (1/3) with fish oil. The low LC-PUFAs (LL) treatment was achieved by diluting the Ori-green with (1/3) with olive oil. Six tanks stocked with 1500 larvae were fed rotifers enriched with Algamac 3000^TM (Bio-Marine Inc.) for the first 17 DAH. At 18 DAH, larvae were fed either HL or LL enriched Artemia. Three replicates per treatment were used. At 31 DAH, larvae were weaned onto a commercial diet (Otohime, Japan). Samples to assess digestive tract development, digestive enzymes and muscle growth were taken 1, 17, 30 and 46 DAH. Standard length (SL) was measured every sampling date and dry weight (DW) at 17 and 30 DAH. At 201 DAH, a salinity stress test (SI) was conducted and skeletal deformities (SKD) were recorded. At 46 DAH growth in terms of SL and wet weight (WW) were significantly higher in larvae fed live-feed enriched with HL treatment but the survival was lower compared to those enriched with LL treatment (Table 1).

At 201 DHA final weight were significantly higher in larvae fed the HL treatment, Additionally, SKD incidence and SI was lower compared to those enriched with LL treatment (Table 2).

Results obtained from this study suggest that feed quality during the larval stage not only has important effects in growth during the larval period,  but also significantly influences performance during the grow-out period and should be taken into consideration. Digestive capacity data will be presented and discussed.