DOES LARVAL FEED QUALITY AFFECT GROW-OUT PERFORMANCE OF MARINE FISH: A CASE STUDY with Totoaba macdonaldi.

Juan P. Lazo, José P. Fuentes*, Benjamín Barón-Sevilla,
 
Centro de Investigación Científica y de Educación Superior de Ensenada
Carretera Ensenada-Tijuana No. 3918 Zona Playitas Ensenada, B.C., México
jplazo@cicese.edu.mx

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 an extremely 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 juveniles for grow-out, resulting in highly variable survival and growth performance, 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 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 (SKD), stress tolerance and nutrient utilization during the grow-out stage. Two dietary LC-PUFAs levels were used as enrichments of live feed fro 3 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 either treatment for the first 17 DAH. At 18 DAH, larvae were larvae from each treatment were split in half and 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. Additionally 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. 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. Digestive capacity data will be presented and furhter discussed. Results obtained from this study suggest that feed quality during the larval stage not only has important effects in growth and survival during the larval period,  but also significantly influences performance during the grow-out period and should be taken into consideration.