Search

The larval rearing performance of California yellowtail ( Seriola lalandi) and white seabass ( Atractoscion nobilis) was compared between larvae fed taurine-supplemented rotifers ( Brachionus plicatilis) and Artemia ( Artemia franciscana) and control groups fed live feeds with no taurine enhancement. Results from the S. lalandi trial demonstrated that when fed taurine-supplemented rotifers, survival was significantly higher than the control group (20.1% vs. 9.1%, P < 0.01) as was notochord length (5.43 mm vs. 5.13 mm, P < 0.005). No larval performance differences were detected between experimental and control treatments of A. nobilis. Biochemical analyses demonstrated that taurine concentrations were significantly elevated in both S. lalandi (23.7 vs. 2.7 mg g−1, P < 0.001) and A. nobilis (33.0 vs. 21.0 mg g−1, P < 0.005) when live feeds were supplemented with taurine. Results suggest that taurine is a limiting nutrient in the larviculture of S. lalandi but may not be for A. nobilis. [ABSTRACT FROM AUTHOR]

This study focused on methods to reduce bacterial loads in the larval culture tanks of California yellowtail ( Seriola lalandi). We conducted two trials to evaluate methods to minimize bacterial loads in the larval rearing water. The first trial examined the use of bentonite clay as a turbidity agent to replace algae in a green water-type environment. This trial consisted of three treatments: (1) clay with continuous feeding ( CCO), (2) clay with batch feedings ( CBA) and (3) algae paste with batch feedings ( ALG). The results showed that both clay treatments had significantly fewer Vibrio colonies in the water column ( CBA - 180 ± 78; CCO - 377 ± 120 CFU mL−1) than the ALG treatment (5692 ± 2396 CFU mL−1) after 14 days of culture. Survival was significantly higher in the CCO treatment (14.1 ± 2.6%) than either the CBA (2.3 ± 0.5%) or ALG treatments (2.8 ± 1.5%). The second trial attempted to limit bacterial loading in the larval culture tank by passively transferring the larvae into an adjacent, clean tank at 1, 5 and 9 days post hatch during the first 2 weeks of culture. The results from this trial showed that after 12 days of culture, water in the transfertank had fewer Vibrio colonies (1025 ± 541 CFU mL−1) than the water in the control tanks (1962 ± 1415 CFU mL−1). Also, survival was significantly higher among larvae that were transferred (43.9 ± 13.5%) than in the control tanks (23.1 ± 6.3%). [ABSTRACT FROM AUTHOR]

A captive population of California yellowtail ( Seriola lalandi) was used to document spawning patterns, including measures of egg production, population fecundity and egg and larval quality from 2007 to 2010. Spawned eggs were also used to document larval development and to develop rearing techniques for aquaculture in the region. Broodstock growth and condition factor were best when feeding rations were maintained at 10-15% body weight week−1 during the warm summer months. A winter ration based on satiation feeding was typically 4% body weight week−1. During the 4-year study period, the only broodstock health issue was an infestation by the parasitic gill fluke Zeuxapta seriolae, which was readily treated. Spawning occurred naturally in the 140 m3 tank when the ambient water temperature reached 16°C and ended when the temperature exceeded 22°C. Egg production reached a maximum in 2010 when 43 spawn events were recorded from a pool of nine females yielding 36.8 million eggs in total. The average female size at this time was 20 kg, which equated to a total annual population fecundity of approximately 226 000 eggs kg−1 female year−1. Larval rearing trials yielded survival rates as high as 5.8% from egg to 50 days post-hatch (dph). Successful larval culture methods included the addition of algae paste for green water culture, rotifers (20 rotifers mL−1) at 2 dph and Artemia (5 Artemia mL−1) at 6 dph. Larvae were transferred from the incubation tank at 10 dph to a shallower tank with 33% greater surface area to accommodate the larvae's strong orientation to surface waters. This research represents the first documentation of successful spawning and larval rearing for S. lalandi in the eastern Pacific. [ABSTRACT FROM AUTHOR]