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.

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Despite the growing number of recreational anglers targeting white seabass Atractoscion nobilis in California, no information is available on the mortality rates of juveniles following catch and release. We captured juvenile white seabass (430-577 mm total length) with 4/0 offset circle hooks (n ϭ 113) or 4/0 J-type hooks (n ϭ 108) or with a net (control, n ϭ 30) to investigate the effect of hook type on anatomical hook location. We also examined how hook location affected growth and survival for 90 d following release. Offset circle hooks penetrated the lip region significantly more frequently (73%) than did J-type hooks (41%). Hook location was directly correlated with mortality; all mortalities involved hook damage to the visceral region. A 10% postrelease mortality rate was observed for fish caught on both offset circle and J-type hooks. All mortalities occurred within 5 d postrelease. Survival was enhanced when deeply embedded hooks were left in place rather than removed from the visceral tissue. Hook-caught fish showed no reduction in growth when compared with control fish, but deeply hooked fish grew at a significantly lower rate than did fish hooked in the mouth. Angler success rates did not differ significantly between hook types. We recommend that catch-and-release mortality be incorporated into the management plan for white seabass.

Surface disinfection trials were performed on eggs from three marine finfish species: California yellowtail (CYT; Seriola lalandi), white seabass (WSB; Atractoscion nobilis) and California halibut (HA; Paralichthys californicus). All three species were spawned from captive populations maintained at the Hubbs‐SeaWorld Research Institute (HSWRI). Five disinfection treatments were used for each species; Treatment 1 included 100 mg L−1 of formalin (F100) for 60 min (current HSWRI treatment), Treatment 2 included 1000 mg L−1 of formalin for 15 min (F1000), Treatment 3 included povidone–iodine of 50 mg L−1 for 15 min (PI50), Treatment 4 included povidone‐iodine of 100 mg L−1 for 10 min (PI100) and Treatment 5 involved a control with no chemical treatment (CONT). For each treatment, the per cent egg hatching rate, per cent survival to first feeding and notochord length at the time of hatching to the nearest 0.1 mm were recorded. Bacteria were also cultured from eggs after treatment to determine the effectiveness of each treatment in reducing the bacterial counts (CFU mL−1). Treatments F100, F1000 and CONT yielded the highest hatch rates for each species (70–80%), whereas treatments PI50 and PI100 yielded the lowest hatch rates (0–2%). There were no significant differences in survival to first feeding or notochord length, which suggests that the disinfection treatments did not have a negative effect on the yolk sac larvae. The PI50 and PI100 treatments had the lowest bacterial colony counts, showing almost zero bacterial growth. The highest bacterial growth occurred in the F100, F1000 and CONT treatments. Based on the results from this study, the F100 treatment provided the best balance of disinfection and larval health for CYT, WSB and HA.

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White seabass Atractoscion nobilis (family Sciaenidae) form transient spawning aggregations in the spring and summer throughout southern California and northern Baja California, Mexico. Although spawning activity has been linked with sound production in other sciaenid fishes, the function and acoustic characteristics of white seabass sounds have not previously been identified. We described the spawning behavior and characterized the sounds generated by 62 white seabass maintained within the seminatural conditions and free‐field acoustic environment of a net‐pen moored in Catalina Harbor, California. In addition to visual observations, video and audio recordings were made during periods of peak spawning activity in 2001‐2003. The physical characteristics of white seabass sounds were described and illustrated with sonogram, waveform, and power spectrum displays. Gravid females were identifiable during courtship and spawning by shifts in behavior and the development of dark bars across the dorsal region. During spawning, 1‐9 males tightly surrounded a gravid female and the resultant pack shuddered in unison as gametes were simultaneously broadcast into the water column. Five distinct types of sound were produced by white seabass: Single and multiple pulse trains during courtship, drumrolls and thuds during spawning, and booms during yawning and burst swimming. During the actual release of gametes, a rapid succession of overlapping drumroll and thud sounds resulted in identifiable spawning chants lasting 7‐55 s. Consistent physical, behavioral, and acoustical patterns during courtship and spawning indicated that white seabass utilize visual, tactile, and sonic cues to communicate their reproductive state.

White seabass Atractoscion nobilis reared at a production and research hatchery have been observed to occasionally suffer from ocular emphysemas. To identify a possible cause of these lesions, cultured juvenile white seabass were exposed to five gas saturation levels between 98% and 122% total gas pressure (TGP). Experiments were run for 96 h using fish weighing 3 and 22 g at water temperatures of 17.9 ± 0.3°C or 23.0 ± 0.3°C. Fish were observed every 8 h for symptoms of gas bubble disease. Throughout the trial, no fish died when exposed to 98, 102, or 109% TGP and only one fish died at 116% TGP. When fish were exposed to 122% TGP, however, mortality was 5 percentage points greater for both small and large fish in 23°C water than for those at 18°C and 20 percentage points greater for the large than for the small fish at both temperatures. The most prevalent and severe lesions were in large fish exposed at 23°C, followed by small fish exposed at 23°C, large fish exposed at 18°C, and small fish exposed at 18°C. Corneal emphysemas were the most common lesion, affecting even the control group of large fish in 23°C seawater. For fin emphysemas, only the large fish at 18°C were affected at both 116% and 122% TGP. These fish also had the highest incidence of fin emphysemas (50%), followed by the large fish at 23°C (38.3%), small fish at 18°C (6.7%), and small fish at 23°C (1.7%). These results indicate that temperature, size, and gas supersaturation all play roles in the onset of gas bubble disease for white seabass. These factors should be investigated in any hatchery setting when ocular emphysemas arise.