Research Report **** June & July 2012 **** Captive-bred California Halibut Spawning for the First Time Hubbs-SeaWorld Research Institute () maintains actively spawning populations of three marine finfish species native to the Southern California Bight: the white seabass (Atractoscion nobilis; WSB), California yellowtail (Seriola lalandi; YT), and California halibut (Paralichthys californicus; CH; Figure 1). We are currently holding two separate populations of CH. The first breeding group is made up of 15 large adult CH Figure 1: researchers conduct annual weight sampling that were caught in the wild by hookand-line. Nine came to us this year from and examination of California halibut (Paralichthys californicus) broodstock. the Los Angeles area (see article below). These new wild fish were a welcome addition and will supplement the other long time breeders already in the system. The second breeding group consists of approximately 100 captive-bred F 1 CH. These fish are currently ~4.5 years old, and much like our F 1 YT (see Closing the Loop on California Yellowtail Culture in the June & July 2011 Aquaculture newsletter), were offspring of the original wild-caught breeding group. Figure 2: Eggs from the first spawn of captivebred F 1 California halibut reared at the. Evidence of fertilization can be seen in the eggs at center left (see arrows), although the remaining clear eggs may be viable, too. These F 1 CH will ultimately be used to augment the offspring of the wild-caught adults toward year-round production of food fish, but spawning had been nonexistent until recently. Typically in the wild, 100% of male CH are reproductively mature by age three, which means most, if not all, of our F 1 males are able to spawn. Female maturation, however, is delayed relative to the males; females are 4-7 years old before they start releasing eggs. Right on schedule, though, we observed the first spawning earlier this spring (Figure 2), an event that was significant on two levels. First, it means that these fish are fully 1 10/3/2012
acclimated and old enough to reproduce in captivity. Production has been sporadic and the egg quality is still marginal but we expect that it will improve over time as the fish continue to mature. Secondly, and perhaps more importantly, it confirms that we have females in the group. Flatfish are well known for their temperature-based sex determination, and all male populations are easy to achieve. We had running males (producing milt), but sub-adult female CH have been difficult to identify. Due to the presence of spawned eggs, however, we now know that our F 1 CH group is of mixed sex, although the ratio of males to females is still unknown. We are now very optimistic that this group will become a highly productive broodstock in coming years. Broodstock Collection Efforts Continue Recently, led two efforts to collect wild adult broodstock. First, in June, Research Scientist Mike Shane worked with the Marina Del Rey Anglers in Los Angeles to collect adult CH as part of their 37 th annual Marine Del Rey Halibut Derby (Figure 3). Entrants in the tournament were encouraged to return to the dock with live fish. If they then released or turned over their live halibut in good condition to after it was weighed, they received a 20% weight credit. Over the two-day weekend, 10 fish were turned over for broodstock, with the largest weighing 18.2 kg (40 lbs). The angler that turned over the largest halibut won the Derby and a fishing trip to the East Cape of Baja México because of the weight credit he received. The fish were transported down to our research facility on Mission Bay. After a standard quarantine period, they were integrated into the main breeding tank. This was considered an extremely successful event and one that we plan to repeat in coming years. Thanks to the anglers and to Chevron for providing support for our halibut culture research. Figure 3: A junior angler at the Marina Del Rey Halibut Derby decided to keep this fish for dinner, after donating a live halibut for broodstock the day before. Also in June, we readied our cages at Santa Catalina Island, to receive live white seabass (Atractoscion nobilis) brood fish. Fishing trips in June and July yielded 25 and 14 fish, respectively. As in previous years, Jock Albright graciously donated his assistance with transportation, net deployment, and fish collection. Caring for the system at Catalina isn t a simple job either, however, and to oversee the cage operation at Catalina, we recently hired Sylvia Castano. Sylvia has been very proactive in looking after the brood fish and will continue to do so until the fish are transferred to the hatchery in Carlsbad later this year. There, they will become new broodstock for our white seabass replenishment program, which was initiated in 1983. 2 10/3/2012
California Yellowtail Egg Quality Varies Within and Among Seasons Egg quality is of primary concern for aquaculturists. As expected, high-quality eggs typically produce larvae and juveniles that survive and thrive better than those coming from lesser quality eggs. The quality of eggs is often assessed using measures of physiological resource content, such as egg size or protein and lipid concentration; larger eggs with greater lipid volume are assumed to produce larger offspring with greater yolk reserves. Alternatively, egg quality may be inferred through developmental processes like fertilization success, cleavage morphology, and hatch rates. Variation in these different egg metrics is, in part, a result of the natural variation available within and among species, but it may also occur as a result of nutritional deficits in the breeding population (e.g. insufficient vitamin, protein, or fatty acid content in the feed) or the spawning method employed (e.g. natural, hormone injection, strip spawning), among other reasons. Figure 4: Viable YT larvae developed from eggs (e.g. inset) produced by wild-caught adult YT at the. For the California yellowtail (Seriola lalandi) maintained at, which includes both wild and F 1 breeders, egg quality has become a focus of research recently (Figure 4). With improved understanding of the factors affecting egg quality, we hope to be able to increase larval survival rates significantly as well as fish quality attributes (e.g. malformations, swim bladder inflation). Preliminary research on the wild-caught broodstock, for which we have good data from 2008-2011, indicates that larval viability and the length of time unfed post-yolk sac larvae survive are significantly correlated to egg and lipid volume and percent lipid volume (P < 0.05). We only have one year of data for the F 1 s, but a similar relationship was noted for percent lipid volume. Other characteristics, such as percent hatching and larval notochord length, were also correlated with survival to starvation and viability but only sporadically correlated to the egg and lipid metrics. When comparing the two breeding populations, it was interesting to note that mean percent lipid volume was higher in the F 1 s than in the wild-caught fish (1.2 ± 0.1% vs. 1.1 ± 0.2%, respectively), although the difference was not significant. The reason for this was that the eggs from the wild-caught fish were larger than the F 1 eggs by an average of 0.2 mm 3 (1.36 ± 0.16 mm 3 vs. 1.14 ± 0.11mm 3, respectively), despite nearly identical lipid volumes. This work was funded by Chevron and an internal NOAA Office of Aquaculture Research grant through collaboration with Dr. John Hyde at the NMFS Southwest Fisheries Science Center. 3 10/3/2012
Acknowledgements This document reports on aquaculture research projects supported by numerous grants, contracts and private contributions. It also represents the hard work of many dedicated staff and volunteers throughout southern California. This information was contributed by staff and compiled by Aquaculture and Fisheries Research Coordinator Dr. Kristen Gruenthal under the direction of Senior Research Scientist and Aquaculture Program Director Mark Drawbridge. The aquaculture research program has been active for more than 30 years at. The primary objective of this program is to evaluate the feasibility of culturing marine organisms to replenish ocean resources through stocking, and to supply consumers with a direct source of high quality seafood through aquatic farming. Please direct any questions to Dr. Kristen Gruenthal at kgruenthal@hswri.org. Aquaculture research at is currently supported by these major contributors: Cabrillo Power/NRG California Sea Grant Chevron Corporation Darden Restaurants Foundation Nebraska Soybean Board NOAA Fisheries NOAA s Saltonstall-Kennedy Program San Diego County Fish and Wildlife Advisory Commission Santa Monica Seafood SDG&E Environmental Champions SeaWorld Parks and Entertainment SeaWorld San Diego The Boeing Company The California Department of Fish and Game s Ocean Resources Enhancement and Hatchery Program The Catalina Seabass Fund The Fletcher Foundation The Shedd Family The U.S. Fish and Wildlife Service s Sport Fish Restoration Account United Soybean Board USDA National Institute of Food and Agriculture Western Regional Aquaculture Center (WRAC) 4 10/3/2012
Hubbs-SeaWorld Research Institute is a 501(c)(3) non-profit charity. If you would like to become a financial supporter of the Institute s aquaculture research, please contact s Development Department at (619) 226-3870. You can also make an online donation by clicking here: Donate Now. For more information on the Institute visit www.hswri.org or become a fan at www.facebook.com/hswri. 5 10/3/2012