Rockfish

Abstract: 1. 1. [1-14C]linolenic acid was injected into the rainbow trout, Salmo gairdnerii, ayu, Plecoglossus altivelis, eel, Anguilla japonica, red sea bream, Chrysophrys major, rockfish, Sebastiscus marmoratus, globefish, Fugu rubripes rubripes and prawn, Penaeus japonicus (molting stage D1″-D2), and the bioconversion of linolenic acid (18:3ω3) to highly unsaturated fatty acids such as eicosapentaenoic (20:5ω3) and docosahexaenoic (22:6ω3) acids was investigated. 2. 2. Linolenic acid was converted to 20:5ω3 and 22:6ω3 intensively in the rainbow trout, moderately in the ayu, eel and prawn, but slightly in the red sea bream, rockfish and globefish. 3. 3. These results were discussed in relation to the essential fatty acid requirements of the aquatic animals.

Abstract: The average surface pH of the ocean is dropping at a rapid rate due to the dissolution of anthropogenic CO2, raising concerns for marine life. Additionally, some coastal areas periodically experience upwelling of CO2-enriched water with reduced pH. Previous research has demonstrated ocean acidification (OA)-induced changes in behavioural and sensory systems including olfaction, which is due to altered function of neural gamma-aminobutyric acid type A (GABAA) receptors. Here, we used a camera-based tracking software system to examinewhether OA-dependent changes in GABAA receptors affect anxiety in juvenile Californian rockfish (Sebastes diploproa). Anxiety was estimated using behavioural tests that measure light/dark preference (scototaxis) and proximity to an object. After one week in OA conditions projected forthenextcenturyintheCaliforniashore(1125+100 matm,pH7.75),anxiety was significantly increased relative to controls (483+40 matm CO2, pH 8.1). The GABAA-receptor agonist muscimol, but not the antagonist gabazine, caused a significant increase in anxiety consistent with altered Cl 2 flux in OA-exposed fish. OA-exposed fish remained more anxious even after 7 days back in control seawater; however, they resumed their normal behaviour by day 12. These results show that OA could severely alter rockfish behaviour; however, this effect is reversible.

Abstract: The Fisheries Ecology Division (FED, https://swfsc.noaa.gov/GroundfishAnalysis/) of the Southwest Fisheries Science Center (SWFSC) has conducted a midwater trawl survey off central California since 1983 with the primary goal of developing pre-recruit indices for young-of-the-year (YOY) rockfish (Sebastes spp.). The survey also samples numerous other components of the epipelagic micronekton, including other YOY groundfish (such as Pacific hake, Merluccius productus, and sanddab, Citharichthys spp ), coastal pelagic fishes (such as Pacific sardine, Sardinops sagax, and northern anchovy, Engraulis mordax) and other forage species. Additional details regarding the survey methods and results are described in Ralston et al. (2015) and Sakuma et al. ( http://calcofi.org/publications/calcofireports/v57/Vol57-Sakuma_pages.163-183.pdf). Ralston, S., J.C. Field and K.S. Sakuma. 2015. Longterm variation in a central California pelagic forage assemblage. Journal of Marine Systems 146: 26-37. http://dx.doi.org/10.1016/j.jmarsys.2014.06.013. Sakuma, K.M., J.C. Field, B.B. Marinovic, C.N. Carrion, N.J. Mantua and S. Ralston. In revision. Anomalous epipelagic micronekton assemblage patterns in the neritic waters of the California Current in spring 2015 during a period of extreme ocean conditions. CalCOFI Reports.