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Studies on spawning and larval culture in the purple-hinge rock scallop (Hinnites multirugosus) are described together with information on growth of juveniles and adults. Gravid individuals were collected from field populations throughout most of the year. These produced viable eggs when induced to spawn in the laboratory. Larval development appeared normal over the range 8–18°C (optimal for culture, 14–18°C). Acceptable growth and survival were achieved on a mixed diet of Isochrysis, Monochrysis, Tetraselmis and Skeletonema. Metamorphosis began in larvae 200 μm in shell diameter (age, 3 weeks). Most rapidly growing post-larvae reached 1.8 mm at two months (15–18°C). Pre-cementing juveniles held in cages in Mission Bay, San Diego, averaged approximately 8 mm/mo during summer (18–22°C) and half that rate throughout the rest of the year (13–18°C). Individuals 1.5 to 3.0 cm in October, 1975, reached shell diameters of 5.0 to 7.5 cm one year later.

Minimum surface tension and phospholipid composition of fish lung and swim-bladder wash and tissue extract were determined on an obligate water breather, Hoplias malabaricus, two species of facultative air breathers, Hoplerythrinus unitaeniatus and Erythrinus erythrinus, and two species of obligate air breathers, Arapaima gigas and Lepidosiren paradoxa. In addition, lung tissue slices were incubated with [1-14C]acetale and [1-14C]palmitate.All lung and swim-bladder wash lipid extracts showed a minimum surface tension of 20–25 dyn/cm (1 dyn = 10 μN). The principle phospholipid of all species is phosphatidylcholine; no phosphatidylglycerol was detected in any sample.The two obligate air breathers had higher rates of incorporation of isotope in tissue slices than facultative air breathers and nonair breathers. This observation correlates well with the greater vascular supply to their lungs.The phospholipid patterns of these fishes are significantly different from those of mammals. We speculate that these lipids recovered from saline wash may not be important in the maintenance of lung stability. Perhaps their function is keeping water from leaking into the lung and swim bladder.

Bones contain the majority of body lipid in some marine fish. In the sheepshead wrasse Pimelometopon pulchrum and the sablefish Anoplopoma fimbria, the bone lipid comprised 79 to 93% and 52 to 82% of the total body lipid, respectively. The senorita Oxyjulus california, another species of wrasse, has only 14% of its body lipid in bone. To determine whether dietary lipid is deposited quickly in the bone lipid, three species of fish were fed 1-14C-palmitic acid. Radioactivity appeared in the bone lipid as soon as 12 h after feeding, with the species rich in bone lipid incorporating the highest activity relative to the flesh. Roughly 80% of the radioactivity recovered in A. fimbria bone lipid was found in triglyceride. Radioactivity was equally distributed between phospholipid and triglyceride in P. pulchrum bone lipids. The results suggest that in some marine fish the bones contain the majority of the organism's reserve energy.

Protein components of the membranous foamy tissue collected from the swimbladder of Coryphaenoides acrolepis, a continental slope/deep sea grenadier fish, were partially fractionated and characterized by procedures used successfully for erythrocyte membrane proteins. Methods involving pH and ionic strength adjustment in the presence of EDTA and beta-mercaptoethanol resulted in some protein fractionation but no distinct separation or isolation of membrane proteins. Gel filtration by Sephadex G-100 and Sepharose 2B in the presence of dodecyl sulfate partially fractionated protein species between 18,000 and 150,000 molecular weight (as confirmed by dodecyl sulfate polyacrylamide gel electrophoresis). Low molecular weight proteins were resolvable into a few diffuse and streaky bands by dodecyl sulfate and chloral hydrate polyacrylamide gel electrophoresis, the former giving superior reso-ution. A major fraction of large molecular weight protein (greater than or equal to 40 X 10(6)) was not resolved by any method. A possible explanation for these unusual findings is that decompression due to rapid ascent of the fish from deep ocean caused irreversible alteration of swimbladder membrane proteins.

Assessment of candidates for investigation of bone lipid metabolism yielded the following findings. (1) A tropical marine butterflyfish, Chaetodon ornatissimus, had oil-filled bones (66-80% lipid, percent dry weight) hence may be a suitable condidate. (2) The tropical marine fishes Exallias brevis, Pomacentrus jenkensi, and Chromus agilis, and a Canadian fish Sebastes ruberrimus, had intermediate quantities of oil in their bones (12-49% lipid). (3) In all the foregoing species the major bone lipid was triglyceride, usually more abundant in skull than spine. Sterol and phospholipid were also present. (4) The major fatty acids of the triglycerides (and phospholipids) were 16:0, 18:0, 18:1, and C20, C22 acids. Those acids were dominated by 20:4, 20:5, 22:5, and 22:6. (5) There was more total unsaturation in the bone lipids of S. ruberrimus (from 10 degrees C water; 67-72% unsaturation) compared to the tropical fish (from 25 degrees C water; 32-67% unsaturation) with the exception of E. brevis. (6) One of the tropical species (Arothron meleagris) and a Canadian Chimaeran (Hydrolagus colliei) contained only 1-3% lipid in their bones.

The ability of liver of pink salmon,Onchorhychus gorbuscha, to synthesize triglycerides is lost after migration into fresh water and spawning. Triglyceride fatty acids are probably mobilized as cholesterol esters as energy sources in these starving fish. Total lipid decreases; cholesterol remains constant; and relative values of protein and water increase in the liver of the spawned out fish. Both hepatic lipogenesis and cholesterol synthesis decrease. Control values are given for river whitefish. *** DIRECT SUPPORT *** A00M6041 00006

WE have found an accumulation of cholesterol within the oxygen-filled swimbladders of some deep sea benthic fishes, which suggests that certain steps in cholesterol biosynthesis and/or degradation are affected by hyperbaric oxygen. The lipid content of these swimbladders included as much as 49 % (dry wt basis) of cholesterol. The lipid included major amounts of unsaturated fatty acids which resist auto-oxidative processes within the swimbladder which contains oxygen at pressures up to 380 atmospheres.