Search

Spawning performance and egg quality were compared in wild-caught and F1 generation southern flounder broodstock following induction with mammalian mLHRHa or piscine sGnRHa at different doses. Forty F1 and 33 wild vitellogenic females (mean oocyte diameter ≥ 0.385 mm) were implanted with an 80% cholesterol-20% cellulose pellet at doses (μg/kg bw) of 0 (control), 5 (low), 25 (mid) and 50 (high) mLHRHa, or with similar doses of sGnRHa. Ovulated females (N = 5–8 per treatment) were strip-spawned and eggs were fertilized in vitro with sperm from two males. Egg quality was categorized according to fertilization and hatching success: 75–100% (high), 50–75% (medium-high), 25–50% (medium-low), and 0–25% (low). Egg production (number of eggs/kg female bw × 103) was highest at the low dose of mLHRHa in F1 females (146.4) and sGnRHa in wild females (128) and was lowest at the intermediate dose sGnRHa in F1 females (61.9) and the high dose sGnRHa in wild females (40.6). Number of fertilized eggs produced per kg bw (× 103) was highest at the low dose mLHRHa in F1 females (113.5) and sGnRHa in wild females (95.4) and lowest at the high dose sGnRHa in F1 females (18.7) and sGnRHa in wild females (7.8). Number of yolksac larvae produced per kg bw (× 103) was highest at the low dose of mLHRHa in F1 females (74) and sGnRHa in wild females (73.5) and was lowest at the high dose of sGnRHa in F1 females (2.0) and in wild females (1.2). Number of larvae per kg bw (× 103) surviving to 96 h post-hatching was highest at the low dose mLHRHa in F1 females (67.5) and sGnRHa in wild females (66.5) and was lowest at the high dose sGnRHa in F1 (0.72) and sGnRHa in wild females (0.68). In F1 females, larval production was significantly greater (P

Cottonseed meal (CSM) proteins from genetically-improved (glandless) low-gossypol seed (GI-CSM, 52.1% crude protein, CP), genetically-modified low-gossypol seed (GMO-CSM, 56.0% CP) and from an untreated regular (glanded) seed (R-CSM 49.9% CP) were evaluated to replace fish meal (FM) protein (59.5% CP) in juvenile southern flounder Paralichthys lethostigma diets. Eight isonitrogenous (45% CP) and isolipidic (16% crude lipid, CL) diets were formulated. A control diet (0% CSM) contained 40% fishmeal (FM) and other practical protein sources. Six diets replaced 50, 75 and 100% FM protein with GI-CSM or GMO-CSM protein. One diet replaced 100% FM protein by R-CSM protein. Fifteen fish (mean = 1.81 g) were stocked in each of twenty-four 75-L tanks (N = 3 per treatment) and were fed the treatment diets for eight weeks. Final percent weight gain was not significantly (P > 0.05) different in fish fed the GI- and GMO- and R-CSM protein diets (898–1405%) compared with the control diet (0% CSM) (1242%), but percent weight gain was greater (P 0.05) interactive effects between CSM sources and FM replacement levels on final weight, FCR and PER were observed. Arginine levels in the diets increased as CSM was increased, consistent with the high arginine concentrations found in CSM. Liver gossypol was only detectable in fish fed the 100% R-CSM diet (37 μg/g). Replacing up to 75% FM protein by GI- or GMO-CSM protein did not affect on whole body omega-3 PUFAs, or liver gossypol. The results suggest that up to 75% of fish meal protein may be replaced by GI- or GMO-CSM protein in the diet of juvenile flounder without adverse effects on growth performance and body composition. Statement of relevance Cottonseed meal (CSM) is a potentially cost-effective alternative plant protein source for use in aquafeeds. The results suggest that a 75% of fishmeal protein could be replaced by genetically-improved and genetically modified (GMO) low gossypol based cottonseed flour protein in the diet of southern flounder. These ultra-low gossypol cottonseed flour proteins could be inexpensive protein sources for the commercial culture of southern flounder and other finfish species.

Eight isonitrogenous (46% crude protein) and isolipidic (14% crude lipid) diets were formulated for juvenile black sea bass Centropristis striata to replace menhaden fish meal (FM) protein (59.5% CP) by three cottonseed meal (CSM) proteins: a CSM prepared from glandless seed (GCSM, 50.4% CP), a CSM that had been solvent extracted with acidic ethanol to remove the gossypol (SCSM, 53.8% CP), and a CSM prepared from regular (glanded) cottonseed (RCSM, 45% CP). Three diets replaced 50, 75 and 100% of FM protein with GCSM, and three diets replaced 50, 75 and 100% of FM protein with SCSM. One diet replaced 100% FM protein with RCSM protein. A control diet (0% CSM) was formulated with high FM protein and other practical protein sources. l -methionine and l -lysine were supplemented to the diets to equal the control diet. Fifteen fish were stocked in each of twenty-four 75-L tanks, and each test diet was fed to triplicate groups of fish (mean initial weight = 7.7 ± 0.10 g) for 56 days at 22–24 °C, 32–35 salinity, and ambient photoperiod conditions. Fish were fed twice per day to apparent satiation. Final (day 56) mean body weight (BW, 24.16–31.62 g), body weight gain (BWG, 211.2–311.3%), specific growth rate (SGR, 1.70–2.18%/d), and feed intake (FI, 0.37–0.43 g/fish/d) were not significantly different (P > 0.05) among the control, GCSM or SCSM treatments, but were reduced (P Statement of relevance Cotton seed flour is an inexpensive agricultural by-product. The results demonstrate successful replacement of fish meal protein with genetically-improved cottonseed flour protein in the diet of black sea bass. These findings may substantially lower aquafeed costs (a key operational cost) for finfish growout operations to boost profitability and accelerate expansion of commercial production of black sea bass and other finfish species.

To investigate the effects of dietary salt supplementation on growth performance, survival, body composition, and plasma electrolytes of black sea bass Centropristis striata, a feeding trial was conducted in a semi-pilot scale RAS under low salinity (10.8 ± 0.69 g L−1) rearing conditions. Four isolipidic and isonitrogenous test diets were formulated with graded levels of sea salt (99.86% NaCl): 0%, 2.5%, 5%, and 7.5% dry wt. In addition, two control diets (0% salt test diet and a premium commercial diet) were tested for fish raised in full-strength seawater (34 g L−1). Twelve tanks (vol = 2-m3) of the low-salinity RAS were each stocked with black sea bass (mean wt. = 19.6 g) at a density of 100 fish per tank and at a starting salinity of 34 g L−1 and salinity was gradually decreased (0.5 g L−1 per day) to 10.1 g L−1 in 30 days. In addition, six tanks (2-m3) of a RAS supplied with full-strength seawater were each stocked with 100 fish from the same cohort, with 3 tanks fed either of the two control diets (0% salt or the commercial diet). After the 8-month feeding trial, fish grown at low salinity were fed their respective diets for an additional 5 weeks under adverse low-salinity conditions in which salinity was further decreased gradually from 10.1 g L−1 to 4 g L−1. Survival over the 8 months remained high (93–100%) among treatments. Growth (% body weight gain) among the treatments in low salinity ranged from 766 to 825%, comparable to fish raised in full seawater (788–813%). Plasma osmolality (mOsm kg−1) for fish ranged from 336 to 357 among all treatments. However, no significant relationships between weight gain, feed conversion ratio, survival, plasma osmolality, and electrolyte concentrations and dietary salt level were observed among fish raised in low salinity. When salinity was further reduced from 10.1 g L−1 to 4 g L−1, fish fed 0% salt showed poor survival (29%), whereas fish fed 7.5% salt showed highest survival (67%), and a significant (P

Traditionally used in the construction and excavation industries to remove solids from runoff, geotextile fabric tube (Geotube) technology has been adopted by freshwater aquaculture facilities as a method of effluent management. The effectiveness of a Geotube is improved by using chemical polymers to bind suspended solids in the effluent for greater retention; however, polymers used in freshwater systems may not be effective in marine systems. Using laboratory jar tests, seven organic polymers of different molecular weights and ionic charges were evaluated at doses ranging from 0 to 50 ppm for solids removal efficiency (SRE) from effluent from a marine (33 ppt) finfish RAS growing black sea bass. Of the seven polymers screened, two cationic high molecular weight polyacrylamide polymers Drewfloc (DF) 2449 and DF 2468 had high SRE of total suspended solids (TSS) (36.1–84.4 %). Further tests using miniature geotextile bags confirmed that DF 2449 at 10 ppm and DF 2468 at 5 ppm had high SRE (73.3–75.9%) compared to the untreated control (43.4 %). When applied to a commercial-scale Geotube, DF 2449 at 10 ppm removed 92.1 % of the TSS in the effluent of the marine finfish RAS growing black sea bass. Rinsing the saline biosolids with freshwater at a rate of 1.63 L per 100 g dry solids reduced the salinity to

Two feeding trials were conducted to investigate the effects of dietary sea salt supplementation on growth and survival of black sea bass Centropristis striata reared under sub-optimal salinity conditions at 15 and 10 g L− 1. In experiment 1, six iso-nitrogenous (46% crude protein) and iso-lipidic (10% lipid) test diets containing a mineral premix were formulated to supplement graded levels (0, 2.5, 5, 7.5, 10, and 12.5% dry wt.) of natural sea salt (99.9% NaCl). Diets were fed twice daily to juveniles (mean wt. = 8 g) held in triplicate 75-L tanks at a salinity level of 15 g L− 1 under controlled laboratory conditions for 56 days. In experiment 2, six natural salt-based diets as in experiment 1 and another diet with 0% salt and no mineral mix were formulated. Diets (experiment 2) were fed to triplicate groups of fish (mean wt. = 9.37 g) held at 10 g L− 1 salinity for 70 days. In both experiments, final survival was 78–97%, with no treatment differences. At 15 g L− 1 (experiment 1), no differences in weight gain were observed among dietary salt treatments. In contrast, a 5% salt diet significantly (P 5% salt at 10 g L− 1 showed higher survival when challenged with a further reduction in salinity to 4 g L− 1. Gill Na+/K+ ATPase activities appeared to be higher in fish fed the diet with highest level (12.5%) of supplemental salt, whereas intestinal Na+/K+ ATPase activity appeared to be maximal at lower levels of dietary salt. Irrespective of dietary salt treatment, black sea bass juveniles maintained good growth and survival and normal whole body electrolyte concentrations at rearing salinities of 10 and 15 g L− 1, indicating that these fish are good osmoregulators and could be potentially cultured under these low salinities. The results indicate that dietary salt supplementation at 5% improved growth and averted mortality under low salinity conditions. These findings may enable black sea bass to be grown in recirculating aquaculture systems in low-salinity brackish water. Relevance with commercial aquaculture These results indicate that dietary salt supplementation may be used to avert mortality when a producer is faced with adversely low salinity conditions due to weather and tides as may occur in coastal black sea bass fish farms sourcing brackish water from tidal creeks.

A pilot-scale finfish mariculture hatchery was established at the University of North Carolina Wilmington. In 2011, research-based hatchery protocols were scaled up to produce 37,000 advanced (1–5 g) black sea bass fingerlings. Based on engineering, biological, and cost data from operating the pilot hatchery, an economic analysis of a hypothetical commercial scale black sea bass hatchery operation was conducted. The financial performance of two alternative facilities that produce 97,200 5-g and 388,800 1-g fingerlings per year over a 30-year project life showed cumulative net present value (NPV) of $445,000, and $3,168,000, modified internal rates of return (MIRR) of 6.52% and 10.52%, and per unit breakeven prices of $1.67 and $0.47, respectively. Sensitivity analyses showed that final stocking density was critical to financial performance. Fingerlings were supplied to startup growers in NC and in VA, and market-size fish from these growout facilities were distributed (live or whole on ice) to premium-val...

Three experiments were conducted to evaluate the effects of micro-bound diets (MBD) on southern flounder larvae. In experiment 1, four MBDs were formulated with different protein sources as follows: MBD 1: herring meal, MBD 2: menhaden meal, MBD 3: menhaden and squid meal; MBD 4: menhaden, squid and herring meal. In experiment 2, four MBDs were formulated as follows: MBD 5: menhaden, squid and herring meal; MBD 6: menhaden, squid, herring and attractants; MBD 7: menhaden, squid, herring and casein, and MBD 8: menhaden, squid, herring, casein and attractants. In experiment 3, three groups were maintained as follows: Group 1: live feed; Group 2: co-fed with MBD 6; and Group 3: MBD 6. In experiment 1 on 35 dph, survival and body weight (BW) of the fish fed MBD 4 was significantly higher than the MBDs 1 and 2. In experiment 2 on 34 dph, fish fed MBD 6 had significantly higher BW than the commercial microdiets. In experiment 3 on 21 dph, fish receiving only MBD had significantly lower survival than the other groups. Growth, survival and larval fatty acid composition suggested that co-feeding MBD 6, a mixture of marine protein sources plus attractants was more effective than the other MBDs.

Two feeding experiments were conducted to study the effects of different levels of solvent-extracted soybean meal on the growth and body composition of juvenile southern flounder Paralichthys lethostigma. In experiment 1, seven diets were formulated, replacing menhaden fish meal protein (FMP) with soybean meal protein (SBP) at 0, 10, 20, 30, 40, 50, and 60% without supplementing amino acids. In experiment 2, eight diets were formulated, replacing FMP with SBP at 0, 10, 20, 30, 40, 50, 60, and 70% and supplementing with l-methionine and l-lysine. In the test diets, l-methionine and l-lysine were supplemented to approximate the methionine and lysine level found in the 45% whole-body protein of southern flounder. All diets were formulated to have the same crude protein (45%) and lipid levels (12%), and all diets contained 9% squid meal and 5% krill meal to improve palatability. Each of the test diets was fed two times a day to triplicate groups of flounder (average weight = 0.61 g for experiment 1 a...

The influence of four formulated practical diets, with different protein and lipid levels, on the growth and body composition of black sea bass (Centropristis striata L.) pre-adults was evaluated in a pilot-scale marine recirculating system. Four test diets were prepared with a combination of two protein levels (44% and 54%) and two lipid levels (10% and 15%). The diets were as follows: low protein and low lipid (LP:LL; 44:10), low protein and high lipid (LP:HL; 44:15), high protein and low lipid (HP:LL; 54:10) and high protein and high lipid (HP:HL; 54:15). Fish (mean weight=75.5 g) were fed the respective diets for 90 days. For fish fed LP:HL, body weight gain was significantly (P

A feeding trial was conducted in a recirculating system to determine the dietary protein requirement for juvenile black sea bass. Six isocaloric diets were formulated to contain varying levels of crude protein (CP) ranging from 36 to 56% (36, 40, 44, 48, 52, and 56%) by substituting a mixture of carbohydrates and lipid for fish meal. The feeding experiment was carried out in 18-75 L aquaria stocked at a density of 15 juveniles (initial average weight 6.7 g) per tank. Fish were fed test diets in triplicate tanks to apparent satiation twice a day for 8 wk. Whole-body proximate composition was analyzed after the feeding trial. After the feeding trial, weight gain and specific growth rate of fish fed the 44% CP diet were not significantly different from those fed the 48, 52, and 56% CP diets, but were significantly higher (P < 0.05) than those fed the 36 and 40% CP diets. Feed conversion efficiency and protein efficiency ratio were significantly affected by dietary protein level. The dietary requirement of protein for maximum growth of black sea bass juveniles, estimated using broken-line regression analysis on weight gain, was 45.3% and maximum weight gain occurred at 52.6% based on polynomial regression analysis.

A study was conducted to test the performance of a high-density (>3000 individuals/mL) continuous recirculating system for rotifers (B. rotundiformis) fed nonviable Nannochloropsis oculata and using sodium hydroxymethanesulfonate to neutralize ammonia. Three different microalgae feed rates (g of N. oculata [68 × 109 cells/mL] per million rotifers/d) were tested in successive trials. In Trial 1 (feed rate = 1.5), during a 30-d period, rotifers were harvested daily to 3000 individuals/mL, for an average yield of 178 million/d. Feed efficiency (million rotifers/g/d) was 0.33. In Trial 2 (feed rate = 1.1), during a 32-d period, an average of 106 million rotifers were harvested daily, and feed efficiency was 0.26. In Trial 3 (feed rate = 1.3), during a 30-d period, an average of 107 million rotifers was harvested daily, and feed efficiency was 0.23. An economic analysis based on a feed rate of 1.5 showed that production cost was 40% lower than the traditional batch culture method (US$ 0.29 vs. 0.46 per million rotifers/d). The continuous culture system tested reliably produced large quantities of rotifers on a daily basis without the use of a biofilter and with a lower production cost than a batch culture system.

Pilot-scale trials were conducted to evaluate growout performance of hatchery-reared summer flounder fingerlings in a state-of-the-art recirculating aquaculture system (RAS). The outdoor RAS consisted of four 4.57-m dia × 0.69-m deep (vol. =11.3 m3) covered, insulated tanks and associated water treatment components. Fingerlings (85.1 g mean initial weight) supplied by a commercial hatchery were stocked into two tanks at a density of 1,014 fish/tank (7.63 kg/m3). Fish were fed an extruded dry floating diet consisting of 50% protein and 12% lipid. The temperature was maintained between 20 C and 23 C and the salinity was 34 ppt. Under these conditions, growth, growth variation (CVwt), feed utilization, and survival of fish fed to 100% and 82% of a satiation rate were compared. Due to clear changes in growth patterns during the study, data was analyzed in three phases. During phase 1 (d 1–d 196), fish showed rapid growth, reaching a mean weight of 288 g ± 105 and 316 g ± 102, with a CVwt of 0.36 and 0.32 and FCR's of 1.38 and 1.36 in the subsatiation and satiation groups, respectively. During phase 2 (d 196–d 454), fish displayed slower growth reaching mean weights of 392 g ± 144 and 436 g ± 121, with a CVwt of 0.37 and 0.28, and increasing FCR's of 3.45 and 3.12 in the subsatiation and satiation groups, respectively. During phase 3 (d 454–d 614), fish showed little growth reaching mean weights of 399 g ± 153 and 440 g ± 129, with a CVwt of 0.38 and 0.29 in the subsatiation and satiation groups, respectively. Over the entire growout period (d 1–d 614), feed conversion ratios were 2.39 and 2.37 and survival was 75% and 81 % in the subsatiation and satiation treatments, respectively. The maximum biomass density reached during the study was 32.3 kg/m3. The satiation feed rate was superior to the 82% satiation rate, since it maximized growth rates, with no effect on FCR. The higher CVwt in the subsatiation group suggests increased competition for a restricted ration led to a slower growth with more growth variation. The decrease in growth in phases 2 and 3 was probably related to a high percentage of slower growing male fish in the population and the onset of sexual maturity. This study demonstrated that under commercial scale conditions, summer flounder can be successfully grown to a marketable size in a recirculating aquaculture system. Based on these results, it is recommended that a farmer feed at a satiation rate to minimize growout time. More research is needed to maintain high growth rates through marketable sizes through all-female production and/or inhibition of sexual maturity.

A study to determine the effects of four stocking densities on growth and feed utilization of wild-caught black sea bass Centropristis striata was conducted in a pilot-scale recirculating tank system. The outdoor system consisted of 12 insulated fiberglass tanks (dia. = 1.85 m; vol. = 2.17 m3) supported by biological filters, UV sterilizers, and heat pumps. Subadults (N= 525; ×± SD = 249 ± 16.8 g) were stocked at densities of 4.6 fish/m3 (1.18 kg/m3), 16 fish/ m3 (3.91 kg/m3), 25.3 fish/m3 (6.83 kg/m3), and 36 fish/m3 (7.95 kg1m3), with three replicate tanks per treatment. Fish were grown under 35 ppt salinity, 21-25 C, and under ambient photoperiod conditions. A commercial flounder diet containing 50% protein and 12% lipid was hand-fed twice daily to satiation for 201 d. Mean (range) total ammonia-nitrogen, 0.61 (0-2.1) mg/L, nitrite-nitrogen, 0.77 (0.04-3.6) mg/L, and nitrate-nitrogen 40.1 (0-306) mg/L were significantly higher (P 0.05) in growth (RGR = 196.8-243.1%; DWG = 2.55-2.83 g/d; and SGR = 0.55-0.61%/d), coefficient of variation of body weight (CwtV., = 0.24-0.25), condition factor (K = 2.2-2.4), feed consumption (FC = 1.45-1.65%/d), and feed conversion ratio (FCR = 1.45-1.52) among stocking densities. Final biomass densities on day 201 reached 3.48, 12.0, 21.1, and 27.2 kg/m3 at stocking densities of 4.6, 16, 25.3, and 36 fish/m3, respectively. Survival (83.8-99.1%) did not differ among treatments. Apparent net protein retention (ANPR) was significantly higher (P 0.05) in apparent net energy retention (ANER = 55.9-59.1 %) among stocking densities. Final whole body protein (15.3-16.3%) and lipid (23.1-26.4%) levels did not differ significantly (P > 0.05) among treatments. The results demonstrated that growth, survival, and feed utilization were not impaired under stocking densities ranging from 4.6-36 fish/m3 (3.48-27.2 kg/m3), despite a slight reduction in water quality at the higher densities. In addition, growth variation and final whole body protein and lipid levels were not influenced by these densities. The results suggest that black sea bass are tolerant of crowding and moderate variations in water quality during intensive culture in recirculating tank systems and that higher stocking densities are possible.

The effects of four practical diets on growth, feed utilization, and body composition of wild-caught juvenile and subadult black sea bass Centropristis striata (316 ± 113 g =±± SD) were compared for 221 d in a recirculating tank system consisting of 12 2,660-L tanks. Salinity averaged 33.5 ppt and temperature averaged 20.9 C but vaned from 12 to 27.1 C. Diets differed in crude protein (CP) and crude lipid (CL) as follows: 1) low CP (44.0%), low CL (11.4%) trout diet; 2) low CP (44.8%), high CL (15.0%) trout diet; 3) midlevel CP (47.9%), midlevel CL (12.8%) Bounder diet; and 4) high CP (53.9%), high CL (15.1%) marine finfish diet. Energy: protein ratios (E: P) were 44.6, 45.3, 41.8, and 39.1 W/g. Survival to 221 d on all diets was 100%. Significant (P < 0.05) differences in growth rates were observed among diets. Final weights were higher for midlevel and high CP diets 3 and 4 (1,051 and 1,013 g) than for low CP diet 1 (873 g). Relative growth rate (RGR, % total increase in weight), specific growth rate (SGR, % increase in body weight/d), and daily weight gain (DWG, g/d) were higher for higher CP diets 3 and 4 (RGR = 223 and 221; SGR = 0.53; DWG = 3.28 and 3.16), than for low CP diet 1 (RGR = 181; SGR = 0.47; DWG = 2.54). There were no significant differences between initial and final whole body protein and fiber content among diets. Lipid and gross energy levels significantly increased (P < 0.0001) in all treatments while moisture levels significantly decreased (P < 0.001). Although these differences were not significant, feed conversion ratio (FCR = dry weight fed/wet weight gain) was lower for fish given midlevel CP diet 3 (1.49) and high CP diet 4 (1.52) than for those fed low CP diets 1 and 2 (1.60 and 1.62). Protein efficiency ratios (PER = weight gain/weight protein fed) (1.43 to 1.24), apparent net protein retention (ANPR = weight protein gain/weight protein fed) (20 to 25%), and apparent net energy retention (ANER = energy gain/energy fed) (53.3 to 56.8%) were not significantly different among treatments. The midlevel CP (50%), midlevel CL (12%) diet maximized growth rates and was also significantly less expensive per kg fish weight produced ($1.40) than the high CP diet ($1.94) which produced the second highest growth rates. These results demonstrated that wild-caught black sea bass can be successfully reared in recirculating tanks from juvenile to marketable sizes with high survival and with good feed conversion and growth on commercially prepared diets with a wide range of protein and lipid levels.

Hormone-induced spawning of southern flounder Paralichthys lethostigma has produced substantial numbers of viable eggs, but wide variations in fertilization and hatch rates have been reported. Recently, sustained natural spawning of southern flounder broodstock, without hormone induction, has been achieved in our laboratory. Adults (average weight = 1.12 kg; N= 25), including 6 captured as juveniles in 1993 and 19 captured as adults during September 1998, were stocked in two 4.8-m3 controlled-environment tanks in October 1998 and held under natural photothermal conditions until January 1999, when an artificial winter photo-period of 10 L:14 D was initiated and then maintained through April 1999. Sex ratio was approximately 13 females:8 males:7 unknown. Natural spawning was observed in early December 1998 and increased in frequency to a peak in March 1999, before declining in late April. Water temperature ranged from 13.9 to 24.5 C during the spawning period. Natural spawnings over 142 d produced a total of 18.3 × 106 eggs, with a mean fertilization rate of 28.0% (range = 0–100%), yielding 4.94 × 106 fertilized eggs. The mean percentage of eggs that remained buoyant in full-strength seawater (34 ppt) was 41.3% (0–98%), while hatching rate of buoyant eggs was 37.3% (0–99%) and survival of yolksac larvae to the first-feeding stage was 30.2% (0–100%). Gonadal biopsies in late April identified six females from both tanks as probable spawners. A preliminary comparison suggests that natural spawning produced much larger numbers of viable eggs per female, with higher egg quality (i.e., fertilization and hatching success) than hormone-induced spawning. In contrast to natural spawning, hormone-induced strip-spawning enabled timing of spawnings to be more precisely controlled. These results suggest that a combination of both natural and hormone-induced spawning of photothermally conditioned fish will help produce the large numbers of eggs required to support commercial production.

Ever since Schilder's1description in 1912 of a peculiar clinical and pathologic syndrome which he called encephalitis periaxialis diffusa, various continental observers have reported isolated examples of this rare and interesting disease. Recently, Collier and Greenfield2of England and Bouman3of Holland reported four instances with thorough clinical and pathologic investigation. Up to date, thirty-two observations of encephalitis periaxialis diffusa have been reported, and the reader is referred to the later articles, especially Bouman's, for detailed analysis of thirty of these cases. A study of our case and the literature confirms the belief that we are dealing with a syndrome having a fairly typical course and pathology, which frequently should be capable of diagnosis during life. It may be pointed out that Collier recognized his second case during the patient's life. These English writers describe the disease as: A malady usually occurring in children and young subjects