Bacterial destruction of the egg shell of common wolffish during incubation

Mortality of artificially fertilized, laboratory incubated eggs of common wolffish,Anarhichas lupus L., was 100% within 2–3 weeks, at the gastrulation step. The eggs from batches with a high proportion of normally cleavaged eggs died later than the eggs from batches with a low proportion of such eggs. Light micrographs of egg shells showed ulceration of the outer layer and subsequent destruction of the inner layer of zona radiata, caused byFlexibacter sp. The bacterial infection provoked premature hatching at later stages of embryonal development. Treating eggs with glutaraldehyde at a concentration of 600 mg l^–1 every third to fifth day during incubation prevented the mortality caused by bacteria.     

Chemical treatment of lobster eggs against epibiotic bacteria

Eggs of the European lobster, Homarus gammarus (L.), were exposed to malachite green (5, 10, 15 mg 1^–1: 10 min), glutaraldehyde (50, 100, 150 mg 1^–1: 3 min) and iodine as Buffodine^TM (50, 100, 150 mg 1^–1: 10 min). The efficiency of the treatments was tested by incubating eggs individually in wells of multiwell dishes with TSB agar for 14 days after exposure. In order to find any effect on viability, batches of 30 eggs from each of three females were incubated artificially in a recirculation system for 19 days and repeatedly exposed to the disinfectants. Iodine as Buffodine (150 mg 1^–1) was the only treatment that resulted in a significant decrease of the bacterial growth on lobster eggs, but the treatment also resulted in inhibited hatching compared with the control group. Thus, our results indicate that treatment with 150mg^–1 iodine as Buffodine could be a strategy for reducing bacterial growth on lobster eggs when massive egg mortality due to bacteria is otherwise unavoidable. The treatment could, however, lead to decreased viability of larvae due to inhibited hatching.     

Induction of Out-of-Season Spawning of Pikeperch, Sander Lucioperca (L.)

Pikeperch were induced to spawn 3 months prior to the natural spawning period through photothermal and hormonal stimulation. Females (five specimens in each group) were stimulated with injection of human chorionic gonadotropin (hCG) once (200 IU kg^–1), twice (200 IU kg^–1, second dose after 48 h–400 IU kg^–1) or three times (200 IU kg^–1, after 24 h–200 IU kg^–1 and after another 24 h–200 IU kg^–1). The control group was injected once with 0.9% NaCl. The males were stimulated with a single hormone dose of 200 IU kg^–1. Eggs were obtained from all the hormonally treated fish. None of the control group females, which were only stimulated photothermally, ovulated any eggs. The time of ovulation was 66–71 h following the first injection, and the eggs viability until the eyed stage (from 71.5 to 77.5%) did not depend on the number of hormone doses (P > 0.05). The out-of-season spawning method described in this paper could be used to provide pikeperch larvae for intensive culture systems (recirculating water systems) before natural spawning season and to produce larger-sized pikeperch fingerlings for stocking.     

Grow-out culture of tropical abalone, Haliotis asinina (Linnaeus) in suspended mesh cages with different shelter surface areas

Thisstudy investigated the effects of shelter surface area (SSA) on the feeding,growth and survival of the donkey-ear abalone, Haliotisasinina reared in mesh cages (0.38×0.38×0.28m) suspended in flow-through tanks (water volume = 6m³). Cages had sections of polyvinylchloride (PVC) thatprovided shelters with surface area of 0.22 m², 0.44m² and 0.66 m².Hatchery-produced abalone with initial shell length of 32 ± 1mm and wet weight of 7.5 g were stocked at 50individuals cage^–1 that corresponded to stocking densities ofca. 227, 113 and 75 abalone m^–2 of SSA. The ratios of sheltersurface area to cage volume (SSA:CV) were 5.5, 11 and 16.5. Abalones wereprovided an excess red seaweed Gracilariopsis bailinae(= Gracilaria heteroclada) at weekly intervals overa 270-day culture period. Feeding rates (18–20% of wet weight), foodconversion ratio (26–27) and percent survival (88–92%) did notdiffer significantly among treatments (p > 0.05). Body size at harvest rangedfrom 56 to 59 mm SL and 52 to 57 g wet body weightwith significant differences between abalone reared at SSA 0.22m² and 0.66 m² (p < 0.05).Abalone reared in cages with 0.66 m² SSA grewsignificantly faster at average daily growth rates of 132 m and188 mg day^–1. Stocking densities of 75–113m^–2 SSA in mesh cages suspended in flow-throughtanks resulted in better growth of abalone fed red seaweed.     

Use of egg custard augmented with cod liver oil and Moina micrura on production of freshwater prawn postlarvae

Use of egg custard augmented with cod liver oil (CLO) fed during the day, and of an overnight feed with Moina micrura, were evaluated in terms of its effects on production of freshwater prawn (Macrobrachium rosenbergii) postlarvae (PL). Four levels of CLO (0, 1,3 and 5%) were tested. Significantly higher mean (sd) productions, ranging from 11.27 (1.16) to 13.02 (1.70) PL l^–1, were obtained for larvae fed egg custard enriched with CLO compared with that of 7.83 (1.58) PLl^–1 for larvae fed egg custard without CLO. The development and survival of larval stages were also higher for the CLO diets. The -3 highly unsaturated fatty acid (HUFA) in egg custard increased with increasing CLO level (0–5%). The fatty acid composition of postlarvae reflected the composition of the diet.     

Replacement of Artemia with Moina micrura in the rearing of freshwater shrimp larvae

The effect of an abrupt change in the live diet of shrimp larvae was investigated by replacing Artemia with Moina micrura. The control treatment consisted of feeding Artemia throughout the rearing period (regime A), while in the other treatments the onset of Moina feeding was arbitrarily chosen at larval stages iv (A3M), vi (A5M), viii (A7M) and x (A9M). No significant differences ( = 0.05) were observed among the treatments during larval production, mean stage development (MSD) and growth of postlarvae. The mean (SD) yields of postlarvae (PL) were 11.97 (1.98), 15.10 (2.92), 14.72(1.56), 13.51 (1.74) and 12.70 (1.40) PL l^–1 respectively for the feeding regimes A3M, A5M, A7M, A9M and A. Up to stage v, the ingestion rate in the Moina treatment was as low as 0.01–0.47 larva^–1 h^–1 compared with that in the Artemia treatment (0.29–1.77 larva^–1 h^–1). However, the ingestion of Moina increased from stage vi–vii onwards.     

Surface disinfection of Atlantic halibut and turbot eggs with glutaraldehyde: evaluation of concentrations and contact times

To evaluate the effects of glutaraldehyde treatment at different disinfection temperatures, Atlantic halibut, Hippoglossus hippoglossus (L.), and turbot, Scophthalmus maximus (L.), eggs, incubated at 5 and 12°C, respectively, were disinfected with 400–1200 mg glutaraldehyde l-1 at three different contact times (2.5, 5 and 10 min). Egg batches of both poor and good quality were tested for halibut. Positive effects were more pronounced in poor than in good-quality batches at hatching. Egg disinfection had a highly positive effect on the viability of yolk-sac larvae in both types of batches. A level between 400 and 800 mg l-1 at a contact time of 5–10 min was optimal for halibut: at lower levels, the bactericidal effect was reduced, and at higher levels, there were indications of toxic effects. Halibut eggs disinfected with optimal doses of glutaraldehyde had furthermore a reduced hatching time and more synchronous hatching as compared with untreated eggs. Turbot was more sensitive to higher doses than halibut, and the best larval performance was obtained for 400–800 mg glutaraldehyde l-1 at a contact time of 2.5 min. A further evaluation should, however, be performed before recommendations are given for species incubated at temperatures higher than 5°C.     

The effect of dietary vitamin E on the pleopodal egg number of Astacus leptodactylus (Eschscholtz, 1823)

The effect of vitamin E on the pleopodal egg number of Astacus leptodactylus (Eschscholtz, 1823) was studied. Crayfish were fed 2% of their total wet weight daily with vitamin E supplemented diets and a control for 70 days. The vitamin E content of the control diet, diet 1, diet 2 and diet 3 were 20 mg kg^–1, 40 mg kg^–1, 80 mg kg^–1 and 160 mg kg^–1 respectively on a dry weight basis. Vitamin E levels of the control and experimental diets were analysed by High Performance Liquid Chromatography. Results showed that diets containing supplemental vitamin E were associated with an increase in the number of pleopodal eggs. The best result was obtained with diet 2 containing 80 mg kg^–1 supplemental vitamin E.     

The First Attempt to Artificially Reproduce the Endangered Cyprinid Lake Minnow Eupallasella Perenurus (Pallas)

The standard artificial reproduction technique with the use of Ovopel (GnRH analogue) was evaluated for the critically endangered cyprinid species in Poland, the lake minnow Eupallasella perenurus. Wild spawners were angled at the beginning of the spawning season. Only females with a condition coefficient value higher than the mean were included in the experiment and then stimulated with Ovopel. Group A (n = 20) was given standard treatment (0.2 pellet kg^–1 and 1.0 pellet kg^–1 after 12 h), whereas group B (n = 8) was treated with a single dose of 2.0 pellets kg^–1. After fertilisation with the dry method, the glutinous eggs attached to the bottom of flow-through aquaria were incubated at 17.1–18.4°C. Throughout incubation (85D°), dead eggs were removed and counted. The same was done with dead larvae, those with deformed bodies or those with empty alimentary tracts after 2 days of external feeding. Two injections of Ovopel resulted in a significantly (P 0.05) higher ovulation rate in comparison with the single dose (70 and 25% in groups A and B, respectively). The individual hatching rates were very high (98.4–100%), as was the share of good quality larvae (91.1 and 96.5% of stripped eggs in groups A and B, respectively). These results indicate that the standard propagation method used with commercially important cyprinid species can also be used to successfully breed E. perenurus.     

Quantifying the dietary biotin requirement of the catfish,Clarias batrachus

Asian catfish, Clarias batrachus, were fed semi-purified basaldiets containing 0, 0.1, 0.5, 1, 3 and 5 mg biotin kg^–1diet for 60 days. Fish fed the control diet (no biotin) showed(P < 0.05) higher mortality, lower weight gain, specificgrowth rate (SGR), feed efficiency ratio (FER) and protein efficiencyratio (PER) than in fish fed diets supplemented with biotin. The highestweight gain, SGR, FER and PER were noticed in fish fed 1 mg biotinkg^–1, followed by 0.5, 5, 3 and 0.1 mg biotinkg^–1, except for PER (followed by 0.5, 5, 0.1 and 3 mgbiotin kg^–1). Quadratic analysis showed that the optimumdietary biotin requirements for maximal weight gain, PER and PER were2.49, 2.54 and 2.52 mg kg^–1, respectively. Liver biotinconcentrations were influenced by levels of biotin in the diet.Concentration of liver biotin increased as level of dietarysupplementation increased and no biotin was detected in the liver of thecontrol fish. Liver pyruvate carboxylase and acetyl CoA carboxylaseactivities were higher in fish fed biotin-supplemented diets than incontrols. Biotin concentrations, pyruvate carboxylase and acetyl CoAcarboxylase activities in liver associated with normal growth rangedfrom 10.59 to 10.66 g g^–1, 147.97 to 148.18 units mgprotein^–1 and 12.76 to 12.78 units mg protein^–1, respectively. Biotin deficiency symptoms such as anorexia, darkskin colour and convulsions were observed in fish fed the control diet.The optimum dietary biotin requirement for maximal growth of C.batrachus is about 2.49 mg kg^–1 diet.     

Growth and production of the Amazonian tambaqui in fixed cages under different feeding regimes

Experimental culture of the native Amazonian fish tambaqui, Colossoma macropomum, in fixed cages was carried out over a period of 8 months, in Lake Urubu (Rio Grande do Norte, Brazil), to assess the viability of fixed cage culture of tambaqui and to test the influence of diet on growth rates. Nine synthetic net cages (1 m³) were each stocked with 45-day-old fish (mean weight 3 g; mean total body length 51 mm) at a density of 34 fry m^–3. During the first 2 months of culture, fish were fed a balanced formulated feed on an as-fed basis at the rate of 5% body weight day^–1. During months 3–8 this continued for fish in treatment 1 while those in treatment 2 were fed tropical regional fruits, on a wet weight basis at the rate of 5% body wt day^–1. Fish in treatment 3 were given no supplementary feed. Monthly biometric measurements were made on all fish. Fixed cage fish culture was shown to be a viable and simple technique. Survival in all treatments was 100%. With balanced supplementary feed, production was 14.4 kg m^–3, compared with 4.9 kg m^–3 and 2.1 kg m^–3, respectively, in the treatments where fish were fed with fruits and were not given any supplementary feed.     

Production of Australian freshwater crayfish in earthen-based systems using pelleted diets and forage crops as food

Juvenile Cherax destructor (commonly called theyabby) were cultured in earthen-based ponds and tanks for 70–105d, and were fed pellets and/or a forage crop of the perennialwhiteclover, Trifolium repens. Three supplementary feedingstrategies were evaluated. Yabby growth on pellets consistently exceeded (by67–159%) that obtained on clover. Base-line yields for extensiveproduction systems are around 400 kg ha^–1. Thesupplementary addition of T. repens produced yields of 635kg ha^–1 (in ponds) to 1086 kgha^–1 (in tanks). The sequential addition of cut-cloverto tanks stimulated growth to levels approaching those achieved on pellets.Yabbies stocked into ponds at 17 m^–2 and fed 33%protein pellets for 100 d, resulted in a yield of 1117 kgha^–1.Pellet inputs at a rate of 129–249 g m^–2(dry matter) and 38–83 g m^–2 (protein) over70–100 d resulted in acceptable growth and feed utilisationindices. Clover inputs of 534–682 g m^–2 (asdry matter) or 84–177 g m^–2 (as protein)produced reasonable growth rates but poor feed utilisation indices. Aconsiderable quantity of the dry matter and protein content of clover waseitherinefficiently utilised or directed into other production pathways. In tanks,clover inputs from 113–296 g m^–2 (drymatter) and 24–54 g m^–2 (protein) weresufficient to maintain high growth rates for 4 weeks, while in ponds, inputs of21 g m^–2 (dry matter) and 4.3 gm^–2 (protein) were sufficient for 3 weeks. During theearly weeks of production no growth advantage was gained by providing pelletstoanimals cultured in forage-based systems. Forage depletion occurred after3–4 weeks and was probably a major growth limiting factor.     

Sublethal effects of ammonia in soft water on Atlantic salmon smolts at a low temperature

Atlantic salmon (Salmo salar L.) smolts were exposed to ammonia at 4 °C in an open flow system. The concentrations of un-ionized ammonia nitrogen (NH₃-N) and total ammonia nitrogen (TAN) were increased abruptly twice during a period of 28 days. For concentrations in the range 1–15 µgl^–1 un-ionized ammonia nitrogen (4.3–21.1 mgl^–1 TAN), no effects were observed on the smolts. However, plasma glucose was not measured in this range. The observed results for higher concentrations may be divided into two categories of sublethal effects. (1) In smolts exposed to the concentration range 19–37 µgl^–1 NH₃-N (average 26 µgl^–1 NH₃-N; 34.9–50.5 mgl^–1 TAN), the mean plasma glucose concentration was 1.3 times the mean of the control group. No other measured parameters were significantly altered. (2) For smolts exposed to 37–65 µgl^–1 NH₃-N (average 47 µgl^–1 NH₃-N; 57.7–84.5 mgl^–1 TAN), the mean plasma glucose concentration was increased to 2.3 times, the mean plasma chloride level was reduced to 0.9 times, and mean haematocrit was increased to 1.1 times the control values. Histological examination of the gill tissue revealed extensive lamellar hypertrophy. Weight, length, condition factor and ventilation frequency were not significantly affected and no mortality took place during the exposure period (1–65 µgl^–1 NH₃-N; 4.3–84.5 mgl^–1 TAN). Plasma glucose seemed to be the most sensitive parameter in detecting the sublethal stress response, and this investigation may thus demonstrate the importance of measuring plasma glucose in experiments concerning safe levels for ammonia.     

Development of wolffish eggs at different temperature regimes

Embryonic development of common wolffish (Anarhichas lupus L.) was studied at constant temperatures 5.0, 7.0, 9.0, 11.0, 13.0 and 15.0°C. Duration of development from egg activation to several morphological stages including 50% hatching was determined. At 5.0–11.0°C, the survival rate of eggs to hatching ranged from 51 to 88% with a tendency to increase at 5.0 and 7.0°C. Morphological anomalies, bacterial contamination and large mortalities were observed in eggs incubated at 13.0 and 15.0°C. The period of hatching lasted from 10 to 50 d in different egg groups. Embryo length and yolk sac volume at identical morphological stages of development showed only slight relation to temperature. At lower temperatures newly hatched larvae were longer and at more advanced stages of ontogeny. Normal numbers of fin rays in larvae (mean values 74 for dorsal fin and 46 for anal fin) were observed at 5.0 and 7.0°C and in most larvae at 9.0°C. At 11.0 and 13.0°C, many rays were absent, with mean values for dorsal fin 60 and 39 respectively and for anal fin 28 and 4 respectively. The approximate upper limit for normal development of fin rays appeared to be 9.0 °C.     

Tilapia wild spawning control through predator fishes: Israelitrial with red-drum and hybrid bass

Tilapia wild spawning is a nuisance in warm freshwater aquaculture growout ponds. To cope with this problem two experiments were carried out with predatory fish that do not reproduce in fresh water. One experiment tested the capacity of hybrid bass (Morone saxatilis × M. chrysops) and red-drum (Sciaenops ocellatus) as predators of wild spawning of hybrid tilapia (Oreochromis niloticus × O.aureus), and the other compared predation effectiveness of red-drum of different sizes and stocking densities.Both hybrid bass and red-drum effectively reduced tilapia wild spawning and improved by 15–20% tilapia performance and food conversion ratio. These effects were obtained stocking small red-drum (20 g) or large red-drum (60–80 g) or bass (135 g) at stocking densities of 500–1000 predators/ha, together with 15000 tilapia/ha of 65–75 g. Hybrid bass stocked at 750/ha and large red-drum stocked at 500/ha presented over 90% survival. Red-drum at higher stocking density and/or lower stocking weight presented reduced survival (40–60%). Red-drum of all examined stocking weights presented better growth rates when stocked at 500/ha than at higher densities.     

Effects of dietary carnitine and lipid on growth and body composition of hybrid striped bass (Morone chrysops ♀× M. saxatilis ♂)

A study was undertaken to investigate the effects of graded dietary levels and different types of carnitine on hybrid striped bass (Morone chrysops × M. saxatilis %) fed different levels of lipid. An incomplete factorial design was utilized in which diets containing lipid at either 5 or 10% were supplemented with l-carnitine at 0, 500, or 1000 mg kg^–1 diet, dl-carnitine at 1000 mg kg^–1 diet, or carnitine chloride to provide 1000 mg carnitine kg^–1 diet. Juvenile hybrid striped bass (3.3 g fish^–1) were stocked into individual 38-l aquaria connected as a brackish water (6), recirculating system and fed each diet in triplicate for 9 weeks.Supplementation of the diet with 1000 mg carnitine kg^–1 increased muscle carnitine from 35.5 to 47.7 g g^–1 tissue. Carnitine supplementation did not result in increased weight gain regardless of carnitine level or type; however, weight gain showed a significant (p<0.05) response to dietary lipid with fish fed diets containing 10% lipid growing 34% more than fish fed diets with 5% lipid. The hepatosomatic index also was unaffected by diet, but the intraperitoneal fat (IPF) ratio was significantly elevated (5.1 vs 3.2%) in fish fed diets with 10% lipid compared to those fed diets with 5% lipid. Fish fed diets containing 1000 mg carnitine kg^–1 had increased IPF ratio values at 4.7% compared to 3.9% for fish fed the basal diet. Liver lipid also was responsive to dietary treatment, increasing from 6.7 to 8.8% of wet weight as dietary lipid increased from 5 to 10%. The relative quantities of triglycerides, free fatty acids and phospholipids in muscle and liver were not influenced by carnitine level, carnitine type or dietary lipid level. Supplementation of carnitine does not appear to be beneficial to hybrid striped bass based on either growth performance or body composition.     

Rates of oxygen consumption and ammonia excretion of juvenile Eurasian perch Perca fluviatilis L.

The impact of feeding, fish size (body weight from 18.5 to 56.5 g) and water temperature (20 and 23 °C) on oxygen consumption (OC, mg O₂ kg^–1 h^–1) and ammonia excretion (AE, mg TAN kg^–1 h^–1) was studied in Eurasian perch held in recirculation systems. OC for both fed and feed-deprived (3 days) fish was higher at 23 °C (278.5 and 150.1 mg O₂ kg^–1 h^–1) than at 20 °C (249.3 and 135.0 mg O₂ kg^–1 h^–1; P < 0.01). AEs for both fed and feed-deprived fish were also significantly higher at 23 °C than at 20 °C (P < 0.001). Water temperature and fish size had a significant impact on the oxygen:feed ratio (OFR, kg O₂ kg^–1 feed fed day^–1) and ammonia:feed ratio (AFR, kg TAN kg^–1 feed fed day^–1; P < 0.001). Their average values at temperatures of 20 and 23 °C were 0.17 and 0.19 kg O₂ kg^–1 feed fed day^–1 and 0.009 and 0.011 kg TAN kg^–1 feed fed day^–1, respectively.     

The effects of temperature in the life cycle of two consecutive generations of the cuttlefish Sepia officinalis (Linnaeus, 1758), cultured in the Algarve (South Portugal)

We are presently culturing the 4^th generation of thecuttlefish, Sepia officinalis in our laboratory. A firstgeneration (F1) was grown from eggs collected from the wild (Ria Formosa–South Portugal) during the summer, at mean temperatures of 27°C ± 3°. In the present study, a second generation(F2), originated from eggs laid in the laboratory by females from F1 wascultured between the start of autumn and the end of spring, at meantemperaturesof 15 °C ± 4 °C. The life cycle ofcuttlefish from F2 was compared to F1. Populations of 30 cuttlefish were usedineach experiment. Cuttlefish were grown from one day old until the cycle wascompleted (when the last female in each population had died). Cuttlefish fromF2cultured at much lower temperatures had a longer life cycle, of almost 9 months(260 days) compared to cuttlefish from F1, which completed their cycle in lessthan 6 months (165 days). Cuttlefish from F2 grew significantly larger (U =0.00; p < 0.01) with mean weights of 343.3 ± 80.5 g and248 ± 33.1 g for males and females, respectively, comparedtoF1 (199.6 ± 40 g and 143.3 ± 30.9 g formales and females, respectively). Females from F2 had higher fecundity (225eggsfemale^–1) compared to females from F1 (144 eggs perfemale^–1), produced bigger eggs (t = 45.60752; p < 0.0001),weighing 0.74 ± 0.18 g, compared to 0.46 ± 0.11 fromF1,and bigger hatchlings (t = 7,144783; p < 0.0001), weighing 0.10 ±0.02g, compared to 0.09 ± 0.02 g for the summerpopulation.     

Gill Na+-K+ ATPase, carbonic anhydrase activities and plasma osmotic and ionic variations during smoltification of Atlantic salmon in the north of Portugal

Gill Na⁺-K⁺ ATPase and carbonic anhydrase activities were measured, on a fortnightly basis, from February to July, in 0₊ age Atlantic salmon (Salmo solar), hatched and reared in a freshwater experimental station in Covas, northern Portugal. Plasma osmolarity and ionic composition were also measured. Gill Na⁺-K⁺ ATPase activity increased slowly until April (15–19 moles Pi mg prot^–1 h^–1). From April to late May there was a great increase in activity (19–32 moles Pi mg prot^–1 h^–1) followed by a sharp decline in June (15 moles Pi mg prot^–1 h^–1). In contrast, carbonic anhydrase activity decreased significantly from early April to early June (170-70 moles p-nitrophenol mg prot^–1 h^–1) and increased in late June, suggesting the existence of a compensatory mechanism for the changes in Na⁺-K⁺ ATPase activity. Plasma osmolarity and sodium concentration showed lower levels during the period of high ATPase activity. On the other hand, plasma calcium concentrations showed an increase during the same period (3.47–5.98 mm1^–1 of plasma). A transitory decrease in osmolarity and plasma sodium and chlorine concentrations occurred in March, prior to the surge in Na⁺-K⁺ ATPase activity, suggesting that the physiological changes, characteristic of parr-smolt transformation can be a consequence of this loss of freshwater osmoregulatory capacity.     

Influence of the gametogenic cycle on the biochemical composition of the ovary of the great scallop

The oogenic cycle and biochemical composition of the ovary of raft-cultured great scallop (Pecten maximus) were studied during the period April 1990–July 1991. The ovary condition index (FGI) and stereological studies showed the existence of two principal spawning periods, winter and late spring-early summer. No sexual resting period was found. Oocyte lysis was high throughout the year. Ovarian lipid levels displayed a clear seasonal pattern linked to the gametogenic cycle. Total lipid (TL, 16–21% dry weight), acylglycerol (AG, 20–65% TL) and free sterol (FS, 2.8–6.4% TL) levels were, generally, higher in the ripe ovary and a decrease coincided with spawning. Protein (59–63% dry weight), glycogen (<3% dry weight) and phospholipid (PL, 26–35% TL) levels showed no clear seasonal trend. The TL and AG were a good index of ovarian sexual maturity. The TL % of dry weight) correlated well with the female gonad condition index (r _s = 0.779, p < 0.001), and AG (% f TL) correlated well with the mean oocyte diameter (r _s = 0.630, p < 0.01) and the female gonad condition index (r _s = 0.443, p < 0.05).