Biometric parameters and biochemical composition of wild wreckfish (Polyprion americanus)

Wreckfish (Polyprion americanus) is considered to be a good candidate for European aquaculture. The main biometric parameters were recorded from 86 wild-caught fish (2.6-18 kg of total weight) for 14 months and the gonadosomatic index (GSI), hepatosomatic index (HIS) and viscerosomatic index (VSI) were obtained. Biochemical analyses of muscle, liver and gonads from wild wreckfish showed that wreckfish has a high level of protein in muscle, 84% of dry weight (DW), and low level of lipids (7% DW). Capture season, sex, size or weight of the fish did not have a strong effect on the variability observed in the levels of proteins, lipids and fatty acids of the different tissues. Reared wreckfish have more lipids in mature gonads than wild fish, which may be due to a more lipid-rich diet. However, some polyunsaturated fatty acids (PUFA) such as arachidonic acid (ARA) and docosahexaenoic acid (DHA) reached higher values in wild female gonads than in reared gonads, which could indicate the wreckfish has high requirements in these fatty acids. This study obtained valuable data on the biology and biochemical composition of wreckfish to estimate its nutritional requirements, which could be useful for the future of this species in aquaculture.European Union's Seventh Framework Programme Research, Technological development and demonstration (KBBE-2013-07)Postprint1,48

Description of the annual reproductive cycle of wreckfish; Polyprion americanus, in captivity

Successful spontaneous reproduction and the production of viable offspring of wild fish in captivity can take some years of adaptation, and may also involve different environmental conditions, sex ratios and densities compared to natural populations. We followed the reproductive cycle of wreckfish Polyprion americanus—a late maturing, deep-sea benthic species—in captivity in three different broodstocks in Spain under natural photoperiod and temperature, and one broodstock in Greece under a constant temperature of 16 °C for two consecutive years, to describe the reproductive cycle of the species and the associated sex steroid hormone profiles. Oogenesis begun in the fall and post-vitellogenic oocytes of 1250 μm were present between March and June. Males were in spermiation condition and produced good-quality sperm throughout the year, regardless of the temperature profile to which they were exposed. Some females completed oogenesis, underwent oocyte maturation, and spawned spontaneously under both constant and fluctuating temperatures. The sex steroid hormones of both males and females followed the already-known profiles during fish gametogenesis, except for 17,20β-dihydroxy-progesterone, which did not seem to be related to either female or male maturation. The female reproductive dysfunctions that were identified included (a) the arrest of oogenesis at the cortical alveoli stage in certain females; (b) the failure to undergo oocyte maturation in others; and (c) the production of large percentages of unfertilized eggs from the females that spawned spontaneously. Our study suggests that reproduction in captivity is possible in wreckfish maintained under typical marine aquaculture conditions, but that reliable spawning and production of high-quality eggs may require some years of adaptation to captivity, before the reproductive dysfunctions will be overcome.Versión del edito

Description of the wreckfish (Polyprion americanus) reproductive cycle in captivity

Within the DIVERSIFY project for the diversification of species in European aquaculture, wreckfish is a special case because of its late sexual maturation, which does not occur until 7-8 years of age (Peleteiro and Brunzón, 2014), besides existing very few data on its reproductive biology because it is a demersal species whose adult specimens tend to live at the range of 100-1000 meters of deep. This work sets out the progress made in the study of the reproductive cycle of this species in stocks established in Galicia (Spain).European Union’s Seventh Framework Programme for research, technological development and demonstration (KBBE-2013-07 single stage, GA 603121, DIVERSIFY)

Cría en cautividad del pez de San Pedro, Zeus faber (Linnaeus, 1758)

An artificial fertilization of the Zeus faber was realised by stripping of 2 females and 4 males. Photographs were taken and the principal stages of embryonic and larval development were identified. The eggs were 1.99 ± 0.036 mm of diameter, totally spherical, with a clear and unsculptured eggshell, a narrow perivitelline space and a single oil globule of 0.41 ± 0.014 mm of diameter; incubation was realised to a temperature of 16 ± 0.5 °C and hatching took place on the 11th (176 degrees/day ± 5). The larvae measured 4,3 ± 0,21 mm of length at hatching and were maintained during 20 days to 19,5 ± 0,5 °C. They fed Artemia salina from the fourth day after to hatch (two days after the reabsorption of the yolk-sac). The larvae presented an extensive pigmentation with two typical spots in the dorsal and anal fins; the pigmentation was in increase along the development except in the caudal fin and last vertebral segments and the pelvic fins were shaped large and colourful. The biometric measures indicated an important increase in the height growth whereas the total length increased very slightly for the first days of life