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- Effects of culture density on growth and broodstock management of the cuttlefish, Sepia officinalis (Linnaeus, 1758)Publication . Correia, Miguel; Domingues, Pedro M.; Sykes, António V.; Andrade, José PedroThe effects of culture density on growth and broodstock management of the cuttlefish S. officinalis were studied. Cuttlefish used were one month old at the start of the experiment, on average; two densities were used (16 and 76 cuttlefish m 2). During the first experiment (until day 43), dead cuttlefish were replaced by individuals of similar weight. From that day onwards, no cuttlefish were replaced. No significant differences in growth and feeding rates, or food conversions were found between densities, during the first experiment. Results indicate that densities up to 76 cuttlefish m 2 are suitable for cuttlefish weighing approximately 10 g. After day 43 until first female layed eggs (second experiment), no statistical differences were found between densities for all the parameters studied with the exception of growth. In this case, cuttlefish cultured at the lower density grew more than those ones cultured at the higher density, with average weights at the start of egg laying of 137.3F21.6 and 91.8F12.3 g, respectively. This difference in growth could be explained mainly by the different culture densities and biomass associated. Fecundity obtained for cuttlefish cultured at the lower density (834 eggs female 1) was higher than for those ones cultured at the higher density (290 eggs female 1), however fertility was higher for the higher density. These results were expected, since fecundity is directly related to the size of females. Significant differences were found in fertility (hatching percentage) between densities. Mean hatching percentage was of 35.8F9.4% and 62.0F16.9% for low and high density, respectively. This difference was unexpected since we expected eggs from females cultured at lower densities to have higher quality. Mean hatchling weight was of 0.079F0.011 and 0.072F0.012 g for low and high density respectively, and significantly different. Results indicate that lower culture density promoted higher growth, larger eggs and hatchlings, but had no influence on juvenile and adult survival. On the contrary, eggs from females cultured at higher densities resulted in higher hatching rates.
- Nucleic acid derived indices or instantaneos growth rate as tools to determine different nutritional condition in cuttlefish (Sepia Officinalis, Linnaeus 1758) HatchingsPublication . Sykes, António V.; Domingues, Pedro M.; Andrade, José PedroWhen culturing any species in intensive aquaculture, time of first feeding is of extreme importance. Food should be available when larvae or hatchlings are finishing the absorption of the inner yolk reserves and starting to feed externally. Cuttlefish are known to be voracious feeders throughout their life cycle and accept a wide range of prey (Guerra 1985, Castro & Guerra 1989, Pinczon du Sel & Daguzan 1992, Domingues et al. 2001a, Domingues et al. 2003). Some authors (Wells 1958, Richard 1971, Richard 1975, Boletzky, 1983, Boletzky 1987, and Nixon 1985) have studied the embryonic development and the early life history of cuttlefish and set the end of the inner yolk reserves around the 3rd day of life.However, according to Domingues et al. (2001b), cuttlefish in unfed or poor nutritional condition (as result of prey with poor nutritional profile) can last as much as 20 days. The only way to determine optimal timetables for first feeding, thus optimizing cuttlefish production, is the use of condition analysis. Condition is a measure of the physical status or well being of an animal and may be used to evaluate growth or survival rates (Bolger & Connoly 1989, Ferron & Leggett 1994).
- Assessment of European cuttlefish (Sepia officinalis, L.) nutritional value and freshness under ice storage using a developed Quality Index Method (QIM) and biochemical methodsPublication . Sykes, António V.; Oliveira, Ana R.; Domingues, Pedro M.; Cardoso, Carlos M.; Andrade, José Pedro; Nunes, Maria L.Cephalopod landings and consumption have been increasing worldwide during the past decades. The main reason for this increasing demand is that cephalopods are a good protein and lipid source (Kreuzer, 1984; Sinanoglou & Miniadis-Meimaroglou, 1998, 2000; Zlatanos, Laskaridis, Feist, & Sagredos, 2006), thus a highly nutritious food that represents an alternative to over exploited fish resources. Nutritional value of most Japanese squid and cuttlefish are described (Okuzumi & Fujii, 2000). Nevertheless, for the European cuttlefish (Sepia officinalis) as for most cephalopods of the Mediterranean and North Atlantic markets it is not yet well studied (Karakoltsidis, Zotos, & Constantinides, 1995; Ruı´z-Capillas, Moral, Morales, & Montero, 2002a).
- Nucleic acid derived indices or instantaneous growth rate as tools to determine different nutricional condition in cuttlefish (Sepia officinalis, linnaeus 1758) hatchlingsPublication . Sykes, António V.; Domingues, Pedro M.; Andrade, José PedroTwo groups of 100 cuttlefish hatchlings each were used to determine the duration of the yolk reserves, during which growth can be obtained with no food supply. One group was fed live grass shrimp ad libitum from the 3rd day of life onwards, while the other was starved during the whole experiment. The experiment lasted 7 days, because this was the 1st day where a negative growth rate was obtained. Nucleic acid derived indices and instantaneous growth rates (IGR) were used as a way to describe their condition, when all the yolk reserves would be exhausted and to determine the most accurate tool to express growth and condition. RNA/DNA ratios described clearly the differences (P < 0.05) between fed and starved hatchlings cultured at 23 ± 2°C, especially from day 4 onwards. Correlation between IGR and RNA/DNA ratios was only attained for the starved population (R 0.90; P 0.0374). DNA concentration was identical (P > 0.05) between groups and did not displayed a clear pattern with increasing age. Correlation between IGR and DNA was only attained for the fed population (R −0.90; P 0.0374). RNA concentration values were different from day 5 onwards. Any of the nucleic acid derived indexes were not accurate enough to express growth and condition, so IGR seems to be the most accurate and inexpensive way to describe hatchlings growth and condition in controlled conditions.
- The influence of culture density and enriched environments on the first stage culture of young cuttlefish, Sepia officinalis (Linnaeus, 1758)Publication . Sykes, António V.; Domingues, Pedro M.; Loyd, Maria; Sommerfield, Anne; Andrade, José PedroThe cuttlefish (Sepia officinalis) is one of the most well-known cephalopods (Boletzky 1983). Successful culture throughout the life cycle has been done in many places around the world (Pascual 1978; Forsythe et al. 1994). However, it is known that the first stage culture of this species is the most problematic phase and when most mortality occurs (Richard 1971; 1975; Domingues et al. 2001). Recent studies showed that grass shrimp (Palaemonetes varians) can and should be considered as an adequate prey for the culture of the early stages of cuttlefish. It promotes very similar results in life span, survival, and growth, when compared to mysids (Sykes, unpublished results). Furthermore, grass shrimp has been used successfully to culture cuttlefish throughout the life cycle (Domingues et al. 2002, 2003). One of the most important aspects in commercial culture of marine animals is culture density. These studies are important to maximize biomass cultured in each tank while attaining optimal growth and survival, to reduce production costs.