António V. Sykes

Growth and survival of cuttlefish (Sepia officinalis) of different ages fed crustaceans and fish. Effects of frozen and live prey

Abstract Three feeding experiments, using live mysid shrimp, grass shrimp or fish fry as prey for 1-, 30- and 60-day-old cuttlefish were conducted to determine the efficiency of each dietary source in relation to cuttlefish size and age. Additionally, a fourth experiment using fish fry and grass shrimp, but previously frozen, was also conducted. The results showed that when 1-day-old cuttlefish were fed mysids, grass shrimp or fish for 4 weeks, mysids were the best prey, but only during the first week. From this moment until the end of the experiment, the best growth rate was when cuttlefish were fed grass shrimp. Cuttlefish fed fish fry showed the poorest growth rate throughout the experiment. Similarly, cuttlefish aged 30 or 60 days fed grass shrimp or fish fry had the best growth rates when fed grass shrimp. When cuttlefish were fed live fish, survival increased with size of cuttlefish (73.3%, 91.7% and 100% for 1, 30 and 60 days cuttlefish, respectively). In the fourth experiment, using frozen diets, overall acceptance of each diet (feeding rates) was the same for fish and shrimp. However, lower growth was obtained when cuttlefish were fed fish compared to grass shrimp. This lower growth was due to a lower food conversion (28% vs. 41%). Since cephalopod paralarvae and juvenile most likely need prey rich in polyunsaturated fatty acids (PUFA), phospholipids and cholesterol, and a moderate content in neutral lipids, we have analyzed the biochemical compositions of the different prey to evaluate the influence of this factor on growth and survival.

Effects of culture density and live prey on growth and survival of juvenile cuttlefish, Sepia officinalis

The effects of culture density on growth and survival of juvenile cuttlefish were tested. Groups of 1, 3 and 5 hatchlings were placed in small containers with bottom surface of 80 cm2, obtaining individual densities of 125, 375 and 625 cuttlefish m−2, respectively. Additionally, groups of 5 hatchlings were placed in containers with 2 different bottom areas (80 and 240 cm2), providing culture densities of 625 and 42 cuttlefish m−2, respectively. A total of 120 hatchlings were used and experiments lasted for 40 days. No differences were found in growth between any of the densities tested throughout the experiment until 35 days old. After this, cuttlefish placed in isolation grew significantly larger. A second experiment was conducted in a flow through system, using two rectangular tanks with bottom surface of 0.5 m2. Two groups of 25 cuttlefish hatchlings were used in this experiment, which lasted for 40 days. Both groups were fed live juvenile shrimp (Crangon crangon) during the first 5 days. Afterwards, one group was fed live fish fry of different species, while the other continued to be fed shrimp. After day 10 and until the end of the experiment, hatchlings fed shrimp grew significantly larger than those fed fish fry. Survival of hatchlings fed shrimp or fish fry after 40 days was of 100% and 68%, respectively. Total protein content of both prey types was similar. Therefore, the higher polar lipid content, especially due to the higher phosphatidylcholine and phosphatidylethanolamine levels observed in the shrimp, compared to fish fry could possibly be one of the major factor to explain the significantly higher growth rates for S. officinalis juveniles fed shrimp. Also, the percentage of polar lipids in the shrimp (47.4%) was closer to the one of juvenile cuttlefish (38.1%) than the composition of polar lipids in fish fry (10.4%). This could also be an important factor to explain the poor growth and survival obtained when feeding fish fry to the cuttlefish.

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 4th 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.

The use of Artemia sp. or mysids as food source for hatchlings of the cuttlefish (Sepia officinalis L.); effects on growth and survival throughout the life cycle

Twoexperiments were conducted to determine the effects ofArtemia sp. or mysids on growth and survival ofS. officinalis hatchlings, and their effect throughout thelife cycle. For experiment I, for the first 20 days, one group was fed adultArtemia sp. and the other was fed mysid shrimp(Paramysis nouvelli). Eggs laid by females in both groupswere counted and weighed, and hatchlings were weighed, to determine differencesin both groups. For experiment II, during the first 10 days, one group was fedArtemia sp. and the other was fed mysids (P.nouveli). After the period of differentiated feeding, the 2 groupsinexperiment I were fed grass shrimp (Paleomonetes varians)to 70 days old, and dead crabs (Carcinus maenas)afterwards. Cuttlefish in experiment II were fed grass shrimp from day 10 untilthe end of the experiment. For both experiments, hatchlings fed mysids grewsignificantly bigger (p < 0.01) and survival was higher. For experiment I,eggs laid by females fed mysids and the hatchlings born from these eggs werebigger (p < 0.001) compared to the group fed Artemiasp.initially. Individual fecundity was slightly higher for females in the groupfedArtemia sp. (163 eggs female−1) than forthe group fed mysids (144 eggs female−1). Egg laying startedatthe age of 125 days and lasted 45 days in both groups. Time between first egglaying day and first hatchlings to be born was 21 days. The last female to die(after spawning) in both groups was 167 days (less than 6 months old).

Effects of feeding live or frozen prey on growth, survival and the life cycle of the cuttlefish, Sepia officinalis (Linnaeus, 1758)

The effects of feeding live or frozen grass shrimp (Palaemonetes varians) to the cuttlefish, Sepia officinalis, were determined in two experiments. During Experiment I, two populations of 30 cuttlefish (aged 90 days old) were fed either live or frozen grass shrimp. Cuttlefish fed live shrimp grew larger, matured earlier, had a shorter life cycle (255 days) than the ones fed frozen shrimp (282 days), and had lower mortality. Females from the group fed frozen shrimp matured a month later but were significantly larger, 130.9 ± 38.5 g, compared to 74.2 ± 16.0 g, laid larger eggs, 0.47 ± 0.11 g, compared to 0.28 ± 0.10 g, and had higher individual fecundity (411 eggs female−1, compared to 150 eggs female−1). Newly born hatchlings from both groups had similar weights. During Experiment II, six replicates of 15 cuttlefish (50 days old) were used, three for each of the two diets tested. The exact same amount of live or frozen shrimp was provided to both populations twice a day. No differences in growth and feeding rates or food conversions were found at the end of the experiment. During the first week, cuttlefish fed frozen shrimp grew larger, and had higher conversion rates, compared to the ones fed live shrimp. Mortality was higher for the group fed live shrimp (36.6%) in Experiment II, mainly occurring during the last week. Mortality for cuttlefish fed frozen shrimp in Experiment II was 2.2%. Results obtained here indicate that freezing the grass shrimp only had a negative effect on the survival of S. officinalis in Experiment I.

Nutrition as a Key Factor for Cephalopod Aquaculture

Cephalopods are fast-growing animals, active swimmers and top predators, which require substantial amounts of food. As such, they show high metabolic rates dependent on a carnivorous diet, thus hypothetically linked to a predominant amino acid metabolism. Their body composition is mainly constituted by high levels of total protein, and their lipids, although quantitatively low, reveal the presence of substantial amounts of long-chain polyunsaturated fatty acids. All in all, little is known about their nutritional requirements, especially during the early stages, very prone to high mortalities under culture. This chapter is a brief account of key information concerning relevant points linked to the nutritional requirements that cephalopods have for proteins, lipids, carotenoids, carbohydrates, minerals and vitamins. Moreover, some considerations on populational metabolism are also presented.

The influence of culture density and enriched environments on the first stage culture of young cuttlefish, Sepia officinalis (Linnaeus, 1758)

The culture of Sepia officinalis hatchlings and juveniles at different densities and enriched environments was investigated. Experiments were conducted to determine effects of culture density and the use of a substrate on growth and survival. Experiment I studied the effect of three different densities (52, 515 and 1544 hatchlings m−2). Experiment II tested the effects of the enriched environment, using a sandy bottom with pvc shelters. Experiment III tested the effects of density on growth, survival, feeding rates and food conversions. Cuttlefish were fed live grass shrimp at rates of 20% body weight per day (BW d−1). Grass shrimp (Palaemonetes varians) was supplied ad libitum as food in all experiments. In experiment I, growth was different between the three densities, with highest growth for density of 515 hatchlings m−2. IGR was of 8.8, 9.6 and 9.2% BW d−1 for the three densities tested, respectively. Both groups of experiment II had similar growth. IGR was of 10.1 and 9.7% BW d−1 for enriched and non-enriched environments, respectively. Densities of 10, 45 and 120 juvenile m−2 were used in experiment III. Significant differences in feeding rates were only found between densities of 10 and 120 cuttlefish m−2 during the last week. Results indicate that culture of cuttlefish hatchlings could be done in a non-enriched environment, with densities not exceeding 500 hatchlings m−2 and minimum bottom areas of about 600 cm2. Densities of 120 juveniles m−2 in a minimum area of about 1083 cm2 should be considered for juveniles between 5 and 25 g.

Current Status and Future Challenges in Cephalopod Culture

This chapter presents an overall perspective on the current status of cephalopod culture, its bottlenecks and future challenges. It focuses on the species that have received more research effort and consequently accumulated more sci- entific literature during the present century, namely Sepia officinalis, Sepioteuthis lessoniana, Octopus maya and Octopus vulgaris. Knowledge regarding physiology, metabolism and nutrition of different species is still lacking. Two main challenges are identified: the development of a sustainable artificial diet and the control of reproduction. Understanding cephalopod physiology and nutrition will probably be the biggest challenge in developing the large-scale culture of this group of molluscs

Model based optimization of feeding regimens in aquaculture: application to the improvement of Octopus vulgaris viability in captivity.

The culture of common octopus (Octopus vulgaris), one important candidate to the aquaculture diversification, faces significant difficulties, mainly related with an inadequate first development stages diet. A mathematical model integrating disperse information on the nutrient composition throughout the species ontogenic development as well as on the effects of broodstock feeding and diet composition data of O. vulgaris, allowed us to predict the time evolution of paralarvae nutritional composition in terms of protein and lipid fractions and to design an optimal diet composition with the objective to ensure the maximal survival. The optimization routine showed that a diet based on the spider crab (Maja squinado) zoea composition is the most suitable for reaching the best survival rates. Results are verified by comparison with available experimental data. The obtained results and the prospective developments are a good example of how the systemic, quantitative model based approach can be used to analyse and contribute to the understanding of complex biological systems.

Metabolic rate and rates of protein turnover in food-deprived cuttlefish, Sepia officinalis (Linnaeus 1758)

To determine the metabolic response to food deprivation, cuttlefish (Sepia officinalis) juveniles were either fed, fasted (3 to 5 days food deprivation), or starved (12 days food deprivation). Fasting resulted in a decrease in triglyceride levels in the digestive gland, and after 12 days, these lipid reserves were essentially depleted. Oxygen consumption was decreased to 53% and NH4 excretion to 36% of the fed group following 3-5 days of food deprivation. Oxygen consumption remained low in the starved group, but NH4 excretion returned to the level recorded for fed animals during starvation. The fractional rate of protein synthesis of fasting animals decreased to 25% in both mantle and gill compared with fed animals and remained low in the mantle with the onset of starvation. In gill, however, protein synthesis rate increased to a level that was 45% of the fed group during starvation. In mantle, starvation led to an increase in cathepsin A-, B-, H-, and L-like enzyme activity and a 2.3-fold increase in polyubiquitin mRNA that suggested an increase in ubiquitin-proteasome activity. In gill, there was a transient increase in the polyubiquitin transcript levels in the transition from fed through fasted to the starved state and cathepsin A-, B-, H-, and L-like activity was lower in starved compared with fed animals. The response in gill appears more complex, as they better maintain rates of protein synthesis and show no evidence of enhanced protein breakdown through recognized catabolic processes.