Development towards commercialization of marine fish larvae feeds – Microdiets: Final FRDC report - Project 2004/258

The project specifically focused on developing formulated diets for marine fish larvae, specifically targeting more physical aspects of microdiets such as feeding methods, feed availability and particle recognition. A commercially ready microdiet formulation was developed that achieved better ingestion, digestion and survival for yellowtail kingfish than other commercially available diets. Two manufacturers of aquaculture feeds showed interested in the formulations, however neither of the companies have started producing the diet commercially

Development of octopus aquaculture: Rearing, handling and systems design for Octopus tetricus commercial aquaculture FRDC Project No 2009/206

The following document ‘Development of octopus aquaculture, rearing, handling and systems designs for Octopus tetricus commercial aquaculture’ contains protocols developed during the FRDC project 2009/206. These protocols encompass the most up-to-date rearing, handling and systems designs for Octopus tetricus commercial aquaculture. These protocols are the result of extensive research and development work carried out over the past four years by the Department of Fisheries, Western Australia and summarised in the final project report

Development of octopus aquaculture Final Report FRDC Project No 2009/206

During the past four years, the marine aquaculture group at the WA Fisheries and Marine Research Laboratories (WAFMRL) in collaboration with Occoculture Pty Ltd (subsidiary of Fremantle Octopus) and as a part of the FRDC project ‘Octopus Aquaculture Development’, investigated the potential of octopus aquaculture in Western Australia. Hatchery methods were developed in an attempt to close the life cycle. Advanced systems, rearing and feeding protocols were established for ranching Octopus tetricus juveniles

Fish larval nutrition and feed formulation: knowledge gaps and bottlenecks for advances in larval rearing

Despite considerable progress in recent years, many questions regarding fish larval nutrition remain largely unanswered, and several research avenues remain open. A holistic understanding of the supply line of nutrients is important for developing diets for use in larval culture and for the adaptation of rearing conditions that meet the larval requirements for the optimal presentation of food organisms and/or microdiets. The aim of the present review is to revise the state of the art and to pinpoint the gaps in knowledge regarding larval nutritional requirements, the nutritional value of live feeds and challenges and opportunities in the development of formulated larval diets.Norwegian Ministry of Fisheries; Research Council of Norway [CODE-199482, GutFeeling-190019]; Spanish Ministry of Science and Innovation MICINN + FEDER/ERDF [AGL2007-64450-C02-01, CSD2007-0002]; project HYDRAA [PTDC/MAR/71685/2006]; Fundacao para a Ciencia e a Tecnologia (FCT), Portugal; FEDER; EC [LIFECYCLE- 222719]; EU RTD [FA0801]info:eu-repo/semantics/publishedVersio

Metabolic fingerprinting of gilthead seabream (Sparus aurata) liver to track interactions between dietary factors and seasonal temperature variations

Farmed gilthead seabream is sometimes affected by a metabolic syndrome, known as the "winter disease", which has a significant economic impact in the Mediterranean region. It is caused, among other factors, by the thermal variations that occur during colder months and there are signs that an improved nutritional status can mitigate the effects of this thermal stress. For this reason, a trial was undertaken where we assessed the effect of two different diets on gilthead seabream physiology and nutritional state, through metabolic fingerprinting of hepatic tissue. For this trial, four groups of 25 adult gilthead seabream were reared for 8 months, being fed either with a control diet (CTRL, low-cost commercial formulation) or with a diet called "Winter Feed" (WF, high-cost improved formulation). Fish were sampled at two time-points (at the end of winter and at the end of spring), with liver tissue being taken for FT-IR spectroscopy. Results have shown that seasonal temperature variations constitute a metabolic challenge for gilthead seabream, with hepatic carbohydrate stores being consumed over the course of the inter-sampling period. Regarding the WF diet, results point towards a positive effect in terms of performance and improved nutritional status. This diet seems to have a mitigating effect on the deleterious impact of thermal shifts, confirming the hypothesis that nutritional factors can affect the capacity of gilthead seabream to cope with seasonal thermal variations and possibly contribute to prevent the onset of "winter disease"

Terrestrial chemical cues help coral reef fish larvae locate settlement habitat surrounding islands

Understanding the degree of connectivity between coastal and island landscapes and nearby coral reefs is vital to the integrated management of terrestrial and marine environments in the tropics. Coral reef fish are capable of navigating appropriate settlement habitats following their pelagic larval phase, but the mechanisms by which they do this are unclear. The importance of olfactory cues in settlement site selection has been demonstrated, and there is increasing evidence that chemical cues from terrestrial sources may be important for some species. Here, we test the olfactory preferences of eight island-associated coral reef fish recruits and one generalist species to discern the capacity for terrestrial cue recognition that may aid in settlement site selection. A series of pairwise choice experiments were used to evaluate the potential role that terrestrial, water-borne olfactory cues play in island–reef recognition. Olfactory stimuli tested included near-shore water, terrestrial rainforest leaf litter, and olfactory cues collected from different reef types (reefs surrounding vegetated islands, and reefs with no islands present). All eight island-associated species demonstrated high levels of olfactory discrimination and responded positively toward olfactory cues indicating the presence of a vegetated island. We hypothesize that although these fish use a suite of cues for settlement site recognition, one mechanism in locating their island/reef habitat is through the olfactory cues produced by vegetated islands. This research highlights the role terrestrial olfactory cues play in large-scale settlement site selection and suggests a high degree of ecosystem connectivity

Enrichment of Artemia nauplii in vitamin A, vitamin C and methionine using liposomes

Several types of liposomes were used to enrich Artemia nauplii in vitamin A, vitamin C and free methionine. In a first experiment, unilamellar liposomes formulated with krill phospholipid extract and retinyl palmitate demonstrated their capability to enhance the retinol content of Artemia nauplii. Furthermore, the increase in retinol was related to the amount of retinyl palmitate included in the liposomes as vitamin A source. These findings yield the possibility of using such vesicles to bioencapsulate simultaneously both vitamin A and essential fatty acids present in the krill phospholipid extract. A second enrichment was carried out with unilamellar liposomes composed of soybean phosphatidylcholine and loaded with sodium ascorbate as vitamin C source. Our results did not show that vitamin C content in the nauplii could be increased using unilamellar liposomes. This was most likely due to the degradation of the vitamin C during enrichment as well as the ascorbate leakage. Finally, a third experiment assessed enrichment in free methionine using liposomes of different lamellarity (unilamellar or multilamellar) and composed of either soybean phosphatidylcholine or dipalmitoyl phosphatidylcholine, both combined with cholesterol as a membrane stabilizer. Results indicated that multilamellar liposomes represent a useful tool to deliver methionine to Artemia nauplii. Enhanced protection given by their multiple bilayers in comparison to unilamellar liposomes could account for the higher ability displayed by multilamellar vesicles for free methionine bioencapsulation

Feeding behaviour and digestion physiology in larval fish – current knowledge and gaps and bottlenecks in research

Food uptake follows rules defined by feeding behaviour that determines the kind and quantity of food ingested by fish larvae as well as how live prey and food particles are detected, captured and ingested. Feeding success depends on the progressive development of anatomical characteristics and physiological functions and on the availability of suitable food items throughout larval development. The fish larval stages present eco-morpho-physiological features very different from adults and differ from one species to another. The organoleptic properties, dimensions, detectability, movements characteristics and buoyancy of food items are all crucial features that should be considered, but is often ignored, in feeding regimes. Ontogenetic changes in digestive function lead to limitations in the ability to process certain feedstuffs. There is still a lack of knowledge about the digestion and absorption of various nutrients and about the ontogeny of basic physiological mechanisms in fish larvae, including how they are affected by genetic, dietary and environmental factors. The neural and hormonal regulation of the digestive process and of appetite is critical for optimizing digestion. These processes are still poorly described in fish larvae and attempts to develop optimal feeding regimes are often still on a ‘trial and error’ basis. A holistic understanding of feeding ecology and digestive functions is important for designing diets for fish larvae and the adaptation of rearing conditions to meet requirements for the best presentation of prey and microdiets, and their optimal ingestion, digestion and absorption. More research that targets gaps in our knowledge should advance larval rearing

Growth, biochemical response and liver health of juvenile barramundi (Lates calcarifer) fed fermented and nonfermented tuna hydrolysate as fishmeal protein replacement ingredients

© 2018 Siddik et al. Conventional aquaculture feed materials available in Australia are expensive, which has prompted the search for alternatives that would be cost-effective and locally available. The present study was undertaken in order to maximize the use of a tuna hydrolysate (TH), which was produced locally from the tuna-processing discards. The growth performance, biochemical status, antioxidant capacity and liver health of juvenile barramundi (Lates calcarifer) were assessed. Two series of isonitrogenous and isocaloric diets labelled as TH50, TH75(non-fermented tuna hydrolysate) and FTH50, FTH75(fermented tuna hydrolysate) were formulated to replace FM at 50% and 75%, respectively. A basal diet without the TH supplementation was used as a control. The experimental diets were fed to the triplicate groups of fish three times a day for 56 days. The results of the experiment revealed that fish fed on both fermented and non-fermented TH-containing diets significantly reduced (p < 0:05) the final body weight, weight gain and specific growth rate compared to the control. The highest apparent digestibility coefficients for dry matter, protein and lipid were obtained in the control group, and decreased with the increasing level of TH in the diets. However, the whole-body proximate compositions and the blood biochemical indices of fish were not affected by the TH inclusion in the diets. The fish fed on TH diets of TH50, FTH50and TH75exhibited reduced (p < 0:05) glutathione peroxidase (GPx) activity compared to the control; whereas the FTH75exhibited no difference with the control. The excessive inclusion of TH in the diets of TH75and FTH75resulted in cytoplasmic vacuolization, with an increased amount of lipid accumulation, and necrosis in the liver tissue. These results indicated that the replacement of the FM protein with TH at 50% and 75% inclusion levels negatively affected the growth performance, feed utilization, and digestibility in juvenile barramundi; and it also increased the potential risk of hepatic failure in the fish. Further investigation is, therefore, required in order to optimize the TH levels in the fish diets which would be suitable for the growth of fish, as well as for maintaining the enhanced biochemical response in juvenile barramundi