STUDIES UPON REQUEST
Broodstock management (Dr. C.C. Mylonas)
The Institute of Aquaculture offers the possibility of carrying out studies for the development of broodstock management protocols for various fishes reared at commercial aquaculture operations in Greece and Europe. Fish culture has a very short history, not exceeding 30 years. As a result, the fish used as broodstocks are still wild and it is very common to exhibit various problems with their husbandry, having negative implications on their reproductive performance.Broodstock management aims at the correct acclimation of fish with interest for the aquaculture industry, to rearing conditions, in order to achieve proper reproductive maturation and the production of good quality gametes under controlled conditions. The correct management will allow a commercial hatchery to optimize the use of space, using the least number of broodstocks for the necessary production of eggs. Also, year-round egg production allows the planning of the hatchery according to the needs of the fry market, instead of the reproductive biology of the fish of interest. Finally, using appropriate management methods, it is possible to employ artificial insemination for the production of genetically improved strains of fish, exhibiting traits of interest to the aquaculture industry, such as fast growth, flesh quality and external morphology.
Rearing of Juveniles (Drs P. Divanach and N. Papandroulakis)
The Institute, upon request and based on contracts can produce selected fry of various species (sea bass, seabream, sharpsnout sea bream, white sea bream, brown meager, red Pandora, shy drum, common dentex and red porgy). The need to diversify fin-fish production has been recognized as one of the ways to alleviate the reduction in prices observed in the last years in the aquaculture industry and to fuel the sustainable expansion of the aquaculture industry in the years to come. The HCMR has responded promptly to this demand of the aquaculture sector and has already established controlled reproduction procedures and larval rearing and weaning methods since 1992 of various new species, such as white bream (Diplodus sargus), sharpsnout sea bream (Puntazzo puntazzo), common pandora (Pagellus erythrinus), red porgy (Pagrus pagrus), common dentex (Dentex dentex), corb (Sciaena umbra), shi drum (Umbrina cirrosa), dusky grouper (Epinephelus marginatus) and greater amberjack (Seriola dumerili).
Use of probiotics in live food cultures (Dr. P. Makridis)
The Institute of Aquaculture runs experiments used to test various probiotics in the cultures of live organisms and application in the rearing of marine fish larvae in collaboration with R&D department of fish feed companies. High mortalities are often observed in the rearing of marine fish larvae, which could be explained by the proliferation of opportunistic bacteria. Cultures of probiotic bacteria are used for the inhibition of opportunistic bacteria in live food cultures and consequently in the gut microflora of the larvae.
Challenge Room (Dr. G. Rigos & Dr. I. Nengas)
A challenge room, a facility lacking in Greek aquaculture industry, has been developped to provide an opportunity to evaluate the efficacy of several substances used as dietary additives to improve fish resistance to diseases. Agents such as micronutrients, immunostimulants, probiotics, antibacterials and vaccines can be tested against important fish pathogens under controlled parameters.
Fish Immunology (Dr. M. Henry)
The Institute of Aquaculture has developed methodologies to assess the immune system of different Mediterranean fish species. The fish immune system can be assessed in vitro or in vivo after dietary supplementation. It can also be assessed in conjonction with various naturally occuring or bath-induced diseases or after different types of stress.
Fish for consumption (Dr N. Papandroulakis)
At its cage facility the Institute is able to produce fish of various species (Argyrosomus regius, Pagrus pagrus, Dentexd dentex, Pagellus erythrinus, etc) that are marketed based on contracts with private companies. As a result of its research activities the Institute has to keep populations of various species at its facility until marketable size. Furthermore, for evaluation purposes populations are reared until marketing.
Technological products (Drs P. Divanach and N. Papandroulakis)
The Institute produces and provides technological products such as automated feeding systems for hatcheries, ammonia and nitrate analyzers.
Hormone delivery systems for the induction of spawning (Dr. C.C. Mylonas)
Many aquacultured species exhibit reproductive dysfunctions, resulting in the absence of maturation, and thus absence of ovulation in females and reduction in sperm volume/quality in males. The reason for this dysfunction is the low levels of the reproductive hormone responsible for this function, namely luteinizing hormone (LH). The Institute has developed controlled release delivery systems of gonadotropin releasing hormone against (GnRHa), which induce a long term increase in LH release from the pituitary, which is necessary for the induction of the necessary steroidogenesis in the gonads. These gonadal steroids, in turn, induce final oocyte maturation and ovulation in the females and spermiation in the males. After administration to the broodfish, GnRHa is releases continuously for a period of 14 – 28 days, depending on water temperature. Due to this sustained release, a single administration therapy during the reproductive season is usually adequate, in contrast to the need for multiple injections of GnRHa in physiological saline. Therefore, there are savings in the necessary handling of the fish and the employed personnel. These GnRHa implants have important applications in the aquaculture industry, and specifically in broodstock management, in fish that exhibit reproductive dysfunctions, or in situation where maturation and spawning has to be achieved with artificial methods (e.g., in genetic selection methods or hybrid production). These implants have been used successfully for various Mediterrranean species, including the dusky grouper (Epinephelus marginatus), meagre (Argyrosomous regius), greater amberjack (Seriola dumerili), sole (Solea senegalensis) and bluefin tuna (Thunnus thynnus).
Phytoplankton production by use of photobioreactors (Dr. P. Makridis)
The Institute of Aquaculture runs consultancy work with fish farms, but also with other enterprises interested in phytoplankton production. Phytoplankton production is used in aquaculture when applying green water technique and in the production of rotifers. The Institute of Aquaculture has a long experience in use of large scale photobioreactors (1.5 m3), which are adapted to the climatic conditions in Greece. High cell concentration can be obtained by use of photobioreactors. The technology of high cell density-cultures of phytoplankton may find applications not only for aquaculture purposes, but also in biotechnology (production of pigments, energy, bioactive compounds etc.).
Fish quality (Dr. K. Grigorakis)
The analytical evaluation of the postmortem changes resulted to the establishment of organoleptic evaluation schemes for the Greek aquacultured fish species that are widely used from the companies to check their commercialized fish. Furthermore, through the various studies on fish quality, the diets, as well as the feeding management, have been improved and thus the quality characteristics of the cultured fish have been progressed.
Drug analysis (Dr. G. Rigos)
The Institute of Aquaculture has developed methodologies to detect registered and banned chemicals (antibacterials) in fish tissues. Having this ability, consumer welfare can be protected from potential hazards arising from the indiscriminate use of chemicals in aquaculture products. Used legal chemicals must be below Maximum Residue Levels (MRLs) established by agencies of the European Union (EMEA) to ensure fish safety.