(Click to see presentation)

Initiated in the seventies and eighties with various species of sparids, soleid and mugillid, the research in specific diversification of finfish Mediterranean mariculture rermained unexploited and at low level untill the mid nineties when prices of sea bass and sea bream began to drop, cause for a renewing interest for this interesting alternative solution of sustainable aquaculture.

In 2003, the diversification was a reality and 32 candidate species of fishes belonging to 14 families were studied. 13 of them, from which 9 sparids, 3 sciaenids and 1 siganid were globally mastered, allowing a possible reliable culture based on hatchery nursery and ongrowing of about 28 millions fry (about 10 % of the bass-bream production). 5 others candidates from which 1 sparid (Dentex dentex), 1 carangid (Seriola dumerilii), 2 epinephelids (Epinephelus marginatus and E. aeneus) and a polyprionid (Polyprion americanus) will be soon very promissing with the same strategy of production when some light  limiting segment of production be mastered. 3 species from which 2 sparids (Boops boops and Pagellus acarne) and 1 mugilid (Mugil cephalus) were sometimes reared in cages (for their  flesh) or in lagoons (for their gonads) from wild fry recruited locally and might fulfill some local small productions. And 1 species (Thunnus thynnus) was very successfully (about 12 000 t production) fattened in large cages (for japanese sashimi market) from big live individuals provided by commercial tuna fishery specially contracted for this purpose.

  Most of the new candidates are reared with a technology globally mimetic with that of sea bass and sea bream. But they are less eurythermidc and less euryhaline, thus needing more stable and better quality of water, cause for a probable further more regionalized production and for a better conformity of these species with in-sea cage than on-land tank technolgy of on-growing. Others (like Solea solea and S. senegalensis) will be only adapted to  on land culture.

Some of the candidates (from which Diplodus sargus and D. vulgaris, Lithognathus mormyrus, Oblada melanura, Sarpa sarpa, Boops boops, Pagellus acarne, Siganus rivulatus) presented worst growth performances than sea bass and seabream (2 to 3 years for 300 g portion sizeanimal) making them probably less competitive (except on local niche markets) if ex farm price of bass and bream rises up. 8 candidates (from which Puntazzo puntazzo, Pagellus erythrinus, Pagrus pagrus, Pagrus major, Pagellus bogaraveo, Sciaena umbra, Solea solea and S. senegalensis) presented globally similar growth performances with bass and bream, thus offering real possibility of cost effective diversification despite some specific problems with actual technology (darkening of P. pagrus, feeding of S solea and S. senegalensis). 2 of them (Umbrina cirrosa and Dentex dentex) presented slightly better growth performances than bass and bream (about 1 kg at 2 years) making them soon very interesting candidates for diversification when light difficulties be solved (feeding and pathology of D. dentex and cage technology of U. cirrosa). 3 of them (Argyrosomus regius, Seriola dumerilii, Polyprion americanus) are big and fast growers presenting real better growth performances than bass and bream (1.5 - 2 kg in 1 year and 3-5 kg in 2 years, 5 - 8 kg at 3 years), making them very interesting new candidates for world wide market of transformation. In the future 3 other big and fast growers (more than 3 kg at one year and 5-10 at 2 years) from which 2 fish (Schedophilus ovalis and Coryphaena hippurus) and a cephalopod (Octopus vulgaris) will probably enrich the panoply of diversification when basic biological problems be solved.

The actual success of specific diversification resulted mainly from well organised and harmonised research in a sery of complementary integrated models from specific (SBA), biologic (BBA), techno-economic (TEBA) Basis of Aquaculture, Optimisation of Rearing Condtions (ORC programs), as well as a good transfer of knowledge and knowhow. But mainy gaps are remaining. Total mastery of the biological cycle (still needed for mainy species) and avoidation of remaining limiting factors (conformity of development with wild standards, pathology, etc) will depend on sustainability of R & D activity in actual programs.

But specific diversification will also present new special Research constraints. This strategy of production is aimed at provision of real diversity on the market and not of supply of different images with similar taste, texture structure induced by too homogenous feed. Tailorisation of specific quality of flesh with their respective wild standards through new specific feed would be needed. Furthermore, mass production of big and fast growers with feeding needs of 200-250 % body weight / day in hatchery will not be possible with actual technologies due to induced cannibalism and anomalies of development. Only combination of semi intensive techniques (mesocosm), feeding automation, co-feding and early weaning, associated with good enrichment of food, will avoid the rearing difficulties of these new "metabolical bombs".  

Dr. Pascal Divanach is a director of research and Head of the Aquaculture Department of Intitute of Marine Biology of Crete (IMBC). He has 29 years experience in finfish mediterranean aquaculture and a special knowledge in early life of fish (eggs, prelarvae, larvae, fry), and in the biology / technology of hatcheries (from extensive to hyperintensive), mainly the so called mesocosm ones. He also has much experience in methods/techniques used in hatcheries for increasing quality and productivity.

Contact details: IMBC, PO Box 2214, GR 71003  Heraklion, Crete, Greece
Tel: +302 (810) 243127 Fax: +302 (810) 241882