Gadoid Mariculture:
Development
and Future Challenges

Scientific Programme

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• received contributions
• planned time schedule
  

Scope and Objectives

A symposium targeted on the cultivation of gadoids (cod, haddock, pollock, and hake) has not been held for over 15 years. In the face of dwindling stocks and a weakened market value of farmed salmon, several countries are currently initiating large projects to significantly expand gadoid mariculture. Due to the different physical or administrative restrictions in the various countries, different methodologies may be required.

This symposium aims to integrate international state-of-the-art science on the topic of development and future challenges of gadoid mariculture in the North Atlantic, and elsewhere, including knowledge on environmental considerations connected to fish farming.

Given that demersal harvest fisheries remain depleted and global human demand for 'whitefish' continues to rise, it is of particular importance to re-visit gadoid culture at this time.

Cod culture was initiated during the 1980s primarily for the purpose of stock enhancement/restoration, but the needs and requirements for stock enhancement are in many respects different than for mariculture.

During recent years, many ICES member countries have launched large scientific programmes in support of gadoid culture as a potential supplement to the culture of salmonids. Cultivation technologies that require scientific research span a number of important integrated areas:

(i) reproduction, genetics, biotechnology

(ii) development, physiology, and behaviour

(iii) early feeding

(iv) nutrition

(v) environmental factors and on-growth

(vi) fish disease, health, and welfare

(vii) rearing technology

(viii) environmental impact and sustainability

(ix) quality, market and economics

A symposium designed to synthesize recent scientific developments in these areas, and identify imminent future challenges, is thus justified and timely considering the recent initiatives by several countries to annually raise hundreds of thousands of juveniles of each species for market grow-out.

These themes will be organised into the following sessions:

Session 1: Quality, Market and Economy of cultured gadoids
High product quality related to marked demands and preferences, and its generation using cost-effective culture, is an essential target for the development of this pioneering industry. Profitability modelling, sale of juveniles for stocking to sea cages, hatchery design and operations, shortening time to market, species comparisons, are key to evaluate financial plans for sustainable development and private and government investment. Presentations on these aspects of economic modelling of gadoid culture are welcome.

Session 2: Genetics and Environmental impact of gadoid culture
Genetic markers, quantitative trait loci, pedigree development, dam and sire effects, selective breeding for desirable traits, estimates of heritability, and potential genetic impact on wild stocks are areas in which contributions are sought. Profitability of gadoid mariculture may provide fish farmers with a choice to develop multi-species finfish sites or begin exclusive gadoid sites. Co-existence of different species may influence disease transmission. Amount of uneaten food, detritus and fecal deposits in sediments around sea cages needs to be minimized. Studies describing potential environmental impacts of gadoid mariculture in comparison to salmon culture are invited.

Session 3: Fish disease, Health and Welfare issues
Diseases, particularly nodavirus, are causing major losses during the early larval period in various countries and studies in this area are strongly encouraged. The identification of diseases, method of transmission (vertical, horizontal), appropriate practices to avoid spreading, are regarded of high priority. Methods of early detection, symptoms (lethal and non-lethal sampling of different life stages and tissues), and eventual development of appropriate vaccines will be needed as this industry moves forward.

Session 4: Early feeding and Nutrition
The enrichment of rotifers, copepods and Artemia, and use of “green water” are in many circumstances considered essential for successful larviculture. Choice of algal species used for live food enrichment and their culture are labour intensive aspects of hatchery operations. Studies outlining methods of producing live feed at experimental and large-scale grow-out levels are invited. Levels of essential fatty acids (HUFAS, PUFAS), feeding schedules, methods used to wean from live to particulate food, size grading, and development of microparticulate diets, are facets of culture that are critical to cost-effective production of juvenile gadoids. Experimental research on required dietary levels of protein, lipid and carbohydrate for different gadoid species and life stages is at the basis of feed development. Excess fat in foods can produce fish with enlarged livers. Optimizing growth and minimizing this allocation of energy to viscera is required. Ration, meal size and frequency of wet, moist and dry pelleted feed used for hatchery and sea cage fish need to be determined. Papers reporting on these nutritional aspects of diet development and others (e.g., protein sparing effects, vitamins, and minerals) for various gadoids are encouraged.

Session 5: Early development, Behaviour and Juvenile rearing
Ontogenetic development is rapid during the embryo and larval stages and strongly shapes growth and survivorship. Hatchery operations and cultivation techniques should be finely tuned to match these life history changes and the behaviour characteristics of each stage. Studies that examine morphological, physiological and behavioural changes with increases in age and body size are of interest. For example, morphological features at time of hatch, first feeding, gut development, swim bladder inflation, and pelagic to demersal life style changes are of import. Improved knowledge of physiological, bioenergetic and behavioural processes during larval, juvenile and adult phases will broaden the information base on which to perfect cultivation practices. Aggressive cannibalistic behaviour is of particular concern and methods of detection and avoidance are of interest

Session 6: On-growth and Rearing Technology
The coastal areas in which sea cages are located will strongly influence gadoid growth potential, and this will vary among species and region, based principally on suitable growing temperatures and daylenth. Photoperiod manipulation and use of continuous underwater illumination to increase growth and reduce incidence of sexual maturity is of prime interest for these species. Stocking size, density, and grading in sea cages may also be important to maximize growth. Some environments may be near a species’ extreme metabolic range, and periodic dips in temperature to near freezing may lead to winter mortalities, whereas in southern regions summer temperatures may periodically lead to large losses. Studies dealing with environmental factors, their influence on production, and their potential manipulation are invited. Size, shape, and colour of tanks, water flow and circulation, and use of lighting (e.g., specific spectra) are aspects of culture that often undergo site-specific development. These innovative practices may have universal application. Submissions are encouraged on rearing technology that demonstrate improvement in gadoid growth through cost effective modifications of hatchery infrastructure.

Session 7: Biotechnology and Reproduction
These are the foundations for developing the optimal seedstock for successful culture. Controlling seasonal timing of the production of high quality eggs and the prediction of gamete production using controlled breeding technology is essential. The development of monosex stocks, triploid stocks or husbandry protocols to delay puberty of farmed gadoids may be essential for successful farming.