Marketing involves the whole chain of links between producers and consumers which determine the relationship between the earnings of producers and the supply of the product. Markets and the transaction systems utilized can vary greatly. Some may be characterized by barter, auctions may characterize others, while futures markets are found for certain products. Because of the short shelf-life of fresh fish, fish markets in some places have responded readily to the use of electronic communications to facilitate the speed of transactions and delivery of the product. Marketing systems often evolve over time, adjusting dynamically to market signals about consumers' needs. If prerequisites for well operating markets are missing, corrective interventions by policy makers can be made.
Markets are not uniform. A large number of market segments exist, relating to income, taste, specific needs, and cultural and religious backgrounds, and to combinations of these. The larger and wealthier import markets are demanding more sophisticated products, such as convenience foods and value-added products. In many developing countries most of the higher value fish products are exported and consumer needs are met largely from low value domestic production and imports.
Labeling and certification have become increasingly important factors in marketing, either meeting regulatory requirements of the importing countries or targeting particular consumer requirements through labeling products as "organic", "dolphin-safe", as "fair-trade" items, or "ecolabelling" them as having been produced sustainably.