In order to design an adequate rearing environment for marine organisms, we must first know details of their fundamental biology and ecology: their sensory abilities (particularly vision and olfaction, since their feeding behaviour is guided primarily by these two senses), their behaviour under different rearing conditions, and also how both of these change with size and developmental state. Until recently, this kind of information was extremely difficult (sometimes impossible) to obtain, and it was always time-consuming to generate.
The kinds of questions which we must ask, and answer, before attempting to develop husbandry protocols for a marine species are, for example:
– What can these organisms see (light intensity and quality, imaging of prey and feed particles, etc.) at different life stages? This knowledge can be used to optimize the lighting conditions under which they are raised. Even small changes in light intensity and quality can have significant effects on the feeding behaviour and, therefore, survivorship and growth, of marine organisms. Despite this, the choice of light environment for rearing has, with few exceptions, been little more than guesswork.
– What can these organisms smell at different life stages and do they “prefer” some odours (e.g. exudates of specific prey) over others? Can such odours be used to enhance feeding rates? Very little is known about the olfactory abilities of marine organisms, nor of its role in feeding. In fact, only a handful of such studies exist for fishes, and that work has been mostly on salmonids, which do not have a true larval period.
– What roles do container size and colour, and water movement, temperature, salinity etc., play in feeding behaviour? Although these issues have been examined separately, their interaction has not been rigorously investigated.
– What prey characteristics (e.g. size, colour, movement pattern, odour, consistency) determine food preferences of marine organisms at different life stages?
These are only a small subset of the questions that remain to be addressed. To increase the probability of successfully developing a species for commercial production, we must be able to systematically address these types of questions, from first principles.