Gar biology and culture: status and prospects

Many lepisosteid populations in North America have declined and many are now threatened as a consequence of habitat loss and alteration and commercial and sport over¢shing. Over the last two decades, morphological, histological and molecular studies allowed distinguishing between diierent phases of development and the nutritional condition of larvae. Ontogeny of the digestive enzymes of gar larvae indicated the possibility to feed them arti¢cial feeds since early developmental stages. An in vitro digestibility system to test diierent feed ingredients has been used. Important characteristics of arti¢cial diets were identi¢ed through diierent feeding experiments. Endocrinological studies showed the feasibility of altering larval development and the digestive capacity of larvae. Cloning of gar growth hormone opened new avenues to enhance growth in the gars. Plasmatic vitellogenin was isolated and puri¢ed, to develop a competitive enzyme-linked immunosorbent assay, which allowed the straightforward separation of males from females to establish appropriate proportions for reproduction and also was used to evaluate hormonal protocols to induce gonad recrudescence and spawning. This review analyzes the biology, ecology and physiology of diierent gar species as a basis for their domestication, mass production of larvae for repopulation experiments and for the culture of commercial-size gar.