ABSTRACT
This chapter provides a peek into fish evolution, zoogeography, ecology, and fisheries science. Fishes are not only the oldest but also most species-rich vertebrates on Earth (>28,000 species). Chondrichthes and Osteichthyes comprise the two major extant fish lineages; within the Osteichthyes most fish belong to the Actinopterygii. Within those, most fishes are Teleosts that contain the most species-rich vertebrate order, the Perciformess. Large-scale distribution patterns of extant fishes are mostly the result of vicariance, i.e. of plate tectonics, glaciations, or sea level rise and fall. Fish consumption must energetically match all metabolic and excretion losses, before resources can be allocated to the production of tissue or gametes. Fish are poikilothermic organisms; hence, nearly every mentioned process is temperature-dependent, resulting in highly plastic growth and metabolism. Fishes evolved diverse reproductive patterns, exhibiting external or internal fertilization, gonochorism or hermaphrodism, as well as different spawning times, breeding modes, or parental care. Fecundity, egg size, and egg quality are maternal contributions that vary with age, size, food quantity and quality. For a fish larva the odds of survival are exceedingly small, but not random. Faster larval growth resulting from inherent, genetic advantages or external factors like more favorable temperature and feeding conditions generally confer a higher probability of survival. Survival of fish early life stages is a major determinant of recruitment success, which drives the productivity of fish stocks and is therefore of scientific and economic interest. To sustainably exploit fish populations, we must understand why they vary.
