Modeling Viability of Fish Populations: An Overview

• Main Author: Wood, Chris C
• Format: Book Part
• Language: unknown
• Published: Oxford University PressNew York, NY 2004
• Subjects: Arctic
• Online Access: http://dx.doi.org/10.1093/oso/9780195166460.003.0017; https://academic.oup.com/book/chapter-pdf/52323753/isbn-9780195166460-book-part-17.pdf

Abstract A fish is a poikilothermic, aquatic chordate with appendages (when present) developed as fins, whose chief respiratory organs are gills and whose body is usually covered in scales (Berra 2001). Allowing for a few exceptions, fish are classified in three phyla comprising about 25,000 species (Nelson 1994). Although not as rich in species as plants or invertebrates, fish account for about half of all vertebrate species (the subject of Parts III to VI of this book). Fish lineages are over 400 million years old (Carrol 1988), and fish occur in virtually all aquatic habitats on Earth. Marine species are found from tropical reefs to sunless abyssal plains; freshwater species may occur in frozen arctic lakes or as resting stages in ephemeral desert ponds; others are diadromous, negotiating both marine and fresh-water habitats at different life history stages. Slightly less than half (41%) of fish are freshwater species, but these live in only 0.01% of the Earth’s visible water (Horn 1972). From a modeling perspective, fish exhibit life histories that span most of those encountered in vertebrates, enough to tax even the flexibility of RAMAS. Longevity ranges from a few months in some cyprinodonts to more than a century in some rockfishes (Sebastes). Most fish lay eggs, but ovovivipary and vivipary occur in some taxa so that fecundity (in the sense of litter size) spans at least seven orders of magnitude; for example, the basking shark and the manta ray produce only one to two “pups” per year, whereas the ocean sunfish and greasy grouper may produce 300 million eggs.