Population dynamics of fisheriesA fishery is an area with an associated fish or aquatic population which is harvested for its commercial or recreational value. Fisheries can be wild or farmed. Population dynamics describes the ways in which a given population grows and shrinks over time, as controlled by birth, death, and migration. It is the basis for understanding changing fishery patterns and issues such as habitat destruction, predation and optimal harvesting rates. The population dynamics of fisheries is used by fisheries scientists to determine sustainable yields.
Fishing down the food webFishing down the food web is the process whereby fisheries in a given ecosystem, "having depleted the large predatory fish on top of the food web, turn to increasingly smaller species, finally ending up with previously spurned small fish and invertebrates". The process was first demonstrated by the fisheries scientist Daniel Pauly and others in an article published in the journal Science in 1998. Large predator fish with higher trophic levels have been depleted in wild fisheries.
PiscivoreA piscivore (ˈpɪsᵻvɔr) is a carnivorous animal that eats primarily fish. The name piscivore is derived . Piscivore is equivalent to the Greek-derived word ichthyophage, both of which mean "fish eater". Fish were the diet of early tetrapod evolution (via water-bound amphibians during the Devonian period); insectivory came next; then in time, the more terrestrially adapted reptiles and synapsids evolved herbivory. Almost all predatory fishes (most sharks, tuna, billfishes, pikes etc.) are obligated piscivores.
MaricultureMariculture or marine farming is a specialized branch of aquaculture (which includes freshwater aquaculture) involving the cultivation of marine organisms for food and other animal products, in enclosed sections of the open ocean (offshore mariculture), fish farms built on littoral waters (inshore mariculture), or in artificial tanks, ponds or raceways which are filled with seawater (onshore mariculture). An example of the latter is the farming of marine fish, including finfish and shellfish like prawns, or oysters and seaweed in saltwater ponds.
Cascade effect (ecology)An ecological cascade effect is a series of secondary extinctions that are triggered by the primary extinction of a key species in an ecosystem. Secondary extinctions are likely to occur when the threatened species are: dependent on a few specific food sources, mutualistic (dependent on the key species in some way), or forced to coexist with an invasive species that is introduced to the ecosystem. Species introductions to a foreign ecosystem can often devastate entire communities, and even entire ecosystems.
Mesopredator release hypothesisThe mesopredator release hypothesis is an ecological theory used to describe the interrelated population dynamics between apex predators and mesopredators within an ecosystem, such that a collapsing population of the former results in dramatically increased populations of the latter. This hypothesis describes the phenomenon of trophic cascade in specific terrestrial communities. A mesopredator is a medium-sized, middle trophic level predator, which both preys and is preyed upon.
MesopredatorA Mesopredator is a predator which occupies a mid-ranking trophic level in a food web. There is no standard definition of a mesopredator, but they are usually referred to as being medium-sized, compared to apex predators and the preys in the food web. Mesopredators typically prey on smaller animals. Mesopredators vary in different ecosystems depending on the food web. When new species are introduced into an ecosystem, the role of the mesopredator often changes; the same happens if species are removed.
