In an article in that issue, PFEG Oceanographer George Boehlert described the relationship of biodiversity and marine fisheries. This suggests that the fishing up process is occurring on a worldwide basis.
Marine fisheries cause changes at three levels of organization of biodiversity.
At the genetic level, fisheries increase mortality and act as an agent of directional selection, affecting age distribution, age and length at maturity, and growth rates, among other life history characteristics. Of particular concern are genetic effects induced by marine aquaculture and ocean ranching, where fish husbandry and large scale releases decrease genetic diversity, selecting for particular traits that may not be best suited to long-term environmental variability. At the species level, fisheries affect species composition in fished ecosystems and consequently interactions among fished species and their prey. Direct effects of fishing on species diversity are caused by removals of target species, by-catch of unwanted species, physical disturbance, and discards. Fisheries often begin on large predators and decreased populations may lead to increased abundance of prey species, which may themselves become subject to fisheries.