Conservationists are trying hard to oceans and their inhabitants are not affected by the depletion of fish stocks. It should determine what types are at risk to a greater extent. However, on a global level such species are not yet defined. In terrestrial ecosystems most affected by anthropogenic factors are considered types of large predators and the top of the food chain. It was assumed that this rule applies to the fish fauna. However, a recent publication in PNAS (the official periodical of the National Academy of Sciences of the USA) indicates that this is not the case.
Malin Pinsky with a group of researchers analyzed two independent database of ichthyofauna in together describe five hundred seventy-eight species for more than sixty years, to find out what life history characteristics may be associated with a reduction in numbers. They took into account many of the features that are previously thought to be the cause of vulnerability to human activities in the oceans, including large body size, long maturation, greater life expectancy, low fertility, high parental involvement in the care of the offspring (large diameter eggs) and high trophic level (being at the top of the food chain).
Contrary to expectations, they found that the percentage reduction in the number of small fish low trophic level higher than the percentage reduction in the number of high trophic level predators almost doubled. They were not able to establish a connection between the decrease in the number and properties of biological cycles in any combination.
Small fish living near the surface, often grows rapidly and very easily produced, which is particularly increased risk of decline. They also may have a "fast" strategy biotsiklov makes people mistakenly suppose that they are less susceptible because of downsizing of fishing. Perhaps the difference in the response to anthropogenic interference between fish fauna and terrestrial species caused quite the catching mostly small fish because of the assumption that its population is more elastic than it actually is.
High birth rates and short life of one generation could also make these short-lived species are particularly sensitive to changes in environmental conditions. There are many such examples. Summer flounder (Paralichthys dentatus) and Spanish mackerel (Scomberomorus maculatus) — two short-lived species, whose numbers declined, herring (Clupea pallasii) — a small, fast-growing species, whose numbers declined. Winter flounder (Pseudopleuronectes americanus) and Japanese mackerel (Scomber japonicus) are other tasty species, found at the bottom of the food chain, the amount of which has also decreased.
In his book, "Four Fish," Paul Greenberg argues that we almost destroyed stocks of edible fish in the oceans, and in the end, we will have to limit the selection of diluted tuna, cod, sea bass and salmon. It is hoped that the information presented here like, change the way the fish fauna on a global scale, and we can continue to enjoy the gifts of the ocean without prejudice to him.