Overfishing--It Is Selective!

Research on overfishing has largely focused on target species. The status and roles of the entire fish community have received little consideration in the debate of overfishing. Fishing by nature is always selective. Among more than 30,000 fish species, only a small proportion is targeted and an even smaller proportion overfished. The classical recruitment overfishing (catch too many spawners), growth overfishing (catch fish before they reach their critical age), and ecological overfishing (catch certain groups), are all selective overfishing. Biomass of large fish, top predators, or highly-valued species have declined more than that of smaller fish, forage species, or species with low economic value. If we take all fish species into consideration, the overall fishing mortality is likely to be less than 0.05 per year in the ocean. If this current global fishing mortality is redistributed proportionally to each species’ natural productivity, all species should be able to sustain such a fair pressure and overfishing may not occur to any one. We conducted sustainability assessment for fishing effect on hundreds of bycatch species and found that overfishing may occur to only a few vulnerable non-target species, but a large proportion of target species suffer high fishing pressure. The basic goals of fishery management aim to reduce impact on 1) biodiversity and 2) sustainability of fisheries. This requires distributing fishing pressure across a wider range of ecological groups in proportion to their productivity. Finding ways to utilize components that currently have low value to our society is the key to solve overfishing while meeting an increased demand for food and protein.