From BBC News Online and other sources

   The demand for seafood has allowed commercial fishing to decimate the population of every large fish species. Onboard refrigeration and longline fishing are extremely effective methods of providing a great number of deep-water fish to supply the international demand. In 15 years of longline commercial fishing off the coast of Brazil, the Japanese harvested 200,000 bluefin tuna the first season and zero the last. Statistics indicate that we are killing fish much faster than they are capable of reproducing. Scientists have determined that in order to survive a species cannot tolerate more than 50% reduction in its population. It has also been determined that size of large predatory fish presently caught is only one-fifth to one-half the size of their ancestors indicating that most fish harvested never reach reproduction capability. Scientists suggest the creation of no-fishing zones to provide nurseries for the fished areas surrounding them.