worldwide web: ftp://ftp.fao.org/FI/STAT/SUMM_TAB.HTM.
(^) You should check these sources in addition to the summaries below, since it is best
to inform yourself about the status of fisheries with up-to-date results. Even data for
years well past are often updated as new reports are received at the FAO from
fisheries agencies around the world. For a second opinion on global fisheries status,
see Garcia and Rosenberg (2010).
(^) We (the people) fish harder and harder all the time. Whether or not the overall
fishery production of the oceans is sustainable remains to be seen (Box 17.1). In about
1973 total production of all marine fisheries stopped increasing at the dramatic quasi-
exponential rate, about 6% per year, which had persisted since World War II (Plate
17.1). The last phase of growth at that rate was sustained by development of the
Peruvian anchoveta fishery, which peaked around 12 Mt. This temporary ceiling was
reached in the 1970s with surprising suddenness as the Peruvian anchoveta fishery
crashed in 1972. For a time after 1973, the world total stayed close to 65 Mt live
weight, perhaps increasing at an unsteady 1% per year. Continued growth of demersal
(near-bottom) fisheries held the total up during the 1970s. This latter phase was
accompanied by substantial investment in large, world-ranging trawlers. However,
that came to an end in 1978 as the industrial fishing nations (most importantly Japan
and the USSR) stretched the world demersal resources to their limit.
Box 17.1 Potential fishery production
(^) Several workers (Ryther 1969; Pauly & Christensen 1995) have supposed that it should be possible to
predict the rate at which fisheries can remove biomass from the sea by combining a global estimate of
primary production with a simple ecological calculation. They approximate the trophic level (T) of
“fish” taken by fisheries, apply a general ecological efficiency at each food-chain step leading to T;
take account of the need to leave much new biomass in the ocean to support the health and
reproduction of stocks; then provide a final estimate by appropriate multiplications. Current estimates
of global primary production are approximately 44 GtC per year (Behrenfeld & Falkowski 1997).
More productive coastal areas might be roughly 10% of ocean area, but they produce about 50% of
fishery output. They also have relatively short food chains with much fishery production from the
third and fourth trophic levels, so perhaps T ≈ 3.5. The remaining seas are more oligotrophic, and
food chains are longer, with fishery production at perhaps T ≈ 5.5.
(^) Ecological efficiency, EE, the fraction of its production that one tropic level transfers on average to
its predators, is in fact extremely difficult to estimate. Of course, the value is constrained: it cannot be
zero, and it cannot be greater than typical lifetime growth efficiency, that is, (tissue formed)/(food
eaten). For many marine animals, growth efficiency is quite high, especially for juveniles, perhaps
30%. Ecological efficiencies are less, since only transfers “upward” to higher-order predators count,
not “losses” to the decomposer trophic level. So, like Ryther and all other practitioners of these
predictions, let us guess. As a start, let EE ≈ 20%.
(^) Expressing the model as an equation and leaving two-thirds of production for stock maintenance (not
a strongly prudent number, actually), we have:
(^) This must be converted from carbon to “fish”. Using reasonable, approximate factors (carbon/dry