examples. Perhaps the best case study was the near removal of the blue, fin and other
krill-eating whales around Antarctica in the 1960s and 1970s. We have no direct
evidence that krill increased, but crab-eater seals, penguins, and other populations of
krill-eating animals doubled and redoubled. Such rearrangements of food webs
probably always occur when large stocks are heavily exploited, we just don’t generate
the data to see them.
(^) Overall levels of exploitation of fishery stocks and the degree and significance of
habitat modification by fishing activity are currently areas of active study and intense
dispute. There is no question that the fauna of the modern ocean, at least above the
bathypelagic and abyssal plains is substantially different from what it was (whatever it
was) before industrial fishing. Even the very first fishing industries modified ocean
biota. An excellent review of the historical development of fisheries was provided by
Callum Roberts in The Unnatural History of the Sea (2007), and Anthony Koslow in
The Silent Deep (2007) has covered the more recent effects of trawling in very deep
habitats, particularly the destruction of rich soft-coral communities on seamounts in
the hunt for orange roughy and other long-lived fish. Orange roughy were rapidly
fished to “commercial extinction”. Roberts shows that 17th- to 19th-century whaling
generated all but permanent endangered-species status for the right whales and sperm
whales, although the latter may finally be coming back. Those devastations were
accomplished from sailing ships by launching rowing boats armed with hand-thrown
harpoons. Virtually no tropical islands have their former assemblage of large
carnivorous fish, particularly groupers (Serranidae) and snappers (Lutjanidae). Those
have mostly been fished out by sport and artisanal fishers, and sometimes by large-
scale attacks with rotenone or explosives. Rosenberg et al. (2005) have roughly
reconstructed from boat logs and other data a history of the New England and Scotian
shelf cod stocks. They put biomass of the lightly fished stock of 1852 at 1.26 × 10^6
Mt. Industrial fishing and habitat damage in the middle to late 20th century reduced
that to “less than 5 × 10^4 Mt today”. Recovery has not been obvious during a near
moratorium on cod fishing (they still are taken as bycatch) since 1994. There are too
many such sad tales to recount here.
(^) Prominent in the recent controversies was a paper by Ransom Myers and Boris
Worm (2003), based partly on the development of the Japanese long-line fishery for
tuna and billfish after World War II. Excellent records were kept for this fishery as it
expanded east from Japan into the Pacific and eventually across the world, and a time-
series of contour maps of its catches per unit effort show high initial catches at the
leading edge of the expansion, followed by progressive declines that finally are
global. On the basis of CPUE (catch per 100 hooks fished; Fig. 17.23) trends for
oceanic areas, Myers and Worm (2003) estimated that residual stocks are ∼10% of
their mid-20th-century size for this overall species mix. Criticism followed quickly.
For example, Maunder et al. (2006, discussed above) strongly criticized use of CPUE