increase fishery production. However, it does not pay to say that a ceiling has been
reached; leave it to the Japanese fishing masters to find more edible stocks. Mid-water
squid populations might be a resource with some potential, if efficient means of
capture can be devised. At present, jigging under night-lights for species that migrate
to the surface in the dark is the only effective capture method. Japanese vessels
fishing worldwide obtain large takes with automated jigging gear. Returns to trawling
at depth are not large enough to make it economical. Antarctic krill (Euphausia
superba) are a resource with potential to produce 50 to 200 Mt per year, and the
Japanese, West Germans, and Eastern Bloc nations tried for a while to develop that
fishery. However, a decade of research and preliminary commercial development
brought the 1982 catch to 0.53 Mt, and it has been less in all years since, e.g. 0.016
Mt in 2008 (not among the top 69 species on the world list). The stock is in the most
remote region of the world ocean, fuel costs for exploitation are extreme, and efforts
to make krill palatable to people are only marginally successful. Processing is
difficult, since the digestive glands of the animals tend to break, spilling enzymes into
the tissue which digest it and make it rot almost instantly. Very rapid, specialized
preservation methods are required to produce a usable product. As a consequence of
these difficulties, krill have not been very promising compared to alternative
investments.
(^) Pauly et al. (1998) have shown that we are progressively moving closer to the base
of the food chain in our exploitation, which they characterize as “fishing down the
food chain”. They argue that we are reducing stocks of higher-trophic-level fish (e.g.
cod, tuna, swordfish) and moving more and more effort to planktivorous fish
(pilchards, anchoveta, etc.). It is arguable whether placing our take at higher or lower
trophic levels is the best strategy for fishery exploitation, but it is very likely that the
trend does not represent a strategy. It simply reflects (i) the recurring reduction in
stocks of the predatory fish favored at the table, as noted by Pauly et al., but just as
important is (ii) the recurring resurgence and exploitation of forage fish stocks,
particularly the Peruvian anchoveta. At times the “mean trophic level” statistic used
actually moves up. That occurs when the anchoveta or similar stocks collapse. The
overall changes are a small fraction of one trophic level and probably do not mean
much.
Ecological Impacts
(^) Pollution and fishing impose the largest impacts of human activity on marine
environments. The obvious impact of fishing is removal of fish, which disrupts food
chains directly by removing biomass from populations of the larger animals. There
must be “top-down” effects from removing predators, freeing prey stocks to increase,
then to over-exploit their own food sources. There are relatively few documented