Medidas de Gestao das Pescarias Marinhas e Aquicultura 2019 The State of World Fisheries and Aquaculture 2018 | 页面 57

THE STATE OF WORLD FISHERIES AND AQUACULTURE 2018
FIGURE 15
PERCENTAGES OF STOCKS FISHED AT BIOLOGICALLY SUSTAINABLE AND UNSUSTAINABLE LEVELS
BY FAO STATISTICAL AREA, 2015
Mediterranean and Black Sea
Pacific, Southeast
Atlantic, Southwest
Tunas
Atlantic, Eastern Central
Atlantic, Western Central
Indian Ocean, Western
Atlantic, Southeast
Indian Ocean, Eastern
Atlantic, Northeast
Atlantic, Northwest
Pacific, Southwest
Pacific, Western Central
Pacific, Northwest
Pacific, Northeast
Pacific, Eastern Central
0
20
40
60
80
100
PERCENTAGE
Biologically sustainable
Biologically unsustainable
NOTE: Tuna stocks are singled out as they are largely migratory and straddling across statistical areas.
harengus), Atlantic cod (Gadus morhua), Pacific
chub mackerel (Scomber japonicus), Chilean jack
mackerel (Trachurus murphyi), Japanese pilchard
(Sardinops melanostictus), skipjack tuna
(Katsuwonus pelamis), South American pilchard
(Sardinops sagax) and capelin (Mallotus villosus),
77.4 percent of stocks were fished within
biologically sustainable levels in 2015 – better
than the average for all stocks, which may reflect
the fact that large fisheries attract greater
attention in policy-making and management
implementation. Of these ten species, Chilean jack
mackerel, Atlantic cod and capelin had higher
than average proportions of overfished stocks.
The first group had the highest proportion of
biologically sustainable stocks (72.6 percent), in
comparison with the second group (67.0 percent)
and the third group (62.8 percent).
Linking the catch pattern with stock status is not
straightforward. In general, an increasing trend
in catch usually suggests an improving stock
status or an expansion in fishing intensit y,
whereas a decreasing trend is more likely to be
associated with declines in abundance or with
management measures that are either
precautionar y or aimed at rebuilding stocks.
However, many other factors may also contribute
to a decreasing catch, such as environmental
changes and market conditions.
Tunas are of great importance because of their
high economic value and extensive international
trade, and their sustainable management is
subject to great challenges owing to their highly
migrator y and often straddling distributions.
Total landings of the principal market tuna
species – albacore (Thunnus alalunga), bigeye
(Thunnus obesus), bluefin (Thunnus thynnus,
Status and trends by major species
Productivity and stock status also vary greatly
among species. For the ten species that had the
largest landings between 1950 and 2015, including
anchoveta (Engraulis ringens), Alaska pollock
(Theragra chalcogramma), Atlantic herring (Clupea
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