The Ecology Book

267

See also: A holistic view of Earth 210–211 ■ Pollution 230–235 ■ Human

devastation of Earth 299 ■ Sustainable Biosphere Initiative 322–323

jobs. For 500 years, the cod fishery

had supported Maritime residents,

particularly in Newfoundland.

The 1992 moratorium was

initially supposed to last only two

years, but, with the stocks not yet

recovered, it is still largely in place.

From around 2005 to 2015, the

volume of northern cod rose by

about 30 percent each year along

Newfoundland’s northeast coast,

although stocks further south did

not recover as fast. In 2017 and

2018, however, cod numbers

declined sharply, and the overall

stocks are still too low to support

large-scale fishing. Climate change

has contributed to the problem:

higher temperatures have created

THE HUMAN FACTOR

conditions in which both the cod

and its food sources struggle to

survive. A further blow to

Newfoundland’s fishermen—who

largely turned to catching shrimp

and crab—is that where cod

numbers improved, cod began

eating the shrimp. The ecosystem

cannot support both a large-scale

shrimp and crustacean industry,

and large-scale cod fishing.

A sustainable harvest

The Newfoundland problem

demonstrates the complexities of

fishery management, which often

relies on the concept of maximum

sustainable yield: the volume of fish

harvested from the sea should be ❯❯

Trawlers catch too many fish

Fish stocks decline or become unsustainable

Large predator

fish

Changes balance

of species in

ecosystem

Mature fish

Loss of breeding

stock

Immature fish

Do not live to

reproduce

Solution:

Set quotas and/

or institute

moratoriums

Solution:

Institute lengthy

moratoriums

Solution:

Set minimum

size limits

Marine reserves

A promising tool for fish

management is the creation of

marine protected areas

(MPAs), which legally protect

fish stocks and ecosystems.

MPAs cover around 3.5

percent of the world’s oceans,

but only 1.6 percent of MPAs

are the strongest “no-take

zones” where fishing,

extraction of materials,

dumping, drilling, and

dredging are banned. One

meta-analysis of scientific

studies showed that the

volume of fish species is on

average 670 percent greater

in fully protected “no-take”

marine reserves than in areas

that have no protection, and

343 percent greater than in

partially protected MPAs.

No-take zones effectively

preserve and restore damaged

ecosystems, too; coral reefs in

protected zones of the Pacific

Line Islands recovered from an

El Niño event within a decade,

but those in unprotected areas

did not. Some studies suggest

that legally enforced reserves

may even help replenish

fisheries outside their borders.

Bigeye trevallies are among the

many species in the Malpelo Fauna

and Flora Sanctuary, the biggest

no-fishing zone in the Eastern

Tropical Pacific, noted for its sharks.

US_266-269_Overfishing.indd 267 17/12/2018 14:34