income, the per capita consumption has reached 31.9 kg
per annum. While the production of fisheries and aquaculture has varied considerably between geographical
regions, shellfish production in many areas has remained
steady. A declining global marine catch over the last few
years and the increased percentage of overexploited species have led to both negative ecological effects and ongoing negative social and economic consequences. For many
years, China has been the world’s leading shellfish and
fish exporter, but some countries, such as Vietnam, have
experienced rapid growth. Vietnam is now the fourth largest exporter in the world. The largest importers are the
USA and Japan. In many parts of the world, fisheries production is small scale and susceptible to fluctuations. New
guidelines are being developed to promote good
governance as well as inclusiveness, transparency, gender
equality, and respect and involvement of stakeholders.
World fisheries production statistics are divided into
wild capture and aquaculture, with further divisions into
inland and marine production. Using these divisions, it is
often difficult to identify and single out the brackish water
production in estuaries. Data for mussels, clams, cockles,
and scallops are included in the marine–water aquaculture
group, where in 2010 they comprised 75.5 % of the total
catch, down from 84.6 % in 1980. After 1980, there was
an increase in finfish culture which continued to increase
at a rate of seven times that of molluscs. Brackish water
aquaculture, however, has increased over the past 20 years,
and while only contributing 7.9 % of the world production
in terms of quantity, it corresponds to 12.8 % of the total
value because of the high value of marine shrimps
cultured in brackish ponds. Brackish water crustaceans
dominate aquaculture production with bivalves making
up only a small percentage (2.1 %) of the total (FAO data
in 2010). The aquaculture statistics for 2010 are impressive: 2.7 million tons of white leg shrimp; 4.8 million tons
of clams, cockles, and arc shells; 4.5 million tons of oysters; and more than 1.5 million tons of mussels and scallops. The question is – are these production rates
sustainable?
Catch and aquaculture trends
Over the last 20 years, changes have occurred in catch
statistical trends for marine bivalve species. Clams and
cockles once formed more than half of the annual capture
catch (Figure 6; FAO, 2012), but more recently they have
been equalled by scallops, where the most productive fisheries are in coastal offshore habitats rather than estuaries.
In estuaries, the production of mussels and oysters appears
to have remained steady or even have declined over the
past 10 years; however, there appears to be increased
scope for future expansion. There is, however, some
uncertainty with the FAO database; not all countries
identify catches by species, and aquaculture numbers
may not be distinguished from capture fisheries.
Global aquaculture production has increased since
1990, although at a slower rate than was recorded in the
1980s and 1990s, with Asia contributing 89 % of the
world aquaculture production in 2010. In Europe,
increased aquaculture production has been due to cage
culture of salmon, with notable declines in bivalves from
61 % of the total in 1980 to 26.2 % in 2010. In North
America, bivalve production appears to be declining,
whereas in South America, Brazil, and Peru, there has
been strong growth. This increase in bivalve production
may be due to the formation of the non-fed aquaculture
systems, which avoid the problems associated with feed.
Shellfish species in estuaries
Broadly defined, shellfish are edible invertebrates usually
molluscs, crustaceans, or echinoderms. While mussels,
oysters, scallops, clams, lobsters, and shrimps are wellknown shellfish, less recognized groups include sea
urchins, sea cucumbers, abalone, and whelks. All have
a hard external covering, a shell or exoskeleton which protects them from extremes of environment and/or predators. Shellfish species that live or are cultured in
estuaries are generally euryhaline or salt tolerant, the main
groups being mussels, oysters, clams, and shrimps. These
are further divided into capture species that are harvested
from natural populations and aquaculture species grown
in shallow embayments or brackish water ponds. Even
with the increasing expansion of aquaculture, wild
populations remain important in many parts of the world.
Bivalves are a traditional food for many people.
Collecting methods have changed over the years,
combining traditional methods with new technology.
The collection and aquaculture methods for bivalves are
summarized by Gosling (2003); wild shellfish are collected by hand, dredges, and metal baskets, but in deeper
water they are collected by diving or in small boats.
Mussel and clam production is often higher in estuaries
than in the open sea, but this may be a consequence of
increased food availability or food quality rather than
a direct salinity effect (Seed and Suchanek, 1992). Production from a biological and/or ecological viewpoint
requires knowledge of the life history of species; this is
because it depends on population regulating mechanisms,
including recruitment, growth, and reproduction.
Capture species
Oyster fisheries have a long history; for example, the flat
oyster Ostrea edulis in Europe and the American oyster
Crassostrea virginica in the USA are the species which
contributed most to the commercial harvest. There have
been declines in these species over time (Gosling, 2003),
and they now make up only a small percentage of the oyster landing from aquaculture (FAO data). Numerous species of mussels are consumed worldwide; many belong
to the genera Mytilus and Perna. The extent of the wild
fishery is uncertain because, even where this is claimed,
there may be enhancement by transferring seed from natural habitats onto culture beds for ongrowing. Countries
that identify wild mussel catches include the Netherlands,
574
SHELLFISH PRODUCTION
per annum. While the production of fisheries and aquaculture has varied considerably between geographical
regions, shellfish production in many areas has remained
steady. A declining global marine catch over the last few
years and the increased percentage of overexploited species have led to both negative ecological effects and ongoing negative social and economic consequences. For many
years, China has been the world’s leading shellfish and
fish exporter, but some countries, such as Vietnam, have
experienced rapid growth. Vietnam is now the fourth largest exporter in the world. The largest importers are the
USA and Japan. In many parts of the world, fisheries production is small scale and susceptible to fluctuations. New
guidelines are being developed to promote good
governance as well as inclusiveness, transparency, gender
equality, and respect and involvement of stakeholders.
World fisheries production statistics are divided into
wild capture and aquaculture, with further divisions into
inland and marine production. Using these divisions, it is
often difficult to identify and single out the brackish water
production in estuaries. Data for mussels, clams, cockles,
and scallops are included in the marine–water aquaculture
group, where in 2010 they comprised 75.5 % of the total
catch, down from 84.6 % in 1980. After 1980, there was
an increase in finfish culture which continued to increase
at a rate of seven times that of molluscs. Brackish water
aquaculture, however, has increased over the past 20 years,
and while only contributing 7.9 % of the world production
in terms of quantity, it corresponds to 12.8 % of the total
value because of the high value of marine shrimps
cultured in brackish ponds. Brackish water crustaceans
dominate aquaculture production with bivalves making
up only a small percentage (2.1 %) of the total (FAO data
in 2010). The aquaculture statistics for 2010 are impressive: 2.7 million tons of white leg shrimp; 4.8 million tons
of clams, cockles, and arc shells; 4.5 million tons of oysters; and more than 1.5 million tons of mussels and scallops. The question is – are these production rates
sustainable?
Catch and aquaculture trends
Over the last 20 years, changes have occurred in catch
statistical trends for marine bivalve species. Clams and
cockles once formed more than half of the annual capture
catch (Figure 6; FAO, 2012), but more recently they have
been equalled by scallops, where the most productive fisheries are in coastal offshore habitats rather than estuaries.
In estuaries, the production of mussels and oysters appears
to have remained steady or even have declined over the
past 10 years; however, there appears to be increased
scope for future expansion. There is, however, some
uncertainty with the FAO database; not all countries
identify catches by species, and aquaculture numbers
may not be distinguished from capture fisheries.
Global aquaculture production has increased since
1990, although at a slower rate than was recorded in the
1980s and 1990s, with Asia contributing 89 % of the
world aquaculture production in 2010. In Europe,
increased aquaculture production has been due to cage
culture of salmon, with notable declines in bivalves from
61 % of the total in 1980 to 26.2 % in 2010. In North
America, bivalve production appears to be declining,
whereas in South America, Brazil, and Peru, there has
been strong growth. This increase in bivalve production
may be due to the formation of the non-fed aquaculture
systems, which avoid the problems associated with feed.
Shellfish species in estuaries
Broadly defined, shellfish are edible invertebrates usually
molluscs, crustaceans, or echinoderms. While mussels,
oysters, scallops, clams, lobsters, and shrimps are wellknown shellfish, less recognized groups include sea
urchins, sea cucumbers, abalone, and whelks. All have
a hard external covering, a shell or exoskeleton which protects them from extremes of environment and/or predators. Shellfish species that live or are cultured in
estuaries are generally euryhaline or salt tolerant, the main
groups being mussels, oysters, clams, and shrimps. These
are further divided into capture species that are harvested
from natural populations and aquaculture species grown
in shallow embayments or brackish water ponds. Even
with the increasing expansion of aquaculture, wild
populations remain important in many parts of the world.
Bivalves are a traditional food for many people.
Collecting methods have changed over the years,
combining traditional methods with new technology.
The collection and aquaculture methods for bivalves are
summarized by Gosling (2003); wild shellfish are collected by hand, dredges, and metal baskets, but in deeper
water they are collected by diving or in small boats.
Mussel and clam production is often higher in estuaries
than in the open sea, but this may be a consequence of
increased food availability or food quality rather than
a direct salinity effect (Seed and Suchanek, 1992). Production from a biological and/or ecological viewpoint
requires knowledge of the life history of species; this is
because it depends on population regulating mechanisms,
including recruitment, growth, and reproduction.
Capture species
Oyster fisheries have a long history; for example, the flat
oyster Ostrea edulis in Europe and the American oyster
Crassostrea virginica in the USA are the species which
contributed most to the commercial harvest. There have
been declines in these species over time (Gosling, 2003),
and they now make up only a small percentage of the oyster landing from aquaculture (FAO data). Numerous species of mussels are consumed worldwide; many belong
to the genera Mytilus and Perna. The extent of the wild
fishery is uncertain because, even where this is claimed,
there may be enhancement by transferring seed from natural habitats onto culture beds for ongrowing. Countries
that identify wild mussel catches include the Netherlands,
574
SHELLFISH PRODUCTION