Medidas de Gestao das Pescarias Marinhas e Aquicultura 2019 The State of World Fisheries and Aquaculture 2018 | Page 67

THE STATE OF WORLD FISHERIES AND AQUACULTURE 2018
developed into an important industr y, with a
growing focus on their handling in a controlled,
safe and hygienic way. Fish by-products are
usually only placed on the market after further
processing because of consumer preferences and
sanitar y reg ulations, which may also govern their
collection, transport, storage, handling,
processing, use and disposal.
associated price variation, many researchers are
seeking alternative sources of PUFAs, including
large marine zooplankton stocks such as
Antarctic krill (Euphausia superba) and the
copepod Calanus finmarchicus, although concerns
remain over the impacts for marine food webs.
However, the cost of zooplankton products is too
high for their inclusion as a general oil or protein
ingredient in fish feed. Krill oil in particular is
destined for products for direct human
consumption. Krill meal is finding a niche in
production of certain aquafeeds.
Fish by-products can ser ve a wide range of
purposes. Heads, frames and fillet cut-offs and
skin can be used directly as food or processed
into fish sausages, cakes, snacks (crispy snacks,
nuggets, biscuits, pies), gelatin, sauces and other
products for human consumption. Small fish
bones, with a minimum amount of meat, are
consumed as snacks in some Asian countries.
By-products are also used in the production of
feed (not only in the form of fishmeal and fish
oil), biodiesel and biogas, dietetic products
(chitosan), pharmaceuticals (including oils),
natural pigments, cosmetics and constituents in
other industrial processes. Some by-products, in
particular viscera, are highly perishable and
should therefore be processed while still fresh.
Fish viscera and frames are a source of potential
value-added products such as bioactive peptides
for use in food supplements and in biomedical
and nutraceutical industries (Senevirathne and
Kim, 2012). Shark by-products (cartilage, but also
ovaries, brain, skin and stomach) are used in
many pharmaceutical preparations and reduced
to powder, creams and capsules. Fish collagens
are used in cosmetics and in extraction of gelatin.
Fishmeal and fish oil are still considered the most
nutritious and most digestible ingredients for
farmed fish feeds, but their inclusion rates in
compound feeds for aquaculture have shown a
clear downward trend, largely as a result of
supply and price variation. They are increasingly
used selectively, for example for specific stages of
production, particularly for hatcher y, broodstock
and finishing diets. Their incorporation in grower
diets has decreased over time. For example, their
share in grower diets for farmed Atlantic salmon
is now often less than 10 percent.
Fish silage (Kim and Mendis, 2006), a rich source
of protein hydrolysate, is a less expensive
alternative to fishmeal and fish oil and is
increasingly important as a feed additive, for
example in aquaculture and in the pet food
industry. Obtained by preserving whole fish or
fish by-products with an acid and letting enzymes
from the fish hydrolyse the proteins, silage has
potential to increase growth and reduce mortality
of animals that receive it in their feed.
The internal organs of fish are an excellent source
of specialized enzymes. A range of proteolytic
fish enzymes are extracted, e.g. pepsin, tr ypsin,
chymotr ypsin, collagenases and lipases. Protease,
for example, is a digestive enzyme used in the
manufacture of cleaning products, in food
processing and in biological research. Fish bones,
in addition to being a source of collagen and
gelatin, are also an excellent source of calcium
and other minerals such as phosphorus, which
can be used in food, feed or food supplements.
Calcium phosphates present in fish bone, such as
hydrox yapatite, can help hasten bone repair after
major trauma or surger y. Fish skin, in particular
from larger fish, provides gelatin as well as
leather for use in clothing, shoes, handbags,
wallets, belts and other items. Species commonly
The expansion of fish processing is creating
increasing quantities of offal and other
by-products, which may constitute up to 70
percent of fish used in industrial processing
(Olsen, Toppe and Karunasagar, 2014). In the
past, fish by-products were often thrown away as
waste; used directly as feed for aquaculture,
livestock, pets or animals reared for fur
production; or used in silage and fertilizers.
However, other uses of fish by-products have
been gaining attention over the past two decades,
as they can represent a significant source of
nutrition and can now be used more efficiently as
a result of improved processing technologies. In
some countries, the use of fish by-products has
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