Medidas de Gestao das Pescarias Marinhas e Aquicultura 2019 The State of World Fisheries and Aquaculture 2018 | Page 195

THE STATE OF WORLD FISHERIES AND AQUACULTURE 2018
FIGURE 47
BLOCKCHAIN TECHNOLOGY
Blockchain:
how it
works
Blockchain allows for the
secure management of a
shared ledger, where
transactions are verified and
stored on a network.
Cryptographic hash functions
protect the blockchain’s
integrity and anonymity.
PENDING
1
TRANSACTION
Two parties exchange data, for example
catch-related data (species, tonnes, catch
methods, storage and money).
2
VERIFICATION
Depending on the network’s
parameters, the transaction is either
verified instantly or transcribed into a
secured record and placed in a queue of
pending transactions, which are
validated based on a set of rules agreed
to by the network members.
BLOCK N
3
BLOCK N-1
BLOCK N-2
STRUCTURE
Each block is identified by a hash, a 256-bit
number, created using an algorithm agreed
upon by the network, which includes a
reference to the previous block’s hash and
a group of transactions.
BLOCK N
BLOCK N
4
VALIDATION
Blocks must be validated first to be
added to the blockchain, usually
through proof of work – the solution
to a mathematical puzzle derived
from the blockchain through
blockchain mining.
5
BLOCKCHAIN MINING
Incremental changes are made to
one variable in the block until the
solution satisfies a network-wide
target. The correct answers cannot
be falsified.
6
THE CHAIN
When a block is validated, the miners
are rewarded and the block is
distributed through the network.
7
BUILT-IN DEFENCE
If an altered block is submitted to the chain,
the hash function of that block and all
following blocks will change. Other nodes
will detect these changes and reject the
block, preventing corruption along the chain.
SOURCE: Adapted from Piscini et al., 2018
The use of disruptive technologies in fisheries
and aquaculture may not be widespread now, but
a look at three disruptive technologies that were
not on the sector’s horizon a few years ago –
blockchains, sensors and automatic identification
systems (AIS) – demonstrates the potential of
disruptive technolog y to change the processes,
profitabilit y and sustainabilit y of the sector.
lands in the consumer’s hand in real time
(Figure 47). The product’s activity is recorded as a
block of information, with a unique time-stamp
alphanumeric code that is accessible by all of the
parties in the value chain. The ledger distributes
the information (in blocks), but the information
cannot be changed. The record of the transactions
along the chain is in the form of an incorruptible
ledger which can record all or part of the
information associated with the transactions.
Blockchains
The interlinked system of blocks of information
avoids vast record-keeping as well as complicated
and time-consuming reconciliation of
information. Since the information is distributed,
A blockchain is an information technolog y that
acts as a shared ledger for digital storage and
tracking of data associated with a product or
service, from the raw production stage until it
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