6.4.1 Bycatch Solutions
Currently there is no solution available to harvest ghost
nets weighing several hundred kilograms while simultaneously
locking out vertebrates larger than ~50 cm, and
therefore vertebrates must be deterred from the platform
in a different way. In the past, a scientific approach was
taken to bycatch reduction in commercial fisheries. This
has resulted in the use of nets fitted with turtle exclusion
devices (TEDs), acoustic devices (“pingers”), and changes
in hooks and bait, resulting in significant bycatch reduction
(Table 6.4) (Cox et al., 2007). Other means might be
effective as well (Southwood, Fritsches, Brill, & Swimmer,
2008).
Accidental bycatch of marine vertebrates by The Ocean
Cleanup Array might be reduced in the same way. Bycatch
reducing devices (BRDs) are mostly used to deter a specific
species of fish, mammal, or bird. Because a variety
of animals is expected to accumulate in front of the platform,
the BRDs should incorporate an equal variety in
signals used to repel these animals, with an emphasis on
repelling the species listed in the ESA. Companies such
as SaveWave, that provide custom solutions for ecologic
problems, will be employed to reduce vertebrate bycatch.
Since impact of the Array cannot be predicted based on
small scale testing, more options to reduce as much as
possible bycatch will be investigated in large scale testing
during Phase II.
Mooring
The Ocean Cleanup Array will be moored to the ocean
floor by Stevmanta VLA anchors from the company Vryhof
Anchors. These anchors are designed to penetrate the
ocean floor and cause minor disturbance to environment.
On removal of the Array, these anchors can be extracted
from the ocean floor. As a result, no significant ecologic
impact is expected from the mooring.