Ghost Gear Report - 17

GHOST GEAR
DANGERS FOR SEALS
AND SEA LIONS
The entanglement by plastic
pollution in the seas is a threat to
at least 243 marine species60. Most
of these entanglements appear to
be caused by monofilament lines,
ropes, and other fishing related
equipment61. Even though nets can
affect different species of marine
mammals, it appears that sea lions
and seals (scientifically known as
pinnipeds) are the most susceptible.
In Australia, for example, it is
estimated that 1,500 Australian
sea lions (Neophoca cinerea) die
annually from entanglement with
monofilament gillnets because of the
overlap between shark fisheries and
foraging sea lions62.
This susceptibility may be due to
their exploratory nature, especially
of juveniles when they play, or due to
their encounter with such debris on
the coast63. In a population of 30,000
Australian fur seals (Arctocephalus
pusillus doriferus) in Southern
Australia, 138 entanglements were
reported between1997 and 2012. 50%
of the entangling objects were plastic
twine or rope, which included trawl
nets, and 17% were monofilament
fishing lines that included gillnets.
Most of the entanglements (94%)
involved pups (53%) or juveniles
(41%)64.

As a natural panic reaction, these
animals rotate their bodies causing
more entanglement with fishing
gear and end up carrying it wrapped
around themselves for long periods.
Sea lions and seals entangled, or even
ingesting these marine debris items,
can experience sudden and serious
problems such as suffocation; or
"chronic" effects where the impacts
on the welfare of the species increase
over time as infections, injuries to
the skin and muscles, potentially
even leading to amputation of the
entangled limbs or even cutting to
the bone. It is known that, depending
on the material with which they have
been entangled, the impact differs;
for example, multifilament nets
may be more prone to harboring
bacteria, causing infections. In this
way, their ability to move, feed and,
in general, behave normally for their
species is compromised. In the case
of pregnant females, it can generate
complications such as edema,
reducing their potential for survival
and fertility65.
These estimates of animal
entanglements and ingestion rates
are based on the information
obtained from live or recently
dead animals, so are likely
underestimated. The number of
likely unobserved mortality of sea
lions and seals entangled in ghost
gear is unknown66.

17
Ghost Gear Report

Table of Contents for the Digital Edition of Ghost Gear Report
