Fisheries - Enviro Dynamics Namibia

F I S H E R I E S , M A M M A L S A N D S E A B I R D S S P E C I A L I S T S T U D Y
As such direct impacts on non-target species are unlikely to occur. Rather it is the potential for
the fishery to increase mortality on an
already depleted target resource that is the
main concern. Small pelagic species (sardine,
horse mackerel, bearded gobies are an
important link in marine food webs (Cury et
al. 2000) and reductions in their abundance
can have negative impacts on ecosystem
structure and functioning (Crawford et al.
1985, Crawford et al. 1987, Boyer and
Hampton 2001b).
3.5 DEMERSAL LONG-LINE FISHERY
Final Report
Namibian Marine Phosphate (Pty) Ltd.
Page 28
Figure 14. Typical gear configuration of a pelagic
purse seine vessel targeting small pelagic species
Like the demersal trawl fishery the target
species of this fishery is the Cape hakes, with a small non-targeted commercial by-catch that
includes kingklip. The catch landed is predominantly prime quality (PQ) hake for export to Europe.
The catch is packed unfrozen on ice – the fresh product is approximately 50% higher than that of
trawled hake. Longline vessels fish in similar areas targeted by the hake-directed trawling fleet, in
a broad area extending from the 300 m to 600 m contour along the full length of the Namibian
coastline. Approximately 18 boats are currently (2011) operating primarily in three broad areas.
Vessels based in Lüderitz work south of 26°S towards the South Africa border while those based
in Walvis Bay operate between 23°S and 26°S and north of 23°S. Operations are ad hoc and
intermittent, subject to market demand. A total hake TAC of 131,780 tonnes was set for 2011 but
less than 10,000 tonnes of this is caught by long-line vessels.
A demersal long-line vessel may deploy either a double or single line which is weighted along its
length to keep it close to the seafloor (Figure 15). Steel anchors, of 40 to 60 kg are placed at the
ends of each line. These anchor positions are marked with an array of floats. Lines are typically 20
– 30 nautical miles in length. Baited hooks are attached to the bottom line at regular intervals (1
to 1.5 m) by means of a snood. Gear is usually set at night at a speed of 5 – 9 knots. Once
deployed the line is left to soak for up to eight hours before it is retrieved. A line hauler is used to
retrieve gear (at a speed of approximately 1 knot) and can take six to ten hours to complete.
During hauling operations the vessel’s manoeuvrability is severely restricted.