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
is expected at the dredging location. Both the displacement and mortality of this species will have
a moderate impact on the whole ecosystem in the MLA only.
Sole : (Figures 35 and 36) – Similar to monk, sole are a sedentary species preferring muddy
substrate. They feed on polychaetes and other worms and fauna in the substrate. Their
distribution is throughout the MLA and extending into the adjacent zone. Dredging operations
will have a significant impact on sole abundance due to localise mortality. Some displacement of
sole to adjacent areas away from the mining is expected. This localised impact will be long-term
(at least 15 years) due to the removal of the preferred substrate of sole.
Orange roughy : (Figures 37 and 38) – Orange roughy are only found in deeper waters and well
outside of the MLA. No impact on the ecosystem is expected.
Table 4. Impact assessment table of phosphate mining on the ecosystem
Nature of the
impact
Extent
Duration
Intensity
Probability
Status (+ or -) Negative
Significance
(no mitigation)
Mitigation
Significance
(with
mitigation)
Confidence
level
The impact of phosphate mining on the ecologically important demersal and pelagic fish
species. The impact will result in the redistribution and/or displacement of hake, monk,
horse mackerel, sole, orange roughy, bearded goby populations and small pelagics because
of 1) actual mining activities due to dredging operations and vessel activities 2) habitat
disturbances and the removal of substrate and 3) sediment plumes (turbidity)
MLA - demersal and pelagic fish species will be displaced or redistributed from inside the
MLA and possibly from the surrounding areas into Zone 1.
Permanent (>20 yrs) - the impact will cease once the mining activity ends after 20 years
(the period for which the mining licence is issued) however fish recovery is expected to
occur sooner
Moderate effects - only a small fraction (compared to the regional extent) of fish inhabit
the MLA and fish populations will recovery or settle in areas after mining operations ceases
however habitat destruction may cause a longer period of recovery particularly for monk
and sole.
Highly probable - fish (and in particular demersal fish) are expected to move away from the
mining activity resulting in displacement of biomass
Medium - the duration of the impact is permanent but recovery of fish populations in the
area may occur in the long term. The intensity is minor to moderate and the extent is
confined to the MLA and Zone 1
In terms of the ecosystem as a whole there are no particular mitigation measure that can
be implemented.
Not applicable (no mitigation alternatives)
Low to medium - assumptions based on fish ecology is limited by the data available
Final Report
Namibian Marine Phosphate (Pty) Ltd.
Page 64