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
Monk : (Figure 42) – Juvenile monk (< 21 cm) are found throughout the MLA but are not in high
abundance (note this is surmised from hake survey data only). The impact on juvenile monk as a
direct result of the dredging operation will be high (mortality) – the data given however suggest
that the extent of the mining area is small compared to the overall distribution of monk. Total
recruitment effects on monk are therefore expected to be low.
Small pelagics : (Figures 43, 44, 45, 47 and 48a) – The known distribution patterns of small pelagic
juveniles (species combined) suggests that they are predominantly found landwards (shallower)
than the MLA. Further, egg and larval surveys suggest spawning occurs well north of the MLA.
Historical data suggests also that spawning occurred north of Walvis Bay and far away from the
MLA. There is however some evidence that historically sardine and anchovy eggs were found in
small numbers south of Walvis Bay and across the MLA. In the context of the attempts to rebuild
the much depleted small pelagic stocks however, any minor disturbance or disruption of
potential spawning by small pelagic species raises the impact implications to moderate.
Fish Recruitment Summary
- In general the mining operations are unlikely to have a significant impact on the
recruitment of most commercially and ecological important fish species. However Cape
hake spawn in deep water (100 and 400 m) between Cape Cross and Conception Bay (22-
24°30’S) (Sundby et al. 2001). Depending on environmental conditions (cross-shelf
circulation, low oxygen layers, meso-scale gyres), the dredging activities could impact on
the hake spawning throughout the water column
- The potential increased turbidity around the mining area is unlikely to impact on all species
but it should be noted that turbidity plumes might extend into important areas for Cape
hake (M, capensis) and monk juveniles. There is, therefore a concern that the mining
operations might have an effect on recruitment of these species
- The distribution of sardine and anchovy ichthyoplankton (eggs and larvae) (Figures 44 –
48a) are found further north and do not overlap with the MLA. It should be noted that this
could purely be a result of the lack of survey stations in the southern areas of Namibia.
Final Report
Namibian Marine Phosphate (Pty) Ltd.
Page 66