Environmental Assessment
Volume C-4.3
Slurry Pipeline
Fish and Aquatic Resources
Ambatovy Project
121
January 2006
pipeline LSA (Table 4.3-2). The high species diversity in the pipeline LSA
compared to the mine or Toamasina study areas can be attributed to the high
diversity in both water body and habitat types traversed by the pipeline route.
However, except for isolated instances, species richness and abundances were
generally low at individual sampling sites; species richness of >5 occurred at
only 5 of the 15 sites. The highest richness of 12 and 10 species occurred at sites
107+200 and 145+700, respectively. The introduced species,
Xiphophorus
maculatus
, was the most ubiquitous species occurring at 8 of the 15 sites. As
expected, generally the endemic fish species dominated in un-disturbed habitats
(IHIA Classes A and B; Table 4.3-1) while introduced species, such as the
anabantid, Ctenopoma ansorgii
, and the
poecelid, Xiphophorus maculatus,
were
more prevalent in disturbed (IHIA Classes D-F, Table 4.3-1) areas.
Similar to other LSAs in the aquatics study area, a majority of fish encountered
in the slurry pipeline area were relatively small-bodied species, which are not
heavily used by the artisanal fisheries. Abundances and species occurrence of
the larger food fish species collected from the study area (e.g.,
Oreochromis
macrochir, Tilapia zilli, Ophicephalus striatus, Terapon jarba, Osphronemus
goramy
and
Caecula pterygera
) were generally low, except for
O. macrochir
and
T. zilli
that were collected at moderate densities from one site
(site 107+200).
Locations where artisanal fisheries were observed during the study included:
•
Ivondro River (178+900): gillnetting (monofilament) for
Tilapia zilli
;
reed traps for
aytid
shrimps and
Bedotia madagascariensis
.
•
Morongolo River (145+700): gillnetting and spearing for
Tilapia
sp. and
Paretroplus poliactis
.
•
Sahanavo River (136+200): monofilament gillnets and baited hook,
captured
Tilapia zilli
and
Channa maculata
.
•
Rianila River (107+200): diving and conventional spear guns for
Tilapia
zilli.
