Re: NANFA-- Rare South African fish

Jeremy Tiemann (
Wed, 20 Nov 2002 16:42:19 -0600

For my Master's thesis, I examined the effects of lowhead dams on the
federally threatened Noesho madtom (Noturus placidus). We sampled 8
sites once a month. At each site, we laid out 5 transects, and had
up to 5 sampling points (depending on environmental conditions) per
transect. We kicked seined a 4.5 m2 area, identified the fishes
after each point, and released the fishes after each site. We did not
kill any fish, or mark any fish. We have a few pubs resulting from
this (effects of dams, interspecific competition, and
spacial/temporal aspects). I do not know if this is much help.
Please let me knw if I can be of any help. Good luck.

Jeremy Tiemann
Illinois Natural History Survey

>I am an ecologist working for the Water Research Commission of South
>Africa at the University of Cape Town. We are currently planning a
>study of three endangered fish species in the Olifants River to the
>north of Cape Town in the Western Cape, South Africa. There is little
>expertise in South Africa for studying threatened fish species and it
>is difficult to know which questions can be answered using non-lethal
>The three species we are interested in occur in very low numbers as
>result of the introduction of exotic fish species and damming -
>the Clanwilliam yellowfish, Barbus capensis, the Clanwilliam
>sandfish and the sawfine. However, management strategies to conserve
>these fish urgently need to be developed. Extremely low numbers and
>threatened status of these species makes this a difficult job. I am
>interested to know how fisheries biologists in the US have gone about
>acquiring information on aspects of life history of fish which are
>rare. Failing this, I would appreciate it someone could refer me
>to any other people or publications which may be able to help in this
>First of all acquiring information on age-growth, age at
>maturity, fecundity, survival at all life stages and recruitment,
>require killing fish. I would need to sacrifice a minimum of 100 fish
>per species in several age classes. Firstly I am not sure the present
>populations could stand this kind of sampling pressure, and secondly,
>but more realistically, I don't think we could catch that many fish
>over the 3 year project.
>Secondy, the fish are so rare and mobile that mark-recapture has
>proved almost impossible - in the last year and a half I have had no
>recaptures. Estimates of absolute abundance would not therefore be
>possible using this technique. To give you an inidication of the
>densities - in 18 gillnet hours of sampling on the mainstem of the
>Olifants River we caught two fish. Smaller fish are more abundant in
>the tributaries, but large adult fish in the mainstem are almost
>impossible to find. We don't even know where they are spawning, or if
>they have spawned at all in the last ten years.
>Combined with this is that there are is no historical data on these
>species apart from anecdotal information which suggests that they were
>originally present in the river in their thousands and would
>regularly migrate up the river to spawn in riffles of the middle and
>upper reaches. The presence of the Clanwilliam dam now prevents this
>and recruitment by the remaining fish is being severely impacted by
>introduced largemouth and smallmouth bass populations (which are now
>very abundant in the river).
>Unless I am missing something, I am almost inclined to believe that
>studies should be laid aside in favour of a programme to eradicate
>bass and restore habitat.
>Bruce Paxton

Jeremy Tiemann
Illinois Natural History Survey
Center for Biodiversity
607 E. Peabody Dr.
Champaign, IL 61820
Phone: (217) 244-4594
Fax: (217) 333-4949
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