Cape Natures Proposal To Poison Rivers

[CTHOMAS]

Hi I am the son of C Thomas and this is the first time i have written on this forum... but i need some feedback from people who probably know more about this than me.

Does anyone know what is being done in relation to the article published on the second page of the weekend argus (10 may 2008) regarding the proposed plan of poisoning rivers in the cedarberg. the idea that i got from the article is that cape nature is wanting to poison the trout and bass populations in the rivers and then restock the rivers with indigenous fish.

does anyone know what EIAs (Environmental Impact Assessments) have been done in regard to the overall impact this will have on the ecosystems surounding these rivers??? prehaps a major fishing event should be proposed rather than having to POISON A RIVER!!! what are the farmers opinions on the matter, seeing as thier water comes fo these rives, and what is the long term efect ging to be? we all know that bass are virile reproducers and ravenous eaters, but prehaps having these fish in our streams, but with reduced numbers, would be the lesser of two evils.with a sufficent amount of co-operation amoungst the fishing community, could we not find better alternatives to turning our rivers into deserts and risk destroying the aquatic ecosystems of one of the most beautiful areas in the country, if not the world??

is the biology of a yelow fish so different from that of a bass that the poison will not affect them? i am basically clueless in this regard, but some knowledge of rudimentary biology points to the conclusion that no!... it probably wont be. what of the risk of this poison building up in higher order animals, similar to the ddt problem in the USA, back in the day... this caused eagles to lay eggs with thin shells that broke really easily, and then caused the Bald eagle population to decrease dramatically...

DDT is banned in north america and Europe, for good reason, but even our own health department has used it in areas to kill mosquitoes in the fight against malaria. This has happened in the face of very blatant research that has shown that DDT is not your friend. nothing will happen about this plan if the people who use these rivers and have a vested interest in the water quality, as well as the ecological balance in the ecosystem do not make sure that if someone wants to mess with a beautiful pristine landscape, they protect what they care about.

Rotenone is extremely lethal to both fish and insects. fish and insects are more at risk as they absorb chemicals in the water straight into their blood stream and the piso does not hae time to break down. mammals are not as affected, but this is due to the way that the poison is ingested into mammal and bird bodies. this being said, there is research to show that this poison, when injected into the blood of lab rats, causes parkinsons disease. this being said, natural rodent populations that use these rives as water sources will not have the poison injected into them.

Rotenone was used by native populations in South america to poison fish. it has a "Natrual" reputation, but what does this mean?? Anthrax is "natural", poisonous mushrooms are "natural", radiation is "natural". this does not mean that the poison will be any less devastating to the aquatic opuation in these rivers. any life form that absorbs oxygen straight from the water into the blood stream will be eradicated from this ecosystem, not just the Bass (my father tells me that trout are not found ithe cederberg, but the point still stands as this is apparently these rivers are just the first stage of the plan)

the fact remains that some people in Cape Nature want to POISON THE RIVERS!!!

Guy Thomas.

ps. for further reading on the nature of Rotenone please consult this link below

http://www.pan-uk.org/pestnews/Actives/rotenone.htm

or please get a hold of me at

thmguy002@uct.ac.za

[Jasper]

Hi Guy

have a look here .... and use the "search" facility above as well ... there has already been a lot written about the subject.

http://www.flytalk.co.za/forum/showt...light=Rotenone

say hello to your folks from me!!!!

[Jasper]

Guy ... ask your folks to have a look at the thread on the forthcoming Lakenvlei Trip! .. I distincly remember getting seriously stuck there with them a long time back!!!

[shector]

Guy
I will refer you to the latest edition of Piscator (Nov. 2007) where this topic is discussed from both sides of the camp. Also some previous editions carry some articles relevant to this topic.

Cheers
Stanton

[Yellowfever]

Guy,

The gentleman at Cape Nature are pretty level headed and certainly do have the best intentions for preserving the natural environment. That said some may be a bit over zealous when it comes to yellowfish but we like that:-)

To my knowledge these projects are limited to very small rivers with natural boundaries for migration of bass e.g. waterfalls. No use dumping the stuff in the Breede! So the small stream is cleared of everything and when appropriate stocked with indigenous fish. One cannot put any fish in with bass as they just exterminate everything!!

No amount of fishing can erradicate the bass, not over a time span required to make this feasable. Keep in mind that these are remote rivers hardly ever visited by the angling frat except the dedicated few.

Also feel free to contact the gentleman at CN, their contact details are on the Fosaf website under the Yellowfish Working Group. Dean and Pierre are great guys with many years of conservation under the belt. Dean esp is a FFM so that makes him one of us.

Carl

[Chris Shelton]

The three rivers to be targeted for alien fish eradication and justification therefor are as follows;

Suurvlei River, Cederberg

The Twee River redfin, Barbus erubescens, is restricted to the Twee River system and is critically endangered. In the last 10 years this species has disappeared from the Suurvlei tributary with the exception of a pool below a waterfall at the head of the stretch of 5 km previously occupied by B. erubescens. The loss of B. erubescens is primarily blamed on the escape of introduced cape kurper, Sandelia capensis, from a broken dam above the affected stretch of the Suurvlei. Elsewhere in the Twee River system, introduced American bluegill sunfish, Lepomis macrochirus, and Clanwilliam yellowfish, Labeobarbus capensis, also threaten Barbus erubescens as well as a Twee River endemic Galaxias sp. While alien fishes are not the only problem in the Suurvlei and the rest of the Twee River system, eradicating them will be of major benefit to the redfin.

The stretch proposed for alien eradication in the Suurvlei River is from the upper limit of alien invasion for 5 km downstream to a weir to be constructed at or near the Suikerbossie road bridge


Rondegat River, Cederberg

The upper reaches of the Rondegat River, which flows directly into Clanwilliam Reservoir supports thriving populations of five indigenous fish species, fiery redfin, Pseudobarbus phlegethon, Clanwilliam redfin, Barbus calidus, Clanwilliam yellowfish, Labeobarbus capensis, Clanwilliam rock catfish, Austroglanis gilli and the Olifants system endemic Galaxias sp. This stretch of river (~20 km) terminates in a small waterfall below which the fish population is dominated by American smallmouth bass, Micropterus dolomieu and bluegill. Adult yellowfish are also in evidence in the pools below the waterfall, but no juvenile yellowfish or any redfins. The stretch of this upper catchment river holding indigenous fishes is short and vulnerable, and the stretch of river downstream of the waterfall contains numerous pools that are larger than those found in the present indigenous species zone upstream and form ideal habitat for the indigenous species. Removing alien fishes downstream of the waterfall to another barrier (an existing water offtake weir near Clanwilliam Reservoir for a fruit farm on the shores of the reservoir) will add approximately 4 km (an extra 20% in length) of habitat for the indigenous species, greatly enhancing their survival prospects.

Krom River, Cederberg

The Krom River arises in the Cederberg and flows for about 8 km down a steep-sided valley before levelling off into the Kromrivier farmland, from which it flows for another 10 km to enter the Matjies River. At present the only indigenous fish species in the river is Austroglanis gilli, the distribution of which extends for a few hundred metres above the farm. It is almost certain that the Krom River was formerly populated by redfins, specifically the Doring River strain of Pseudobarbus phlegethon. The fast-flowing stream in the valley is invaded by rainbow trout, Onchorhynchus mykiss, up to the Disas Pool below a substantial waterfall that forms an effective barrier to upstream fish movement. The farm dams contain American bass species and from the farm downstream the river is also invaded by bass and bluegill. By eradicating the alien fishes from the river it will create extensive habitat for the reintroduction of Pseudobarbus phlegethon using the Doring River strain either from the adjacent Breekkrans tributary or the Doring River. There is also an option to reintroduce other fish species under threat that are native to the Doring River, i.e. Barbus calidus, Labeobarbus capensis and the Clanwilliam sawfin, Barbus serra.

The stretch proposed for alien eradication is the 18 km stretch from Disas Pool at the head of trout distribution down to a weir just above the confluence with the Matjies River.

[Chris Shelton]

I received the following background information from Enviro-fish Africa;


The introduction of alien fishes to rivers of the Cape Floristic Region (CFR) in the late 1800s and early to mid 1900s, primarily for angling purposes, has had major impacts on the indigenous aquatic faunas. Almost all the fish species of this region are now classed in threatened categories in the IUCN red data list, with alien fishes highlighted as having the major impact in almost all species assessments.

An idea of the scale of the problems facing endangered indigenous fish species in the CFR is given in the forthcoming report from the current southern African freshwater red data assessment programme, from which the following two paragraphs on the Olifants River system are extracted.

“Cederberg tributaries of the Olifants River system in the north-western parts of the Cape Floristic Region (CFR) have some of the most extreme examples of how alien fishes have devastated indigenous populations. A typical scenario is to find five to six indigenous species above a small natural barrier, with no indigenous species surviving below the barrier in the presence of alien, North American, smallmouth bass (Micropterus dolomieu), e.g. in the Rondegat River, the indigenous species Pseudobarbus phlegethon, Barbus calidus, Labeobarbus capensis, Austroglanis gilli and Galaxias zebratus survive above a small waterfall that prevents M. dolomieu from spreading upstream. Only a few large Labeobarbus capensis are able to survive with the bass, but without successful recruitment.

Smallmouth bass, together with largemouth and spotted bass (M. salmoides and M. punctulatus), also from North America, now dominate the fish fauna in more than 80% of the Olifants River system, with indigenous fish often surviving in less than 1 km of river in headwater streams. Throughout the CFR these three bass species have had a catastrophic impact on indigenous fish species.”

The above scenario has prompted Cape Nature, the regulatory and management body responsible for these river systems, to consider reducing the threats to indigenous fish species by extending their river habitats through the eradication of alien fish species in sections of particular rivers in critical areas in an attempt to conserve existing indigenous populations and rehabilitate affected rivers. In order to do this in a rational and responsible manner, CapeNature wishes to investigate the options of fish eradication in selected priority rivers, or more precisely, sections within these rivers.

The eradication of alien species by whatever means is not a listed activity in terms of South Africa’s environmental legislation and does not require formal Department of Water Affairs and Forestry authorisation. However, under the National Environmental Management Act 107 of 1998, a duty of care should be exercised when engaging in activities that may have a detrimental effect on the environment. The World Bank’s safeguard policies suggest that an impact assessment is needed to determine whether the proposed use of piscicides (one of the eradication options, see below) is viable and environmentally safe. Thus, in response to this recognised need for an EIA, and following a tendering process, Cape Nature has appointed Enviro-Fish Africa (Pty) Ltd (EFA) to carry out the EIA on its behalf.

This Background Information Document (BID) gives an overview of the proposed EIA process and presents the way forward. Details on how to register as an Interested and Affected Party, and how to obtain further information on the project are also included at the end of the document.

Possible eradication methods

Possible methods of alien eradication that will be investigated in this EIA include the use of piscicides. Several have been used extensively in other parts of the world, e.g. rotenone, a natural product derived from Derris root that is widely used throughout the world and particularly in the USA to remove pest species such as alien invasive fishes. Antimycin A has also been used in some areas as an alternative piscicide. Physical eradication methods are also an option and could include extensive and intensive trapping, electric fishing, and targeted angling and spear fishing, repeated until all fish have been eliminated.

The experiences elsewhere indicate that the envisaged alien eradication approach is feasible. Alien eradication is, however, an expensive option and needs to be weighed up against a number of factors, including e.g. the importance of alien species for angling purposes.

Justification

Key considerations in the selection of the pilot sites have been the conservation importance of the site for indigenous species, and the physical characteristics of the section of river, which should prevent re-colonisation once eradication has occurred, as well as being discrete enough to allow effective and complete eradication to be practically achievable.

Following a detailed review of many rivers in which indigenous species are severely threatened by aliens, and extensive consultation between freshwater biodiversity experts, four pilot sections of river, for which justification is given below, have been selected as having potential for alien fish eradication and as a result, great benefits for the indigenous fish populations. Three of these rivers are tributaries of the Olifants-Doring system in the Cederberg, i.e. the Suurvlei, Rondegat and Krom rivers

[Chris Shelton]

You can get the results of the EIA by getting in contact with Denis Tweddle. Following is the note that went out to all interested parties;

INVITATION TO REGISTER AS INTERESTED AND AFFECTED PERSONS

In order to ensure that you have an opportunity to participate in the EIA and comment on its findings, please register as an interested and/or affected party by submitting your name, contact information, and interest in the proposed activity and/or way in which you might be affected, to Denis Tweddle (whose details are given below) by 14th March 2008. Registration may be done via email, fax, phone or post.

Subsequent to your registration, you will be kept informed of progress on the EIA and will be invited to review the Draft reports, attend public consultation meetings at the specified times and dates and submit your written comments.

Denis Tweddle
Project Coordinator

Email: d.tweddle@ru.ac.za
Phone: office, 046 6035813 (direct)
Phone: office, 046 6035800 (switchboard)
Fax: 046 6222403
Mobile: 072 4368777

[smallstreams.co.za]

It is almost certain that the Krom River was formerly populated by redfins, specifically the Doring River strain of Pseudobarbus phlegethon.

Sounds like a plan to me

[Chris Shelton]

Sounds like a plan to me

hehehe Mario, I knew I could count on you to pick up on the finer uncertain details