Fish behavior

Category Archive Fish behavior

A tagging study : movements of KwaZulu-Natal yellowfish in the upper uMngeni River.

Riverine ecosystems are affected by anthropogenic activities and environmental changes. One of the ways in which to evaluate the effect of these impacts is assessing the behaviour ecology of fish populations. Fish behaviour tells us how fish adapt to human activities (survival and recruitment) and how they improve their use of ecosystem resources. Behavioural variables include habitat selection, reproduction and reproductive strategies and migration behaviour. Information on fish behaviour can be used in conservation of fish and the aquatic ecosystems they occupy.

As part of a study on the uMngeni River we will be looking at the reproductive biology and migration behaviour of the KwaZulu-Natal yellowfish (Labeobarbus natalensis). This involves evaluating the location, timing and duration of spawning migrations of yellowfish in the uMngeni River. Thus far, 22 yellowfish have been tagged with VI tags (Figure 1) at the inlet of the uMngeni River into Midmar dam, with the intention to tag more over time. We would like to call on all anglers in the upper uMgeni River for the assistance in recording data from any tagged yellowfish they may catch as this will aid the study immensely.

We need your help ! In the event that a tagged yellowfish is caught please, at best, take note of the following and let us know:

1. The location (include site coordinates if possible)
2. The date
3. The VI tag number (e.g. D 55)
4. The standard length of the fish (mm)*
5. The weight of the fish (g)
6.Note any abnormalities (e.g. deformity, disease or injury)
7. Photo of VI tag and full body photo (see examples below)

Figure 1: Orange arrows shows : on the left, the placement of the VI tag behind the eye, and on the right the placement of the VI tag in relation to the body of the fish.

Please Contact the following people below with any information or questions:
Pumla Dlamini: pumladlamini1@gmail.com, Matthew Burnett: matthew@riversoflife.co.za and Dr. Gordon O’Bien: obrien@ukzn.ac.za

 

* Standard length :

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Tagging Natal Yellowfish in the uMngeni River

The tagging of Natal Yellowfish (Labeobarbus natalensis) in the uMngeni River,

Figure 1: One of the tagged Natal Yellowfish at Albert Falls dam, showing the good size and condition of fish needed for tagging.

As part of the uMngeni Fish track study headed up by the Aquatic Ecosystem Research Group a yellowfish tagging survey was organised. This is for the component of the real time remote monitoring project that is crucial in assisting AER to understanding Natal Yellowfish behaviour and establishing the remote monitoring network. Having tagged fish in the river will allow the team to assess yellowfish movements and strategically place water probes and remote stations to obtain data in real time. This is exciting to see as some of the results start to come in.
The AER team went out to Albert Falls Dam and Fountain Hill Estate to tag Natal Yellowfish. The fish were caught using gillnets and electro-shocking. Gill nets were monitored constantly to prevent injury to fish. Suitable fish were remove from the net immediately on capture and then transferred to a holding net. Electroshocking was using in shallow fast flowing rocky habitats, suitable fish caught were transferred to a holding net. In total 3 fish were acquired that were fit to be tagged.

Figure 2: Catching yellowfish using the electro-shocking method at Fountain Hill Estate, one can see the yellowfish in front of the excited researchers

Tagging procedures took place under 17 minutes for each fish. The procedure requires surgically implanting of the tag into the abdominal cavity. Two fish surgeons were scrubbed up to maintain a sterile environment while operating, the surgical equipment was sterilized beforehand in an autoclave and opened on site during the operation. Assistants helped handle the fish and non-sterile equipment while the surgeons operated. These steps were taken to create a sterile environment around the incision to prevent infection. The following steps were taken to ensure a smooth quick operation; Fish were anaesthetized using phenoxyethanol. Once signs of narcosis were shown, the fish was then moved onto the operating table and put into position. A pipe pumping water over its gills was maintain throughout the operation to minimize exposure of the fish to the air. An incision was then made in the area between the pelvic fins and anal fin into the abdominal cavity being careful not to cut too close to the anus or pelvic fins. This insertion cuts through to the abdominal cavity were the tag is the inserted. The tags aerial is set using a spinal needle and then once the tag is in place the abdomen is stitched up using suture material. Wound-gel is then applied over the wound to protect it from bacterial infection and allow the mucus layer to recover. To further assist with this anti-biotics are applied. Finally, the fish is placed into a recovery container and held there until signs of narcosis are no longer evident. The fish is then release by allowing it to swim away from the tagger.

All three fish were successfully tagged and released. The Fountain Hill yellowfish named “Drone” is already swimming around one of our remote stations and providing us with valuable data. The two Albert Falls yellowfish (named David and Fortunate) were released and picked-up within the dam later in the day. The AER team is currently setting up the remote network to be able to track them. The tagging procedure was a great success and will get better as we expand the study showing how fish can help us monitor the environment in real time.

Figure 3: Shows the release of the Natal Yellowfish after the tagging procedure, swimming freely on its own.

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Our aquarium facilities

The Aquatic Ecosystem Research (AER) Aquarium is located at University of KwaZulu-Natal, Pietermaritzburg campus. The main purpose of building this facility is for fisheries scientists to conduct research on behalf of the department. Research to be conducted includes culture of Mozambique Tilapia, Oreochromis mossambicus, which will be used as feed for crocodile culture project, which aims to evaluate the suitability of fish as crocodile feed. Cultured Tilapia will also be used for a study that focus on evaluating the suitability of crocodile carcass as protein source for fish culture. some of the tanks will be used to culture O. mossambicus populations sampled from different rivers around KwaZulu-Natal to select suitable population for conservation of the species for Aquaculture purposes. O. mossambicus broodstock will be collected from Unizulu and culture experiment will be initiated.

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Culture of Yellowfish will also be conducted in the aquarium to carry out a tag retention study on the KwZulu-Natal yellowfish, Labeobarbus natalensis. Comparing different tagging techniques and the use of external versus internal tags within a tropical environment.in terms of the aquarium progress, currently tanks, pipes and filters has been installed and the system is running very well and is in good condition for fish culture.

The following colleagues are acknowledged for operating the aquarium in success; Dr Gordon O’Brien, Matthew Burnett, Fortunate Mahlatse Mashaphu and Rendani Luthada-Raswiswi.

INVITATION – Dialogue to celebrate the World Fisheries Day and workshop on SA Fish Swimway Programme

We are pleased to announce that the SA Fish Swimway Programme will be hosting a workshop on the 21st of November 2016 in Pretoria. The University of KwaZulu Natal, together with WRC and SA Fish Swimway Programme Partners, will be hosting an event to celebrate World Fisheries Day. This will include presentations by fish specialists, followed by discussions reviewing the Swimway programme and refining the next steps. One of the speakers will be Mathew Ross, who in 2015 completed his PhD on fishway design in South Africa.  Representatives from the Kingfisher Project have also been invited, to talk about the current plans for Catchment Management Agencies in South Africa. During the workshop, we would like to specifically refine a suitable proposal that can be used for funding applications relating to fish migration in South Africa. We hope you will be able to attend ! 

Interested ? Please RSVP events@wrc.co.za

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In the press – “Namibia takes pride in freshwater fisheries resources” by Francois Jacobs

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Fish catches bird in flight !

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