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Jun 22 2018

Use of chlorine compounds for eradicating the left-over organisms from fish ponds (Video)

Video credit: Zanou Dossou (Togo)

Review: Abdel Rahman El Gamal (Founder of the video channel)

 

Before starting any fish farming operation, it is essential that culture unit is free of aquatic organisms which could be accidently left-over from earlier operation whether in fry nursing or grow-out. While this matter is simple in completely drained tanks and/or ponds, it turns a real concern in situations where culture units cannot be completely drained. Small water buddies scattered in earthen ponds could be sufficient to host various organisms including fish fry, fingerlings, molluscs, insects, snails and others. In fact, the adults of some hardy species can survive un-noticed in watery footprints (e.g. tilapia and African catfish). These left-over organisms –depending on their types and densities- may threaten the following crops, and so the eradication of such organisms is a must to ensure a safe crop.

There is a long list of compounds which can be used for such disinfection process. The effectiveness, availability and cost are criteria used in choosing a given disinfectant. Moreover, the easiness of neutralizing the applied substance is an important criterion to consider.

The video shows the use of chlorine solution for the eradication of possible left over organisms. As the remained water scattered in the pond is not easy to estimate, the volume and concentration of chlorine required for such task would depend on personal experience as well as the immediate reaction of organisms that may occur in shown water buddies. In such situations, fish farmers may lean more to overdosing than under-dosing.

It is often recommended to allow water sufficient to cover the whole pond bottom before the application of chlorine. Doing so will ensure a better mixing of chlorine solution with the entire bottom water. Afterwards, and before stocking the fish, no sign of life should be observed in treated water otherwise, repeating the process is possible.

The most common chlorine source used in aquaculture ponds are calcium hypochlorite whether in the form of powder or tablets.

After a day or two of the chlorine applications, pond water is raised and the dead organisms are netted out before stocking the new batch of farmed organisms.

 

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Permanent link to this article: http://fishconsult.org/?p=14523

Jun 15 2018

Small-scale aquaculture in Malawi

Photo credit: Spriano Mpango and Thokozire Gwaza (Malawi)

Review: Abdel Rahman El Gamal (Founder of the website)

The inserted picture shows the digging of a small fish pond by a group of women in Malawi. In fact, there have been several programs in Malawi which are supported by the government as well as by NGOs that promote small-scale aquaculture especially among the families with little resources with a special emphasis on female-headed households. This approach has been implemented through either fish farming clubs or similar fish farming groups.

As expected, a small pond like the one shown in the picture should be manually constructed as the use of machinery is usually not possible and/or not justified.

In dry regions, most small ponds are rain-fed constructed on the land as long as the soil is suitable for retaining water.

A small pond as such is usually used to grow the popular fish to the community such as “chambo” which is a tilapia species (Oreochromis lidole) and African catfish (Clarias gariepinus). This type of ponds is valuable towards addressing nutritional deficiencies at household level in rural communities.

 

 

Permanent link to this article: http://fishconsult.org/?p=14518

Jun 14 2018

Artificial reproduction of grey mullet (Mugil cephalus) in Egypt – Video

Video credit: Ahmed Shaheen (Egypt)

Review: Ahmed Shaheen and Abdel Rahman El Gamal (Founder of the video channel)

This video was filmed in the first constructed governmental marine hatchery located in Alexandria (Egypt).

Since the grey mullet cannot reach its full sexual maturation in captivity, the broodstock that are required for the artificial reproduction has to be obtained from the wild.

As the video starts with the catching of broodstock then stocking and maintain them in outdoor tanks until moving the ready-to-spawn broodstock into the indoor facility in the hatchery. The video shows the egg sampling process using a catheter.

In this particular process, females are hormonally induced while males can be only checked based on releasing sperm upon a light pressure.  If males are not ready, hormonal induction is administered.  In order for a successful reproduction, egg diameter has to reach 500 microns.

The hormone used in case of females is done as follows:

First injection: Human Chorionic Gonadotropin (HCG) at the dose of 10,000 IU/kg of the female size

Second injection: LHRH at the dose of 10-20 microgram/kg of the female size

In regard to unready males, the injection is done under skin using 17-alpha methyl testosterone at a dose of 10 microgram/male size (about 300-350 g/specimen). This is done 3 weeks before the spawning period.

The broodstock are stocked the spawning fiberglass tank of about 4 to 4.5 m3 size at a rate of three males to one female. Once the spawning is observed, the broodstock are lifted from the spawning tank leaving the fertilized eggs to develop. In a tank as such, about 250,000 – 500,000 embryos are produced bearing in mind the high fecundity of the species which is about 1.5 million eggs/kg of a female weight. Hatching occurs after about 100 to 110 hours at 25 C.

 

Note: the technology of the artificial reproduction of grey mullet is available in Egypt but it is carried out only at experimental scale. Fish farms rely on naturally collected mullet fry which is always larger in size and at much lower cost compared to hatchery-produced seeds. The scaling up of the artificial reproduction of mullet would be only justified upon the stopping of the collection practice of the mullet fry from the wild.

https://youtu.be/2wABlV6htBM

 

 

Permanent link to this article: http://fishconsult.org/?p=14515

Jun 11 2018

Musoma fish market in Tanzania

Photo credit: KIVA-API (build.kiva.org)

Review: KIVA – API and Abdel Rahman El Gamal (Founder of the website)

The market shown in the picture is located in Musoma District, which is among the six districts of Mara Region with its ~ 130,000 population is located in the northern part of Tanzania.  Most people in Musoma make a living from Lake Victoria either by selling small fish known as dagaa, to larger fish such as tilapia, or much larger fish such as Nile perch.  As the case with fresh fish markets, Musoma market suits best the heavier population centers.

It appears that tilapia dominates the displays in the market indicating the consumer preference as well as its quantities.

In regard to Nile perch, occasional shipments can be arranged to reach Dar es Salaam using cars with specially built freezers or via the few refrigerated wagons of the railway, while special shipments of fresh Nile perch may be arranged via the air services.

Because of the importance of Nile perch to the export market, fishing regulation have been formally in place to minimize the over-fishing practices. In that regard, the Musoma fish market like other markets in Tanzania is subject patrols to ensure that fishmongers are not selling immature Nile perch with less than 50 cm in length.

In regard to fish consumption in Tanzania, and according to FAO statistics, the consumption has been 7.2 kg/capita in the year 2013.

Permanent link to this article: http://fishconsult.org/?p=14510

Jun 08 2018

Landing and auctioning of Bluefin tuna in Oman (Video)

Ownership and review of this video: Abdel Rahman El Gamal (Founder of the video channel)

The video was filmed in the Berka fish market, Oman. This fish market has witnessed a significant improvement as the design of the market has been adopted the participatory approach including officials, fish quality staff, and fishermen.

During the visit, I had the chance to witness the unloading of a number of Bluefin tuna specimens (Thunnus thynnus) which has been caught at about 80-90 km distance from the shore.

The auctioning in a typical marketing system in which the auctioneer manages the operation and sells each piece at the price as offered by the buyers who are witnessing the auctioning exercise.

As the case in most fish markets, tunas are valuable fish and enjoy a high market price and in such large fish such as the Bluefin tuna, it is sold in slices as shown by the end of the video clip.

https://youtu.be/xbVow1fEup4

Permanent link to this article: http://fishconsult.org/?p=14503

Jun 05 2018

Sampling of tilapia fingerlings in Togo (Video)

Video credit: Apetse Sena Kdzo (Togo)
Review: Abdel Rahman El Gamal (Founder of the video channel)

 

This video was filmed for the sampling of tilapia fingerlings in an earthen pond using a cast net. There are several comments I was able to notice. First, the fish farmer seems well-trained in casting the net. Second, he dived several times I guess for setting the net over the sampling area. Lastly, the mesh size of the net should smaller in order to avoid gilling the sampled fish and ensure a safe removal of sampled fish.

 

 

https://youtu.be/xaF2-duFctg

Permanent link to this article: http://fishconsult.org/?p=14501

Jun 05 2018

Sun-drying of sardines for the use in fish feed in Gabon

Photo credit: Firmin Sangangoumou Nicaise and Talia Gladis Elingui (Gabon)

Review: Firmin Sangangoumou Nicaise, Talia Gladis Elingui and Abdel Rahman El Gamal (Founder of the website)

The inserted picture shows the sun-drying of sardines in Gabon. On the average, two days are sufficient for the drying of sardines which are caught from the sea.

The use of sardine in fish feed may be justified for experimental purposes especially sardine is of top importance for the poor and low-income people in Gabon.

In order to ensure a sustainable sardine fishery in Gabon, the government has taken several actions and issued necessary regulations including period banning in certain locations, specifying the fishing gears and others.

Based on the nations encyclopedia, the Gabonese waters are estimated to be able to support an annual catch of 12,000 tons of sardines.

 

 

Permanent link to this article: http://fishconsult.org/?p=14496

Jun 04 2018

Purse seining of bluefin tuna in Libyan waters – Video

Video credit: Abdallah Elmgawshi (Libya) Review: Abdel Rahman El Gamal (Founder of the video channel)

 

The video shows a typical fishing of Bluefin tuna (Thunnus thynnus) in Libyan Mediterranean waters.

In the present, almost all tuna fishery in Libya is carried out by longline and purse seining. This video shows the purse seining of the Bluefin tuna. The fishing season generally starts in the middle of May and extends to the middle of July or reaching the approved quota whether for the whole country and/or for the particular fishing vessel.

Typically, before taking a fishery action, the tuna stocks have been explored using appropriate equipment such as HD Binoculars, sonars, etc. As shown, the frozen sardines are thawed and moved from the mother ship to a boat where sardine is distributed in the target zone to attract and keep the tuna stocks in place.

Immediately after, the seine surrounds the tuna stocks to the tuna stock to keep the fish in place and then the purse seiners act immediately surrounding the tuna fish and crowding them in order to be lifted easily on the mothership. It seems that the fishing crew is pleased with their catch.

https://youtu.be/9IxZSe0spWs

 

 

Permanent link to this article: http://fishconsult.org/?p=14493

May 31 2018

Role of women in the farming and processing of seaweed in Tanzania

Photo credit: Lucka Paschal and Erick Kiiza (Tanzania)

Review: Lucka Paschal – Erick Kiiza (Tanzania) and Abdel Rahman El Gamal (Founder of the website)

So far, the culture of seaweed is limited to soap making. The culture and processing of seaweed are mainly conducted by women who form groups in seaweed culture and soap making. The culture of seaweed is conducted in Zanzibar Island, and recently it has drawn attention for the Coastal community.

 

 

Permanent link to this article: http://fishconsult.org/?p=14489

May 29 2018

Processing of rainbow trout in Colombia

Photo credit: Marleyi Acuna Torres and Sandra Magally Sanchez Trujillo (Colombia)

Review: Marleyi Acuna Torres, Sandra Magally Sanchez and Abdel Rahman El Gamal (Founder of the website)

The inserted picture shows a fish processing facility located in Silvia, Cauca (Colombia). The facility processes rainbow trout (Oncorhynchus mykiss). This processing plant belongs to “Apropesca” -Association of producers and traders of aquaculture and agricultural products of Silvia.

This processing plant -as expected- targets to enhance the quality of marketed trout whether for national and international markets in addition to securing a constant supply of fish in the market.

The main product of the plant is the frozen rainbow trout. However, smoked trout may be produced upon specific requests.

It may worth noting that the annual production of rainbow trout from aquaculture in Colombia slightly exceeds 6000 tons.

 

 

Permanent link to this article: http://fishconsult.org/?p=14483

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