Dec 29 2015

Development of blood cockle culture in Thailand

Photo Credit: Worawut Koedprang (Thailand)

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

culture of blood cockle in Thailand

 

 

 

Blood cockle contributes by about 80,000 tons in Thai aquaculture and represents close to 13% of total coastal aquaculture in Thailand in 2013. The culture of a local species of cockle, Anadara nodifera, began in Thailand since more than 100 years ago in Phetchaburi Province. For very many years, the collection of cockle spats of 0.3-0.5 g average size from natural settling grounds was the sole source of seeds required for culture.

Because cockles are highly favored in Thailand and the production of the native cockle (A. nodifera) could not meet the local demand, cockle farmers imported the spats of Anadara granosa from Malaysia beginning in 1973 to overcome the shortage of natural supply of spat and to promote the cockle farming which has developed considerably in places such as Satun, Nakhon Sri Thammarat and Surat Thani. The blood cockle is usually reared close to the shore in estuarine areas with fine mud at the depths of 0.5-1 m. The cultivated area should not be exposed above sea level for more than 2-3 hours during low tide. The culture period is about two years to reach the marketable size of 14-17 grams. The photo shows manual grading of harvested blood cockle.

 

 

Permanent link to this article: https://fishconsult.org/?p=13060

Dec 25 2015

Traditional fish smoking in Chad

Photos’ credit: Aliadoumadji Rimadoum (Chad)

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

Fish smoking in Kiln in Chad (01) Fish smoking in Kiln in Chad (02)

 

 

 

The processing of fish catch from Lake Chad is done by three main methods whereas smoking is one of the oldest and most common methods used. Traditionally, smoking kiln is being in use (shown in the inserted pictures). The smoking kiln measures 1-3 m square x 0.5-1 m high and constructed of mud bricks overlaid with a metal grating to hold the fish, and topped with corrugated metal sheeting or matting to retain the smoke generated by fire from below a rafter; local wood is used for that.

Usually fish is washed, gutted, sun-dried and then smoked. Large fish is usually cut into pieces for proper smoking while small fish are smoked whole. In such traditional smokers, the intensity of heat and smoke is not easily regulated. When large catfish (Clarias gariepinus) is smoked, each fish is coiled head-to-tail. The disadvantages of this method are mainly related to the high wood consumption, less ability to regulate the intensity of heat and smoke as well as the relatively long time required for smoking.

Fish smoking in Chad is women’s responsibility. Women fish processors occasionally hire young men to assist in dressing fresh fish especially during the peak periods of processing.

 

 

Permanent link to this article: https://fishconsult.org/?p=13055

Dec 22 2015

California sea lion (Zalophus Californianus) – Key characteristics – interactions with humans – communications (Video)

I filmed this video in the Sea World, Saint Diego, California, USA during December 2014.
Source: www.fishconsult.org

 Sea lion (Part one)

 

Introduction: California Sea Lion,  Zalophus Californianus  belongs to the family “Otariidae” is found along the coast of the eastern North Pacific, from southern British Columbia to western Mexico including Baja California. California sea lions breed on islands off the coasts of California and Baja California, including the Channel Islands, Guadalupe, San Benitos, and Cedros. They inhabit rocky and sandy beaches of coastal islands and mainland shorelines. They may frequent sandbars; sheltered coves; tide pools; and structures such as piers, jetties, and buoys. California sea lions live for an average of 15 to 25 years. However, they can live 30 or more years.

Key characteristics: Male California sea lions reach about 2 to 2.5 m and 200 to 400 kg while female reaches about 1.5 to 2 m and 50 to 110 kg. Their bodies are tapered at both ends giving them a sleek, fusiform shape.

Generally, adult males are chocolate brown, females and young males are tan, and pups are darker in color than the adults. As adult males age, the hair around their heads lightens to a light tan.

The foreflippers of California sea lions are large and wing-like which are modified and used in an up-and-down, wing-like motion to propel themselves through the water. The hind flippers are smaller than foreflippers and when rotated underneath they body, they support the sea lion weight and enable them to walk and stand on all four limbs.

The California sea lion has visible external ear flaps on either side of its head. Adult male California sea lions have a raised forehead while females have a lower, smoother forehead.

Like all mammals, California sea lions have short stiff hair covering their bodies. They shed their hair once each year. This molt usually occurs after the breeding season.

Interactions with humans: Sea Lions are considered to be highly intelligent animals. Some species of sea lions are readily trainable and are often a popular attraction at zoos and aquariums. Far important, sea lions have been trained by the U.S. Navy Marine Mammal Program, to help the Navy in water needs especially training them to detain scuba divers.

It is very unusual for sea lions to attack humans and the reported incidences of such attacks or biting has been suggested as territorial acts.

The Moche people of ancient Peru who worshipped the sea and its animals, often depicted sea lions in their art.

Communications: It is believed that Sea Lions are among the most social animals in the world. They are very active when it comes to communication having plenty of ways to send and receive messages to and from each other.

California sea lions are among the most vocal of all animals, through vocalization they produce sounds include barks, growls, and grunts whether above and below water. Roaring is a way that sea lions use to protect their territory when they feel threatened and to keep humans and other animals away. The sea lions also bark and often use do that to interact with each other. Male sea lions barking is when they are looking for and attracting females before mating occurs. Females use a specific vocalization during the mother-pup recognition sequence.

In regard to hearing, sea Lions are believed to have excellent hearing both on land and in the water being the most important senses especially in water where hearing is probably acute. For example, the pups are able to identify the calls and sounds on their mother’s instinctively. It is believed that from birth they are able to memorize what their mother sounds like.

California sea lions have are very sensitive eyes with rounded lenses that allow their eyes to focus on light that is refracted upon entering water. They enjoy the light-gathering ability of the rod cells. In the water, their eyes adapt easily to decreasing light levels while on lad, their visual acuity is the dramatically decreased.

The smell is important to sea lions especially on land, in particular in female-pup recognition and male recognition of estrous females. Sea lions may be able to detect a human by smell from hundreds of meters away.

The sea lions use their sensitive vibrissae to explore objects on land and in the water. They seek out physical touch with other sea lions and form groups and lye with each other on land.

Permanent link to this article: https://fishconsult.org/?p=13053

Dec 22 2015

Pond feeding of snakehead using extruded feed in Vietnam – Video

Video credit: Hai DO Xuan (Vietnam)

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

Source: www.fishconsult.org

Snakehead (02)

 

 

 

Carnivorous snakehead is a popular freshwater fish in Vietnam because of its fine flesh and flavor as well as its important role in human health. The main species of snakehead farmed in Vietnam is the common snakehead (Channa striatus); the giant snakehead (Channa micropeltes) is also farmed.

Traditionally, snakeheads were mainly fed trash fish (by catch from marine fisheries) or wild freshwater fish. The growing demand on wild fish by snakehead farming exerted significant pressure on freshwater resources in the Mekong. The use of trash/wild fish in snakehead feeding has been found unstable and said to contribute to the depletion of wild fish resources, more water pollution, and unsustainable development. This led to gradual shifting to extruded snakehead feed.

Reports and case studies show that the use of commercial extruded feed resulted in higher growth rate, better pond economics and more sustainable farming system. Upon the use of extruded feed, an average value of feed conversion ratio of about 1.2 – 1.4:1 is a reasonable estimate. The 5 to 6 month growing period is enabling a two crops/year. The popular for common snakehead is 600-700 g/fish.

The video has been filmed in a typical snakehead pond whereas the high density of stocked fish as well as the aggressive feeding is obvious.

 

 

Permanent link to this article: https://fishconsult.org/?p=13049

Dec 21 2015

Building fish enclosure in Lake Nasser, Egypt – Video

Video credit: Ahmed Haggagi Abdullah (Egypt)

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

Source: www.fishconsult.org

Building fish enclosure in Lake nasser

 

 

 

 

 

This video shows the construction of an enclosure in Wadi Abyad in Lake Nasser. This activity was funded by the Challenge Program on Food and Water.

The area of the enclosure varies according to the water level reaching 99 ha, 156 ha and 199 ha when the water level is 170 m, 175 m and 180 m above sea level. The mouth of the enclosure measures about  100 m while water depth within the enclosure fluctuates and ranges from 1-12 m.

The enclosure shown in the video was selected using contour maps having in consideration key criteria such as width at the opening, depth of the opening where the nets will be set, area of the enclosure at different water levels, distance from landing harbors and availability of natural food.

The nets were designed to close up the enclosure mouth completely down to the bottom, to ensure that no fish escape.

Nets are made of multifilament nylon, treated with antifouling, and had a stretched-mesh opening of 3 centimeters. Nets pieces were sewn together using nylon thread to make one piece of 140-m length with ropes at both extremities, the upper part to fix the float line and the bottom extremity to fix the weight line.

The buoys, measuring 100 x 60 x 40cm, were made of painted 2-millimetre (mm) iron sheet, fitted with rings and set at 5-metre intervals along the float line. The float line was made of 12 -mm steel cable with rope. The weight line was made of 8-mm iron chain twisted along a rope to settle the net to the bottom.

After the net closing of the enclosure, the removal of predators was done using bottom gill nets for Nile perch, Lates niloticus,  Malapterurus electricus & Mormyrus kannume and floating gill nets for Hydrocynus froskalii and Alestes dentex.

Afterwards, a total of 2.2 million of Nile tilapia fingerlings of about 15 g and fry of an average weight of 2-5 g were released in the enclosure over three consecutive stockings. Fishing in the enclosure began six months after stocking.

The final report of this project could be visited at the following link:

https://cgspace.cgiar.org/bitstream/handle/10568/3923/PN34_WorldFish_Project%20Report_Jun09_final.pdf?sequence=1

Permanent link to this article: https://fishconsult.org/?p=13037

Dec 16 2015

Fish Culture Development training course (2015) – Prior to graduation

EICA 2015 Group picture (03) EICA 2015 Group picture (02) EICA 2015 Group picture (01)

 

 

 

 

 

The inserted group photos were taken on 12 December, 2015 during the session whereas the group projects were presented. The course has been concluded yesterday December 15.

This 75-day “Fish Culture Development” training course started in Cairo on the 8th of October, 2015. The course has been annually organized and supported by the Egyptian International Centre for Agriculture (EICA) since 1989 for trainees from Africa, Asia and Latin America. The participants in the 2015 course are:

Herman Hennig Hernando (Argentine), MD. Abdul Wahed (Bangladesh), MD. Abdul Hannan (Bangladesh), Andres Loayza Apaza (Bolivia), Fabrice Juliot Mougang (Cameroon), Zanga Adalbert Donatien (Cameroon), Aliadoumadji Rimadoum (Chad), Cristian Camilo Suarez Barazeta (Colombia), Karen Sachica (Colombia), Diego Mauricio Carrillo Freire (Ecuador), Kassa Kassa Eugene (Gabon), Ebrima K.M. Jabang (Gambia), Gloria Akuffo (Ghana), Abdallah Elmgawshi (Libya), Muhammad Hafeez-ur-Rehman (Pakistan), Macedo Aguirre Raul Sergio (Peru), Tariq Mohammed Zakaria (Sudan), Parinya Sutthinon (Thailand), Oberu Charles (Uganda), and DO Xuan Hai (Vietnam).

As occurs every year, Dr. Abdel Rahman El Gamal delivered the first lecture and continues contributing to this course through several lectures as well as supervising the group projects.

 

 

 

Permanent link to this article: https://fishconsult.org/?p=13032

Dec 13 2015

Collection of Spirulina and production of dihé in Chad

Photo credit: Aliadoumadji Rimadoum (Chad)

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

Collection of Spirulina in Lake Chad

 

 

 

 

The inserted picture is for a woman while collecting Spirulina platensis in the brackish waters of the regions of Kanem and Lake Chad. The collection of spirulina is In Chad Dihé is customarily harvested by women from the shallow pools of water where it forms at certain times of the year. Harvested spirulina is used to make dihé. It is estimated that more than 250 tons of dry dihé is produced per year placing Chad; in particular Chadi women as the highest producer of spirulina of lowest cost in the world.

 

 

Permanent link to this article: https://fishconsult.org/?p=13026

Dec 09 2015

Trade and consumption of dried fish in Myanmar

Photos’ credit: Yin Win Myat (Myanmar)

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

Dried fish market in Myanmar (02) Dried fish market in Myanmar (01)

 

 

 

 

The inserted photos were taken in a dried fish market in Yangon, Myanmar. Preserved fish including dried fish in Myanmar plays an important role in the local diet. Even people whose cultural tendency is towards vegetarianism, will still consume dried as well as fresh fish as an essential supplement to their vegetarian habits.

A household consumption study revealed that the expenditure (%) for dried fish ranges from 1.75 – 1.95% of total household expenditure for food. There are quite a few registered plants for dried fish in Myanmar.

Due to the quality concerns especially in regard to chemicals which could be in use to kill flies and maggots that infest dried fish, the use of pesticides is considered illegal according to a new Ayeyarwady Region law whereas violations can result in a significant penalty of jailing and fine. In line with that, the health agencies in regions producing salted fish offer education to the owners of dried fish companies targeting to stop the practice of pesticide use in the salting process.

 

 

Permanent link to this article: https://fishconsult.org/?p=13018

Dec 06 2015

Frog reproduction and metamorphosis – Video

 

Source: www.fishconsult.org

Video provided by: Juan Martin Canturin Garcia (Peru)

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

 

The video starts with the mating in bull frogs which is known as “Amplexeus”. During mating, the male fertilizes the eggs upon their release from female’s body. On the average, a female frog lays up to 4,000 eggs at one time. Fertilized eggs hatch into tadpoles that live in water and are equipped with gills, a mouth, and a tail.

Tadpoles undergo metamorphosis as they develop starting with back legs, then front legs. Afterwards, the mouth starts to widen, then eyes start to bulge out and the tail begins to shrink and eventually disappear.  As the lungs turns full develop, the froglet by then are frogs that make its way onto the land. The changes and modifications through metamorphosis prepared the frogs for a terrestrial existence.

In addition to mentioned changes, the metamorphosis in frogs also includes the replacement of the cartilaginous skull of the tadpole by the predominantly bony skull of the young frog. Moreover, the horny teeth the tadpole uses to tear up pond plants disappear as the mouth and jaw take a new shape, and the fly-catching tongue muscle of the frog develops. In order to suit the feeding behavior of frogs, the large intestine of tadpole (herbivores) shortens in frogs (more carnivorous).

 

If interested to know more on frog culture, you are invited to watch the full video on the following link:

https://youtu.be/22Q2S5KxPBU

 

Permanent link to this article: https://fishconsult.org/?p=13016

Dec 03 2015

Introduction and culture of Pacific oyster in Vietnam

Credit for the photo and key information: DO Xuan Hai (Vietnam)

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

Culture of Pacific oyster in Vietnam

 

Oyster culture in Vietnam (02)

Pacific oyster (Crassostrea gigas) was introduced into Vietnam from China and Australia in 2002 (for research/aquaculture). Several methods have been adopted in the culture of oyster in Vietnam.

Some of the cages shown in the inserted picture are used for finfish culture while oysters are cultured on ropes which are fastened to the bamboos above. The culture of Pacific oyster within marine finfish cages is a common practice as the nutrient-rich waters result from the finfish cages provide a nutrition base to oyster that feeds by filtration; grouper and cobia are the common fish species cultured in such cages. Water depth in this location is about 9 meters.

The major advantages of rope method include higher growth rate and better quality of produced oyster. This is in addition to higher survival rate due to the avoidance of bottom dwelling predators.

Farmers grow their oysters on recycled shells whereas each shell hosts three spats. Shells are placed to 1.5-m ropes which are fastened to the upper bamboos with about 50-cm intervals. The growing season of oysters in this region takes about 9 months from a spat to a commercially acceptable mollusk.

The culture of Pacific oyster takes place in several provinces including Halang Bay and Calaba Island. There is at least 10,000 low-income families do live in the Ha Long Bay area with the ability to adopt or diversify into oyster farming.

Because Vietnamese consumers readily accept and appreciate oysters, produced oysters are mainly marketed locally through oyster markets which are developing rapidly and allow to absorb the vast majority of oyster production. Export markets for Vietnamese oyster would always depend on quality assurance of produced oyster.

 

 

 

 

Permanent link to this article: https://fishconsult.org/?p=12984

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