According to 2005 statistics, the production of milkfish in brackishwater in the Philippines comprised the largest proportion of milkfish production, followed by fish cage farming in marine waters and finally the culture of the species in pens in freshwater areas. In regard to the productivity of the species per unit area, it was highest in marine environments which could be attributed to the proper depth of pens, favorable water conditions and the strict use of commercialized feeds.
Video credit: Waleed Masood (Egypt)
Review: Abdel Rahman El Gamal
The video shows the catch by two members of the sport fishery team while using two different fishing methods; long line and hook and line.
Hamata is the most southerly diving resort in Egypt’s Red Sea; situated about 180 km south of Marsa Alam, and about 360km south of Hurghada. Recently, Hamata is quickly becoming one of the southern Red Sea’s finest attractions. The mangroves attract a wide variety of birds all year round, with many more passing by during migration times.
Hamata is one of the best dive sites in the Red Sea. Similarly, Hamata could be one of the best fishing locations in the Red Sea region. Along with the great coral life there is the chance to see a variety of marine life including Barracuda, Dolphins, Turtles, Napoleon Wrasse, Reef Sharks, Stingrays, Moray Eels, Pipefish and even the occasional passing Whale Shark or Manta Ray.
This project is is located in Mullak Valley, Ismaelia, Egypt. This integrated project has two main components; fish and horticulture. The total acreage of the project is 8 hectares.
Fish production component includes four 250-m3 tanks of 130 cm water depth. One of which, is allocated for the production of Nile tilapia fingerlings of 25-g average size while the three remaining tanks are allocated for grow-out. The target average harvestable size is 350 g after 7-8 months. Fish tanks are aerated using paddle aerators. The rate of water renewal is based on the requirements of agricultural crops. Fish unit has the structure that provides its coverage by plastic sheets during winter months and hence allows regular growth during cold weather.
The project is served by three sedimentation tanks which receive the surface water from the supply canal and provide enough retention time before passing water to fish tanks as well as to agriculture. Each of the four tilapia tanks (fingerlings and grow-out) is served by one of the four biological filters. The media used for bio-filtration is locally available plastic materials which provide large surface areas as required for the bio-filtration. Biological filter tanks are aerated using fountain type aerators.
The project is also equipped with a mechanical filter unit which has a capacity to trap up to 100 micron particles and allows a water flow of 120 m3/hour. The mechanical filtration serves the fish component as well as the agriculture component to avoid the clogging of nozzles in water supply system.
The estimated target production is 50 kg/m3/production cycle. As the project has been planned to support 1.5 production cycle/year, the total market size fish produced is 54 tons/year.
The agriculture component which covers the rest of the 8 hectares are used for guava and mango production bearing in mind that Ismaelia is the principal mango producer in Egypt.
If you are interested to see the construction phases as well as some of the project equipment (e.g. mechanical filter), you are advised to visit the sister website of this channel: www.fishconsult.org
This image was taken in the Centro de investigación y produccion acuicola Henry von Prahl “Research and Production Center Aquaculture Henry Von Prahl” of the Pacific University, in the municipality of Buenaventura, Valle del Cauca – Colombia.
In the photo one can see a coconut palm and lush greenery around in a region with a rainfall of 8,000 mm / year. The 1000-m2 ponds shown in the photo are of the typical size used by peasant families whereas red tilapia are farmed at a density of 5 individual /square meter which is considered a semi-intensive farming.
The attached photos are from Germany on the farming of Mytilus edulis (blue mussel) in the Kiel Fjord (Western Baltic Sea, brackish water with approximately 15 PSU salinity).
Mussels are grown on longlines (100m long, 7.5m distant from each other, 10 m water depth). On the longlines mussel substrates (collector material during spatfall of mussels) and app. 4 months thereafter mussels are restocked in special mussel”socks” (net tubes with different mesh sizes) that contain young mussels with a size of 1-2cm. Mussels grow 18 month from larvae settlement until harvestable size (5 cm) in 1-4m water depth. Harvest season is from autumn until spring (September until April), when temperatures are low.
This video was taken in Monterey Bay Aquarium (USA)
Introduction: Sea pens are colonial invertebrate marine cnidarians which belong to the order “Pennatulacea”. They are named because of their upright feathered appearance that resemblance the old fashioned quill pens. It is believed they occur in shallow and deep waters in tropical and temperate waters worldwide. They live possibly as long as 15 years.
Habitat:Sea pens are found in sheltered inshore of calm current waters, or in deeper offshore waters at depths which could range from 12 m to deeper water of 100 m or possibly at greater depths. They often prefer deep water where turbulence is less likely to uproot them. Their preferred substrate is the sandy one that enables anchoring themselves in sand or mud beds on water beds.
Description: Sea pen is a colonial animal with a central rigid stem (developed from a polyp) that bears polyps (hollow stalks with a mouth and eight tentacles like leaves on either side of the stem which acts as the foot that anchors the colony in the sand or the mud, supports the whole colony and retracts the whole colony into the ground at low tide. This central stem is usually stiffened by an internal structure made of calcium. Although the Sea Pen is anchored into the ground, it is possible for them to detach the anchor from the sand or mud and move to a new spot whereas they get more protection or more food.
Sea pens come in a variety of colors and sizes. In regard to size, they can grow up to 60 cm in length. Their color ranges from dark orange to yellow and white.
Feeding habits: Sea pens are suspension feeders, meaning they need some water current for drifting their food into their grasp. Their food is mainly small organisms especially zooplankton which are captured by the tentacles at the end of each polyp. Once a feeding session is done, the sea pens retreat and contract.
Reproduction: The sexes are separate with each colony of polyps are either male or female. In some sea pens while the eggs and sperm are released from the polyps in other sea pen species whereas external fertilization occurs. A female colony can release more than 200,000 eggs. After about a week of hatching, the free-swimming larva (planula) settle to the sea floor and metamorphoses to form the axial polyp of a new colony.
Vulnerability to predators: Sea pens are preyed upon by some predators especially most sea stars. Their predators include also some snails and a number of nudibranchs.
Human uses: These animals are sometimes taken for the live aquarium trade. However, they require special care which is there with less experienced keepers.
References: BBC, Wikipedia, WiseGEEK, National Geographic, Wild Fact Sheets, Encyclopaedia Britannica, Scuba Diver Life, the Columbia Encyclopedia.
The fish specimen shown in the photo is White Cachama, (Piaractus brachypomus) which belongs to the family Serrasalmidae. The Cachama white is a native to Colombia and widely distributed within South America, The species enjoys consumer preference and so good market due to its good quality flesh. This species suits well to aquaculture conditions and can reach an average weight of 500 g in 6 months when stocked at a density of 4 fish/m2density with a constant water supply.
This species is recommended for rural communities. It accepts commercial concentrates as well as can feed on palm seed cultivation, bore, papaya, guava, banana, maize, cassava leaves, etc. as a dietary supplement. This means they could be fed on concentrates in the morning while offered any of the mentioned supplemental food in the afternoon.
The specimen in the photo is for a male of white cachama that undergoes the selection for reproduction induction.
The top structures seen over the fish ponds are lines of thread, which are used as a network to prevent fish poaching by birds. These lines of thread are made of weather-resistant materials, and must be placed at a height of 1.8 meters above pond dikes to act against birds and in the same time to allow pond workers to perform their duties. The lines are normally tied to a thick steel wire, this is located in parallel at each end of the pond, and the ropes are performed every 8 feet away from the other a line. The use of such non-lethal, environmentally safe methods of bird exclusion methods has increased in compliance with the protective wildlife legislations.
Rosario Rivera Meneses, Juan Suárez Sánchez, Luz del Carmen Pérez González, Johannes C. Van der Wal, Hipólito Muñoz Nava and Salvador Morales Moreno, 2013. Comparison of experimentally elaborated food from regionally available products with commercial foods of common carp (Cyprinus carpio) in the Mexican highlands.
This one-slide bite tackles the sea-water ice in regard to the rationality and effectiveness in preserving fish. A comparison between freshwater ice and sea-water ice has been highlighted especially in regard to the melting temperature and possible effect on chilled fish.
