Aug 06 2014

Enforcing inland fishery regulations in SriLanka

Credit: Ajith Kumara (SriLanka)

One of the photos shows one of the monthly visits to a fish landing site as carried out by fishery officials which is done in several reservoirs. The purpose of these visits is to acquire biological data on commercial fish species which were in this reservoir Nile tilapia, Oreochromis niloticus and O. mossambicus. During the monthly visit, the data collected include length frequency and reproductive biology such as stage of maturity, fecundity, gonado-somatic index, etc.).

The gill nets of mesh size above 84 mm are the only fishing gears allowed to operate in inland waters. If the fishing regulations are violated, it turns to court and appropriate penalty is applied. This is in addition to destroying the illegal nets (usually burning).

The second photo shows a holding device which is used by fishermen who temporary hold their catch for overnight till selling it in the following morning as fish vendors show-up. This wired device when placed in an identified body of water will help to keep the caught fish alive for overnight.

 

Enforcing fishery regulations (01) SriLanka Enforcing inland fishery regulations in SriLanka (02)

 

Permanent link to this article: https://fishconsult.org/?p=11473

Aug 05 2014

Kraal fishery in lagoons and bays in SriLanka

Credit: Ajith Kumara (SriLanka)      Review: Ajith Kumara and Abdel Rahman El Gamal

The photos show a traditional fishing method “Kraal fishery” which has been in practice for centuries in SriLanka. This trapping method is designed to catch shrimps in lagoons and bays. This pen enclosure is prepared against tidal fluctuations blocking the migration pathway of shrimp and fish that accumulate inside the trap. The local name of this trap is “Jakotu”. Wooden poles, nylon nets and circular steel parts are materials used in the construction of “Kraals”.

There are some negative effects which could be related to the practicing of “Krall fishery”; catching of under-sized fish is a key side effect. In order to address such possible negative effects, regulations have been issued during the licensing procedures or throughout the operation. The mesh size, the distances to be left for passage of craft, the distance between Kraals, night lightening and the closing of fishery season are examples of the governing regulations of Kraal fishery. It should be noted that the enforcing the governing regulations on “Kraal” fishery is not easy due to social matters.

Kraal fishery (Srilanka) 01 Kraal fishery (Srilanka) 02

 

 

Permanent link to this article: https://fishconsult.org/?p=11468

Aug 04 2014

Selective harvest of farmed mullet in Egypt

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

The inserted photos were taken in a fish farm in Egypt whereas the management in this farm is similar to many other farms in Egypt. As shown in the photos, the target species is mullet especially flathead grey mullet (Mugil cephalus). Usually, in such system, Nile tilapia is the main farmed species in freshwater and brackish water systems. Tilapia could be cultured in a monoculture systems otherwise mullets are may be incorporated with tilapia in a polyculture system.

Even though, mullets often enjoy higher farm gate prices, its monetary value turns much higher when marketed in the spring for salting operations. Traditionally, the consumption of salted mullet is remarkably high during the Eastern that falls in April every year. The attractive farm gate price for mullets during this season encourages fish farmers to postpone the harvest till sometime in March especially mullets can continue growing –even at lower rate-during winter. The fishing gears used along with the experienced labor allow the harvesting of selected mullets of around 400 g and above leaving the remaining standing crop of tilapia and mullet to continue growing for some more time.

Selective harvest of mullet 02 Selective harvest of mullet 01

 

 

Permanent link to this article: https://fishconsult.org/?p=11463

Aug 03 2014

A typical fishing trip and catch in Golinga Dam, Ghana – Video

Source: www.fishconsult.org

Credit: Ivan Venkonwine Kaleo (Ghana)

Golinga Dam is the fishery resource in which fishing practice is taking place. One of the two fishermen lives in Tamele town while the other lives in Gbulahgu Village. Canoes are the common fishing boats operating in the dam; the local name of this canoe is “Narin”; “Dagbani” in local language.

The quantity of fish shown in the canoe was caught after 2-hour fishing trip in the dam whereas the cast net is the common fishing gears in use. The principal fish species in the dam are Nile tilapia, Oreochromis niloticus, Sarotherodon Galilaea, Tilapia zillii, Heterotis niloticus, Brycinus spp and catfish. However, the catch shown in the video consists of Heterotis niloticus (Bigger fish) in the extreme right while smaller-size fish of Brycinus nurse and Oreochromis niloticus are found in the middle. The modest quantity of the catch could be a result of the time of the day they started fishing and also the method used in fishing which is cast method. It may worth mentioning that the Dam is subjected to over fishing.

The Golinga Dam is of importance due to the fact that it is the main source of affordable protein source for the rural people living around the dam and also Tamale Township and beyond. Moreover, the dam serves as the source of water to a number of earthen fish ponds which have been constructed for community management.

Consumer preference is usually skewed toward the bigger fishes, but the smaller fishes are sold at moderate prices.

 

 

 

 

 

Permanent link to this article: https://fishconsult.org/?p=11244

Aug 01 2014

Cage culture of Nile tilapia in Volta Lake (Ghana)

Credit: Patrick Appenteng (Ghana)

With the booming of cage aquaculture on the Volta Lake in Ghana, more farms keep springing up with varied technologies and materials for construction. This picture shows plastic gallon-like material used as floats for four (4) cages of dimensions 5m×5m×5m.

This picture was taken a few meters from the famous Adomi bridge on the Volta Lake in the Asuogyaman District of Ghana; at a suburb called Atimpoku. Stocked species is Nile tilapia, Oreochromis niloticus.

Cage culture of Nile tilapia in Lake Volta (Ghana)

 

 

Permanent link to this article: https://fishconsult.org/?p=11239

Aug 01 2014

Capturing the moment of molting in shrimp – Video

Credit for the video: Ahmed Shaheen (Egypt)

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

In this short video one can see the molting moment of a shrimp specimen (marked in red). I guess that was a sort of luck to catch this moment.

Molting is an essential process for the growth of shrimp in which molting cycles are repeated several times in order to allow growth throughout its life. Upon molting, the shrimp body will absorb water and grow large, then there hardening of the shell. After a hard outer shell, shrimp body size remains until the next molting cycle. As expected. The molting frequency during the early stages of life cycle of shrimp is much higher compared to that in larger size shrimp; this is based on the high relative growth rate in young animals compared to that in adults.

Molted shrimp lived its most critical phase. Until the new outer shell is hardened, molted shrimp are susceptible to diseases infection and vulnerable to other shrimps (cannibalism) and other predators.

There are two hormones controlling the molting process in shrimp. Molting stimulating hormones are produced and secreted by the Y-organ while the X-organ -which is located on the eyestalk, produces the molt-inhibiting hormone that prevents the release of the molt stimulating hormones. That is why the eyestalk ablation in shrimp leads to precocious molt, and molting occurs several times following ablation.

 

 

 

Permanent link to this article: https://fishconsult.org/?p=11231

Jul 30 2014

Role of vocal sacs in the mating calls in frogs

Photo credit: Ever Edrey Hernández Cuadrado – (Colombia)

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

The vocal sac or pouch is a flexible membrane of skin possessed by most male frogs and is found below its mouth. The vocal sac is used by males to call and attract females from a large area as a part of mating. It is believed that vocal sacs of some species can be heard over 1 km away.

When a frog calls, it inflates its lungs and shuts its nose and mouth. The sound is produced by expelling the air from the lungs, through the larynx, and across the vocal cords. The resulting sound vibrations are amplified by the resonating qualities of the vocal sac.

Muscles within the body wall force the air back and forth between the lungs and vocal sac and hence the sound is produced without expelling air.

Vocal sacs in frogs

 

Permanent link to this article: https://fishconsult.org/?p=11227

Jul 29 2014

Integrated agriculture-aquaculture project (IAA) in Kagera, Tanzania

This project has been developed by a group of trainees who participated during 2014 in the “Fish Culture Development – Africa training course” which is hosted by the Egyptian International Centre for Agriculture (EICA) in partnership with Japan International Cooperation Agency (JICA). The proposed location of this project is Kagera, Tanzania. The project document covered in details the integrated components in which Nile tilapia and African catfish represented the aquaculture component. The chosen agricultural crops were Tomato and cabbage. Moreover, local breed of poultry was also included in the system. The rationality as well as the technical sides of the project is adequately covered in the project document that is supported by diagram as well as the budget analysis ending by economic indicators such as payback period.

This project is one of more group projects which have been supervised by Dr. Abdel Rahman El Gamal.

http://fishconsult.org/wp-content/uploads/2014/07/Integrated-agriculture-aquaculture-project-in-Tanzania.pdf

Permanent link to this article: https://fishconsult.org/?p=11222

Jul 28 2014

Fishery of Beni River (Bolivia)

Credit: Felipe Alviz Costa (Bolivia)

The fishing boat seen in the photo is in the Beni River which is a major river of the Bolivian Amazon Basin. The most commonly fished and consumed species are pacú, tambaquí, surubí, palometa (a type of piranha), sábalo, bagre (catfish), and blanquillo. Alligators are also hunted for their leather and meat, which is considered a delicacy and is a common part of meals in Beni.

Fishery of River Beni (Bolivia)

 

 

Permanent link to this article: https://fishconsult.org/?p=11217

Jul 27 2014

Water lily on the Kpong stretch of Volta River (Ghana)

Credit:Patrick Appenteng (Ghana)

Aquatic weeds which pose a lot of threat to the natural ecosystem of most water resources can never be overlooked; most of which are invasive. Apart from the fact that it hinders the optimum growth of target fishes, it also obstructs navigation, among many others.The insert shows water lily taking a toll on the Kpong stretch of the Volta river in the Lower Manya Krobo District of Ghana.

Water lily in Volta River (Ghana)

 

 

Permanent link to this article: https://fishconsult.org/?p=11213

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