Photo credit: Rex Vargas (Philippines) Description: Rex Vargas and Abdel
Rahman El Gamal (Founder of the website)
The inserted picture shows the stocking of
tilapia fingerlings in Lake Lahit (Philippines). The lake is one of three lakes
located in South Cotabato in Lake Sebu town. The Lake with its 24-ha size is
the smallest of the three. Because the lake was declared by the government as free-fishing zone, there
are no fish pens in this lake. The dispersal of tilapia fingerlings in the lake
is done
to replenish the captured fish and to balance the aquatic ecosystem.
Photo credit: Diego Mauricio Carrillo Freire
(Ecuador) – Review: Diego Mauricio Carrillo Freire and Abdel Rahman El Gamal
(Founder of the website)
The inserted picture shows a circular tank made of reinforced
concrete located in the Ecuadorian highlands. The tank is used to produce
rainbow trout Oncorhynchus mykiss following semi-intensive practices.
The introduction of trout (Oncorhynchus mykiss) into Ecuador took place in 1940s for sport fishing and then after used in aquaculture. According to FAO statistics, trout production from aquaculture amounted 3,200, 3200, 4500, and 6,051 tons in 2013 till 2016 respectively. Rainbow trout aquaculture has developed mostly in the inter-Andean region of Ecuador.
It is believed that expanding trout culture in Ecuador
would be possible in the light of the availability of the many rivers and cool,
unpolluted waters in the highlands of Ecuador. However, the main problems
related to trout culture need to be addressed; formulating and manufacturing
trout feeds suitable for all life stages of trout with a reasonable cost is
seen a key obstacle at the moment.
In order to enhance the productivity
and in the same time avoid inbreeding within the rainbow trout, the Ministry of
Agriculture, Livestock and Fisheries (MAGAP) in Ecuador has developed a project
for improving the genetic lines of the species through purchasing eggs or fry
from the US, Denmark and Spain. Added to that, the project includes the
upgrading and equipping of the two trout breeding centers.
Away from aquaculture, the species is commonly found in
the rivers and lakes of the country’s sierra region and hence widely available
in stores and roadside stands.
This video was filmed
during my visit to the Sea World, California, USA.
Introduction: The leopard shark, Triakis semifasciata belongs to the hound shark, in the family Triakidae. The species is small and pretty animals. The species
is harmless to humans if they are not disturbed and hence divers can safely
come close enough to the leopard shark and photograph them especially when not agitated
or frightened. In fact, only a single mild injury for a diver was reported in
1955.
The species have lived in aquariums
for up to 20 years while their lifespan in the wild is up to 30 years.
Range and habitats: Leopard sharks are found in the
Eastern North Pacific Ocean: from the coast of Oregon to the Gulf of California, Mexico. They occur in abundance in San Francisco Bay and other large estuaries. The
leopard shark inhabits inshore and offshore cool and temperate waters.
In shallow waters, the species is most common on or near the
bottom between zero to 4 meters. Inhabiting a depth of up to 90 meters has been reported. Leopard sharks
prefer sand flats, muddy bays and rocky bottoms near reef sites and kelp beds.
Description: The leopard shark has been named for its for its distinctive bold dark saddles and spots on
the fins and upper body. The species is characterized by their gray to
bronze-gray upper bodies with light ventral
side.
The species have relatively
broadly-rounded and short snouts. Leopard shark teeth are arranged in
overlapping rows.
The average size of adult leopard
shark ranges between 1.2-1.5 m with a maximum reported total length
of about 1.8 m with a maximum weight of about
19 kg.
Feeding habits: Leopard sharks are opportunistic
feeder preying primarily on bottom-living invertebrates.
While invertebrates dominate their diet, other preys have been found in their
stomachs including worms, crabs, shrimp, clams, octopus, and other small
sharks. Their feeding habits may change according their size as well as the
seasons.
On the other hand, the small leopard
sharks are preyed
upon by large sharks such as the great white shark and the broadnose sevengill
shark.
Reproduction: Leopard sharks are Ovoviviparous animal producing between about 4
to 30 pops per litter after a gestation
period of about 10-12 months. Being an Ovoviviparous, the eggs produced by the female are
maintained in a brood chamber until the embryos develop relying on nourishment from a yolk sac and hatch
internally within the mother’s uterus. Upon birth, the pop size is about 20 cm.
Leopard sharks reach their sexual maturity at
about 10 years whereas the size of mature female ranges from 1.1 to 1.3 m
compared to 0.7 to 1.2 m for mature male.
Habits: The leopard sharks are nocturnal animals and normally sleep during
the day. They can be found resting
still on sandy bottoms.
With the exception of few specimens of
leopard sharks found hundreds of miles away from their home, the species are
known to remain in the same area for much of their lives (homebodies). Leopard
sharks are strong swimmers and they are known to swim a strong undulating
motion in large groups.
Adaptation to environmental conditions: Leopard shark was found to have numerous
small red blood cells compared to related shark species. This adaptation
enables the species to absorb oxygen more easily in low oxygen environments
such as estuaries which is considered a competitive advantage over some of its
close relatives of sharks.
Utilization: The leopard shark’s meat is used for human consumption,
and it is usually commercially fished and by recreational anglers.
Threats and
conservation
Threats: Because of their slow growth rate and their late maturity (about
10 years) as well as their few progeny,this species has been believed
to be vulnerable to overfishing. However, according to the International Union for Conservation of Nature (IUCN) Red List of Threatened Species criteria, the
species have been listed as Least Concern.Conservation initiatives: In order to protect the
core population of leopard shark in the light of the increase of spearfishing,
the state of California (USA) implemented fishery management regulations in
1992 to protect the core population of the species in California and Oregon
waters from overfishing and reduce its harvesting to sustainable levels.
Photos’ credit: Marx Perfecto C. Garcia (Philippines) – Description: Marx Perfecto C. Garcia and Abdel Rahman El Gamal (Founder of the website)
The arrangement of such aquaculture support is managed by the local government units (LGUs) and the Provident Fund Offices (PFOs). Fish fingerlings shown in one photo are either delivered or picked up in the or by the respective provinces or municipalities.
The second photo shows packs of fingerlings that were picked up by one of the municipalities in the Cordillera Administrative Region (CAR) to be dispersed to their constituent fisherfolk beneficiaries. The Bureau of Fisheries and Aquatic Resources (BFAR) in cooperation with CAR provide fingerlings at no cost as input assistance to improve the fisheries production in the region as well as provide fish sufficiency and alternative livelihood to the aquaculture operators.
This video was filmed in a Kenyan fish
farm where different aquaculture activities on several species are taking place
including tilapia, catfish, and ornamental fish. This video shows the feeding
during the larval nursing of African catfish, Clarias gariepinus. As shown, the food provided is decapsulated artemia cysts.
The nutritional value of the decapsulated
artemia cysts has been documented through research and applications upon the nursing
of several fish species including African catfish. For that reason, the
use of decapsulated Artemia cysts is considered a good alternative to artemia nauplii
and hence it has been
widely used for the larval rearing of several species including African catfish
especially under intensive culture conditions. The decapsulated cysts are completely digestible by the fish or shrimp
larvae.
The decapsulation procedure is carried out by chemically removing or
oxidizing the outer chorion of the cyst using hypochloride solution.
The
cysts used in direct feeding are produced through specific processes that do
not consider hatching process. It is believed that the decapsulated cysts have
a higher energy and nutritional value compared to live Artemia nauplii having
in consideration that zero energy is consumed in the hatching process.
Similarly, lipids, amino acids, and enzymes are left intact. The nutritional merit of the dried artemia cysts can be enhanced through its
enriching with vitamin C.
This inserted picture has been taken from a publication by Auburn University (USA) published on December, 1970. Being an Auburn University Alumni, I decided to share this picture along with the description: “Pond culture with Biological Filters: Water, pumped from a pond where fish are fed, is filtered through gravel covered with living microscopic organisms then returned through a gravity flow system. The photo shows a filter in the background, some of the ponds in services, the water return system in the foreground. With this system production of 10,000 pounds of catfish per acre in approximately 6 months has been obtained. Practical applications of the system are now being studied”.
Photo
credit: Muhammad Hafeez-ur-Rehman (Pakistan), Description: Muhammad Hafeez-ur-Rehman
and Abdel Rahman El Gamal (Founder of the website)
The inserted picture was taken inside a feed mill in
Pakistan. Before having commercially produced feed, fish farmers used to
formulate feed based on earlier experience or simply on trial bases.
In the present, several feed mills are furnished with
extruders. The volume of produced feed could be estimated from the species
composition of aquaculture in Pakistan. According to FAO statistics, total
aquaculture production in 2016 amounted 156,430 tons; out of which, cyprinids
represent 97.7% while tilapia, crustaceans (freshwater and marine water), as
well as other freshwater species share the remaining 2.3%.
The ingredients used in fish feed are locally available products
with no imports. The plant-based
ingredients include sunflower meal, soybean meal, rice polish, rice bran, and maize
gluten while animal-based products include fish meal, bone meal, feather meal (hydrolyzed),
and others.
It worth noting that the cost of fish feed represents an
obstacle to fish farming industry in Pakistan especially when compared with the
farm-gate prices of produced fish species.
Video credit: Fadhili
Ruzika (Tanzania) – Review: Abdel Rahman
El Gamal (Founder of the video channel)
The vigorous feeding of tilapia as shown in the present
video indicates the high density of stocked fish in the tank. The video also
shows that the feed provided has been -most likely- mixed on the farm.
Regarding the market size, the size of tilapia as shown in the clip has not
reached the market size yet and hence, more time will be required before
harvesting.
Tanzanian aquaculture with its current 5000 tons in 2016 is
composed mainly of tilapia contributed with 3800 tons in 2016 representing more
than 75% of total aquaculture in Tanzania. The imports of tilapia whether in
the form of frozen fish or chilled fillets indicates decent demand on tilapia
in Tanzania.
Photo credit: Kaulo
Salushando (Namibia) – Review: Abdel Rahman El Gamal (Founder of the website)
The inserted pictures show the harvest of a small fish farm located in Otjozondjupa Region (Namibia). Based on official publications, the fish farmers in the Otjozondjupa region who are mostly private individuals who are culturing fish for subsistence or recreational purposes.
According to FAO statistics, fish production from
aquaculture in Namibia -excluding aquatic plants- amounted 515, 505, and 461 tons
in 2014, 2015, and 2016 respectively.
While farmed oyster dominates the total aquaculture
production (86.3% in 2016), tilapia is the leading freshwater species with a
production of 65, 50, and 46 tons during the period from 2014 to 2016 respectively
representing 12.6, 9.9, and 10% of total aquaculture during the mentioned
period. Minor quantities are produced whether in freshwater or marine water
including African catfish, mussel and abalones.
According to the National Aquaculture Master
Plan for Namibia, the analysis and challenges for developing the potential of
freshwater aquaculture was completed leading to the establishment of a series
of Inland Aquaculture Centers and farms in some regions in Namibia including Otjozondjupa
region.
Video credit: Hisham El Gazzar (Egypt) – Description: Abdel Rahman El Gamal (Founder of the website)
The inserted video was filmed in a sea cucumber hatchery in South Korea. The leading farmed species is (Apostichopus japonicus) known as Dolgi Haesam. Also, the orange-footed sea cucumber (Cucumaria frondosa) has been tried. The hatchery-produced seed are either released in natural waters in stock enhancement programs or grown in farming facilities.
Typically, the broodstock are
collected from the wild about 60 days before the spawning season and then placed
into conditioning tanks at ambient seawater temperatures and then increasing
water temperature by one degree °C/day until reaching 15-18 °C, by then, animals
are ready to spawn. During that period, sea cucumber potential spawners are fed
a commercial diet which mainly consists of powdered algae such as Spirulina
spp. or Dunaliela spp. Feeding stops a day before the spawning that is induced
by a thermal shock through an immediate exposure of the animals to warmer water
of about 3 to 5°C higher.
Once eggs are laid and fertilized, the
fertilized eggs are scooped using nets with appropriate mesh sizes depending on
the species, and transferred to culture rectangular tanks with around 5 x 3
meters and about one-meter depth. According to published reports, the
above-mentioned tank holds up to a million larvae. The newly hatched larvae are
fed a special diet of microalgae according to their age.
After
approximately seven to eight days, the free-swimming larvae are close to the
settlement stage and hence settling plates made from clear corrugated PVC
sheets are placed in the larvae rearing tanks. Upon settlement, different feed
is provided to the new juveniles consisting of a mixture of mud or bentonite,
yeast, and powdered algae. The sea cucumber juveniles are grown on the settling
plates for about a year before transferring them to either the wild in stock
enhancement programs or to sea cages for grow-out.
