May 18 2017

Dungeness crab (Biology, fishery and conservation) – Video

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

 

 

This video was filmed in a retail shop located in Monterey, California (USA) where different fish species and crabs are sold. The Dungeness crab is the crab species shown in this video whether sold iced or displayed live.

The Dungeness crab, Metacarcinus magister (formerly: Cancer magister), is also known as market crab, and San Francisco crab and belongs to the family Cancridae. Its common name comes from the port of Dungeness, Washington.  These crabs are one of California’s most popular shellfish and popular seafood prized for its sweet and tender flesh.

Geographical range and habitats: The geographical range of Dungeness crab extends from Alaska’s Aleutian Islands to Point Conception, California. They inhabit eelgrass beds and are usually found on sandy or sand-mud bottoms. Dungeness crabs generally prefer cooler northern and central California waters while they are uncommon south of Point Conception. Typically, these crabs are found at depths of less than 300 feet. Their recent appearance in the Atlantic Ocean, far from their known range has raised concerns about their possible effects on the local wildlife.

Description: Dungeness crabs have a wide, long, hard shell, which they must periodically molt to grow. They have five pairs of legs, which are similarly armored, the foremost pair of which ends in claws the crab uses both as defense and to tear apart large food items. The crab uses its smaller appendages to pass the food particles into its mouth. As been established, the legal measurement for crabs is defined as the shortest distance through the body from the edge of the shell to the edge of the shell directly from front of points (lateral spines). Dungeness crab is one of the largest edible crabs along the Pacific Coast of America. Dungeness crabs are characterized by their light reddish brown on the back.

Typically, the carapace width of mature Dungeness crabs is less than 20 centimeters with females much smaller than males whereas in the adult stage, the average size of female seldom attains a width much greater than 17 centimeters. In females, the abdomen, or tail flap, is much broader than in the male crab. This broad tail flap is allows to accommodate and protect the very large number of eggs until hatched. In both male and female, the tip of the last segment of the tail flap is rounded. As been established, the legal measurement for crabs is defined as the shortest distance through the body from the edge of the shell to the edge of the shell directly from front of points (lateral spines).

Feeding habits: Dungeness feeds on a variety of marine invertebrates and fish. While juveniles feed on fish, shrimp, molluscs and crustaceans, adults feed on bivalves, crustaceans and fishes. They use their pinching claws in opening shells.

Life cycle: Mating between mature crabs occurs immediately after the female has molted and before the new exoskeleton hardens. Upon mating, the female extrudes the eggs from her body several months later; however, they remain attached under her abdomen for three to five months until they hatch into free-swimming crabs which go through five larval stages before reaching maturity after about 10 molts or two years.

Dungeness crab fishery: The most popular methods for catching the crustaceans are with crab pots (or traps), loop traps and hoop nets. Crab pots or traps which are designed to only capture the target crab of legal-sized, Crab pots and traps are generally designed to target a particular species, which means that under-size crabs and accidental capture is usually rare. Moreover, as the pots or traps do not injure the captured animals, it is easy to release any unwanted species or undersized crabs. Because crab pots and traps sit stationary on the seafloor in one location, they do not cause significant habitat destruction.

Whether traps or hoop net are used, periodic checking of the gear is done in order to capture target crabs and in the same time release unwanted catch unharmed.

Conservation: In addition to the periodic inspection of fishing gears (every two hours), the recreational size limit for Dungeness crab has been set to be five and three-quarter inches measured across the shell. Moreover, conservation measures limit the number of crabs kept by recreational crabbers up to ten crabs per day. In addition, no Dungeness crab may be taken from San Francisco or San Pablo bays, which are important crab nursery areas.

 

Permanent link to this article: https://fishconsult.org/?p=14006

May 18 2017

Country report – Burkina Faso (2016)- in French

cover-country-report-burkina-faso

A permission has been granted to publish the report on this site

http://fishconsult.org/wp-content/uploads/2017/01/Country-report-Burkina-Faso.pdf

Permanent link to this article: https://fishconsult.org/?p=13798

May 06 2017

Great Barrier Reef (Australia) – Video

This video was filmed in the Sea World, San Diego, California (USA) during December, 2014.

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

Great Barrier Reef

 

The video shows a biological sample of the Great Barrier Reef which is the home of a very large number of fish, molluscs, turtles and a much more species. Although estimated number of species inhabiting the Great Coral Reef may slightly vary, there are more than 1,500 fish species live within the reef representing around 10 percent of the world’s total fish species. This is in addition to more than 3000 species of molluscs, more than 100 species of sharks and rays as well as about 30 species of marine mammals (whales, dolphins, and porpoises) and six species of sea turtles that come to the reef to breed. Moreover, there is around 215 species of birds including seabirds and shorebirds which visit the reef or nest or roost on the islands. The reef is also the home of worms, reptiles and other animals. In regard to corals, the Great Coral Reef is made up of about 3000 individual reefs that are composed of about 400 different types of coral.

The Great Barrier Reef stretches approximately 2300 km along the coast of Queensland in north-eastern Australia and is considered the largest living structure on Earth and is visible from outer space. The reef has over 900 islands as well as picturesque golden beaches. The Great Barrier Reef has an average depth of about 35 meters in its inshore waters increasing to more than 2000 meters on outer reefs.

Because of its natural beauty, the Great Barrier Reef is a popular tourist destination which attracts around two million visitors from all over the world each year, generating significant revenue in the Australian economy.

The Great Barrier Reef being and extremely ancient (is to be thought of 20 million years old) and with its impressive collection of reefs is a UNESCO World Heritage area and listed as one of the “Seven Natural Wonders of the World”.

The major threat facing the Great Barrier Reef is the climate change as represented in the warmer ocean temperatures that put stress on coral and lead to coral bleaching. In fact, the Great Barrier Reef has experienced two mass coral bleaching events in 1998 and 2002 whereas aerial surveys in 2002 showed that over 50% of reefs experienced some coral bleaching. Moreover, Sediment, nutrient and agriculture pesticide pollution from river catchment run-off is also affecting the health of the Great Barrier Reef. In recent years, the coral of the Great Barrier Reef has gradually been destroyed by the Crown of Thorns Seastar, a marine organism that eats coral polyps.

 

 

 

Permanent link to this article: https://fishconsult.org/?p=13998

May 06 2017

Cannery row tells the story on the booming and collapse of sardine fishery in Monterey, California

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

Cannery row (02) Monterey Cannery row (01) Monterey

 

The inserted picture was taken on January 22, 2015 during my visit to the cannery row, the street that witnessed the sardine explosion and then collapse of sardine fishery in Monterey, California (USA).

The first cannery in the row was born in 1901 and soon after a second cannery operated in 1903. In less than two decades after and during the World War I (1916-1918), rapid expansion in the cannery took place as driven by wartime demand. The production of canned sardines grew from 75,000 cases in 1915 to 1.4 million in 1918.

The slow-down of canning following the World War I and the Great Depression was utilized by the canneries in the processing of fishmeal until World War II where another booming for the canning industry took place. In fact, the Monterey’s oval sardine can become world-famous by feeding armies and allied nations at war in WW I, and again in WW II.

In order to meet the demand, purse-Seiners along with large and modern boats with nets a quarter mile long and two hundred feet deep, were introduced in 1928 and enabled the overfishing of the sardines which ultimately led to the collapse of the industry resulting in an economic disaster to Cannery Row whereas the last cannery closed in 1973.

During the sardine flourishing era, the annual landings of sardine amounted over 200,000 tons, used for canning and the production of fish meal and fertilizer placing Monterey as “Sardine Capital of the World” as it fed a world at war with the plentiful and nutritious Monterey sardine.

It worth noting that the first public warning about the potential demise of the sardine fishery came in 1919 from the scientists in the Hopkins Marine Station and typically as continues to occur around the globe, there was a bitter battle, pitting fledgling fishery scientists against the fishing and canning interests in the state. It appears that the growing wartime demand on canned sardines and the lack of management tools to conserve the sardine fishery resource.

Cannery Row itself is now a tourist attraction with many restaurants and hotels, several of which are located in former cannery buildings, and a few historic attractions.

Note: My visit to the cannery row was arranged by Mr. Trevor Fay (Owner of Monterey Abalone Company) who hosted during that day.

 

 

Permanent link to this article: https://fishconsult.org/?p=13996

Apr 28 2017

Florida manatee (Threats – conservation)- Part three/three

Video courtesy: the State Archives of Florida, USA

The title of this video: “Florida Silent Sirens: Manatees in Peril” and was filmed during 1980s

The caption of the video states: “This is an excellent film about the plight of the endangered manatee. It is narrated by Leonard Nimoy and is full of beautiful underwater photography. It shows tracking by radio collar, injured manatees and manatee interaction with people”.

Florida Manatee (Part 03)
 
The following review is the responsibility of Dr. Abdel Rahman El Gamal, Founder of the video channel/website
Threats: Human-related activities represent the main threat for manatees. These mainly include hunting, habitat destruction, adverse environmental conditions, ship strikes and others.
Hunting: Manatees were extensively hunted by indigenous people in the 18th and 19th centuries. Manatees were hunted for their meat, fat, and tough hides, Native Americans made shields, canoes, and shoes. Afterwards, manatees were hunted for their bones by Native Americans who used the ground bones to treat asthma and earache. 
Although there is no precise census of Florida manatees, some estimates of less than 2,000 manatees remaining in the United States, while other optimistic views estimate today’s population of Florida manatee at approximately 6,000 individuals.
 Habitat loss and destruction: As the human population increases along with the overall development in Florida (the home of this species) continues, manatee habitats were gradually lost especially when the damage reached the seagrasses (manatees’ main food source).
A key disturbance in water quality may be represented in the less availability of warm water from natural springs that provide manatees with a shelter during cold weather bearing in mind the sensitivity of manatees to cold water which may become fatal or even dangerous at temperatures below 20 degrees Celsius. In that regard, natural warm springs were used to keep manatees warm during winter and along with the reduced number of these springs, most manatees rely on the warm water outfall that power plants produce. However, if plants are shut down for whatever reason, manatees would be left and impacted by the cold.
Ship strikes: The threat of this issue is based on the slow-moving and near-surface swimming nature of the manatees that were involved in many reported violent collisions with propeller-driven boats and ships, leading frequently to maiming, disfigurement, and even death. This type of threat is typically identified by spiral cutting propeller scars on their backs. In severe collisions, manatees have been cut in half by large vessels like ships and tug boats. For survivors, the cuts due to ship strikes lead to infections, which can prove fatal. Studies show that a manatee may not be able to hear the approaching boats when they are performing day-to-day activities or distractions. It may worth noting that the threat from watercraft strikes accounts for about a quarter of Florida manatee deaths. In 2009, of the 429 Florida manatees recorded dead, 97 were killed by commercial and recreational vessels. It seems that number of collisions with motorboats continues to increase at an alarming rate. According to the Florida Fish and Wildlife Conservation Commission, 218 dead manatees were counted over the first six months of 2014. Of the 218 killed specimens, 18% died from encounters with boaters.
Red tide: Red tide which is a bloom of dinoflagellate producing toxins was responsible for incidences of manatee deaths. There are reports on 151 manatee deaths due to red tide in 1996.
Miscellaneous threats: these include variety of threats including occasional ingesting fishing gear (hooks, metal weights, etc.) while feeding. In some situations, ingesting some foreign materials such as monofilament line or string can block a manatee’s digestive system and may slowly kill it. Manatees are occasionally killed by entanglement in fishing gear, primarily crab pot float lines. Moreover, harassing and disturbing the manatees by human has been reported. According to the United States Fish and Wildlife Service, approximately 99 manatee deaths each year are related to human activities. In January 2016, there were 43 manatee deaths in Florida alone.
According to IUCN documents, the Florida manatee subspecies is listed as Endangered in 2008 on the basis of a population size of less than 2,500 mature individuals and the population is estimated to decline by at least 20% over the next two generations (estimated at ~40 years) due to anticipated future changes in warm-water habitat and threats from increasing watercraft traffic over the next several decades.
Conservation measures
Legal protection: According to Florida as well as the federal government, Manatees are classified endangered and hence it is illegal to injure or harm a manatee.
Protected Areas: Manatees have been protected for an unusually long time. The English declared Florida a manatee sanctuary in the 1700s and hunting manatees was prohibited. Establishment of more protected areas for manatees especially in the natural warm springs would serve an ideal warm shelter that the animals warm during winter. Under the Endangered Species Act, the protection of manatee’s critical habitats should be ensured.
Speed boats: Setting speed limits in waterways can help manatees by giving them enough time to avoid collisions and reducing the severity of collisions when they do occur. In particular centers, ships used are propelled only by water jets to protect manatee populations that occur in such regions.
Tourism: Manatee-watching tourism provides local people with financial incentive that encourage them to preserve the manatees and so tourists who are fond of this beautiful animals continue to visit and watch their grazing in their natural habitats. In fact, manatee-watching tourism has been found a very successful conservation action. In that regard, precautions should be in place to assure that boats carrying manatee watchers do not turn into additional threat to the animal populations.
Research: More scientific research is needed to understand manatees and their needs especially on priority topic such as their calving and feeding behaviors.
Citizen Involvement: Citizens are helping to preserve manatees through various initiatives which often vary from the formal approaches. Local people may act effectively in creating awareness regarding the conservation of manatees as well as contacting concerned agencies and in some situations they have created manatee’s defenders. The involvement of citizens proved to helpful to scientists, governmental agencies and utility companies providing them with their opinions to ensure that development plans need to consider the manatee populations and ensure that such plans don’t endanger these marine mammals.
Care facilities: There are a number of manatee rehabilitation centers and critical care facilities in the United States along with zoos and aquariums. Through these centers and facilities, a decent number of manatees have been helped and released.

Note: If you interested to know more on this interesting animal, you are welcome to visit the first part (video) and the second part of the same title on behavior and reproduction.

Permanent link to this article: https://fishconsult.org/?p=13990

Apr 28 2017

Florida manatee (Behavior – reproduction)- Part two/three

Video courtesy: the State Archives of Florida, USA

The title of this video: “Florida Silent Sirens: Manatees in Peril” and was filmed during 1980s

The caption of the video states: “This is an excellent film about the plight of the endangered manatee. It is narrated by Leonard Nimoy and is full of beautiful underwater photography. It shows tracking by radio collar, injured manatees and manatee interaction with people”.

Florida Manatee (Part 02)

 

The following review is the responsibility of Dr. Abdel Rahman El Gamal, Founder of the video channel and website

Behavior: Manatees are generally solitary animals that spend approximately 50% of the day sleeping submerged, surfacing for air regularly at intervals of less than 20 minutes. The remainder of the time is spent grazing. They are extremely gentle and peaceful and have been described as incapable of aggression. Manatees only breathe through their nostrils, since while underwater, their mouths are occupied with eating. Like other air-breathing marine mammals, manatees must periodically surface for air.
Manatees swim at about 5 to 8 kilometers per hour; much speedy swimming has been known in short bursts (up to 30 km/hour).
Reproduction: Female manatees reach sexual maturity between five and nine years of age. Manatees typically breed once every two years. A female manatee usually seeks quiet area in which to give birth after a gestation of about 12 months. Generally, most births are of a single calf about 120 centimeters long with about 30 kilograms weight, although a few cases of twins have been documented.
Immediately after birth, calves vocalize and this is an important part of the mother-calf strong bonding process. Within few hours after birth, calves begin to nurse underwater from teats located behind the mother’s flippers. They begin eating plants a few weeks after birth.
Within minutes of birth, newly born calves swim with -and in parallel to- their mothers directly behind her flipper.
Although a manatee calf is probably nutritionally independent by the end of its first year, it may stay with its mother for another year or two. During this period, mother passes to her calf information on feeding and resting areas, travel routes and warm water refuges.
Note: If you interested to know more on this interesting animal, you are welcome to visit the first part (video) and the third part of the same title on threats and conservation.

 

 

Permanent link to this article: https://fishconsult.org/?p=13988

Apr 27 2017

Florida manatee (Description – habitats – Feeding habits)- Video

Video courtesy: the State Archives of Florida, USA
The title of this video: “Florida Silent Sirens: Manatees in Peril” and was filmed during 1980s

Florida Manatee (Part one)

 

The caption of the video states: “This is an excellent film about the plight of the endangered manatee. It is narrated by Leonard Nimoy and is full of beautiful underwater photography. It shows tracking by radio collar, injured manatees and manatee interaction with people”.

The following review is the responsibility of Dr. Abdel Rahman El Gamal, Founder of the video channel

Introduction: The Florida manatee (Trichechus manatus) is a marine mammal which is also known as “West Indian manatee” or North American manatee. Manatees are occasionally called sea cows as they are similar to cows on land. Manatees belong to the family Trichechidae. This manatee is the largest, fully aquatic surviving member of the aquatic mammal “order Sirenia”. The lifespan of the manatee is 50-60 years in the wild. It is known that manatees have good long-term memory and they demonstrate task-learning abilities similar to dolphins.

Habitats: The primary habitat of this manatee species is the warm Florida coastal waters which provide wintering refuges for manatees in natural warm water springs. They also are attracted to the warm water outflow from power plants. In summer, some individuals migrate as far north as the Carolinas or as far west as Louisiana.

Description: The Florida manatees, Florida’s state marine mammal, are large and bulky aquatic mammals that are grayish brown in color and have thick, wrinkled skin. Their front flippers help them steer, or sometimes crawl, through shallow water. They also have powerful, spatula-shaped tails that help propel them through the water. Despite their small eyes and lack of outer ears, manatees are thought to see and hear quite well. Manatees may live around 50 years old.

Manatees have four rows of cheek teeth, which are not clearly differentiated into molars and premolars. Manatee teeth are continually replaced throughout the manatee’s lifetime with new teeth growing at the rear as older teeth fall out from farther forward in the mouth. At any given time, a manatee typically has no more than six teeth in each jaw of its mouth.

Manatees have a simple stomach, but a large cecum, in which they can digest tough plant matter. In general, their intestines have a typical length of about 45 meters, which is unusually long for animals of their size. Manatees are the only animal known to have a vascularized cornea.
On the average, an adult manatee measures up to 4.0 meters long, and weigh as much as 590 kilograms with recorded measures beyond the mentioned values; females that tend to be larger and heavier have two teats, one under each flipper. A manatee’s lungs are 2/3 the length of its body.

Feeding habits: Manatees are herbivores, with a diet consisting mostly of sea grasses and freshwater vegetation. They are known to eat over 60 different freshwater (e.g. floating hyacinth, pickerel weed, alligator weed, water lettuce, hydrilla, water celery, musk grass, mangrove leaves) and saltwater plants (e.g. sea grasses, shoal grass, manatee grass, turtle grass, widgeon grass, sea clover, and marine algae). An adult manatee will commonly eat up to 10%-15% of their body weight (about 50 kg) per day which requires the grazing for up to seven hours a day. Manatees have been known to eat small amounts of fish from nets.

Manatees use their flippers to “walk” along the bottom whilst they dig for plants and roots in the substrate using the flippers to scoop the vegetation toward the manatee’s lips which are used to tear the ingested plants and the process is completed by the ridged pads located on the roof of the mouth, bearing in mind that manatee does not have front teeth. Their divided upper lip provide them with high flexibility to grasp and take in aquatic plants.
Because of their feeding habits and like other grazing animals, Florida manatees play an important role in influencing the plant growth in their habitats.

Permanent link to this article: https://fishconsult.org/?p=13983

Apr 26 2017

Save a male – African catfish

Image credit: FAO

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

Testes of African catfish Incision in African catfish

 

Unlike many fish species, African catfish males (Clarias gariepinus) –for anatomical features- do not release sperm under abdominal massage after treatment with hormones. Instead, males are sacrificed, opened, and testes are removed out of the abdomen and squeezed to release the milt as required for egg fertilization.

As a consequence, for each sacrificed male, a new male broodstock needs to be added to make-up the deficit in male population. When the size of the founder stock is barely sufficient to start with and cannot afford losing a male specimen after another, this issue would be a problem. Similarly, in selective breeding programs and is specific genetic studies, the use of the same male is repeated and needs to go beyond a single use.

Research initiatives have been conducted to save catfish males rather than sacrificing them. These initiatives include the use of a 2-ml syringe with needle to draw some sperm through a small incision in the belly of tranquilized males. Also, the partial ablation of male testes has been promoted to save males and has probably attracted researchers more.  

The ablation of testes is done through the removal of about three quarter of the testes to be used as usual in egg fertilization. The healing of the incision point in African catfish occurs within about 14 days post-surgery. The regeneration of removed testis, and so the subsequent use of the same male may take about 45 days post-surgery implying the possibility of several re-uses of the same male depending on temperature and other husbandry practices bearing in mind that proper feeding should be ensured  after ablation in order to hasten the development of the gonads.

In all situations where incisions are operated, the wound is stitched using veterinary stitching material and the operation is done while male is properly anesthetized.

It may worth noting that the adaption of “saving a male” approach would depend on educational level of hatchery operators and would be also influenced by the abundance of male broodstock bearing in mind that if a continuous supply of male broodstock is easy, commercial producers most likely would continue sacrificing males rather than putting extra efforts trying to save them.

 

 

 

Permanent link to this article: https://fishconsult.org/?p=13980

Apr 24 2017

Cage culture of rainbow trout in Alicura reservoir in Argentine (Video)

Cage culture of rainbow trout in Argentine

 

Video credit: Herman Hennig (Argentina)

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

 

This video was filmed in Alicura reservoir where cage culture of rainbow trout (Oncorhynchus mykiss) is being practiced.

Rainbow trout was introduced to Argentine at the beginning of the twentieth century with the objective of stocking the Patagonian lakes for sport fishing before using the species in aquaculture especially rainbow trout has adapted to farming with most ease.

Beginning 1990s, most rainbow trout aquaculture has been practiced in suspended cages, while the land-based raceways continued to be used by small producers. In trout farming, 1-gram hatchery produced fingerlings are stocked in cages. However, a small percentage of eyed-eggs are imported from the United States.

Alicura Reservoir -where this video has been filmed- is located approximately 100 km north of San Carlos de Bariloche and is the first of a series of five reservoirs built on the Limay River. The reservoir is 40 km in length with an average depth of 48 m, and an area of 6700 ha. The water quality analysis of Alicura reservoir indicated its suitability for aquaculture which has been encouraged by provincial governments.

 

 

Permanent link to this article: https://fishconsult.org/?p=13976

Apr 23 2017

Use of rice straw bales in the very last fish harvest in earthen ponds in Egypt

Use of rice straw bales in fish harvest in Egypr

 

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

The pictures show how pond workers prepare bales of rice straw to harvest whatever remained in the catch ditch. This is the very last practice in pond harvesting before exposing the pond bottom to sun-drying. Not much fish is expected to recover through pushing the straw bales in the ditch expect some hard to catch specimens of catfish, tilapia and probably fish fry that would most likely die going through such harsh operation. The dense of the rice straw in the bale would push water and its content in front of it.

It may worth noting that rice straw has no cost especially in a governorate such as kafr El Sheikh which is a leading governorate in rice farming and where this fish farm is located.

 

 

Permanent link to this article: https://fishconsult.org/?p=13971

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