Friday, July 31, 2015

The Goblin Sharks Fish


           The goblin shark, is a deep-sea shark, the sole living species in the family is found in the deep ocean, far below where the sun's light can reach at depths greater than 200 m. They can be found throughout the world, from Australia in the Pacific Ocean to the Gulf of Mexico in the Atlantic Ocean. They are best known from the waters around Japan, where the species was first discovered. Goblin sharks feed on a variety of organisms that live in deep waters. Among some of their known prey are deep-sea squid, crabs, and deep -sea fish. Very little is known about the species' life history and reproductive habits, as encounters with them have been relatively rare. As seemingly rare as they are however, there seems to be no real threat to their populations and so they are not classified as endangered species by the IUCN. wo new species of tapeworm were discovered in a specimen captured off Australia

            Male Goblin sharks commonly grow between 2.4 and 3.1 m (7.9 and 10 ft) long and females between 3.1 3.5 m (10 11 ft). The largest verified specimen was 3.9 m (13 ft) and weighed 210 kg (460 lb), although one unusual specimen was estimated to measure an enormous 6.2m (20ft). The pink coloration, unique among sharks, is due to blood vessels underneath a semitransparent skin (which bruises easily), thereby causing the colouring. The fins have a bluish appearance. Goblin sharks lack a nictitating membrane. They have no precaudal pit and no keels. The front teeth are long and smooth-edged, while the rear teeth are adapted for crushing. Up to 25% of the goblin shark's body weight can be its liver. The goblin shark

Wednesday, July 29, 2015

The Mekong Giant Catfish

        Mekong Giant Catfish as fishermen continue to catch and sell the fish despite the fact that the species is critically endangered. The Tonle Sap River bagnet (dai) fishery is one of the two places where wild Giant Catfish are caught on a regular basis. Without regulation, fishing mortality from bagnets equals approximately 5-10 fish per year. 
           The Mekong Wetlands Biodiversity Conservation and Sustainable Use Programme (MWBP), in cooperation with the Cambodian Department of Fisheries and the MRC Fisheries Programme, is reimplementing a Giant Catfish tag and release project in Cambodia in order to study the migratory behaviour of P. gigas. The tag and release programme was first implemented in 2001. The fish caught in the dais are bought from the dai operators, tagged and released. This buy and release approach provides a low cost, short-term solution to fishing mortality. The scheme does not harm the fisher’s livelihood and provides an opportunity for additional research 

      Mekong Giant Catfish captured in the Tonle Sap River bagnet fishery and Tonle Sap Lake fishing lots, October – December 2004. Of the five Giant Catfish captured in the dai, one died before release because the bagnet owners would not sell the fish to the Department of Fisheries and two died after release, presumably due to capture stress. 

The Alligator Gar Fish


            Alligator gar Atractosteus spatula is the largest freshwater fish in Texas and one of the largest species in North America, yet has received little attention from anglers or fisheries managers. Although gars (family Lepisosteidae) have long been considered a threat to sport fishes in the United States (summarized by Scarnecchia 1992), attitudes are changing. Recreational fisheries for alligator gar are increasing, and anglers from around the world now travel to Texas for the opportunity to catch a trophy. Because little data exist, it is unknown how current exploitation is affecting size structure and abundance of alligator gar in Texas. In many areas, alligator gar populations are declining (Robinson and Buchanan 1988; Etnier and Starnes 1993; Pflieger 1997; Ferrara 2001). Concerns by biologists and anglers about alligator gar populations in Texas have led the Texas Parks and Wildlife Department (TPWD) to consider management options for this species. In addition to this review, the TPWD has recently initiated several studies to learn more about Texas alligator gar populations. The purposes of this document are to 1) summarize alligator gar life history and ecology, 2) assess alligator gar status and management activities throughout their range, and 3) make recommendations for future alligator gar management in Texas.

          Life History In the United States, alligator gar spawn from April through June (Etnier and Starnes 1993; Ferrara 2001), coinciding with seasonal flooding of bottomland swamps (Suttkus 1963). Documented reports of alligator gar spawning are limited, though it is thought to occur in flooded backwater areas (Mendoza Alfaro et al. 2008). Spawning was recently observed in a shallow, vegetated-backwater area of Lake Texoma, Oklahoma. Snedden et al. (1999) found that lateral spawning migrations of spotted gar Lepisosteus oculatus onto floodplain areas were correlated with increased river stage and increased temperature. Because spawning is likely 2 linked to seasonal flooding, successful recruitment may be infrequent. Fecundity of alligator gar is highly variable, with means of 157,000 eggs per female and 4.1 eggs/g body weight (Ferrara 2001).
           Juvenile alligator gar likely remain in backwater spawning areas as they develop. Sakaris et al. (2003) reported that tagged juvenile alligator gar demonstrated strong site fidelity to protected backwater areas and remained near their site of capture (thought to be a spawning area), whereas adults were more mobile. Robertson et al. (2008) also captured juvenile alligator gar from backwater oxbow habitats, whereas adults were collected in the river channel. Ferrara (2001) hypothesized that juvenile alligator gar utilize shallow embayments and tributaries, and suggested that identification and protection of such nursery areas may be critical to the recovery of alligator gar populations in areas with limited nursery habitats. 


The Arapaima Fish


            The introduction and establishment of arapaima (Arapaima gigas) in southeastern Peru and northwestern Bolivia is an example of a fish species that appears to be increasingly common and widespread in non-native portions of its range, but whose populations are on the decline within its native range. The arapaima is overfished and considered threatened throughout its native range in the Central Amazon. We gathered and examined data on the distribution of fish and wildlife in the Takana II Indigenous Territory in Bolivia, near the arapaima’s reported initial invasion zone in Peru. Results confirmed the presence of arapaima in several water bodies where local people have also reported a strong decline in native fish populations. Further south in the Takana I Indigenous Territory, monitoring of fisheries by local communities (2002-2008), including observations on arapaima catches, indicate that until 2008 arapaima had not been reported in the area. However in 2009, there were reports of arapaima in the Undumo stream. Our results demonstrate that since the first presence of arapaima in Bolivia at the beginning of the 1980s, it has steadily expanded its distribution. We propose actions to mitigate this situation by managing and controlling populations of this invasive and endangered species, as well as improving income for indigenous communities.

        Arapaima [Arapaima gigas (Schinz, 1822)], known as paiche in Bolivia and Peru and as pirarucĂș in Brazil, is one of the most emblematic species of the Amazon and the focus of numerous studies (Migdalaski 1957; Hrbek et al. 2005; Castello et al. 2009). This giant fish is native to the Central Amazon where it has long been over-exploited by humans as a source of food (Figure 1) (Hrbek et al. 2007). The arapaima was introduced into lagoons in the Madre de Dios region of Peru for aquaculture and during the late 1970s these fish or their progeny escaped into nearby streams during flood events (Wust 2001; Farrel and Azurduy 2006). Local people report that the introduction of arapaima has caused serious environmental impacts. In northern Bolivia, it may be causing a reduction of native fish populations, including many fish of high commercial value

The Bull Shark Fish


          The earliest collection of Mongolian fi shes was made by the German naturalist Peter Simon Pallas in the late 1700s, who described the taimen (Hucho taimen) and the lenok (Brachymystax lenok). Continued exploration in the 1800s led to the description of further fi sh species, notably by B. Dybowski, S. Basilewsky and K. Kessler, and the early 1900s saw the fi rst of numerous studies on the fi shes of Mongolia and Russia by Leo Berg. A number of joint Soviet-Mongolian, Czechoslovakian-Mongolian and German-Mongolian expeditions were carried out in the latter half of the twentieth century, but while providing new collections of fi sh for analysis, they tended to be broad multi-disciplinary studies. However, several specifi c fi sh studies were carried out during the tenure of Prof. A. Dashdorj, the fi rst Mongolian to hold the Chair of Zoology at the Mongolian State University in 1947, as he had a particular interest in ichthyology. The publication of ‘The Fishes of Mongolia’ by G. Baasanjav and Y. Tsendayush in 2001 (published in Mongolian) provided an important taxonomic review of Mongolian fi shes. It also consolidated much of the existing regional biological and fi sheries data. Prior to this, Leo Berg’s ‘Freshwater Fishes of the U.S.S.R. and Adjacent Countries’ (published in Russian, 1949 and English, 1962) was the standard reference to the fi shes of Mongolia.
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The Fish Taimen


         The earliest collection of Mongolian fi shes was made by the German naturalist Peter Simon Pallas in the late 1700s, who described the taimen (Hucho taimen) and the lenok (Brachymystax lenok). Continued exploration in the 1800s led to the description of further fi sh species, notably by B. Dybowski, S. Basilewsky and K. Kessler, and the early 1900s saw the fi rst of numerous studies on the fi shes of Mongolia and Russia by Leo Berg. A number of joint Soviet-Mongolian, Czechoslovakian-Mongolian and German-Mongolian expeditions were carried out in the latter half of the twentieth century, but while providing new collections of fi sh for analysis, they tended to be broad multi-disciplinary studies. However, several specifi c fi sh studies were carried out during the tenure of Prof. A. Dashdorj, the fi rst Mongolian to hold the Chair of Zoology at the Mongolian State University in 1947, as he had a particular interest in ichthyology. The publication of ‘The Fishes of Mongolia’ by G. Baasanjav and Y. Tsendayush in 2001 (published in Mongolian) provided an important taxonomic review of Mongolian fi shes. It also consolidated much of the existing regional biological and fi sheries data. Prior to this, Leo Berg’s ‘Freshwater Fishes of the U.S.S.R. and Adjacent Countries’ (published in Russian, 1949 and English, 1962) was the standard reference to the fi shes of Mongolia.

The Nile Perch


: Evolutionary histories of aquatic species are often characterized by distinct patterns of genetic variation, which in part reflect drainage evolution. In the present study, the consequences of paleo-environmental changes on patterns of genetic variation of the mitochondrial DNA control region in Nile perch Lates sp. sampled from seven water bodies across the African continent were investigated.

These lineages may have developed in geographical isolation during the Pleistocene and have remained largely allopatric without gene flow (Nm = 0.0) since that time. There was also evidence that both of these genetic lineages have undergone recent population expansions. We interpret these results in light of the recent evolution of Africa's modern drainage network.

The Paddlefish

 Paddlefish


         The paddlefish is native to the Mississippi River basin, requiring large expanses of free-flowing river in which to complete its life cycle. Throughout its range, the paddlefish has experienced declines in abundance and distribution (Becker 1983). In Minnesota, paddlefish historically occurred in the Minnesota River to Granite Falls, in the Mississippi River to St. Anthony Falls, and in the St. Croix River to Taylors Falls (Cox 1897). Today, Minnesota's paddlefish are limited to small populations in the St. Croix and Mississippi rivers, including Lake St. Croix and Lake Pepin (Hatch et al. in preparation), with occasional reports from other waters. For example, in the early 1990s there were 2 angling reports of this species from the Minnesota River at Mankato and St. Peter. Minnesota DNR fisheries crews sampled a paddlefish in May 2004 near Granite Falls, an exceptional reappearance of this species. The paddlefish's decline

The paddlefish has a long, paddle-like snout, small eyes that are set far forward, and a shark-like tail. It is blueblack or gray in color on the back, and white below. Its body is scaleless except for small patches of scales on the throat, pectoral girdle, and caudal (tail) fin. Small, paired barbels are present on the under surface of the paddle near the mouth. As adults, paddlefish reach a maximum size of 2.2 m (7.3 ft.) in total length and can weigh over 23 kg (50 lbs) (Page and Burr 1991). Historically, paddlefish have been reported to be over 91 kg (200 lbs.). A more recent record of a paddlefish taken from the lower Chippewa River in western Wisconsin in 1998 measured 1.8 m (5.9 ft.) long and weighed 39.4 kg (86.9 lbs.).