Fish and aquatic news » Anja http://www.aquaticcommunity.com/news The latest news from below the surface Wed, 23 Oct 2013 11:30:17 +0000 en-US hourly 1 http://wordpress.org/?v=3.6.1 Sea Life London Aquarium weans gourami off Kit Kats http://www.aquaticcommunity.com/news/lib/1471 http://www.aquaticcommunity.com/news/lib/1471#comments Tue, 09 Aug 2011 02:45:46 +0000 Anja http://www.aquaticcommunity.com/news/?p=1471 When a 4 kilogram pet gourami named Gary was moved to the Sea Life London Aquarium, he went on a hunger strike and refused to eat the fruit given to him. Eventually, the aquarium staff found out why he was shunning the natural diet of a gourami – Gary had been raised on Kit Kats only. “I have never heard […]

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kitkat Sea Life London Aquarium weans gourami off Kit KatsWhen a 4 kilogram pet gourami named Gary was moved to the Sea Life London Aquarium, he went on a hunger strike and refused to eat the fruit given to him. Eventually, the aquarium staff found out why he was shunning the natural diet of a gourami – Gary had been raised on Kit Kats only.

“I have never heard of a fish being fed chocolate, let alone being brought up entirely on the stuff,” says Gary’s handler, Rebecca Carter. “Gouramis usually eat a diet of fruit but Gary doesn’t appear to have suffered any ill effects from his chocolate addiction. However, we would not recommend feeding fish confectionery of any kind.”

The aquarium personnel is now squeezing crushed pieces of Kit Kat into grapes in an effort to change Gary’s diet.

Fish being fed strange or simply suboptimal food by their keepers is unfortunately very common. Even well-intentioned fish keepers sometimes fail to realize that the various fish species in the world have developed to fit into different ecological niches and a diet that is perfect for one species might be highly unsuitable for another. However, keeping fish on a chocolate coated wafer diet is probably quite unusual.

Another problem is of course people getting fish without making the effort to find out how large the little juveniles they see in the fish shop may grow as fully mature adults.

“Many people don’t do the right research when they buy fish and end up unable to care for them,” says Carter. “Catfish are a good example and we have a number here that outgrew their homes. We simply do not have the space to accommodate the vast number of re-homing requests we receive.”

Facts

  • Gourami are freshwater fish belonging to the family Osphronemidae. Currently, there are roughly 90 described species divided into four subfamilies and about 15 genera. The most famous gourami species is arguably Betta splendens, the Siamese fighting fish. Gourami is native to Asia where they are found from Pakistan to the Malay Archipelago and Korea.
  • Kit Kat is a chocolate coated wafer confection produced by Nestlé and The Hersey Company. Each bar consists of fingers that can be snapped from the bar one at a time. Each finger is made up of three layers of wafer and an outer layer of chocolate. Kit Kat was invented at Rowntree’s, a confectionery company based in York, UK.

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Native American tribes strive to save the lamprey http://www.aquaticcommunity.com/news/lib/1468 http://www.aquaticcommunity.com/news/lib/1468#comments Sun, 07 Aug 2011 02:38:19 +0000 Anja http://www.aquaticcommunity.com/news/?p=1468 Lamprey used to be an important source of food for Native American tribes living along the northwestern coast of North America, and the fish was once upon a time harvested in ample amounts from rivers throughout the Columbia Basin, from Oregon to Canada. Today, the many hydroelectric dams built in these rivers have turned the fish from staple food to […]

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Lamprey used to be an important source of food for Native American tribes living along the northwestern coast of North America, and the fish was once upon a time harvested in ample amounts from rivers throughout the Columbia Basin, from Oregon to Canada.

lamprey Native American tribes strive to save the lamprey Today, the many hydroelectric dams built in these rivers have turned the fish from staple food to rarity. Nowadays, it is only harvested from one location – a 40-foot waterfall on the Willamette River between a power plant and a derelict paper mill. There are no dams between the waterfall and the sea, so the lampreys can still get here.

In July, Native Americans from the Umatilla, Warm Springs and Grande Ronde reservations in Oregon, the Yakama reservation in Washington and the Nez Perce reservation in Idaho who wish to continue eating this traditional food gather by the waterfall and manually pick the lampreys from rocks. The tribal elders will then prepare the fish for the community back at the reservations.

Aaron Jackson who heads the Confederated Tribes of the Umatilla Reservation says the Native American tribes of the Northwest have a special connection to the lamprey. According to legend, the seven gill slits on the side of lamprey’s head marked this fish as a food designated for the region’s tribes by the creator, corresponding to the seven drummers and seven songs of longhouse ceremonies.

While the salmon is receiving billions of dollars in government funds – money used for conservation efforts such as modifying dams and restoring prime salmon habitat – the lamprey is largely being ignored.

Lampreys hatch in freshwater and live in the rivers for many years before swimming downstream to the sea. In the sea, they attach themselves to fish and marine mammals such as whales and sea lions and feed on them. When the lampreys are old enough to breed, they return to the rivers where they die shortly after spawning.

Unfortunately, fish ladders and screens designed for salmon do not work well for the lamprey. Adult lampreys physically resemble eels and lack paired fins, and the species living in this part of the world grow to a length of roughly 2 feet. The fast water and sharp corners of fish ladders designed for salmon are very difficult to traverse for these elongated fishes. Also, young lampreys get stuck on the screens that are put up to keep young salmon safe from turbines.

In 2003, roughly 200,000 lampreys were crossing Bonneville Dam on the Columbia east of Portland. Now, the number has dropped to a mere 20,000 according to Bob Heinith, hydroelectric program coordinator for the Columbia River Inter-Tribal Fish Commission. Biologists estimate that in the 1970s, the number exceeded 1 million, but that was before accurate counts were taken so it is hard to know for sure what the situation looked like.

Aaron Jackson fears that the dams will lead to a complete eradication of lampreys in the region.

“That’s really sad, that something this old would just wink out in my lifetime — that’s unfathomable to me,” says Jackson.

The tribes are now driving the effort to save the lampreys, and one major hope is of course to improve the dam ladders and screens. Based on an agreement with the tribes, the U.S. Army Corps of Engineers is currently trying to make the ladders more suitable for lampreys without making them unsuitable for salmon. According to David Clugston, a biologist for the corps, this has proven to be quite difficult. So far, special ramps have been placed at Bonneville Dam and two fish ladders have been modified at other dams.

Simultaneously, the Native American tribes are capturing adult lamprey and releasing them in tributaries. If this experiment works out according to plan, the adult fish will re-establish lamprey populations in these tributaries. The tribes are also consulting experts in Finland on how to build hatcheries for lamprey.

Elmer Crow, who is a tribal elder and vice chairman of the Nez Perce Tribe’s fish and wildlife committee, says restoring lamprey is a vital part of restoring salmon.

“Life is a complete circle. Remember that,” he says. “If you take something out, a few others go with it.”

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Radioactive strontium-90 found in fish in Vermont, USA http://www.aquaticcommunity.com/news/lib/1466 http://www.aquaticcommunity.com/news/lib/1466#comments Sat, 06 Aug 2011 02:37:26 +0000 Anja http://www.aquaticcommunity.com/news/?p=1466 Vermont health officials have found radioactive strontium-90 in a smallmouth bass taken from the Connecticut River. The fish was collected 9 miles upstream from the Vermont Yankee Nuclear Power Plant, but William Irwin, the state’s chief radiological health officer, says it’s not certain where the strontium-90 comes from. It might come from the power plant, it might come from the […]

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Vermont health officials have found radioactive strontium-90 in a smallmouth bass taken from the Connecticut River.

The fish was collected 9 miles upstream from the Vermont Yankee Nuclear Power Plant, but William Irwin, the state’s chief radiological health officer, says it’s not certain where the strontium-90 comes from. It might come from the power plant, it might come from the Chernobyl disaster and it might come from deposits left over from atomic bomb testing carried out in the 1950s and 1960s.

According to Irwin, the strontium-90 is most likely not from the Fukushima disaster since that release of radioactive material took place so recently.

What makes the finding even more intriguing is that the strontium-90 was found in the fleshy, edible part of the fish instead of in the bones.

Strontium

Strontium is an alkaline earth metal chemical element that is highly reactive chemically. Its symbol is Sr and its atomic number is 38. Strontium is. Strontium is soft and looks silvery-white or yellowish until it is exposed to air which makes it yellow. The 90Sr isotope is present in radioactive fallout and has a half-life of 28.90 years. Natural strontium is nonradioactive and nontoxic, but 90Sr is a radioactivity hazard.

Because strontium is so similar to calcium, it is incorporated in the bone of humans and other animals, including fish. This is true for all four stable isotopes, and analyzing which isotope that has been incorporated into a bone can help us determine the region from which the bone hails. It is an important investigative tool for forensic scientists.

Stable forms of strontium are believed to be safe for humans, and the levels found naturally might actually be beneficial since they strengthen our bones. The 90Sr isotope can on the other hand cause various disorders and disease, including bone cancer and leukemia.

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Gold Nugget pleco and Mango pleco finally described by science http://www.aquaticcommunity.com/news/lib/1461 http://www.aquaticcommunity.com/news/lib/1461#comments Sat, 30 Jul 2011 16:10:34 +0000 Anja http://www.aquaticcommunity.com/news/?p=1461 Two pleco species from the Xingu River drainage that are popular within the aquarium hobby have finally been scientifically described and given scientific names. The fish known to aquarists as Gold Nugget pleco (L18, L85, L177) is from now on officially named Baryancistrus xanthellus, while the pleco called Mango pleco (L47) has been given the scientific name Baryancistrus chrysolomus. The […]

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Two pleco species from the Xingu River drainage that are popular within the aquarium hobby have finally been scientifically described and given scientific names.

The fish known to aquarists as Gold Nugget pleco (L18, L85, L177) is from now on officially named Baryancistrus xanthellus, while the pleco called Mango pleco (L47) has been given the scientific name Baryancistrus chrysolomus.

The species were described and named by Lúcia Py-Daniel, Jansen Zuanon and Renildo de Oliveira in a paper published in the most recent issue of the journal Neotropical Ichthyology (http://www.scielo.br/scielo.php?pid=1679-6225&script=sci_serial).

Golden nugget pleco Gold Nugget pleco and Mango pleco finally described by science

Baryancistrus xanthellus (Golden Nugget pleco)

This is the pleco known to most aquarists as the Golden Nugget pleco, and it has been given three different L-numbers (L18, L85 and L177).

Baryancistrus xanthellus differs from other members of its genus by having a broad light band on the edges of the dorsal and caudal fin in juveniles, a band that turns into a small dot on the tips of these fins as the fish matures into an adult.

The body of Baryancistrus xanthellus is covered in pale spots. You can separate it from B. beggini by looking in its mouth; Baryancistrus xanthellus have more teeth in both the upper and lower jaw than B. beggini.

The authors found congregations of Baryancistrus xanthellus under flat rocks at the bottom in shallow parts of the Xingu River drainage where the water moved rapidly. They analyzed the stomach material and found out that it was chiefly algae.

Baryancistrus chrysolomus (Mango pleco)

This fish is known in the aquarium trade as Mango pleco and has the L-number L47. The scientific name, Baryancistrus chrysolomus, alludes to its yellow fin margins (chrysos and loma are the Greek words for yellow and border, respectively).

Just like B. xanthellus, Baryancistrus chrysolomus sports a broad orange to yellow band along the entire outer margin of the dorsal and caudal fins. This feature distinguishes B. xanthellus and B. chrysolomus from all other described members of the genus Baryancistrus.

To separate Baryancistrus chrysolomus from B. xanthellus, look for spots on the body. If there are no clear spots on the body, it is not a B. xanthellus.

The scientists encountered Baryancistrus chrysolomus under rocks at the bottom of the river in stretches where the water flow was slow to moderate. The fish fed by scraping algae from the rocks.

For more information on these two newly described species of pleco, see the paper: Py-Daniel, LR, J Zuanon and RR de Oliveira (2011) Two new ornamental loricariid catfishes of Baryancistrus from rio Xingu drainage (Siluriformes: Hypostominae). Neotropical Ichthyology 9, pp. 241–252.

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Will grey seals counteract cod recovery in the Baltic Sea? http://www.aquaticcommunity.com/news/lib/1457 http://www.aquaticcommunity.com/news/lib/1457#comments Thu, 28 Jul 2011 16:06:21 +0000 Anja http://www.aquaticcommunity.com/news/?p=1457 Grey seals and cod used to be found in great abundance throughout the Baltic Sea, but today the seals are chiefly present in the northern parts of the sea while the cod is found in the south. Management programs are working on increasing the number of both species and this will likely cause predator and prey to once again inhabit […]

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Grey seals and cod used to be found in great abundance throughout the Baltic Sea, but today the seals are chiefly present in the northern parts of the sea while the cod is found in the south.

Management programs are working on increasing the number of both species and this will likely cause predator and prey to once again inhabit the same region.

Since the grey seal and cod populations could overlap in the future, we investigated whether the management plans to re-establish the populations of cod and grey seals are contradictory since there is a chance that the grey seals can harm the cod stocks as happened in the 1920-30s. Although, back then the grey seal population was much larger than it is now,” says Professor Brian MacKenzie from the National Institute of Aquatic Resources (DTU* Aqua) in Denmark (www.aqua.dtu.dk/English.aspx). DTU is the Technical University of Denmark.

Together with Margit Eero (also from DTU Aqua) and Henn Ojaveer from the Estonian Marine Institute (http://www.sea.ee/en/), MacKenzie has conducted a study where they conclude that fisheries and climate change will affect the cod much more than the grey seals. The study has been published in the scientific journal PloS ONE.

About a decade ago, over fishing, oxygen scarcity and decreased salinity cause the cod populations in the Baltic Sea to plummet to record low levels. The amount of cod is now gradually increasing again, chiefly thanks to a strict fishing management plan and a few good years of cod reproduction.

The environmental conditions of the Baltic Sea are still not perfect, but fishing levels are low at the moment, giving the cod a chance to rebuild the population. This has given rise to an increase in cod numbers during the last four to five years,” MacKenzie explains.

Since grey seals have effected the cod populations in the past, the team of Danish-Estonian scientists wanted to take a closer look at how they may affect a slowly recuperating cod population.

Historically, seals have affected cod stocks, and in many areas they are suspected of being the reason why the recovery of cod stocks has been delayed. Therefore, it was important to determine whether the grey seals could pose a threat to the cod stock in the Baltic Sea,” says MacKenzie.

In order to investigate how grey seals in the Baltic Sea could effect the cod, the researchers made a number of simulations of future scenarios – scenarios that also factored in commercial fishing and climate change. If climate change makes the climate warmer, the salinity of the Baltic Sea would decrease and this would affect the reproductive capacity of the cod. The cod would still reproduce, but the mortality rate for eggs and larvae would be higher.

If the Baltic Sea experiences lower salinity due to climate change, the cod stocks will most likely suffer because the cod will have difficulty reproducing. Furthermore, there will be predation by grey seals. These two ecosystem issues can greatly affect the cod stock so this is why we wanted to find out how large these impacts might be in order to regulate fishing levels accordingly,” says MacKenzie. “Our results show, that fishing and environmental factors like oxygen depletion and decreasing salinity will affect the cod population more than the grey seals in the years to come.”

According to the study, it would be possible to simultaneously increase numbers of cod and grey seals in the Baltic Sea.

For more information, the paper can be found at PloS ONE (http://www.plosone.org)

Brian R. MacKenzie, Margit Eero, Henn Ojaveer. Could Seals Prevent Cod Recovery in the Baltic Sea? PLoS ONE, 2011; 6 (5): e18998 DOI: 10.1371/journal.pone.0018998

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Hilton stops serving sailfish and marlin in Costa Rica http://www.aquaticcommunity.com/news/lib/1455 http://www.aquaticcommunity.com/news/lib/1455#comments Tue, 26 Jul 2011 16:03:28 +0000 Anja http://www.aquaticcommunity.com/news/?p=1455 Four Hilton Worldwide hotels in Costa Rica have pledged to stop serving sailfish and marlin after entering into an agreement with the Billfish Foundation (TBF) and the Costa Rica Sport Fishing Federation (FECOPT). Last year, TBF released a study showing the significant economic value of sportfishing tourism in Costa Rica, and the four hotels are now taking billfish from the […]

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Four Hilton Worldwide hotels in Costa Rica have pledged to stop serving sailfish and marlin after entering into an agreement with the Billfish Foundation (TBF) and the Costa Rica Sport Fishing Federation (FECOPT).

Last year, TBF released a study showing the significant economic value of sportfishing tourism in Costa Rica, and the four hotels are now taking billfish from the menu in an effort to promote responsible and soustainable tourism.

The four hotels that will no longer be serving billfish are these:

  • DoubleTree Resort by Hilton Costa Rica in Puntarenas
  • DoubleTree Cariari by Hilton San Jose
  • Hilton Papagayo Costa Rica Resort and Spa in the in the Guanacaste region
  • Hilton Garden Inn Liberia Airport

The participating Hilton Worldwide hotels in Costa Rica are leading the way for Costa Rica’s tourism industry to move toward new levels of support for sportfishing conservation practices,” says FECOPT’s Executive Director Enrique Ramirez. “Using the impetus of our agreement with the participating properties we look forward to partnering with sustainable tourism tour leader Horizontes to let this precedent spread across the nation’s tourism industry.”

TBF President Ellen Peel applauded the agreement as a new standard for voluntary conservation action in the private sector.

We’re very pleased to see tourism businesses and government tourism officials responding so positively to the facts and information presented by our socio-economic research conducted with the University of Costa Rica that clearly supports TBF’s message that good conservation can be good economics.

TBF is the only non-profit organization focused entirely on conserving billfish populations. Established 25 years ago, it has been working with governments and the private sector to protect billfish from overfishing by fisheries and to implement tag and release programs for sport fishers. In addition to Costa Rica, TBF is active in countries such as Mexico, Panama and Peru.

TBF is proud of the efforts by Enrique Ramirez who secured the participation of the four participating Hilton Worldwide properties in Costa Rica and explained the conservation and business benefits of the world’s sportfishing tourists, reaffirming Costa Rica’s stature as one of the world’s premier fishing destinations,” says TBF Chief Scientist Dr. Russell Nelson. “We specially appreciate the foresight of the general managers at the participating Hilton Worldwide hotels in Costa Rica – Ricardo Rodriguez Gil, Laura Castagnini and Rui Dominguez – that supporting sportfishing conservation efforts are good for the oceans and good for business as well.”

For more information, visit www.billfish.org.

Bill fish

The term billfish is used for a number of large, predatory fish equipped with long, sword-like bills that they use to stun prey. The group includes sailfish, marlin and swordfish. Billfish are important apex predators in the ecosystems where they exist. The richest abundance of billfish is found in the tropics and subtropics, but they do occur in temperate waters as well, especially the swordfish.

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China Releases 1.3 Billion Fish into Yangtze River http://www.aquaticcommunity.com/news/lib/1452 http://www.aquaticcommunity.com/news/lib/1452#comments Sun, 24 Jul 2011 16:03:16 +0000 Anja http://www.aquaticcommunity.com/news/?p=1452 Last week, 1.3 billion fish were released into the Yangtze River by the Chinese Ministry of Agriculture (MOA). The release took place in the provinces of Jiangxi, Hubei, Hunan, Anhui and Jiangsu in the middle and lower reaches of the river. The release is a part of a project that the authorities hope will help restore fishery resources after the […]

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Last week, 1.3 billion fish were released into the Yangtze River by the Chinese Ministry of Agriculture (MOA). The release took place in the provinces of Jiangxi, Hubei, Hunan, Anhui and Jiangsu in the middle and lower reaches of the river.

The release is a part of a project that the authorities hope will help restore fishery resources after the recent drought. 9,000 hectares of the river will be planted with aquatic weeds, and 21 million shellfish will also be released into the water. Examples of fish species that were included in the recent release are black carp, grass carp and bighead carp.

The drought has also affected Chinese lakes, and 100 million fish have been released in nine lakes in China’s Anhui Province. According to an estimated from Anhui Fishery Bureau, the drought caused a loss of 148 000 metric tons of fish in the province.

In the Hubei Province, the Honghu Lake – which is the largest lake in the province – decreased down to 12.6 percent (4,475 hectares) of its normal size during the drought according to sources within the Jingzhou Aquatic Products Bureau. 300 million fish have now been released into a total of 34 lakes.

The Yangtze River

The Yangtze River is the longest river in Asia and the third longest river in the world; only the Nile and the Amazon are longer. During recent years, the Yangtze River has suffered from severe industrial pollution coupled with siltation and agricultural run-off. Loss of wetland and lakes has amplified the problems and exacerbated seasonal flooding. Some parts of the river are now protected as nature reserves.

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New species of Brazilian killifish described by science http://www.aquaticcommunity.com/news/lib/1448 http://www.aquaticcommunity.com/news/lib/1448#comments Wed, 13 Jul 2011 00:42:36 +0000 Anja http://www.aquaticcommunity.com/news/?p=1448 A new species of killifish native to Brazil has been formally described and given a scientific name. The fish, from now on known as Rivulus albae, belongs to the subgenus Melanorivulus and was found in soft and acidic water in northeastern Brazil.

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A new species of killifish native to Brazil has been formally described and given a scientific name. The fish, from now on known as Rivulus albae, belongs to the subgenus Melanorivulus and was found in soft and acidic water in northeastern Brazil.

rivulus albae New species of Brazilian killifish described by science

Rivulus albae. Photo By Javier Rabanal

The fish is named after Alba Garcia, the daughter of José Ramón García, one of the authors of the paper in which the species is described.

Appearance

Rivulus albae distinguishes itself from the other members of the subgenus Melanorivulus by having brown oblique bars on the entire flank which on the dorsal portion of the flank often form chevron-like marks with a posterior vertex (vs. chevron-like pattern with vertex pointing anteriorly when present).

Rivulus albae looks quite similar to Rivulus decoratus, but has 6 branchiostegal rays instead of 5, 13 anal fin rays instead of 10 or 11, and 24-26 scales on lateral series instead of 25-28.

Distribution and habitat

All the other recognized species of the subgenus Melanorivulus live in rivers south of the main channel of the Amazon River, but Rivulus albae was collected north of the Amazon River, in the state of Amapá. So far, the species is only known from a handful of localities belonging to Comprido Lake and Tartaruga Grande River.

Rivulus albae was collected in an environment where the savannah meets the forest, close to the banks of large water bodies with clear water at an altitude up to roughly 50 meters above sea level. This fish lives in lakes and lagoons where the underwater vegetation is dense and the water soft and acidic (pH 6.0-6.5).

Authors

  • STEFANO VALDESALICI, ITALYvaldesalici.stefano(at)gmail.com
  • JOSÉ RAMÓN GARCÍA GIL, SPAIN
  • DALTON TAVARES BRESSANE NIELSEN, BRAZIL

The paper was published in Vertebrate Zoology on June 22, 2011.

http://www.vertebrate-zoology.de/vz61-1/06_Vertebrate_Zoology_61-1_Valdesalici.pdf

http://www.vertebrate-zoology.de/

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The mystery of bonefish spawning solved http://www.aquaticcommunity.com/news/lib/1445 http://www.aquaticcommunity.com/news/lib/1445#comments Sun, 22 May 2011 07:02:45 +0000 Anja http://www.aquaticcommunity.com/news/?p=1445 The Bonefish is an extremely popular fishing that lures 1000s of sport fishermen to try their luck each year but until now it has been unknown how this species reproduce. Andy Danylchuk, a researcher working at University of Massachusetts Amherst and his colleagues have been studying bonefish for the last few years using using ultrasonic transmitters to tag and track the fishes movements. The research have been conducted outside Bahamas. The results can now be found in the online version of journal Marine Biology.

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The Bonefish is an extremely popular fishing that lures 1000s of sport fishermen to try their luck each year but until now it has been unknown how this species reproduce. Andy Danylchuk, a researcher working at University of Massachusetts Amherst and his colleagues have been studying bonefish for the last few years using using ultrasonic transmitters to tag and track the fishes movements. The research have been conducted outside Bahamas. The results can now be found in the online version of the journal Marine Biology.

The research show that bonefish gather by the thousands at pre-spawning aggregation sites for a few days each month during the spawning season (October to May). This usually take place during the full and new moon. The fish than migrate together out into deeper water at dusk where they than spawn at depths of more than 1000 ft (300m).

Andy Danylchuk says that “One possible benefit of bonefish migrating to offshore locations to spawn is that it increases the dispersal of their fertilized eggs, especially with the high tides that happen with the new and full moons.”

He also says that this is “This is the first time movement patterns of bonefish to deep water have been formally described,” and that “This new understanding of bonefish movement and spawning aggregations has significant implications for their conservation,”

The researcher have tagged and followed a total of 60 fish over two years.

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Will a third force field be enough to protect the Great Lakes? http://www.aquaticcommunity.com/news/lib/1444 http://www.aquaticcommunity.com/news/lib/1444#comments Wed, 20 Apr 2011 02:48:48 +0000 Anja http://www.aquaticcommunity.com/news/lib/1444 The U.S. Army Corps of Engineers have constructed an electric barrier in the Chicago Sanitary and Ship Canal, a waterway linking the Mississippi River with the Great Lakes watershed. The idea is to prevent Asian carps from entering the Great Lakes where it could wreck havoc with the ecosystem.

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The U.S. Army Corps of Engineers have constructed an electric barrier in the Chicago Sanitary and Ship Canal, a waterway linking the Mississippi River with the Great Lakes watershed. The idea is to prevent Asian carps from entering the Great Lakes where it could wreck havoc with the ecosystem.

Seven species of carps native to Asia have been introduced to the United States, and four of them are considered a threat to the Great Lakes: bighead carp, silver carp, black carp and grass carp.

The new electric barrier is located slightly upstream from two similar barriers in the canal, and consists of underwater electrodes that creates a forced field by emitting rapid pulses. The force field is meant to repel fish and is capable of shocking those that refuse to turn around.

“We now have great flexibility and redundancy”, says Col. Vincent Quarles, commander of the Army Corps’ Chicago district. “We want to deter the Asian carp threat. The barrier is a very good tool.”

Since the early 1970s, Bighead carp and Silver carp have migrated northward on the Mississippi and its tributaries. Environmental groups have called for physically severing the man-made Chicago Sanitary and Ship Canal, which was completed in the year 1900 to connect the Great Lakes with the Mississippi drainage basins.

Michigan and four other Great Lakes states also wish to sever the canal, and there is currently a federal lawsuit pending against the Army Corps. The Army Corps have pledged to consider that option in a comprehensive study, but that study is not scheduled for completion until 2015.

The first electrical underwater fence in the Chicago Sanitary and Ship Canal was activated in 2002, while the second one was turned on seven years later. Federal and state officials say that the barriers have performed well, but skeptics keep questioning the effectiveness of the barriers. Scientists with the University of Notre Dame and The Nature Conservancy have reported findings of DNA from both Bighead carp and Silver carp in numerous locations above the barriers. However, no Asian carps have been found, save for one single specimen.

“There are still serious gaps in our knowledge about how well it’s working,” says Thom Cmar, an attorney with the Natural Resources Defense Council. “No one ever imagined these electric barriers would be a permanent solution. They’ve always been just a stopgap idea.”

In a newly released report, the Army Corps acknowledges that the 2 volts per inch used in the barriers may not be enough to deter small fish that are just a few inches in length. Increasing the voltage might however endanger the ships moving flammable items across the canal.

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