Tài liệu về Oncorhynchus ( cá hồi)?
- Thread starter bpq
- Start date
Cá hồi là tên gọi cho một số loài cá da trơn sống ở các nước ôn đới và hàn đới thuộc họ Salmonidae. Cá hồi sống ở Đại Tây Dương và Thái Bình Dương và Hồ Great Lakes, Bán đảo Kamchatka, và ở Viễn Đông Nga. Ở Việt Nam, cá hồi đã được nuôi thành công ở Sa Pa và Đà Lạt.
[sửa] Sự di cư của cá hồi
Cá hồi sống trong môi trường "nước động". Cá hồi sinh ra ở môi trường nước ngọt, nhưng cá con chỉ sống một thời gian ngắn ở môi trường này rồi tự bơi ra biển. Phần lớn quãng đời của cá hồi là sống trong môi trường nước mặn. Cá hồi di cư vì hai lý do: nguồn thức ăn và địa điểm sinh sản. Nguồn thức ăn của cá hồi là ở biển, trong khi đó cá lại sinh sản ở vùng nước ngọt.
Loài cá hồi khi di chuyển định hướng bằng mùi. Mỗi chú cá nhớ một mùi của dòng sông nơi nó sinh ra. Khi di chuyển qua đại dương trở về con sông sinh sản, con cá sẽ tìm thấy đường của nó một cách hoàn toàn bản năng vì mùi vị thân quen càng gần càng trở nên rõ rệt.
Sự di cư ngược dòng sông về các bãi đẻ chỉ xảy ra một lần trong đời của hầu hết cá hồi (Salmon). Khi đến tuổi sinh sản, cá hồi di cư hàng dặm để các bãi đẻ trứng. Khi về đến cửa sông, chúng tụ lại trong vùng nước lợ (nước hơi mặn) và đợi con nước lớn đưa chúng ngược lên dòng sông.
Hành trình ngược dòng sông có thể mất vài tháng. Những chú cá thường phải băng mình qua những thác nước và vách dốc để đến những con suối cạn đẻ trứng. Vì cá hồi không ăn ở vùng nước ngọt, nên chúng bị mất 40% khối lượng cơ thể vào thời gian đẻ trứng và thụ tinh cho trứng. Hầu hết chúng đều chết sau đó.
[sửa] Sự di cư của cá hồi
Cá hồi sống trong môi trường "nước động". Cá hồi sinh ra ở môi trường nước ngọt, nhưng cá con chỉ sống một thời gian ngắn ở môi trường này rồi tự bơi ra biển. Phần lớn quãng đời của cá hồi là sống trong môi trường nước mặn. Cá hồi di cư vì hai lý do: nguồn thức ăn và địa điểm sinh sản. Nguồn thức ăn của cá hồi là ở biển, trong khi đó cá lại sinh sản ở vùng nước ngọt.
Loài cá hồi khi di chuyển định hướng bằng mùi. Mỗi chú cá nhớ một mùi của dòng sông nơi nó sinh ra. Khi di chuyển qua đại dương trở về con sông sinh sản, con cá sẽ tìm thấy đường của nó một cách hoàn toàn bản năng vì mùi vị thân quen càng gần càng trở nên rõ rệt.
Sự di cư ngược dòng sông về các bãi đẻ chỉ xảy ra một lần trong đời của hầu hết cá hồi (Salmon). Khi đến tuổi sinh sản, cá hồi di cư hàng dặm để các bãi đẻ trứng. Khi về đến cửa sông, chúng tụ lại trong vùng nước lợ (nước hơi mặn) và đợi con nước lớn đưa chúng ngược lên dòng sông.
Hành trình ngược dòng sông có thể mất vài tháng. Những chú cá thường phải băng mình qua những thác nước và vách dốc để đến những con suối cạn đẻ trứng. Vì cá hồi không ăn ở vùng nước ngọt, nên chúng bị mất 40% khối lượng cơ thể vào thời gian đẻ trứng và thụ tinh cho trứng. Hầu hết chúng đều chết sau đó.
Cá hồi Đại Tây Dương (Salmo salar)
Taxonomy
Kingdom: Animalia
Phylum: Chordata
Class: Osteichthyes
Order: Salmoniformes
Family: Salmonidae
Genus: Salmo
Species: salar Species Description
The average size of Atlantic salmon is 28-30 inches (71-76 cm) long and 8-12 pounds (3.6-5.4 kg) after two years at sea. Although uncommon, adults can grow to be as large as 30 pounds (13.6 kg).
Atlantic salmon have a relatively complex life history that includes spawning, juvenile rearing in rivers, and extensive feeding migrations on the high seas. As a result, Atlantic salmon go through several distinct phases that can be identified by specific changes in behavior, physiology, and habitat requirements.
Juvenile salmon feed and grow in rivers for one to three years before undergoing "smoltification" and migrating to the ocean. Atlantic salmon of U.S. origin are highly migratory, undertaking long marine migrations between the mouths of U.S. rivers and the northwest Atlantic Ocean where they are widely distributed seasonally over much of the region. Most Atlantic salmon of U.S. origin spend two winters in the ocean before returning to freshwater to spawn. Those that return after only one year are called grilse. In the United States, most adult Atlantic salmon ascend the rivers of New England beginning in spring and continuing through the fall, with migration peaking in June.
Habitat
The Atlantic salmon is an anadromous fish, typically spending 2-3 years in freshwater, migrating to the ocean where it also spends 2-3 years, and then returning to its natal river to spawn.
Suitable spawning habitat consists of gravel or rubble in areas of moving water. Eggs hatch in March or April and become fry.
Map: Migration of Atlantic salmon
Fry remain buried in the gravel for about six weeks. The fry emerge from the gravel about mid-May and start feeding on plankton and small invertebrates. Emergent fry quickly disperse from nests (called redds) within the gravel. They develop camouflaging stripes along their sides, and enter what is termed the parr stage.
Parr habitat, often called "nursery habitat," is typically riffle areas characterized by adequate cover, shallow water depth, and moderate to fast water flow.
Salmon parr spend 2-3 years in freshwater and then undergo a physiological transformation called smoltification that prepares them for life in a marine habitat.
Atlantic salmon leave Maine rivers in the spring and reach Newfoundland and Labrador by mid-summer. They spend their first winter at sea south of Greenland.
After the first winter at sea, a small percentage return to Maine while the majority spend a second year at sea, feeding off the southwest or, to a much lesser extent, the southeast coast of Greenland. Some Maine salmon are also found in waters along the Labrador coast.
After a second winter in the Labrador Sea, most Maine salmon return to rivers in Maine, with a small number returning the following year as what is referred to as three sea winter fish.
Atlantic Salmon
Critical Habitat
(click for larger view PDF)
In June 2009, NMFS designated critical habitat for the Gulf of Maine DPS. In September 2008, NMFS proposed critical habitat for the DPS.
Distribution
There are three generally recognized groups of Atlantic salmon: North American, European, and Baltic. Atlantic salmon reproduce in coastal rivers of northeastern North America, Iceland, Europe, and northwestern Russia and migrate through various portions of the North Atlantic Ocean. European and North American populations of Atlantic salmon intermix during their at-sea stage, where they share similar summer feeding grounds off Greenland.
The North American group historically ranged from northern Quebec southeast to Newfoundland and southwest to Long Island Sound. It includes Canadian populations and U.S. populations, including the listed Gulf of Maine DPS. In Canada, significant reproducing populations remain throughout the historic range, though many populations are severely depleted.
Population Trends
By the early 19th century, Atlantic salmon runs in New England, which historically occurred in almost every major river north of the Hudson River, were severely depleted. Overexploitation, degradation of water quality, and damming of rivers were large contributors to the historical decline in abundance. By the end of the 19th century, Atlantic salmon had been extirpated from three of the five rivers with the largest populations (Androscoggin, Merrimack, and Connecticut). In general, the abundance of Atlantic salmon continued to decline in all rivers through the first half of the 20th century. The primary distribution of Atlantic salmon in the United States by the mid-20th century was, except for a few remnant populations, limited to the eastern third of Maine's coast.
Even with current conservation efforts, returns of adult Atlantic salmon to the Gulf of Maine DPS rivers remain extremely low. The 2006 status review [pdf] [2.8 MB] reports an estimated extinction risk of 19% to 75% within the next 100 years for the Gulf of Maine DPS even when current levels of hatchery supplementation are considered.
The populations of Atlantic salmon present in the Gulf of Maine DPS represent the last wild populations of U.S. Atlantic salmon. At the time of listing under the ESA in 2000, there were at least eight rivers in the geographic range of the DPS known to still support wild Atlantic salmon populations:
Threats
Taxonomy
Kingdom: Animalia
Phylum: Chordata
Class: Osteichthyes
Order: Salmoniformes
Family: Salmonidae
Genus: Salmo
Species: salar Species Description
The average size of Atlantic salmon is 28-30 inches (71-76 cm) long and 8-12 pounds (3.6-5.4 kg) after two years at sea. Although uncommon, adults can grow to be as large as 30 pounds (13.6 kg).
Atlantic salmon have a relatively complex life history that includes spawning, juvenile rearing in rivers, and extensive feeding migrations on the high seas. As a result, Atlantic salmon go through several distinct phases that can be identified by specific changes in behavior, physiology, and habitat requirements.
Juvenile salmon feed and grow in rivers for one to three years before undergoing "smoltification" and migrating to the ocean. Atlantic salmon of U.S. origin are highly migratory, undertaking long marine migrations between the mouths of U.S. rivers and the northwest Atlantic Ocean where they are widely distributed seasonally over much of the region. Most Atlantic salmon of U.S. origin spend two winters in the ocean before returning to freshwater to spawn. Those that return after only one year are called grilse. In the United States, most adult Atlantic salmon ascend the rivers of New England beginning in spring and continuing through the fall, with migration peaking in June.
Habitat
The Atlantic salmon is an anadromous fish, typically spending 2-3 years in freshwater, migrating to the ocean where it also spends 2-3 years, and then returning to its natal river to spawn.
Suitable spawning habitat consists of gravel or rubble in areas of moving water. Eggs hatch in March or April and become fry.
Fry remain buried in the gravel for about six weeks. The fry emerge from the gravel about mid-May and start feeding on plankton and small invertebrates. Emergent fry quickly disperse from nests (called redds) within the gravel. They develop camouflaging stripes along their sides, and enter what is termed the parr stage.
Parr habitat, often called "nursery habitat," is typically riffle areas characterized by adequate cover, shallow water depth, and moderate to fast water flow.
Salmon parr spend 2-3 years in freshwater and then undergo a physiological transformation called smoltification that prepares them for life in a marine habitat.
Atlantic salmon leave Maine rivers in the spring and reach Newfoundland and Labrador by mid-summer. They spend their first winter at sea south of Greenland.
After the first winter at sea, a small percentage return to Maine while the majority spend a second year at sea, feeding off the southwest or, to a much lesser extent, the southeast coast of Greenland. Some Maine salmon are also found in waters along the Labrador coast.
After a second winter in the Labrador Sea, most Maine salmon return to rivers in Maine, with a small number returning the following year as what is referred to as three sea winter fish.
Atlantic Salmon
Critical Habitat
(click for larger view PDF)
In June 2009, NMFS designated critical habitat for the Gulf of Maine DPS. In September 2008, NMFS proposed critical habitat for the DPS.
Distribution
There are three generally recognized groups of Atlantic salmon: North American, European, and Baltic. Atlantic salmon reproduce in coastal rivers of northeastern North America, Iceland, Europe, and northwestern Russia and migrate through various portions of the North Atlantic Ocean. European and North American populations of Atlantic salmon intermix during their at-sea stage, where they share similar summer feeding grounds off Greenland.
The North American group historically ranged from northern Quebec southeast to Newfoundland and southwest to Long Island Sound. It includes Canadian populations and U.S. populations, including the listed Gulf of Maine DPS. In Canada, significant reproducing populations remain throughout the historic range, though many populations are severely depleted.
Population Trends
By the early 19th century, Atlantic salmon runs in New England, which historically occurred in almost every major river north of the Hudson River, were severely depleted. Overexploitation, degradation of water quality, and damming of rivers were large contributors to the historical decline in abundance. By the end of the 19th century, Atlantic salmon had been extirpated from three of the five rivers with the largest populations (Androscoggin, Merrimack, and Connecticut). In general, the abundance of Atlantic salmon continued to decline in all rivers through the first half of the 20th century. The primary distribution of Atlantic salmon in the United States by the mid-20th century was, except for a few remnant populations, limited to the eastern third of Maine's coast.
Even with current conservation efforts, returns of adult Atlantic salmon to the Gulf of Maine DPS rivers remain extremely low. The 2006 status review [pdf] [2.8 MB] reports an estimated extinction risk of 19% to 75% within the next 100 years for the Gulf of Maine DPS even when current levels of hatchery supplementation are considered.
The populations of Atlantic salmon present in the Gulf of Maine DPS represent the last wild populations of U.S. Atlantic salmon. At the time of listing under the ESA in 2000, there were at least eight rivers in the geographic range of the DPS known to still support wild Atlantic salmon populations:
- Dennys river
- East Machias river
- Machias river
- Pleasant river
- Narraguagus river
- Ducktrap river
- Sheepscot river
- Cove Brook
- Penobscot River
- Androscoggin River
- Kennebec River
Threats
- Acidified water and associated aluminum toxicity, which decrease juvenile survival
- Aquaculture practices, which pose ecological and genetic risks
- Avian (bird) predation
- Changing land use patterns (e.g., development, agriculture, forestry)
- Climate change
- Degradation of water quality (e.g., contaminants, nutrient enrichment, elevated water temperature)
- Hatchery programs (potential for artificial selection/domestication)
- Incidental capture of adults and parr by recreational fishermen
- Non-native fish species that compete with or prey on Atlantic salmon
- Loss of habitat complexity and connectivity
- Poaching of adults in rivers with listed Atlantic salmon
- Sedimentation
- Water extraction
Đầu tiên xin cảm ơn bạn. Những thứ này mình kiếm được từ Wikipedia rồi
Bạn có thể chỉ tôi những link tổng quát, chuyên sâu hơn không ? Chứ mấy cái này sơ sài quá. Làm sao mình có thể làm 1 bài Seminar 20 trang A4 được
http://animaldiversity.ummz.umich.edu/site/accounts/information/Oncorhynchus_mykiss_aguabonita.html
http://de.academic.ru/dic.nsf/dewiki/1050802
http://bss.sfsu.edu/holzman/courses/spring 05 projects/g. trout/golden trout final website.htm
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