Biology
What is the largest freshwater fish?
How have invasive pythons impacted Florida ecosystems?
Why are pollinating bees and bats important?
USGS science is used by other agencies to help conserve species, lands, resources, and priority ecosystems.
When can salmon be seen migrating to their spawning area?
Most Pacific salmon can be seen migrating from spring though fall, depending on the species. Most adult Atlantic salmon migrate up the rivers of New England beginning in spring and continuing through the fall as well, with the migration peaking in June. Learn more: Western Fisheries Research Center - Questions and Answers about Salmon
Why do salmon eggs come in different colors?
Salmon eggs (roe) range in color from pale yellowish-orange to dark reddish-orange. The color varies both by species and within species and is determined by water temperature, sediment composition, age, and other factors. The eggs vary in size from the tiny sockeye roe (average ¼ inch or 5.6 mm) to the large chum roe (average almost ½ inch or 8.3 mm). Also, if a salmon egg does not get fertilized...
Why are there so few salmon left?
There are many reasons for the decline in salmon populations. Logging an area around a stream reduces the shade and nutrients available to the stream and increases the amount of silt or dirt in the water, which can choke out developing eggs. Dams cause fish to die from the shock of going through the turbines and from predators that eat the disoriented fish as they emerge from the dam. Overfishing...
How many species of salmon are there and how large can they get?
There are seven species of Pacific salmon. Five of them occur in North American waters: chinook, coho, chum, sockeye, and pink. Masu and amago salmon occur only in Asia. There is one species of Atlantic salmon. Chinook/King salmon are the largest salmon and get up to 58 inches (1.5 meters) long and 126 pounds (57.2 kg). Pink salmon are the smallest at up to 30 inches (0.8 meters) long and 12...
Where are salmon most endangered?
Certain populations of sockeye salmon, coho salmon, chinook salmon, and Atlantic salmon are listed as endangered. Sockeye salmon from the Snake River system are probably the most endangered salmon. Coho salmon in the lower Columbia River may already be extinct. Salmon are not endangered worldwide. For example, most populations in Alaska are healthy. Some populations in the Pacific Northwest are...
Are salmon endangered worldwide?
No, salmon are not endangered worldwide. For example, most populations in Alaska are healthy. Some populations in the Pacific Northwest are much healthier than others. These healthy populations usually occupy protected habitats such as the Hanford Reach on the Columbia River and streams of Olympic National Park. Learn more: Western Fisheries Research Center - Questions and Answers about Salmon
Are sturgeon and catfish related?
No. Although sturgeon and catfish can be found in the same habitats and they both have barbels (whiskerlike growths extending from the jaw), they are not closely related. Sturgeon are much more primitive than catfish. There are some catfish sold for aquariums that look somewhat like sturgeon, and some fish have common names that are misleading (i.e. sturgeon chub) but these fish are not related to...
What is the largest freshwater fish?
Sturgeon are the largest of the freshwater fish. The beluga sturgeon in Russia is the largest freshwater fish in the world. The white sturgeon is the largest freshwater fish in North America. White sturgeon have been reported to reach lengths of 15-20 feet and weights of nearly one ton. The second largest freshwater fish in North America is the alligator gar.
Are lamprey and hagfish related?
Yes. Lamprey and hagfish are both jawless fishes. They are the only living members of the taxonomical class Agnatha (Greek for “no jaws”). Learn more: Sea Lamprey Species Profile
Do alligators and crocodiles exist together anywhere in the world?
The American crocodile (Crocodylus acutus) lives in several places within the Americas, including Mexico, Central and South America, the Caribbean, and south Florida. The American alligator (Alligator mississippiensis) is also found in south Florida, among other places. South Florida is the only place you can find both animals in the wild. To distinguish the two, alligators have a more U-shaped...
Why are bats important?
By eating insects, bats save U.S. agriculture billions of dollars per year in pest control. Some studies have estimated that service to be worth over 3.7 billion dollars per year, and possibly as much as 53 billion dollars per year. This value does not, however, take into account the volume of insects eaten by bats in forest ecosystems and the degree to which that benefits industries like lumber...
Are bats dangerous?
All healthy bats try to avoid humans by taking flight and are not purposely aggressive. Most bats are about the size of a mouse and use their small teeth and weak jaws to grind up insects. You should avoid handling bats because several species, such as the hoary and big brown bats, have large teeth that can puncture skin if they are handled improperly. Less than one percent of the bat population...