For decades, fish researchers believed in Gerking’s “restricted movement paradigm”, thinking that river-dwelling fish largely stay in the same place and rarely venture forth. But in recent decades, ecologists have harnessed the power of both advanced tags and improved genetic methods to directly estimate movement distances and average home ranges of different fish species. Now, a new paper has gathered in one place data from more than 200 direct movement studies and more than 200 genetic studies to estimate how far river fish more on average. 

The U.S. Endangered Species Act has saved or recovered many species, and is recognized as one of the most powerful laws in the world for protecting the environment. The primary aim of the Act is to ensure that populations and species persist, and to conserve genetic variation in population. But little attention is paid to the adaptive potential of populations—the capability of populations to evolve when faced with new selective pressures—even though new genetic methods of sequencing the entire DNA of organisms are now cheaper and easier than ever before. 

To protect and recover species, most countries have laws that mandate particular actions when species are classified as threatened or endangered. These classifications can have an enormous impact on industries that impinge on the species in question, for example the declaration of northern spotted owls as endangered led to large-scale shutdowns in logging on old-growth forests. This process of classifying a species as threatened, endangered, or neither constitutes a difficult decision, and difficult decisions can usefully be approached using the theory and tools of decision analysis. 

A new and more accurate study reveals that about 4% of the ocean area experiences fishing each year, a far smaller estimate than previous studies that relied on very large grid sizes. Two recent studies estimated that fishing takes place in 55% of the ocean and 90% of the ocean each year. But these estimates divide the ocean into 0.5°×0.5° grid cells, which are ~3100 km² in size at the equator, and assume each cell is fished if a single fishing location is recorded in the entire cell. 

Whooping Cranes are highly endangered. To improve their recovery chances, a new migratory population was reintroduced into the wild in 2001, but their hatching success has been very low. A new study examines three possible hypotheses for this failure: harassment by black flies of nesting birds, effects of captive rearing, and inexperience of breeding birds. The overwhelming finding was that black fly harassment is the cause of poor hatching success: for example, when black fly numbers were reduced experimentally, breeding success doubled. 

The updated version, contains brand new photos and information about the life cycles of these marvelous fish in freshwater and marine environments.

Dams and river crossings often block the migration routes of stream-dwelling fish in addition to their better-known effects preventing salmon from spawning in upper river reaches. Relatively little is known about the movements of mountain whitefish (Prosopium williamsoni) in the Pacific Northwest, despite their widespread distribution. In the upper Cedar River, Washington, mountain whitefish had been absent above the Landsburg Dam, constructed in 1901, until a fish ladder was built in 2004 that allowed their upstream passage. 

Whooping cranes are endangered and slowly recovering from a low point of just 15 birds and one migratory population in the wild. New efforts have established an eastern second migratory population from captive-bred birds, although not without some difficulty, since migration routes are learned from other adults. In the eastern population two methods were used to teach a new migration pathway: imprinting cranes on ultralight aircraft on the ground, which would lead the cranes to an overwintering destination; or imprinting them to follow older whooping cranes or wild sandhill cranes when they migrate. 

Smallmouth bass are native to much of the midwestern USA and central Canada, but have been introduced to 41 states and 20 countries. While they are sought-after angling targets, they also are voracious predators of small fish and crayfish, which is of particular concern given their taste for baby salmon and trout. Thus it is crucially important for management and conservation to detect which streams have been occupied by smallmouth bass. 

Many fish species repeatedly migrate from feeding areas to spawning areas, and their migration pathways could be innate or learned. Two possible models are examined for learning of these migration pathways: the Diffusion Model holds that fish head to spawning site near where they themselves hatched; while the Go With the Old Fish Model involves young fish joining schools of older fish, and learning migration pathways from the older fish.