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A Tough Balance: Brown Trout Can Interfere with Brook Trout Conservation



A Tough Balance: Brown Trout Can Interfere with Brook Trout Conservation

Cortland, N.Y.— Brown trout introductions could hamper the conservation of declining native brook trout populations, according to a new U.S. Geological Survey study.

Brook and brown trout are valuable sport fish that co-exist in many parts of the world due to stocking introductions. USGS researchers found that, in New York State, direct interactions between the two species, such as competition for food, have minor effects on diminishing brook trout populations compared to human-caused habitat disturbances. However, repeated, disproportionate stocking of brown trout in brook trout habitats could drastically decrease brook trout numbers.

“There is great potential for brown trout stocking to reduce native brook trout populations,” said James McKenna, USGS scientist and lead author of the study. “But brown trout aren’t necessarily causing the current brook trout declines, and managers may be able to develop sustainable scenarios to support both fisheries.”

The USGS study found that human-induced degradation (from dams and roads, among other causes) of the habitats of both species can affect the populations of either. However, because brook trout do better in forested watersheds, whereas brown trout can thrive in more agricultural environments, degraded watersheds and/or the elimination of forests may affect brook more than brown trout. Improper brown trout management could further threaten vulnerable brook trout populations.

Fisheries managers in New York use stocking to maintain brook trout—a native species—and/or brown trout—a non-native species stocked in New York for over 100 years—in some streams. Brook trout have been declining within its native range in recent decades, and there has been concern that the stocking of brown trout has caused these declines.

The report is published in the North American Journal of Fisheries Management and is available online.

For more information on USGS Great Lakes ecosystem research, please visit the USGS Great Lakes Science Center website.

USGS Newsroom



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Parameter Value Description
Magnitude mb The magnitude for the event.
Longitude ° East Decimal degrees longitude. Negative values for western longitudes.
Latitude ° North Decimal degrees latitude. Negative values for southern latitudes.
Depth km Depth of the event in kilometers.
Place Textual description of named geographic region near to the event. This may be a city name, or a Flinn-Engdahl Region name.
Time 1970-01-01 00:00:00 Time when the event occurred. UTC/GMT
Updated 1970-01-01 00:00:00 Time when the event was most recently updated. UTC/GMT
Timezone offset Timezone offset from UTC in minutes at the event epicenter.
Felt The total number of felt reports
CDI The maximum reported intensity for the event.
MMI The maximum estimated instrumental intensity for the event.
Alert Level The alert level from the PAGER earthquake impact scale. Green, Yellow, Orange or Red.
Review Status Indicates whether the event has been reviewed by a human.
Tsunami This flag is set to "1" for large events in oceanic regions and "0" otherwise. The existence or value of this flag does not indicate if a tsunami actually did or will exist.
SIG A number describing how significant the event is. Larger numbers indicate a more significant event.
Network The ID of a data contributor. Identifies the network considered to be the preferred source of information for this event.
Sources A comma-separated list of network contributors.
Number of Stations Used The total number of Number of seismic stations which reported P- and S-arrival times for this earthquake.
Horizontal Distance Horizontal distance from the epicenter to the nearest station (in degrees).
Root Mean Square sec The root-mean-square (RMS) travel time residual, in sec, using all weights.
Azimuthal Gap The largest azimuthal gap between azimuthally adjacent stations (in degrees).
Magnitude Type The method or algorithm used to calculate the preferred magnitude for the event.
Event Type Type of seismic event.
Event ID Id of event.
Event Code An identifying code assigned by, and unique from, the corresponding source for the event.
Event IDS A comma-separated list of event ids that are associated to an event.

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