Yavapai County, Arizona - Region C
Gila (Yaqui) Topminnow
Table of Pesticide Active Ingredients
|COPPER SULFATE (all salts)||2a|
|MALATHION||3x. 5a, 10a|
|METHYL PARATHION||3x, 5a|
* TAR = Threshold Application Rate (Pounds of active ingredient per acre per applications)
|1x||Within the area described under the Shading Key and 1/2 mile up all streams that join the area, do not apply this pesticide within 20 yards from the edge of water for ground applications, nor within 100 yards for aerial applications.|
|2a||Within the area described under the Shading Key, do not apply this pesticide within 40 yards from the edge of water for ground applications, nor within 200 yards for aerial applications.|
|3x||Within the area described under the Shading Key and 1/2 mile, do not apply this pesticide within 100 yards from the edge of water for ground applications, nor within 1/4 mile for aerial applications.|
|5a||Do not apply ultra low volume (ULV) applications within 1 mile from the edge of water within the area described under the Shading Key.|
|41a||Within the area described under the Shading Key, do not apply this pesticide within 1/4 mile from the edge of water for ground applications, nor within 1/2 mile for aerial applications.|
|43a||Within the area described under the Shading Key, do not apply this pesticide within 100 yards from the edge of water for ground applications, nor within 1/4 mile for aerial applications.|
|196||Within the area described under the Shading Key, do not apply this pesticide above the threshold application rate (TAR) indicated within 20 yards from the edge of water for ground applications, nor within 100 yards for aerial applications.|
|296||Within the area described under the Shading Key, do not apply this pesticide above the threshold application rate (TAR) indicated within 40 yards from the edge of water for ground applications, nor within 200 yards for aerial applications.|
|396||Within the area described under the Shading Key, do not apply this pesticide above the threshold application rate (TAR) indicated within 100 yards from the edge of water for ground applications, nor within 1/4 mile for aerial applications.|
Gila and Yaqui topminnow [Poeciliopsis occidentalis]
The Gila topminnow consists of two subspecies, the Gila (Poeciliopsis occidentalis occidentalis) and the Yaqui (P. occidentalis sonoriensis), both of which are federally listed as endangered. This topminow is included in the same family as the domesticated aquarium guppy, and is similar to the guppy in many aspects. This tiny fish averages 3 to 4 centimeters (1.2 to 1.6 in) in length. It is tan to olive on the upper portions of its body and white below. Similar to other fish, the body colors of breeding males will become more vibrant in order to entice the females. Breeding male topminnows darken to jet black and develop bright yellow fins and golden tints along their midsections.
Although the lifespan of the Gila topminnow is only about one year, the species is a prolific breeder. Gestation varies from 24 to 28 days for the Gila topminnow and 12 to 14 days for the Yaqui subspecies. Unlike most other fish, the topminnow gives birth to live young, as opposed to laying eggs. The onset of breeding is affected by water temperature, daylight, and food availability.
Topminnows are able to exist in a broad range of habitats. Though they prefer shallow, warm, and fairly quiet waters, these fish are also found in moderate currents and depths up to 1 meter (3.3 ft). They make their homes in permanent and intermittent streams, marshes, and river banks, where they seek dense mats of algae and debris with sandy substrates for their preferred living environment.
Historically, this topminnow was abundant throughout the Gila River system and Rio Yaqui drainage in Arizona, New Mexico, and northern Sonora and Chihuahua, Mexico. The current severe reductions of population and suitable habitat are reasons for grave concern for the survival of the this species. The Gila Topminnow still occurs in natural populations at only eight isolated locations in the Santa Cruz River System. It is believed that extensive groundwater pumping and diversion of water for the irrigation of agriculture in Mexico have annihilated the species from that country. The Yaqui topminnow is found only at eight US locations within the Yaqui River headwaters, but is more abundant in Mexico.
Water projects such as dam building and crop irrigation transformed all free-flowing southwestern rivers into intermittent, deeply cut streams or broad, sandy washes, reducing the topminnow populations to a fraction of their pre-1860's range. As with other species of fish found in Arizona, the topminnow is also threatened by aggressive and predatory, non-native fish which have been introduced for recreational purposes. Other introduced species like the related mosquitofish harass adult topminnows and feed on the young, and are a major obstacle to the continuing survival of these fish. Only when a habitat is sufficiently large can these two species coexist.
Some of the topminnow populations are found on National Wildlife Refuges and are well protected. The species is also successfully reared in captivity and has been reintroduced into the wild. However, even with the gifted fertility of this fish, it is clear that the Gila and Yaqui topminnows need large, stable habitats to ensure their survival.
Matthews, J.R. (ed.). 1990. The Official World Wildlife Fund Guide to Endangered Species, Beacham Publishing Inc, Washington, DC. Vol II, pp. 928-929.