User:Tylerlove7/Colorado pikeminnow

Threats
The Colorado Pikeminnow was once a species of fish that resided in much of the Colorado River Basin. Due to human impacts and the introduction of non-native fish species, the population has receded to the upper basin. According to the Native Aquatic Species Conservation in Arizona, the instillation of dams has altered the fish's movement. Along with this, dewatering, altered stream flow, channel morphology, water quality, water chemistry, silt loads, and introduction of non-native fish have challenged the Colorado Pikeminnow (Sublette et. al. 1990, Muth and Snyder 1995). It has also been hypothesized that due to the installation of dams, the change in water temperature has altered breeding tendencies. Breeding is water temperature dependent, meaning the temperature of the water must be perfect for spawning to occur. Changes in these conditions have caused breeding grounds to change. Non-native fish have posed a threat in both predation and competition for resources. With the introduction of various invasive catfish species, Greenback Cutthroat Trout, and red shiner (Cyprinella lutrensis), the population of Colorado Pikeminnow has declined drastically. In specific, a study was conducted analyzing the factors of recruiting young Colorado Pikeminnow. In particular, it was found that red shiners feed on the larvae of Colorado Pikeminnow in vivo.

Breeding
As talked about briefly in the biology section, Colorado Pikeminnow tends to spawn in late July, early August in the Green River. A clear indicator of when these fish tend to reproduce is when the water temperature reaches over 18° C. The fish as previously stated migrate towards deep pools and rushing water to lay their eggs. Once a female lays her eggs, male Colorado Pikeminnow will follow the trial of eggs, dispersing semen. These eggs hatch at different rates based on the temperature of the water. When the water is around 20° C, eggs hatched within 3-5 days, and at a higher temperature of 25° C, eggs hatched at around 2-3 days. Along with the fast hatch rate, these eggs are also susceptible to movement. For example, looking at the Green River, one of a few remaining locations, eggs have been observed to move anywhere from 100 to 160 kilometers.

Restoration efforts
In Arizona, hatcheries are in the process of restocking the Upper basin with Colorado pikeminnow. According to the Native Aquatic Species Conservation in Arizona, it was found that small fish could not avoid predation as well as the only successful site for reintroduction was the Green River, more specifically the upper Green river. Fish up to 16 inches long have been released in the hopes of increasing the survival rate of the released Colorado Pikeminnow. There has been evidence that population numbers are increasing in the San Juan River.


 * Muth, R.T. and Snyder, D.E. 1995. Diets of young Colorado squawfish and other small fish in backwaters of the Green River, Colorado and Utah. The Great Basin Naturalist 55 (2): 95-104.