Cooperative Fish and Wildlife Research Units Program: New Mexico
Education, Research and Technical Assistance for Managing Our Natural Resources

New Mexico Project

Differential survival of two size classes of Rainbow Trout and the predatory impact of Northern Pike in a high elevation New Mexico reservoir

July 2019 - June 2022


Participating Agencies

  • New Mexico Department of Game and Fish
Jane is studying the top down effects of an apex predator in Eagle Nest Reservoir, New Mexico.

The New Mexico Department of Game and Fish manages Rainbow Trout at Eagle Nest Lake for New Mexico citizens as a put, grow, and take fishery. Management objectives stipulate that 10 Rainbow Trout per hour of electrofishing with a size structure of 50% Rainbow Trout greater than 254 mm (10 in) total length. However, population surveys reported a decline in Rainbow Trout per hour of electrofishing that presumably coincided with the illegal introduction of Northern Pike into Eagle Nest Lake.
Our goal is to develop a Rainbow Trout stocking strategy for Eagle Nest Lake that meets the objectives for New Mexico's citizens to catch Rainbow Trout greater than 254 mm. We are evaluating the predator-prey relationship of Northern Pike and Rainbow Trout using a combination of stomach contents (i.e., diet) and stable isotopes of Northern Pike to assess whether Rainbow Trout represent a substantive part of Northern Pike diet, or, are a periodic part of the diet that occurs at the time of the Rainbow Trout stockings. Seasonal sample collections timed with stocking of Rainbow Trout will reveal the relative contribution of Rainbow Trout versus other fishes to the Northern Pike diet of Eagle Nest Lake. Ultimately, fish size (fingerling vs. sub-catchable), and season stocked can be adjusted to maximize survival and growth of Rainbow Trout for capture by New Mexico fishers.