A report on the renovation of Los Ojitos Spring, Sonora, M’xico, with comments on the populations of Yaqui chub and Yaqui topminnow occurring there

Authors: Chuck Minckley

Year: 2016 (xlviii)

Abstract

Los Ojitos spring is represented by a roughly rectangular pool (75 X 50 m), 1.5 m deep and flows 200 m into the San Bernardin o River. It is known as part of the ‘Old Ci’nega’ by longtime residents. Historically, it was part of the ci’nega habitat present adjacent to the river in the recent past. It was dammed in 2000 as it had become incised and was back cutting into its source. Today, it emerges some 60 m above the pond, flows into it, and exits through a PVC pipe, into a ditch, flowing into the river some 100 m from its source. I first saw it in 2008, when it was relatively cattail free, and open water. Since that time, it filled in with cattails, and became a very restricted habitat for fishes. Sections became debris filled areas, which were occasionally anoxic and unavailable to the Yaqui chub, Gila purpurea, and the Yaqui topminnow, Poeciliopsis sonoriensis that occur there. A population of the San Bernardino spring snail, Pyrgulopsis bernardina, is also present. How these species came to be in the spring is unknown, and they may represent relicted populations trapped as the ci’nega was down cut and drained. I have found no evidence that they were stocked into the habitat. Because of the uniqueness of these species, and their listed status, it was decided to maintain this habitat. This was done using funds from the Desert Fishes Council to hire a crew from Cuenca los Ojos, to physically remove t he majority of the cattails. This was done in a week in September and I have been followed up with spraying the remaining plants with an appropriate herbicide. The dead material is also being removed with a commercial weed cutter and put in compost piles along the bank. These efforts will continue in order to maintain this habitat into perpetuity. A population estimate will be made for the Yaqui chub population in the pond, in October, and presented at the meetings.