Propagation of Hybrid Devils Hole Pupfish × Ash Meadows Amargosa Pupfish

Abstract

Recent censuses of Devils Hole Pupfish Cyprinodon diabolis revealed that fewer than 100 individuals currently remain in the wild. Captive propagation is among actions being considered to prevent their extinction, but no pure‐strain Devils Hole Pupfish were available for broodstock. To help provide emergency information, we investigated techniques to propagate their most closely related relative, hybrid Devils Hole Pupfish C. diabolis × Ash Meadows Amargosa Pupfish C. nevadensis mionectes. We tested various temperatures and larval feeds with respect to egg production, larval survival, and growth. Larval survival and growth were similar from 24°C to 32°C and egg production peaked at static 28°C; however, reducing water temperatures to 23°C and then raising them to 28°C resulted in even higher production. Larvae fed infusoria, Rio Grande Silvery Minnow Chow (RGSM), or Zeigler larval diet (ZLD) had the highest survival (79.4, 71.6, and 73.4%, respectively), and those fed Otohime (OTO) had the lowest survival (60.8%), although OTO provided greatest (14 mm) 30‐d growth. Supplementation of RGSM or ZLD with Artemia nauplii increased growth but decreased survival. Larval production was maximized by placing six spawning mops, constructed of yarn and tile, in each of four 437‐L parental aquaria, stocked with 24 adult fish each (1:1 sex ratio) for 3 d, to attract adults and provide spawning substrate. A 30% water change conducted on the same day of mop placement lowered water temperature from 28°C to 23°C. Water temperature was raised back to 28°C over 48 h. After 3 d, mops were transferred to hatching aquaria that were held at 28°C and aerated until larval hatch. Although some differences likely exist in effective propagation techniques for hybrid and pure‐strain Devils Hole Pupfish, these data help provide initial recommendations to aid recovery.

Design and Testing of a Mesocosm‐Scale Habitat for Culturing the Endangered Devils Hole Pupfish

“…Hybrid Devils Hole pupfish reproduced successfully in this system, in conditions that were harsher than those in a previous successful propagation experiment (Feuerbacher et al 2015). The conditions in the mesocosm tested here were more similar to those in Devils Hole than were those in this previous study.…”

“…Testing [TL]) were added to the mesocosm. Fish were progeny of hybrid Devils Hole Pupfish, which had been bred and raised at the University of Arizona (Feuerbacher et al 2015). External characteristics were used to sex fish, and an equal sex ratio of fish was introduced.…”

“…A 76-L infusoria grown from Devils Hole benthos and midwater samples (Feuerbacher et al 2015) was added to inoculate the system with microplankton: 20 g (wet weight) each of Spirogyra spp. algae, Chroococcus spp., and Oscillatoria spp.…”

“…Therefore, the hybrid Devils Hole × Ash Meadows Amargosa Pupfish were stocked in the mesocosm. These fish, housed and propagated at the University of Arizona (Feuerbacher et al 2015), were descendants of fishes from the Point-of-Rocks refuge near Devils Hole and represented the nearest genetic equivalent to pure Devils Hole Pupfish.…”

Oxygen Consumption is Limited at an Ecologically Relevant Rearing Temperature in Pupfish Eggs

“…Unfortunately, pupfish from the Death Valley complex of pupfishes may be less temperature tolerant. When these adult pupfish are maintained at temperatures above 32°C, successful breeding is extremely limited (Minckley and Deacon, ; Shrode and Gerking, ; Riggs and Deacon, ; Feuerbacher et al., ). Our similar poor breeding success from 33°C acclimated pupfish required that we use eggs from only 28°C acclimated parents for all but the initial hatch success experiments.…”