No effect of stocking density on the survival or size of late-stage Delta Smelt larvae reared in a small-scale culture system

ObjectiveA small-scale culture system effective in producing larvae of endangered Delta Smelt Hypomesus transpacificus was recently developed to facilitate conservation and research efforts.MethodsTo optimize its use, we examined the effect of stocking density (300, 500, 700, and 900 fish per 92 L of water) on the length, weight, and survival of late-stage larvae (41 days posthatch) reared for 40 days in the small-scale system.ResultStocking density had no effect on larval survival or size. Also, the survival, length, and weight of these fish did not differ from those reared using standard, large-scale culture practices (2500 fish per 320 L of water).ConclusionOur findings validate the methods used for small-scale Delta Smelt rearing, help optimize these protocols, and thereby enhance Delta Smelt rearing capabilities needed for research and conservation. This study optimizes and validates use of a new culture system for rearing a specific life stage of Delta Smelt. In doing so, we enhance ongoing conservation efforts to prevent the extinction of this endangered species.Impact statement

Automated summary

The effect of stocking density on the survival and size of Delta Smelt larvae was examined, and it was found that stocking density had no effect on these factors. The study validated the methods used for small-scale Delta Smelt rearing and enhanced conservation efforts.