Evaluating the Efficiency of a Quantitative Egg-Sampling Gear

Quantitative studies focusing on the collection of semi-buoyant fish eggs, associated with a pelagic broadcast-spawning reproductive strategy, are often conducted to evaluate reproductive success. Many fishes represented in this reproductive guild are considered threatened or endangered. However the efficiency of the sampling gear used to evaluate reproduction is often unknown, rendering the interpretation of data from these studies difficult. Our objective was to assess the efficiency of a modified Moore egg collector using field and laboratory trials. We used a hatchery raceway to assess gear efficiency by releasing a known quantity of artificial eggs with a specific gravity similar to that of eggs from representatives of this reproductive guild, e.g., Arkansas River shiner. We also used field trials to determine how river width influenced gear efficiency given current methodological approaches. Hatchery raceway trials indicated gear efficiency ranged between 0.5% and 7.4% (n = 12 trials) in a simple 2.5-m wide channel. Hatchery and field trials indicated eggs were not distributed evenly across the channels and wider channels resulted in decreased efficiency. In addition, egg-transport patterns were influenced by turbulence indicating channel habitat complexity influenced gear efficiency. These results will be used to guide sampling designs for future field evaluations.