Lindsey LaBrie (University of South Dakota), repository began 8/30/2021
Field data collected by Tanner Carlson (University of South Dakota) and BJ Schall (South Dakota Game Fish and Parks), March 2021. Lab data collected by L. LaBrie, T. Carlson, and B. Schall, March 2021.
The total number of eggs (ova) that are likely to be laid in a spawning season by a female.
Blue Suckers were harvested near the James and Missouri River confluence during trammel netting in Spring 2021 during Spring spawning runs. Three scientists identified the sex of each individual in the field using external sex characteristics (presence/absence of tubricles on the head). If there was disagreement between the three scientists, the majority sex was recorded. Once fourty presumed males and fourty presumed females were collected, the fish were sacrificed and length and weight were measured. Specimens were transported to the SDGFP lab in Sioux Falls for further analysis. Identification of sex in the field was unanimous 78 out of 80 times, and sex was correctly identified 79 out of 80 times.
Once at the SDGFP lab, gonads were removed from each fish and individually weighed to the nearest gram. Three, one-gram egg samples were taken from the posterior, middle, and anterior section of each ovary. The three counts were averaged and then multiplied by the weight of the entire ovary for an estimate of number of eggs in each ovary (gravimetric method).
Currently, I am in the process of creating models so that we can make better predictions about Blue Sucker fecundity, and to reduce the need to sacrifice individuals in the future, since Blue Suckers are a species of concern in South Dakota, though not federally endangered.