Pallid sturgeon size structure, condition, and growth in the Missouri River Basin

Abstract

Summary We synthesized wild and stocked pallid sturgeon Scaphirhynchus albus capture data collected in four recovery areas of the Missouri River during 1998–2007, providing the first basin‐wide analysis of size structure, growth, and condition. Proportional size distribution (PSD) values ranged from 20 to 33 and were indicative of past stockings given the continued lack of natural recruitment. A new weight‐length regression derived from 2268 captured wild (8%), hatchery‐stocked (75%), and unknown origin (16%) pallid sturgeon had a significantly lower slope and intercept from a previously published model that used only 214 wild fish and a truncated size range. Relative condition (Kn) declined after stocking throughout the basin but stabilized at 0.94 within 3 years. Spatially, Kn of juvenile pallid sturgeon (330–629 mm) was generally highest in the reaches of the Missouri River with large tributaries. In accordance with the latitudinal counter gradient growth hypothesis, similar absolute growth increments (both length and weight) of tagged age‐1 pallid sturgeon in the Upper and Lower Missouri River indicated upstream fish grew at faster rates given the 1.3 fold difference in growing season length. From North to South, von Bertalanffy growth coefficients (k) showed a latitudinal increase while L∞ decreased, providing additional support of the latitudinal counter gradient growth hypothesis. However, growth rates of tagged juvenile pallid sturgeon aged 2–6 years were highest at the two most downstream reaches showing an increased influence of growing season length. In the Missouri River, pallid sturgeon (≤ ages 1–9 or 10 years) exhibited linear growth in the two most upstream reaches (Montana and North Dakota), exhibited logistic growth in the inter‐reservoir reach in South Dakota/Nebraska while a power function best described growth downstream of the lowermost dam (Nebraska, Iowa, Kansas, and Missouri). Differing growth models among reaches highlights the confounding affect of habitat fragmentation by dams in the Missouri River on growth as well as potential latitudinal affects on sexual maturation. Relative condition and growth of pallid sturgeon appears adequate throughout the Missouri River indicating success of past stocking efforts to forestall extirpation.

Assessment of pallid sturgeon relative condition in the upper channelized Missouri River

“…Hatchery-reared fish in the lower Missouri River were growing (Shuman et al 2011), exhibiting migratory behavior and reaching sexual maturity DeLonay et al 2012;Steffensen et al 2013a). The numbers of reproductive fish in the lower Missouri River was increasing prior to 2013; however, the proportion of reproductive fish collected annually continues to decrease.…”

“…Fort Peck Dam [rkm 2850.9] to the headwaters of Lake Sakakawea [rkm 2523.5]). Shuman et al (2011) detected differences in Kn by incremental PSD Figure 2. Annual mean ( §SE) relative condition factor (Kn) by gender and reproductive assessment for adult (> 800 mm) pallid sturgeon transported to local hatcheries as potential brood fish.…”

“…Relative condition (Kn) was used to assess change in pallid sturgeon condition with the pallid sturgeon weightÀlength relationship calculated based on the equation provided by Shuman et al (2011) where W is the individual's observed weight and W' is the predicted weight from the weightÀlength relationship as described by the Shuman et al (2011) equation. Seasonal (i.e.…”

Growth model selection for the jumbo squid Dosidicus gigas from the Gulf of California, Mexico

“…The literature shows that for the multi-model inference approach applied to individual growth, it is not unusual that different candidate growth models yield equal values of AIC (Rogers-Bennett et al 2007, Flores et al 2010, Helidoniotis et al 2011). Several studies also have shown that the AIC estimates of the candidate growth models were very close; the magnitude of the change can be < 0.1 (Araya & Cubillos 2006, Shelton et al 2006, Farrell et al 2010, Barreto et al 2011, Grist et al 2011, Mercier et al 2011, Shuman et al 2011. Markaida et al (2005), using mark-recapture data of D. gigas, showed that the daily growth rate diminishes for older individuals; their study analyzed squid between 46 and 80.7 cm ML, and the daily growth rate changed from 1.5 to 1.0 mm d −1…”

Using the robust design framework and relative abundance to predict the population size of pallid sturgeon Scaphirhynchus albus in the lower Missouri River

“…Stocking in the middle Mississippi River has not been as intensive compared with the Missouri River and was limited to the 1992 and 1997 year class (T. W. Huenemann, unpublished data). Hatchery‐reared S. albus are surviving (Steffensen et al ., ; Rotella, ; Steffensen et al ., ) and growing (Shuman et al ., ) and along with a remnant wild population, comprise the current S. albus population.…”