Research Highlights - Fish Biology

Aquaculture/Fisheries Center Research Highlights

Natural Fisheries Biology

Arkansas River largemouth bass study
Mike Eggleton and Ben Batten

For a variety of reasons, the Arkansas Game and Fish Commission (AGFC) has become concerned about perceived declines in abundances of quality-size largemouth bass in the Arkansas River. To address these concerns, UAPB has initiated a 2-year (2004-2005) stock assessment of largemouth bass populations in the lower 11 pools (500 km) of the Arkansas River. Population age structures were skewed towards younger fish with very few individuals older than age 3. Population size structures, expressed as proportional stock density (PSD), were greatest in the lower pools of the river. PSD values averaged 57 (± 4) and 45 (± 8) in the lower and upper pools, respectively, with Lake Dardanelle averaging 47 (± 5). Similarly, relative stock densities using 380-mm total length averaged 20 (± 4) and 18 (± 6) in the lower and upper pools, respectively, with Lake Dardanelle averaging 14 (± 4). Bass condition was generally good throughout the river, though a slight inverse relationship existed with river mile. Preliminary results of this study do not suggest that the quality of largemouth bass populations in the lower Arkansas River is poor.
Influence of stocked hatchery-reared fingerlings on wild largemouth bass fingerlings and productivity of bass in the Arkansas River
Steve Lochmann

Project objectives are to 1) determine the influence of stocking 100-mm largemouth bass fingerlings on the mortality rate and density of naturally-produced largemouth bass fingerling; 2) to determine whether the contribution of stocked fish to a year class changes between age-1 and the point when those fish enter the fishery; and 3) to compare historical trends in the productivity of largemouth bass populations in the Arkansas River with trends in productivity during the same period from other large Arkansas reservoirs.

This is the first year of the project. Plans are to have objective three completed before spring 2007. Pilot studies will be conducted on shocking and marking young of the year largemouth bass with VIE tags. This step is critical in determining abundance of wild fish prior to stocking hatchery-reared fish.
Stocking hatchery-reared fingerlings to improve largemouth bass populations in the Arkansas River
Steve Lochmann

We stocked five backwater coves of pool 4 of the Arkansas River with 50 mm hatchery-reared bass fingerlings from the Lonoke Hatchery. Fingerlings were marked with OTC prior to stocking. We also stocked 50 mm bass fingerlings into three ponds at the UAPB Experiment Station. Those bass were fed minnows at a rate equivalent to 4% of their estimated body weight per day and raised for approximately 60 d. At approximately 100 mm, the bass fingerlings were harvested, marked with OTC, and stocked into five randomly selected coves of pool 4. The 100 mm fingerlings were stocked at a rate of 62 bass/ha in the same manner as the 50 mm fingerlings. Contributions to the year class of 50-mm (13.2%, SD = 6.2) and 100-mm (13.8%, SD = 3.2) stocked largemouth bass were not significantly different in fall 2003. Contributions of 50-mm (17.6%, SD = 6.3) and 100-mm (17.2%, SD = 4.9) stocked largemouth bass in spring 2004 also were not significantly different. There were no significant differences in mean lengths among stocked or wild fish during either season. Stocking five times as many 50-mm as 100-mm largemouth bass yielded similar contributions to the year class. Largemouth bass stocked into the Arkansas River had one-year stocking contributions similar to largemouth bass stocked into reservoirs and lakes.
Improved techniques for managing sunshine bass fingerling production
Steve Lochmann

Eggs from 12 white bass, used to produce sunshine bass fry, were individually photographed and incubated. The largest average egg volume was 0.422 mm3 and the smallest average egg volume was 0.316 mm3. Hatch rates ranged from 49% to 96%. There was no relationship between hatching rate and egg volume. There was no relationship between egg volume and percent total lipids. The yolk-sac fry hatched from these eggs were also photographed within 3 h of hatching. Standard lengths of yolk-sac fry were less variable than egg volumes (CV=6.3%) and ranged from 2.35 to 3.62 mm. Average standard length also varied among females (P<0.0001). There was a significant relationship between egg volume and standard length of yolk-sac fry at hatching (P=0.0536), but the relation only explained about 7% of the variability in size at hatch. A breeding program that selected for females producing larger yolk-sac fry could lead to improvements in fingerling production.