Geology topics

Matthew J. Ward

Publications and source records attributed to Matthew J. Ward.

3 recordsLinked to original sources

USGS2026

Using eye lens stable isotopes to identify the rearing origin of fall age-0 walleye ( Sander vitreus )

Isotope values in fish eye lenses may be useful in differentiating rearing origins. We compared eye lens isotopic values of fall fingerling age-0 walleye ( Sander vitreus ) reared in a hatchery pond, a recirculating aquaculture system (RAS), and a natural lake. Using 10 fish per rearing source, we delaminated layers from one eye lens per fish to assess temporal changes in carbon (δ 13 C) and nitrogen (δ 15 N) and pulverized the whole second eye lens for δ 13 C, δ 15 N, and sulfur (δ 34 S). RAS-reared walleye values exhibited high precision among individuals and were δ 34 S enriched. Pond-reared walleye had lower δ 13 C and δ 15 N core values compared to other rearing sources. For δ 13 C and δ 15 N, values remained consistent among layers for RAS-reared walleye, δ 15 N slightly increased for pond-reared and lake-reared walleye, and δ 13 C increased substantially among subsequent layers in pond-reared walleye. Bayesian 95% ellipses did not overlap among rearing sources. These results demonstrate that eye lens stable isotope analysis may be a useful tool for differentiating hatchery-reared and wild large fingerling walleye, specifically from RAS- and pond-reared sources.

South Dakota↗

USGS2020

Availability and timing of fathead minnow supplementation influence largemouth bass survival and production in rearing ponds

Adjustments to rearing practices should be justified with increases in production, stocking success, or angler satisfaction. Largemouth bass (Micropterus salmoides) production was assessed between hatchery ponds where fish were restricted to an invertebrate diet or received supplemental fathead minnow ( Pimephales promelas ) forage during 2015. At harvest, age-0 bass yield was 4.5 times greater and average fish length was 38 mm longer, in the pond that received fathead minnow. In 2016, a second study evaluated the timing of minnow supplementation that included earlier stockings of small fathead minnow (< 30 mm) compared to delayed supplementation with larger (> 30 mm) minnows. With earlier supplementation, bass yield was 2.3 times greater and fish averaged 14 mm longer at harvest. Bass survival was approximately 38% higher during 2015 when supplementation occurred and 25% higher during 2016 when minnow supplementation began earlier. Our findings show invertebrate forage was probably limiting bass production in hatchery ponds and supplementing with appropriately-sized fathead minnows increased age-0, largemouth bass production.

South Dakota↗

USGS2005

Biotic and abiotic correlates with black bullhead population characteristics in Nebraska sandhill lakes

We explored relationships among black bullhead ( Ameiurus melas ) population characteristics and physicochemical attributes in shallow lakes and quantified relationships between population characteristics of black bullhead and sport fishes. Lake characteristics and fisheries survey data were collected from the Sandhills region of northcentral Nebraska from May through June, 1998 and 1999. Relative abundance of black bullheads was inversely related to proportional stock density (r=-0.672, df=15, P=0.004); however, neither relative weight nor growth was significantly (P ≥ 0.20) related to black bullhead relative abundance. Population characteristics of common panfish species such as bluegill ( Lepomis macrochirus ), green sunfish ( L. cyanellus ), pumpkinseed ( L. gibbosus ), and yellow perch ( Perca flavescens ) were not correlated with black bullhead relative abundance or size structure. Rather, proportional stock density (r=0.655, df=10, P=0.029) and growth (r=0.59, df=11, P=0.04) of black bullhead were positively related to relative abundance of largemouth bass ( Micropterus salmoides. ) Similarly, black bullhead relative abundance was inversely related to largemouth bass size structure (r=-0.51, df=14, P=0.05). Black bullhead mean length at age 3 was positively related to total phosphorous concentration (r=0.65, df=16, P=0.004), and bullhead relative abundance was positively related to shoreline development index (r=0.46, df=22, P=0.03). Population characteristics of black bullhead appeared to have little influence on panfish communities. Rather, black bullhead abundance, predator density, and lake productivity exhibited stronger relationships with black bullhead population characteristics.

Nebraska↗