Factors influencing recruitment of walleye and white bass to three distinct early ontogenetic stages

Determining the factors that influence recruitment to sequential ontogenetic stages is critical for understanding recruitment dynamics of fish and for effective management of sportfish, particularly in dynamic and unpredictable environments. We sampled walleye (Sander vitreus) and white bass (Morone chrysops) at 3 ontogenetic stages (age 0 during spring: ‘age-0 larval’; age 0 during autumn: ‘age-0 juvenile’; and age 1 during autumn: ‘age-1 juvenile’) from 3 reservoirs. We developed multiple linear regression models to describe factors influencing age-0 larval, age-0 juvenile and age-1 juvenile walleye and white bass abundance indices. Our models explained 40–80% (68 ± 9%; mean ± SE) and 71%–97% (81 ± 6%) of the variability in catch for walleye and white bass respectively. For walleye, gizzard shad were present in the candidate model sets for all three ontogenetic stages we assessed. For white bass, there was no unifying variable in all three stage-specific candidate model sets, although walleye abundance was present in two of the three white bass candidate model sets. We were able to determine several factors affecting walleye and white bass year-class strength at multiple ontogenetic stages; comprehensive analyses of factors influencing recruitment to multiple early ontogenetic stages are seemingly rare in the literature. Our models demonstrate the interdependency among early ontogenetic stages and the complexities involved with sportfish recruitment

Development and Evaluation of a Standard Weight (W\u3csub\u3es\u3c/sub\u3e) Equation for Blue Catfish

Using a data set composed of 33 populations from six states, we employed the regression-linepercentile technique to develop a standard weight equation for blue catfish Ictalurus furcatus and validated it with an independent data set composed of 43 populations from 10 states. The equation is log10Ws=-6.067+ 3.400 log10TL, where Ws is standard weight in grams and TL is total length in millimeters. The English-unit equivalent (pounds and inches) is log10Ws=-3.950+ 3.400 log10TL. The equation is valid for blue catfish 160 mm (approximately 6 in) TL and longer. Relative weight (Wr) values computed with this equation did not exhibit any systematic length bias

Larval Black Crappie Distribution: Implications for Sampling Impoundments and Natural Lakes

An understanding of larval fish distributions is essential for developing an appropriate sampling design to monitor larval abundances. We monitored abundance of larval black crappie Pomoxis nigromaculatus to assess spatial differences in Richmond Lake (a 336-ha impoundment) and Brant Lake (a 405-ha natural lake), South Dakota, during 1994–1996. Age-0 black crappies were collected with a 500-µm mesh ichthyoplankton trawl from fixed sites within each water body. In the impoundment, larval black crappies were collected over a longer period at the upper site than at the dam site during 1994 and 1995. In the natural lake, larval black crappie abundances were similar between east and west sites during all 3 years. In light of our results, biologists should spatially stratify sampling sites when collecting larval black crappies in impoundments such as Richmond Lake, whereas random sites may be more appropriate in natural lakes such as Brant Lake

Agate Fossil Beds National Monument Fish Inventory

The Niobrara River flows through Agate Fossil Beds National Monument (AGFO) maintaining about 18-km of riverine habitat. The lack of large-scale human alterations like impoundment and channelization to the Niobrara River within AGFO make this stretch of river an ideal location to support native fish communities. However, concern for native fishes in the Niobrara River in and around AGFO has grown because non-native brown trout Salmo trutta and rainbow trout Oncorhynchus mykiss have been actively stocked in the region. Other species like largemouth bass Micropterus salmoides, bluegill Lepomis macrochirus, and northern pike Esox lucius may have also established populations from stocking activities above or below the AGFO property

A bioenergetic model for zebrafish \u3ci\u3eDanio rerio\u3c/i\u3e (Hamilton)

A bioenergetics model was developed from observed consumption, respiration and growth rates for zebrafish Danio rerio across a range (18–32° C) of water temperatures, and evaluated with a 50 day laboratory trial at 28° C. No significant bias in variable estimates was found during the validation trial; namely, predicted zebrafish mass generally agreed with observed mass

Measured Steam Conversion and Chemical Kinetics in a Hydrolysis Packed Bed Reactor for Hydrogen Production

AbstractActive research on the thermochemical Cu-Cl cycle is providing a promising potential for sustainable hydrogen production. The thermal efficiency of the hydrolysis reaction can drastically influence the viability and cost of the cycle. In the Cu-Cl cycle, the extent of the hydrolysis reaction has a major effect on cycle efficiency. Un-reacted superheated steam is difficult to efficiently separate from the gaseous reactor product, potentially dissipating a significant amount of thermal energy. In this paper, the upper limit of steam conversion in a copper (II) chloride reactor is investigated and new experimental results are presented. The experimental apparatus is designed to provide superheated steam, at 375°C, to excess CuCl2 and provide sufficient reaction time to approach the steam conversion limit. This is achieved by introducing a low steam flowrate to a packed bed reactor with six meters of packing solids. Variable reaction temperature, residence time, and flow rate are investigated for their effect on reaction extent and chemical kinetics. This research provides useful new data to effectively design and integrate a Cu-Cl hydrogen production cycle

Shrinkage of Inland Silverside Larvae Preserved in Ethanol and Formalin

Length measurements of preserved larval fish are necessary in many types of larval fish surveys. If the fixative causes significant shrinkage, then the preserved lengths cannot be used to indicate accurate live lengths. The objective of this study was to determine how preservation in two different concentrations of formalin and ethanol affects the total length of larval inland silversides Menidia beryllina. Larvae were measured (nearest 0.1 mm) and individually fixed in one of four fixative treatments (80% ethanol, 100% ethanol, 5% buffered formalin, and 10% buffered formalin). Fish were remeasured (nearest 0.1 mm) at 15 min; 4 h; and 1, 7, 14, and 21 d after preservation. Most shrinkage occurred within the first day after preservation in all four fixatives. Initial length was positively correlated with absolute shrinkage, but percent shrinkage was not affected by initial length. We found no difference in percent shrinkage between the 80% and 100% ethanol concentrations. The 10% buffered formalin caused more percent shrinkage than 5% buffered formalin. Furthermore, ethanol (80% and 100% combined) caused greater percent shrinkage than either 5% or 10% buffered formalin

Stomach Capacities of Six Freshwater Fishes

We investigated the relationship between stomach capacity and total body length in bluegill (Lepomis macrocirirus), spotted bass (Microplerus punctulatus), white crappie (Pomoxis annularis), black crappie (Pomoxis nigromoculatus), channel catfish (Ictalurus punctatus) , and white bass (Morone chrysops). The rate of change in stomach capacity for a given change in fish length was greatest for spoiled bass and channel catfish, which may indicate greater ontogenetic shifts in feeding strategies. Fish with larger stomach capacities should have more plastic diets because they are capable of consuming a wider range of prey sizes, particularly when they already have prey present in their stomach, compared to fish with smaller stomach capacities and similar feeding strategies