Michael J. Maceina

Recovery of a warmwater fish assemblage after the initiation of a minimum-flow release downstream from a hydroelectric dam

Abstract Artificial fluctuations in streamflow caused by hydroelectric power dams can degrade fish habitat and reduce the abundance and diversity of riverine fish faunas. Increased minimum water releases and reduced fluctuations in discharge may mitigate these effects. In this study, we compared shoreline fish abundance and diversity before and after an enhanced flow regime was implemented on the Tallapoosa River (Alabama) downstream of a hydroelectric dam. Before the minimum-flow regime, only eight species of fish were collected 3 km downstream from the dam, and all were classified as macrohabitat generalists. After the minimum flow was initiated, species richness 3 km below the dam more than doubled, and over half of the species collected were classified as fluvial specialists. Fish community response to the enhanced flow was not as great at a site 37 km downstream from the dam, where species richness was similar between the two periods. However, more species classified as fluvial specialists were colle...

Use of a Split-Plot Analysis of Variance Design for Repeated-Measures Fishery Data

Abstract We present a repeated-measures split-plot analysis of variance (ANOVA) design that can be used to analyze fisheries data collected throughout time from fixed sampling stations. A high percentage (97%) of authors who published papers in the Transactions of the American Fisheries Society and the North American Journal of Fisheries Management during the past 10 years did not use repeated-measures ANOVA for analyzing their data when this technique was appropriate. When data are collected from fixed stations throughout time, the assumption that independent samples are randomly collected from the population is violated for simple ANOVA. Fixed stations may display population characteristics specific to that location, and environmental change or a management practice may influence stations differently. In addition, multiple measurements collected at a fixed station throughout time will likely be correlated. For a dependent variable of interest, a repeated-measures split-plot design will partition the var...

Piscivory in Largemouth Bass as a Function of Aquatic Vegetation Abundance

Abstract The incidence of predation by largemouth bass Micropterus salmoides on fish in Lake Conroe, Texas, was examined over 7 years at two disparate levels of habitat complexity. When areal coverage of submersed vegetation ranged from 39 to 44% of the reservoirs 8,100 hectares, largemouth bass 100 mm and smaller in total length consumed fish infrequently; most did not consume fish until they reached lengths of 140 mm and more, Following the elimination of all submersed vegetation by grass carp Ctenopharyngodon idella, fish were consumed by most largemouth bass 60 mm or longer. The initiation of piscivory at smaller sizes resulted in significantly faster first-year growth for all largemouth bass year-classes produced after vegetation removal. Although shifts in the structure of the forage fish community occurred, ample fish prey existed for largemouth bass before and after vegetation removal. The onset of piscivory remained similar for largemouth bass collected along the dam riprap, where vegetation was...

Simple application of using residuals from catch-curve regressions to assess year-class strength in fish

Residuals associated with catch-curve regressions can represent variable recruitment in fish populations. Catch curves are used to estimate steady-state mortality and assume relatively constant recruitment, but this assumption is rarely met. I documented the presence of abundant year classes of largemouth bass (Micropterus salmoides), from earlier sampling and these dominant year classes persisted over time in two reservoirs. I expanded simple linear catch-curve regressions that used age (in years) as an independent regressor to multiple regression models each of which incorporated an additional independent environmental variable (ENVIR) that was measured when fish were age 0. The age term in the regression was proportionally weighted to the sample size at each age which deflated the influence of older and rarer fish in the analysis. This generalized regression equation: loge (NUMBER) = b0 − b1 (AGE) ± b2 (ENVIR); explained variable abundance-at-age (NUMBER) and the environmental term was related to the formation of weak and strong year classes after accounting for the effects of age. Typically, age will explain the majority (r2 ≥ 0.5) of the variation in abundance-at-age. For two largemouth bass populations, environmental hydraulic variables were significant (P < 0.10) terms in this equation and explained an additional 12 and 16% of the variation in number after accounting for the variation explained by age. For data collected in one population 2 yrs after the initial analysis, the same strong and weak year classes persisted, residuals from these catch curves were correlated (r = 0.86, P < 0.05, N = 6), and the influence of hydrology on year class formation was duplicated. This approach can provide savings in labor and funds as abundance of young fish or recruitment indices do not have to be measured each year.

Current Status and Review of Freshwater Fish Aging Procedures Used by State and Provincial Fisheries Agencies with Recommendations for Future Directions

Abstract In 2006, the Fisheries Management Section of the American Fisheries Society formed the ad hoc Assessment of Fish Aging Techniques Committee to assess the current status of aging freshwater fish in North America. For seven species groups that included black bass ( Micropterus spp.), crappie/sunfish (Pomoxis spp./Lepomis spp.), catfish (Ictaluridae), morinids, percids, salmonids, and esocids, a survey of U.S. and Canadian fisheries agencies (N = 51 agencies responding) revealed that scales, otoliths, and spines were the most common structures used to age fish. Latitudinal clines existed for some of the structures that were examined, with scales typically used more in northern latitudes than otoliths. Many agencies conducted some validation of age estimation techniques and most assessed precision at least for some of the age samples collected. Providing personnel with training to age fish was common. Reasons for the structures used and the types of inferences and information generated from age data ...

Response of a Reservoir Fish Community to Aquatic Vegetation Removal

Abstract Over 3,600 hectares of submersed aquatic vegetation in Lake Conroe, Texas, were eliminated 1 year after 270,000 grass carp Ctenopharyngodon idella were stocked in 1981–1982. Seventeen fish species were commonly collected in cove rotenone samples and the biomasses of eight species declined (P ≤ 0.10) after vegetation removal. The most notable declines were observed for several small, phytophilic Lepomis spp., for bluegill Lepomis macrochirus, and for crappie Pomoxis spp. Biomass of largemouth bass Micropterus salmoides did not decline (P = 0. 12) but the density of age-1 and older fish did decline (P = 0.02). Biomass and density of two cyprinid species and channel catfish Ictalurus punctatus increased. Although biomass of longear sunfish Lepomis megalotis did not increase (P = 0.11), mean size declined and density increased an order of magnitude (P = 0.02). Density of threadfin shad Dorosoma petenense increased nearly fivefold after vegetation removal, coincident with a decline in mean size; howev...

Wind-related Limnological Variation in Lake Okeechobee, Florida

ABSTRACT Lake Okeechobee, Florida, is large (1730 km2) and shallow (Zx = 2.7 m) with 44 percent of the bottom covered by flocculent, unconsolidated mud. Consequently, wind resuspension of sediments was an important determinant of limnological conditions between 1975 and 1988. Higher wind speeds occurred between October and May, and calmer conditions were prevalent during the summer months (June–September). Monthly averages of soluble reactive phosphorus, total phosphorus, nitrate-nitrite, total nitrogen, silica, total suspended solids concentrations, and turbidity were positively correlated with average monthly wind speed (r = 0.66 to 0.90, P <0.05). Annual total wind speed was correlated with average annual total phosphorus (r = 0.78, P <0.01) and soluble reactive phosphorus (r = 0.67, P <0.05) concentrations. From 1950 to present, greater wind speed was also associated with higher lake stages. Wind speed, rainfall on the lake, tributary inflow, and lake levels appeared to be interrelated parameters on L...

Relations between Reservoir Hydrology and Crappie Recruitment in Alabama

Abstract The relation between reservoir hydrology and recruitment of black crappies Pomoxis nigromaculatus and white crappies P. annularis was examined in 11 reservoirs throughout Alabama from 1990 to 1996. Estimates of recruitment were derived from catch rates of age-1 fish in the fall with trap nets and from residuals associated with catch-curve regressions of age 3–7 fish captured in the spring with electrofishing gear. Reservoirs were separated into three hydrologic categories: (1) eight reservoirs with short retention (volume/discharge) times (2–9 d) that fluctuated less than 1 m/year; (2) two reservoirs with longer retention times (44–55 d) that generally fluctuated 1.8 and 4.6 m/year; and (3) one reservoir that fluctuated 1.8 m/year with a relatively short retention time of 15 d. In the reservoirs with low retention times and stable water levels, greater year-class production was related to low winter (January–March) retention before crappie spawning and to higher postwinter (April–December) retent...

Simple Grinding Procedure to Section Otoliths

Abstract This paper describes an inexpensive and simple grinding technique to section otoliths that I have used to determine the ages of both freshwater and marine fish. Depending on their size, 6–15 otoliths can be sectioned, and their annuli counted, per hour.

Variation in Largemouth Bass Recruitment in Four Mainstream Impoundments of the Tennessee River

Abstract Variation in recruitment of largemouth bass Micropterus salmoides was quantified in four mainstream impoundments along an 800-km segment of the Tennessee River and compared with various types of hydrologic and aquatic plant abundance data in an attempt to explain factors related to the formation of strong and weak year-classes. Residuals from four catch-curve regressions for age-2–11 fish collected in 1993 or 1994 were used to describe year-class strength. The formation of strong and weak year-classes was generally synchronous in these four reservoirs. Year-class strength was inversely related to average June–July discharge and positively associated with retention (reservoir volume/discharge) for data pooled from all reservoirs. Thus, weak year-classes were produced during wet early-summer conditions after largemouth bass hatched, whereas stronger year-classes were produced during dryer early-summer conditions. Late-summer aquatic plant abundance and water level fluctuations during April–May whil...