Paul H. Michaletz

A Survey of Catfish Management in the United States and Canada

Abstract We surveyed resource agencies in the United States and Canada to assess the status of the management of catfish species \[primarily channel catfish (Ictalurus punctatus), blue catfish (I. furcatus), and flathead catfish (Pylodictis olivaris)\]. Thirty-two of the fifty-three agencies we surveyed considered catfish to be either moderately or highly important to anglers. Twenty-eight states allowed commercial fishing in selected waters. Catfish populations were managed primarily by creel limits and gear restrictions, and less frequently by size limits. Put-grow-take fisheries for channel catfish were popular in small impoundments, and most catfish stockings were associated with these fisheries. Managers most commonly used gill nets and electrofishing to sample catfishes and used catch-per-unit effort, size structure, and creel information to evaluate catfish populations. Major constraints to the management of catfishes included (1) low priority or angler interest, (2) inadequate habitat, (3) inadequ...

Factors Affecting Abundance, Growth, and Survival of Age-0 Gizzard Shad

Abstract Factors affecting abundance, growth, and survival of age-0 gizzard shad Dorosoma cepedianum were examined in Pomme de Terre and Stockton lakes, Missouri, during 1987–1991. Otolith ages were used to assign larvae (≤25 mm total length, TL) and juveniles (>25 mm TL) to weekly cohorts so that cohort-specific estimates of abundance, growth, and survival could be made. The distribution of initial abundances of larvae among weekly cohorts was influenced by water temperature and reservoir water level but not by characteristics of adult females (abundance, size, condition, fecundity). Intense periods of spawning activity during rising water levels resulted in high peaks in larval abundance and relatively few large weekly cohorts (e.g., 1990). In the absence of water level rises, peaks in larval abundance were much lower and abundances of larvae were more evenly distributed among several cohorts (e.g., 1988). Spring warming also affected spawning; early cohorts in warm springs (1987 and 1991) were relative...

Influence of abundance and size of age-0 gizzard shad on predator diets, diet overlap, and growth

Abstract Relationships among age-0 gizzard shad Dorosoma cepedianum and their predators were examined over 5 years (1987–1991) in Pomme de Terre and Stockton lakes, Missouri. to determine the influence of gizzard shad abundance and size on diets, diet overlap, and growth of predators. Within years, temporal changes in age-0 gizzard shad size affected predator diets and diet overlap of predators more than abundance. Age-0 gizzard shad were not important as prey until they grew larger than 25 mm total length, even though larval densities were much higher. They were the most common prey for most predators during June through October and diet overlap among predators was usually highest during that period. Lengths of age-0 gizzard shad ingested by predators resembled those available in the reservoirs throughout much of the season except in early summer, when predators ingested larger-than-average individuals, and in the fall, when smaller predators ingested smaller-than-average individuals. Among years, variat...

Hydroacoustic Assessment of the Abundance and Distribution of Rainbow Smelt in Lake Oahe

Abstract Hydroacoustic surveys with dual-beam processing and echo integration techniques were conducted on Lake Oahe, South Dakota, in the summers of 1983-1985 to assess the abundance and distribution of rainbow smelt (Osmerus mordax). Rainbow smelt are the primary coldwater forage fish for the developing salmonid fishery in this large Missouri River impoundment. Numerical estimates of pelagic fishes were 98,180,000 ± 5,550,000 (95% confidence limits), 95,430,000 ± 28,600,000, and 106,697,000 ± 21,880,000 for 1983, 1984, and 1985, respectively. Over 98% of the fish collected by midwater trawling and gillnetting during the surveys were rainbow smelt, suggesting that most of the fish sampled acoustically were also rainbow smelt. Biomass estimates for sampled portions of Lake Oahe were 157,100 kg (2.8 kg/hectare), 477,100 kg (8.5 kg/hectare), and 202,700 kg (3.6 kg/hectare) for 1983, 1984, and 1985, respectively. The accuracy of these biomass estimates is unknown because of the indirect method of calculating...

Population Characteristics of Gizzard Shad in Missouri Reservoirs and Their Relation to Reservoir Productivity, Mean Depth, and Sport Fish Growth

Abstract Population characteristics of gizzard shad Dorosoma cepedianum were examined in 14 Missouri reservoirs to determine if they were related to reservoir productivity (chlorophyll-a concentrations, mg/m3, CHLA), mean depth, and sport fish growth. Gizzard shad catch per unit effort (CPUE, >age 1), mean length at age 1, mortality, and a recruitment variability index (RVI, larger numbers indicate more consistent recruitment) increased with increasing reservoir productivity and decreasing mean depth, while proportional stock density (PSD), relative weight (W r ), and mean length at age 3 decreased. In stepwise regression models, gizzard shad mean length at age 1 was negatively related to mean depth; mean length at age 3 was negatively related to CHLA; mortality was negatively related to mean depth and positively related to CPUE; and RVI was negatively related to PSD and positively related to mean length at age 1. Mean lengths at age 3 for largemouth bass Micropterus salmoides and white crappie Pomoxis an...

Feeding Ecology and Growth of Young-of-the-Year Paddlefish in Hatchery Ponds

Abstract Young paddlefish Polyodon spathula raised in hatchery ponds graduated from particulate feeding to filter feeding as they grew past 120 mm. At this body length, gill rakers are about 2 mm long and about 0.1 mm apart, which is sufficient to retain the majority of zooplankton. Particulate feeders were selective for large, slow-moving prey such as Daphnia spp. Filter feeders did not show a similar selectivity for large prey but tended to consume agile prey (for example, calanoid copepods and copepod nauplii) in lesser proportion than their abundance. Growth of particulate feeders slowed markedly when Daphnia spp. became rare in the ponds. Growth rates later increased when fish reached a size at which they could filter-feed. Availability of large, slow zoo-plankton appears important for the propagation of young paddlefish.

Sampling Channel Catfish with Tandem Hoop Nets in Small Impoundments

Abstract Because populations of channel catfish Ictalurus punctatus have been difficult to sample in small impoundments, we determined whether tandem hoop net series (three nets tied in series and baited with cheese) fished for 3 d could effectively sample these populations. In 2000 we compared seasonal catch rates (catch per unit effort (CPUE), defined as the number of fish caught per series) and length frequencies (total length (TL); mm) of channel catfish captured with two types of tandem series (long versus short bridles) and monitored the mortality of channel catfish along with the CPUE and mortality of bycatch in five lakes. Mean CPUE ranged from 12 to 194 fish/series for channel catfish and from 5 to 101 fish/series for bycatch among series types, lakes, and sampling periods. Mean CPUE for channel catfish and bycatch was similar between series types and did not consistently vary with sampling period. Length frequencies of channel catfish were usually similar between series types. Mortality was low ...

Comparison of Catch Rate, Length Distribution, and Precision of Six Gears Used to Sample Reservoir Shad Populations

Abstract Hydroacoustics, trawling, gillnetting, electrofishing, shoreline seining, and cove rotenoning were used concurrently in August 1991 at Lake Texoma, Texas–Oklahoma, to compare sampling efficiency for gizzard shad Dorosoma cepedianum and threadfin shad D. petenense. A simple random-sampling design was used at nearshore and offshore stations in each of three 400–2,000-ha sites in the reservoir. Most gears provided similar evidence of spatial patterns of shad abundance among sites, but length distributions and sampling precision varied among methods. At offshore transects, catch-per-unit-effort (CPUE) data for hydroacoustics, trawling, and gillnetting were positively correlated (r = 0.45–0.80; P < 0.05) when data from all sites were combined. Gears differed in proportions of small (age-0) shad versus larger (age-1 and older) fish. Gears that collected mainly age-0 shad were trawls, surface-set gill nets, and seine, whereas catches of age-1 and older shad were greater with bottom-set gill nets, electr...

A caloric-based evaluation of diet indices for largemouth bass

Selection of methods for quantitative description and assessment of food habits is a concern for trophic investigations. We used diet data for largemouth bass Micropterus salmoides, to compare a caloric-based approach with eight diet indices: percent frequency of occurrence, percent total number, percent total weight, mean relative number, mean relative volume, relative importance index, prey-importance index, and mean stomach fullness. Mean caloric contribution of stomach contents for each prey taxon was used as a standard to compare diet indices. Temporal differences in composition and caloric contents of largemouth bass stomach contents were apparent. Most diet indices provided similar assessments when diets were dominated by a single prey type (i.e., gizzard shad during June-October). However, diet indices evaluated provided dissimilar assessments of stomach contents when a variety of prey with differing caloric densities were consumed (e.g., April). Mean stomach fullness and percent by volume were significantly (p < 0.002) correlated (r = 0.94 − 1.00) with mean caloric contribution of largemouth bass stomach contents during all months. Unlike percent by weight, mean stomach fullness accounted for differences in fish size and stomach capacity. Thus, mean stomach fullness by prey type appears to be the most appropriate index when objectives include simplified caloric-based assessments of fish diets.

Effects on Sport Fish Growth of Spatial and Temporal Variation in Age-0 Gizzard Shad Availability

Abstract Availability of age-0 gizzard shad Dorosoma cepedianum and length increments of piscivorous sport fishes (black crappies Pomoxis nigromaculatus, white crappies P. annularis, largemouth bass Micropterus salmoides, and white bass Morone chrysops) were measured in five large Missouri reservoirs over several years to determine the effect of prey availability on sport fish growth. Two measures of prey availability were used: mean available age-0 gizzard shad biomass (GB), estimated from predator–prey size relationships, and mean fall total length of age-0 gizzard shad (GTL). These two measures were only correlated for age-1, -2, and -3 black crappies and age-1 white crappies. Annual length increments of age-classes of crappies and largemouth bass tended to increase asymptotically with GB; length increments increased linearly for age-2 white bass. Relationships between GB and sport fish length increments were relatively strong for crappies and weak for largemouth bass and white bass. The second measure...