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Climate–growth relationships of fish are of increasing research interest. However, few studies have attempted to characterize the extent to which climate–growth relationships may diverge across fundamentally different types of environments. The goal of this study was to examine the effects of climate variability (i.e., temperature, precipitation, global climate indices) on the growth of Freshwater Drum Aplodinotus grunniens and determine the extent to which these relationships differ between lotic and lentic habitats. Freshwater Drum were collected from five river and five reservoir environments in Georgia, Alabama, and Mississippi. Tree-ring techniques were used to standardize annual growth for age (measured using interannual growth increments from otolith sagittae) and growth indices were correlated to annual thermal, hydrologic, and global climate indices. Freshwater Drum expressed distinct and significant climate–growth relationships by water body type. The general pattern observed was that a...

The ages of freshwater drum Aplodinotus grunniens have typically been estimated by counting the growth increments on their scales or otoliths, but the accuracy of these estimates has not been validated. We used accelerator mass spectrometry (AMS) bomb radiocarbon dating to validate age estimates from sagittal otoliths of freshwater drum from the Lake Winnebago system, Wisconsin. The freshwater drum Δ14C chronology from the AMS assay closely reflects the timing and shape of other bomb radiocarbon chronologies, thus validating the accuracy of otolith growth increments to at least age 52 ± 2 years. The progression of a strong 1983 year-class, which was detected every year sampled over the course of the study (1986, 2003-2007), and indices of year-class abundance calculated from trawling assessments on Lake Winnebago (1986-2007) corroborated otolith ages. Age estimate comparisons between scales, anal spines, dorsal spines, and otoliths showed scales and spines to be completely unreliable as aging str...

Genetic analysis of progeny from 13 spawning events occurring over a 2-week period in a Texas Parks and Wildlife Department (TPWD) hatchery for red drum Sciaenops ocellatus during the spring of 2002 and hatchery spawning and release records over the 2003 spawning season were used to estimate the average genetic effective size of an average spawn and an average hatchery-released population. The purpose of this study was to assess the potential for a Ryman-Laikre effect in the TPWD red drum stock enhancement program. Genetic analysis revealed that 16 of 27 dams (59.2%) and 16 of 18 sires (88.9%) spawned at least once. The average effective size (Ne ) for a single spawn was 2.59, approximately 43% less than the maximum Ne (4.55) predicted if all possible mating (dam × sire) combinations had occurred and family size per mating combination had been equivalent. The reduction in Ne stemming from the actual number of mating combinations was approximately 34% and appeared to be due primarily to nonspawnin...

Knowledge about fish spawning habits and habitats is an essential component of fisheries management. This paper reports on a survey of potential spawning sites for red drum Sciaenops ocellatus in the nearshore western Gulf of Mexico conducted using a towed hydrophone array. Two classes of red drum sounds could be distinguished. One was a low-frequency rumble with a prominent energy peak at approximately 150 Hz. The other was a clearly distinguishable call made by individual or small groups of red drum. Calls of individual red drum were detected along most sections of all transects. There were extensive areas along each transect where no close drumming was heard and where drumming rates were primarily low (

Passive acoustic sampling to locate spawning sites of red drum Sciaenops ocellatus was conducted along the Georgia coast during July-October 1995-1997. Spawning red drum were observed in captivity to determine the level of sound associated with spawning. In 1997, a known red drum spawning site was sampled weekly with a mobile hydrophone and continuously with a remote hydrophone deployed from 23 September to 2 October 1997. Both field and tank observations indicated that red drum males make calls with four or fewer pulses per call without associated spawning. However, calls consisting of at least 8 pulses/call occurred only prior to spawning. In 1995 and 1996, a total of 372 hydrophone observations were made at regularly sampled stations in Doboy, Altamaha, St. Simon's, and St. Andrew sounds and at supplemental locations along the Georgia coast. Only one nearshore spawning site was located; it was found in St. Mary's channel at the mouth of Cumberland Sound. Duration of peak red drum sound product...

We analyzed variations in the age and growth of freshwater drum Aplodinotus grunniens in Alabama rivers and reservoirs. Lotic environments produced significantly more robust freshwater drum (associated with higher growth rates) than did lentic settings. Shorter reservoir retention times (more lotic reservoirs) also produced more robust and faster-growing freshwater drum, which supported the hypothesis that hydraulic-based habitat was an important variable in determining freshwater drum condition and growth. Linear declines in relative weight and percent lipid were revealed along a hydrologic gradient in Lake Logan Martin and were strongest in older freshwater drum. Von Bertalanffy predictions supported these results but also exposed a unique caveat: If freshwater drum lived long enough (>12 years), they were ultimately able to grow to larger sizes (>L ∞) in reservoirs. Freshwater drum may be capable of moving between available lentic and lotic habitats during their lifetime to maximize invertebra...

We compared first-year growth and relative condition (Kn ) of the 1997 and 1998 year-classes of freshwater drum Aplodinotus grunniens among three sites in a 235-km reach of the channelized Missouri River and tested for the occurrence of size-selective overwinter mortality during the first winter. Prewinter mean length was 15 mm greater, mean weight was 8 g greater, and mean Kn was 5% greater at the upstream site than at the downstream site. The prewinter mean length of age-0 freshwater drum was significantly greater in 1997 (115 mm) than in 1998 (109 mm), but Kn was significantly greater in 1998 (107) than in 1997 (102). There was no evidence that density-dependent interactions influenced prewinter growth and Kn. Size-selective overwinter mortality of the smallest size-classes of freshwater drum occurred at two of three sites during the 1997–1998 winter, and Kn decreased 9–15%. Size-selective overwinter mortality of the 1998 cohort of freshwater drum did not occur during the 1998–1999 winter, and...

Red drum Sciaenops ocellatus, a euryhaline fish species, is the target of considerable conservation effort by the Texas Parks and Wildlife Department. To aid the conservation effort, a study was conducted to determine if fatty acid profiles in muscles of subadult red drums (>30 cm total length and sexually immature) differ significantly between wild and cultured fish. This information may help regulatory enforcement by establishing fatty acid profiling as a forensic tool for conservation biologists and law enforcement officials who must distinguish cultured red drums from illegally marketed wild red drums. Red drums were sampled from summer 1990 to spring 1991 from four Texas coastal bay systems and from two commercial aquaculture ventures. Four fatty acids were identified as diagnostic. Linoleic acid (18:2n-6) was significantly lower in wild red drums than in cultured red drums. Arachidonic acid (20:4n-6) and adrenic acid (22:4n-6) were significantly higher in wild than in cultured fish. Docosap...

Physiological changes associated with pronounced capture stress in freshwater drum (Aplodinotus grunniens) were studied. Increasing the exposure of exercised freshwater drums to low-oxygen water resulted in increasing degrees of skin reddening and partial hemolysis in blood samples. Artifacts associated with blood sampling by heart puncture did not cause hemolysis, nor did a loss of Na+ and Cl− ions or an influx of water into the blood. Blood from freshwater drums that were severely distressed by seine capture showed no significant changes in hematocrit and plasma Na+ and Cl− concentrations, compared to fish that were exercised to near exhaustion by capture but were only briefly exposed to low oxygen. After 40 minutes of forced exercise in a low-oxygen aquarium freshwater drums lost equilibrium and had extensive skin reddening, symptoms also observed in freshwater drums that were captured in a commercial shore seine. Blood from cannulated freshwater drums that were exhausted in the laboratory sho...

Adult and juvenile red drum, Sciaenops ocellata (Linnaeus), confined to a saltwater marsh impoundment at South Island, Georgetown County, South Carolina, were studied to determine their length-weight relationship, age according to otoliths, and the time of annulus formation in the otoliths. The equation log W = −1.29596 + 2.74031 log L was determined for the relationship of length to weight. Sectioned otoliths revealed no annulus formed in fish up to 1,070 g and 38.5 cm in standard length, suggesting that no annulus was formed the first spring after hatching in September through November. Annuli were formed in spring (April-May). The largest fish belonged to the 1966 and 1967 year classes, which were in the marsh when the impoundment was formed in May 1968. Reading otoliths before they were cut produced erroneous results.

Food habits of 568 juvenile red drum, Sciaenops ocellata (Linnaeus), ranging from 8.0 to 183.0 mm standard length, were determined during the time the fish utilized a Louisiana salt marsh as a nursery area. Potentially available food organisms were sampled during the 7-mo study. Some degree of selectivity by juvenile red drum was demonstrated, but generally the most abundant organisms of an edible size were utilized most heavily. Changes in food with increasing size can be described in three phases: 1) red drum less than 15 mm ate zooplankton; 2) between 15 mm and 75 mm the red drum ate mostly small bottom invertebrates and the young of other fish; 3) red drum larger than 75 mm ate decapods (crabs and shrimp) and fish. Some differences between day and night feeding were found. For red drum 65 to 85 mm the dominant food eaten was grass shrimp during the day, whereas at night it was fish. The length-weight relationship was log W = −7.2052 + (4.1913) (log L). The average coefficient of condition was...

Instantaneous total mortality rates for planktonic larval freshwater drums (Aplodinotus grunniens) in a channelized stretch of the Missouri River were estimated from analyses of cumulative catch curves. Mortality rates, which ranged from 0.11 to 0.21 per day, were significantly greater in 1976 than in 1974. Basing our interpretation on the underrepresentation of eggs and early larvae in the channelized river samples, we hypothesize that favorable environments upstream represent a more significant source of recruitment of larvae to the freshwater drum population than the channelized river.

The freshwater drum Aplodinotus grunniens is an abundant and underutilized species in Lake Eric. Transportation of live fish from commercial shore seines to pay-fishing lakes causes high immediate and delayed mortality during warm summer months. Freshwater drums transported 6 hours had 4% immediate mortality and 94% delayed mortality (over 1–2 weeks). Salt (5 g/liter NaCl), low hauled-fish densities (60 g fish/liter water), and late-summer transport significantly (P < 0.05) reduced delayed mortality. Fish tagged after transportation had a significantly higher delayed mortality than those not tagged. Capture stress in seines was a more important cause of delayed mortality than transportation or stocking in ponds.

Otolith growth increments were used to estimate the age of 113 larval red drum Sciaenops ocellatus collected in the north-central Gulf of Mexico in October 1983, October 1984, and September 1985. Larval growth, as estimated by correlating age with length and dry weight measurements, was exponential and positively associated with water temperature. Mean growth in length of larvae smaller than 4 mm was relatively slow (≈0.3 mm/d), but at sizes larger than 4 mm, length increased rapidly. Based on growth equations, the mean increases in length of 4–6-mm larvae in October 1984, October 1983, and September 1985, were 0.4, 0.5, and 0.6 mm/d, respectively. These increases in larval growth were associated with increasing water temperature at time of capture; ranges in temperature during the three periods were 24.5–25A, 25.5–26.5, and 27.8–29.0°C, respectively. Larvae that developed in October 1984 grew to a length of 6 mm in about 15.0 d, whereas in September 1985, at the warmest temperatures, larvae grew...

Tucker-trawl collections showed that behavior of larval shad Dorosoma spp. and freshwater drum Aplodinotus grunniens was altered by inflow of turbid water into Lake Texoma (Oklahoma-Texas) in two different years. During periods of increased turbidity, larval shad were concentrated in a reduced volume of water near the surface, and larval freshwater drum were distributed throughout the water column in contrast to their normal concentration near the bottom. In 1981 and 1982, greatest decline in abundance of larval shad came after zooplankton density fell below 100 per liter, and during or immediately following an extended period of high turbidity. Nutritional stress resulting from decline in zooplankton abundance and changes in larval-fish behavior during turbid conditions could be one important factor in population dynamics of shad in reservoirs.

Scale samples from fish taken during the years of 1944 through 1948 were used to analyze the freshwater drum fishery of the Upper Mississippi. Total and fishing mortality rates were calculated for heavily and lightly fished populations in the impoundment system of 26 dams. Mortality rates of drum from the northern section of the river were compared with those from the southern section. Weak year classes were formed during 1942, 1943, and 1945, and strong year classes were formed during 1941 and 1944. Strength of year class was directly related to air and water temperature during May but not to water stage during the spawning season.

A comparison of meristic and morphological characteristics in series of freshwater drum from the lower Ohio River, Kentucky, and Lake Winnebago, Wisconsin, indicates that there are statistically significant differences in some measurements along the long axis of the body. However, there is a remarkable stability among meristic characteristics within the species that has persisted essentially in its present form since early postglacial times.

Age 0 freshwater drum in Lewis and Clark Lake, a main stem Missouri River reservoir, consumed mostly zooplankton and chironomids, and age I and older fish consumed mostly Hexagenia. Zooplankton were important during the entire summer for age 0 fish, but were important only during the spring and fall for older fish. Bottom organisms were important food for age 0 fish longer than 40 mm and for age I and adults. A study of diurnal food habits revealed most zooplankton were consumed during daylight and most Hexagenia during darkness. Freshwater drum growth was poor during the first 6 years after impoundment (1956–1961), then improved between 1962 and 1966. Improved growth was related to an increase in Hexagenia abundance and was accompanied by an increase in freshwater drum density.

(1967). Food of the Freshwater Drum, Aplodinotus grunniens, in Lake Winnebago, Wisconsin. Transactions of the American Fisheries Society: Vol. 96, No. 2, pp. 218-220.