Journal of the Southeastern Association of Fish and Wildlife Agencies

Precise and accurate estimates of demographics such as age structure, productivity, and density are necessary in determining habitat and harvest management strategies for wildlife populations. Surveys using automated cameras are becoming an increasingly popular tool for estimating these parameters. However, most camera studies fail to incorporate detection probabilities, leading to parameter underestimation. The objective of this study was to determine the sources of heterogeneity in detection for trail cameras that incorporate a passive infrared (PIR) triggering system sensitive to heat and motion. Images were collected at four baited sites within the Conecuh National Forest, Alabama, using three cameras at each site operating continuously over the same seven-day period. Detection was estimated for four groups of animals based on taxonomic group and body size. Our hypotheses of detection considered variation among bait sites and cameras.

Channel catfish egg masses are typically incubated in stationary wire mesh baskets suspended in metal troughs with flow-through water that is agitated and circulated between the baskets and around the eggs with rotating paddles. A limiting factor in the successful incubation of channel catfish egg masses is the absorption of oxygen by the developing embryos; low levels of dissolved oxygen in the water result in premature hatching and increased fry mortality. We modified and tested a vertical-lift incubator (the “See-Saw”) for incubating channel catfish egg masses. Both the See-Saw and control (paddle-type) troughs were loaded with 26 egg masses (13.2 kg) per trough which is 1.5-2.0 times higher than recommended loading rates. Swim-up fry survival was 2.3-fold higher for the See-Saw than the control troughs. Many of the sac-fry produced in the control troughs were either dead when removed or died prior to reaching swim-up stage, presumably due to oxygen stress.

The walleye (Sander vitreus) is a large predatory fish distributed throughout Canada and the United States, ranging from Central Canada southward to the Tennessee and Mississippi River drainages. Because of its importance as a recreational sportfish, walleye growth has been studied extensively in the northern portion of its distribution. However, little information is available regarding growth of this species in the southeast, particularly in Georgia. The objectives of this study were to quantify growth of walleye in several north Georgia reservoirs and to compare the growth rates of walleye in north Georgia to the growth rates of walleye throughout North America. Anchored gill nets and boat electrofishing were used to collect walleye on five different impoundments from April 2009 to September 2010. Age estimates for each of 115 walleyes were obtained by counting growth annuli from transverse sections of sagittal otoliths.

The mountain brook lamprey (Ichthyomyzon greeleyi) has no previous embryological description even though the lamprey's primitive developmental patterns are of value to evolutionary biologists. This research describes visible developmental processes of the mountain brook lamprey from the unfertilized ovulated egg to the release of ammocoete larvae into the field. In-vitro fertilization was the process used to produce viable embryos after strip spawning. This process successfully produced about 4000 embryos for descriptive observation. Embryological and larval developmental stages were named using criteria defined for Lampetra reissneri. The findings conclude that the timing of early developmental events is similar to that of other lamprey species.

We investigated the microhabitat selection of largemouth bass (Micropterus salmoides) and Suwannee bass (M. notius) using multivariate logistic regression modeling. Relative use probabilities for cover types were similar among juvenile and adult bass of both species with minor differential use. However, the water velocity and depth selection functions between juveniles were associated with slow and shallow locations, while the selection functions between adults were associated with intermediate speeds and depths. The predictive abilities of the habitat selection models significantly differed between juvenile and adult bass of both species, between adult largemouth bass and Suwannee bass, but not between juvenile largemouth bass and Suwannee bass.

Excessive coverage of aquatic vegetation has reduced aesthetic quality and recreational value in Felsenthal Reservoir, Arkansas. A large portion of the 6,000-ha impoundment of the Ouachita River, located within the Felsenthal National Wildlife Refuge, is covered by dense aquatic vegetation. Grass carp are commonly used to control aquatic vegetation in closed systems, but results of stocking grass carp for vegetation control in open systems is less certain. Radio transmitters were implanted in 48 adult triploid grass carp. Grass carp were released in the reservoir during fall 2006. Radio-tagged grass carp were relocated approximately semi-monthly during a 12-mo period. Of the 48 fish that were stocked, 39 (82%) were consistently located in Felsenthal Reservoir. Three fish (6%) were never relocated, one fish (2%) moved upstream of Felsenthal Reservoir then returned, and five fish (10%) were located upstream of Felsenthal Reservoir in both the Ouachita and Saline Rivers.

The Arkansas River largemouth bass (Micropterus salmoides) fishery has not been intensively managed or studied, especially downstream of Lake Dardanelle. Recent issues that have potentially affected the fishery necessitated a comprehensive assessment of populations throughout the entire Arkansas portion of the river. During 2004-2005, largemouth bass populations were assessed in all 11 Arkansas navigation pools of the river using boat-mounted, nighttime electrofishing. Populations were young with 94% of the individuals consisting of ages 1-4. Across years and pools, size structure measures were within acceptable ranges for largemouth bass (mean PSSQ = 51, range 28-72; mean PSSP = 18, range 8-36), though theoretical maximum sizes generated from growth models were generally smaller than average (mean L∞ = 474 mm TL, range 414-530).

We explored the feasibility of sampling young-of-year (yoy) Gulf sturgeon (Acipenser oxyrinchus desotoi) in the Apalachicola River, Florida, using modified balloon trawls during January and June 2009. Three yoy sturgeon (57 - 120 mm TL) were captured during June 2009 in the lower reaches of the river system. Initially, this method of assessment is labor intensive and may require more than 25 river kilometers (rkm) of trawling per capture. While this gear type has been remarkably efficient for sampling yoy Scaphirhynchus (i.e., pallid and shovelnose sturgeon) in the Mississippi River system, the depressed population size (ranging from a few hundred to perhaps 1,000 individuals) encountered in the Apalachicola River could make assessment of yoy Gulf sturgeon problematic.

When estimating population size of smallmouth bass (Micropterus dolomieu) using the multi-pass removal method with electrofishing, understanding the significance of capture avoidance is important. One-hundred-fifty smallmouth bass were tagged with external radio transmitters and monitored during depletion sampling in seven different river reaches in Virginia. Capture avoidance of radio-tagged smallmouth bass during electrofishing averaged 33.7% (SE = 5.75%). Avoidance appeared to be random across the sample reaches and there were no significant correlations between capture avoidance and fish length, season, river, or physical dimensions of the sample reaches. Emigration from the sample reaches during depletion sampling was observed. However, no pattern in upstream or downstream movement was documented.

Stocking hatchery-reared largemouth bass (Micropterus salmoides) fingerlings to supplement wild populations is a common practice, but assessment of the influence of such stocking practices on the wild population is less common. In September 2007 and 2008, we estimated abundance of wild young (age 0 and age 1, respectively) largemouth bass in backwaters of the Arkansas River before and after stocking with hatchery-reared largemouth bass (100-150 mm TL). Two backwaters were sampled as reference populations, four backwaters were unstocked for comparison with stocked locations. Five backwaters were stocked with 60 fish/ha. We found no differences in mortality, length, weight, or condition of wild age-1 largemouth bass from stocked and unstocked backwaters. Stocking hatchery-reared largemouth bass did not appear to affect mortality, growth, or condition of the wild year class.

Sportfish managers in coastal North Carolina are often challenged with interpreting estimates of largemouth bass (Micropterus salmoides) relative abundance (catch-per-unit-effort, CPUE) due in part to the influence of environmental factors on boat electrofishing techniques. To accurately assess population abundance using relative abundance indices, the effects of environmental variables on largemouth bass catch should be quantified. We sampled largemouth bass populations in Neuse River tributaries weekly in spring 2006 and 2007 to investigate the relationship between CPUE and streamflow. Catch-per-unit-effort appeared to be strongly related to discharge, but the relationship was not linear. Instead, we found that small increases in streamflow between 60 and 100 m3 sec-1 had a large effect on electrofishing CPUE. Above this streamflow threshold, CPUE was usually low and only exceeded 20 fish h-1 in 3 of 41 observations in 2006 and 2007.