No abstract

We examined the longitudinal distribution and population characteristics of shadow bass Ambloplites ariommus in the Spring River and lower Eleven Point River of Arkansas to determine potential length limit regulations for this species. Shadow bass were the second most abundant sport fish species collected in both streams (most abundant sport fish was the smallmouth bass Micropterus dolomieu). Abundances (catch per effort) of shadow bass were greatest upstream and declined significantly downstream (Spring River: 32.6 fish/h upstream versus 3.4 fish/h downstream; Eleven Point River: 13.4 versus 5.0 fish/h). Size distributions and relative weights (Wr) were also greatest upstream (Spring River: Wr = 109 upstream versus 99 downstream; Eleven Point River: Wr = 105 versus 95). Associated with this distribution trend was a downstream decline in stream slope and frequency of riffles. Catch rates and size distributions of shadow bass were greater for the Spring River (proportional size distribution mean = 83) than for the Eleven Point River (mean = 36). Stream differences in preferred size distributions were even greater. Total length at age for shadow bass indicated rapid growth rates compared with results of previous studies; age‐3 fish reached 183 mm total length. The von Bertalanffy equation yielded the following growth model for shadow bass: Lt = 250.8[1 − e−0.381(t−0.477)], where Lt is length at age t. Stomach contents of shadow bass in the Spring River comprised mostly crayfishes, which is consistent with feeding patterns of other rock basses Ambloplites spp. Relative weights were high for shadow bass in both rivers, although Wr was greater for Spring River fish (Wr = 107) than for Eleven Point River fish (Wr = 102). Based on abundance, diet, and condition of shadow bass, upstream reaches of both rivers contain sustainable populations of this species. Despite these positive population and growth features, length limits for shadow bass are not recommended for these streams.

Few studies have evaluated stocking programs for walleye Sander vitreus in the southern United States; this may be the first such study for a southern river. The Eleven Point River, located in southeastern Missouri and northeastern Arkansas, has been supplementally stocked by the Arkansas Game and Fish Commission (AGFC) and the Missouri Department of Conservation (MDC) for many years. Our goals were (1) to assess the contribution of walleye fingerlings in the Arkansas section (∼60 km) of the Eleven Point River using the recapture rates of marked walleyes and (2) to assess the reproductive contribution of stocked walleyes using genetic tracking of mitochondrial DNA markers. All of the walleyes stocked by the AGFC during 1999–2002 were freeze‐branded; these fish possess the A haplotype, which is the most common one rangewide. Wild fish and those stocked by the MDC in the Missouri portion of the Eleven Point River possess the native C haplotype of the Black River system, which includes the Eleven Point River. Electrofishing samples revealed that the stocked fish captured in Arkansas from 2002 to 2004 were almost evenly divided by cohort; 52% possessed the A marker and 43% the C marker. Forty‐three percent of the walleyes older than age 3 (and therefore present in the river before the release of the freeze‐branded fish) had the A marker. Walleyes originating from the AGFC‐source fish had significantly greater relative weights than did native‐spawned walleyes and fish released in Missouri. In addition, haplotype‐A walleyes had significantly greater relative weights than haplotype‐C walleyes. The high relative weights of the sampled fish throughout the study suggests a lack of intraspecific competition as a result of stocking.

Nile tilapia Oreochromis niloticus have been stocked as a forage species annually since 2001 in Lake Hogue, a 101-ha, closed-system public fishing reservoir in northeastern Arkansas. A mail-in reward tag study was implemented in 2003 to determine total estimated harvest, contribution of Nile tilapia to the lake's fishery, and impact of angler harvest on Nile tilapia reproduction. Estimates of harvest were corrected for tag loss (1.1%), tag-induced mortality (1.0%), and nonreporting of tags by anglers (53% reporting rate). Angler-hours were compared between anglers targeting Nile tilapia and those targeting other species. Anglers harvested an estimated 83% of the stocked Nile tilapia (56% of stocked fish were captured by traditional panfishing techniques; 27% were captured by use of dip nets during the winter die-off in late November). Anglers targeting primarily Nile tilapia fished significantly longer (5.7 h/angler) than individuals who incidentally caught Nile tilapia while fishing for other species (4.5 h/angler). Analysis of the economic impact of stocking Nile tilapia demonstrated a benefit-cost ratio of 0.38. Harvest of Nile tilapia did not apparently interfere with the management goal of using the fish as a forage species for game fishes. Tag return data strongly suggested that at midday during the hot summer months, when fishing pressure had traditionally been low, anglers targeted Nile tilapia in favor of the traditional target species (e.g., bluegill Lepomis macrochirus and redear sunfish L. microlophus).