Balancing Fisheries Management and Water Uses for Impounded River Systems

<em>Abstract</em>.—In Ohio reservoirs, a perceived excess of available gizzard shad <em>Dorosoma cepedianum </em>prey and poor recruitment of stocked walleyes <em>Sander vitreus </em>during the 1970s resulted in research to develop and expand a program to stock saugeyes (walleye × sauger <em>S. canadensis</em>), a hybrid better suited for shallow, productive, and turbid reservoirs with short water-residence times. Development of successful production techniques increased saugeye stocking from fewer than 1.2 million to 6–10 million fingerlings (28–42 mm) per year during 1980 through 1990, presenting the challenge of determining stocking rates suited to available prey. To improve <em>Sander </em>spp. stocking practices, we assessed prey supply by quantifying fish biomass in Ohio reservoirs using acoustic technology. Fish biomass varied from 10 to 897 kg/ha as estimated by 53 acoustic surveys conducted on 16 reservoirs during 1999–2006. Among 15 variables associated with reservoir productivity, 84% of the variability in fish biomass was explained by watershed area, trophic state, reservoir area, and reservoir volume; watershed area plus trophic state explained 77% of this variability. Dominance of fish prey smaller than 150 mm, which represented more than 80% of fishes sampled in acoustic surveys, revealed that reservoir fish biomass largely reflected the upper limit of prey fish biomass morphologically available to age-1 and older <em>Sander </em>spp. Gizzard shad represented more than 50% of the fishes captured in 92% of gill-netting surveys conducted in conjunction with acoustic surveys. Unexpectedly, reservoirs with extensive prey biomass occasionally had poor recruitment for <em>Sander </em>spp., and these reservoirs often were stocked at lower rates than ones with better recruitment. Fisheries managers in Ohio can improve stocking practices by using acoustic surveys to predict reservoir capacity for stocked sport fish based on reservoir attributes, then applying these results to details of reservoir-specific recruitment of stocked fishes and their consumptive demand. Refining this supply and demand approach will require continual progress in understanding reservoir ecosystems and their watersheds.

1992 ◽  
Vol 49 (8) ◽  
pp. 1722-1733 ◽  
Author(s):  
Nicholas G. Aumen ◽  
Cindy L. Crist ◽  
Dawn E. Miller ◽  
Keith O. Meals

Sources of particulate organic carbon (POC) and trophic–dynamic relationships were studied in a reservoir with low sportfish populations. Fish community structure and POC input from tributaries, phytoplankton primary production, and vascular vegetation on mudflats were estimated. Gizzard shad (Dorosoma cepedianum) averaged 39.8% of the total fish biomass in 1988, and as much as 94% of the total forage fish biomass was too large to serve as prey for most predators. Phytoplankton primary productivity averaged 1182 mg C∙m−2∙d−1 in 1987 and 1988, contributed 33.57 Gg POC∙yr−1 to the reservoir, and apparently was phosphate limited. POC inflow from tributaries contributed 60.00 Gg∙yr−1with 79% of POC <75 μm in size. Winter and spring stormflow was responsible for 92% of the total POC transported. Considering POC size fractions available to gizzard shad, POC input from tributaries, phytoplankton, and mudflats contributed 21, 54, and 25% of the total POC input, respectively. The trophic–dynamic analysis indicated that phytoplankton POC was adequate to support the reservoir fish community. A more efficient transfer of carbon in the food web might be accomplished by stocking with a smaller forage fish, such as threadfin shad (Dorosoma petenense), which are not common in the reservoir.


1992 ◽  
Vol 49 (7) ◽  
pp. 1466-1473 ◽  
Author(s):  
Xavier Lazzaro ◽  
Ray W. Drenner ◽  
Roy A. Stein ◽  
J. Durward Smith

We quantified the effects of planktivore biomass and planktivore type in an experimental mesocosm study of factorial design in which five levels of fish biomass (0–75 g/m3) were cross-classified with two plantivore types: filter-feeding gizzard shad (Dorosoma cepedianum) and visual-feeding bluegill (Lepomis macrochims). As fish biomass increased, cladocerans, cyclopoids, particulate phosphorus (PP) > 200 μm, and chironomids declined; conversely, rotifers, primary productivity, chlorophyll a, turbidity, unicellular flagellates, colonial and unicellular green algae, pennate diatoms, total phosphorus, and 20–200 and 12–20 μm PP were enhanced. In the presence of gizzard shad, as compared with bluegill, cyclopoids, turbidity, unicellular green algae, pennate diatoms, > 200 μm PP, and chironomid tubes were higher whereas colonial green algae and < 0.2 μm PP were lower. Fish biomass operated independently of planktivore type for most variables, except copepods, colonial green algae, turbidity, and 20–200 μm PP. Although gizzard shad and bluegill have different trophic cascade pathways, fish biomass was more important than planktivore type as a regulator of plankton communities and water quality.


1977 ◽  
Vol 34 (10) ◽  
pp. 1725-1733 ◽  
Author(s):  
Walter T. Momot ◽  
Jack Erickson ◽  
Frederick Stevenson

Hoover Reservoir, a very eutrophic environment, produces a successful fishery for walleye. However the population can only be sustained by stocking due to the absence of high quality summer habitat, intensive exploitation, poor recruitment of most natural year-classes, and poor growth of adult walleye. The oxygen temperature regime brought about by eutrophication forces the adult walleye to live at an above optimum temperature regime for maximum growth during the summer months. Because of the climate and geographical location, the preferred temperatures of the desired prey, young gizzard shad, are far above that of the adult walleye. This makes the shad less accessable to predation for a large portion of the day further reducing the growth of older walleye. Poor recruitment of large natural year-classes results from the absence of gizzard shad fry which spawn much later than walleye, at the time larval walleye convert from a planktonic to a piscivorous feeding habit. Large year-classes of walleye are produced in years when fry were stocked. Stocked fry were produced in hatcheries from spawn obtained at the reservoir. Fry were stocked in the reservoir just at or in advance of shad spawning, whereas in most years naturally produced fry appeared well in advance of shad spawning. This delayed appearance of stocked walleye fry probably accounts for their successful year-class production. This walleye spawning stock had an estimated mean biomass of 13.6 kg/ha and a mean annual production of 2.2 kg/ha between 1967 and 1973. Key words: Hoover Reservoir — Ohio, Percidae, Stizostedion, management, fry stocking


2011 ◽  
Vol 27 (4) ◽  
pp. 287-297 ◽  
Author(s):  
Walt Godwin ◽  
Michael Coveney ◽  
Edgar Lowe ◽  
Lawrence Battoe

The tapeta lucida of three species of teleosts were examined to determine the composition of the reflecting material. The fishes were bay anchovy Anchoa mitchilli (Engraulidae), gizzard shad Dorosoma cepedianum (Clupeidae) and pigfish Orthopristes chrysopterus (Haemulidae). The tapetum of each species was situated in the pigment epithelium of the eye. That of the pigfish contained triglycerides identified as chiefly glyceryl tridocosahexaenoate. A reduced pteridine, 7, 8-dihydroxanthopterin, occurred in the tapetum of the gizzard shad. Guanine occurred in the tapetum of the bay anchovy. The tapetum of the shad contained brightly reflecting particles about 0.5 μm in diameter There were 10.8 mg of dihydroxanthopterin in the tapetum of a shad (total body length 23 cm) and 0.46 mg of guanine in the tapetum of an anchovy (total body length 9 cm). This is the first report of a pteridine acting as a retinal reflector in vertebrates. Various aspects of retinal reflectors of teleosts are discussed and their variety and common characteristics commented upon.


2000 ◽  
Vol 57 (6) ◽  
pp. 1113-1119 ◽  
Author(s):  
James C Smoot ◽  
Robert H Findlay

Measuring digestive enzyme and surfactant activities tested specialization of gizzard shad (Dorosoma cepedianum) digestive physiology to a detritivorous feeding strategy. Digestive enzyme activity was measured in adult and larval gizzard shad using fluorescently labeled artificial substrates. Surfactant activity in gizzard shad was measured by comparing gut juice drop diameters over a range of dilutions. Enzyme activity in the ceca region of adult gizzard shad was high for esterase, beta-glucosidase, lipase, and protease. Enzyme activity was lower in posterior intestine sections than in anterior intestine sections, although protease activity remained high for the greatest distance in the intestine. Micelles were detected in adult gizzard shad gut juice, and surfactant activity was greatest in the ceca region. Larval gizzard shad protease activity was similar to that of adult fish, and surfactants were below their critical micelle concentration. Gizzard shad coupled digestive physiology with gut anatomy to obtain nutrients from detritus, and these adaptations may explain elevated growth rates observed in these fish when they are planktivorous.


1996 ◽  
Vol 15 (10) ◽  
pp. 1752-1759 ◽  
Author(s):  
Alan S. Kolok ◽  
James N. Huckins ◽  
Jimmie D. Petty ◽  
James T. Oris

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