2004 Dakota Chapter American Fisheries Society Meeting Abstracts

The Save Our Lakes Program is in its infancy. It is a 2.5-year-old program authorized by the North Dakota legislature to reduce, and if possible reverse, the ever increasing aging processes within our lakes and reservoirs. Sediment and nutrient loading from agricultural sources have been, and will continue to be the major NPS pollution source into our state’s waterbodies. North Dakota has approximately 300 managed systems and lake by lake, landowner by landowner, watershed by watershed they will be addressed. Backing the cows and the cultivators off the lakeshores is the primary goal of this program. During the past two years some of the practices that have been put into place have been sediment dams, easements (pasture & cultivated), rock weirs, shoreline enhancements, sediment removal, tree plantings, alternate water sources, and low water draw downs (active & passive). The Save Our Lakes Program isn’t a quick fix, it will take time to slow down or reverse the decades of pollution. There is a need out there, we just need to start chipping away at the problems.

The aquatic nuisance specie(s) (ANS) problem(s) is a reflection of global commerce and of mobility. We want the good things now, and we willingly travel to enjoy our recreation. The problems from ANS are well known – they are invasive, injurious, and costly to control. The estimated annual national cost to deal with ANS is $137 billion, Florida spends about $27 million a year, and North Dakota has spent about $20,000 per year. Not addressed in these costs are the reallocating of limited financial resources and the time and manpower lost from legitimate fish management activities.

A few carp can reduce the potential standing crop of desired species to 72% of pre infested conditions. A multi ANS infestation at the lower trophic levels can reduce the upper level to 43% of expectations. Based on a review of life cycle needs, North Dakota will focus on the eight fish species, four invertebrates, and seven plant species as the likely candidates for introduction.

NDGFD field staff inventoried 133 waterbodies in 2002 and found curlyleaf pondweed in the Missouri River system and some lakes in that drainage, purple loosestrife and carp are common throughout the state, and Eurasian watermilfoil has not been found in the one site it was known to have occurred in the last three sampling efforts. The likely locations for ANS infestations are the Missouri River system, Devils Lake, and the lakes along the border with Minnesota.

An intense public educational campaign is being used to prevent the introduction and spread of ANS with an estimated 1.1 million individuals being contacted in 2002. Future strategies will be an increased public education campaign, continue angler contacts during creel surveys, have an ANS State Management Plan approved and funded by the FWS, and develop a marketing effort to contact outdoor recreators prior to their traveling to North Dakota.

Feral landlocked fall chinook salmon from Lake Oahe, South Dakota were reared at two different densities during the last 52 days of rearing at McNenny State Fish Hatchery, Spearfish, South Dakota. One group of approximately 15,000 salmon was split into 12, 1.8-m diameter circular tanks (1,250 fish/tank) after coded-wire tagging and adipose fin-clipping. A second group of 15,000 tagged and clipped salmon was put into 5 circular tanks at normal loadings (3,000 fish/tank). Initial densities were 3.05 kg/m³ and 7.89 kg/m³ in the low and normally loaded tanks respectively. Final densities prior to stocking on June 2, 1999 were 7.29 kg/m³ and 15.02 kg/m³. Two precocious males from each group returned to spawn at Whitlocks Spawning Station on Lake Oahe in October 2000. In 2001, one male and one female (2 total) returned to spawn from the normal density group, whereas 13 males and 4 females (17 total) returned from the group reared at a lower density. Only 1 age-4 female returned in 2002 from the normal density group, compared to 9 reared at the lower density. Overall, 28 salmon reared at low densities returned to spawn versus only 5 salmon reared at normal densities. The differential spawning return rates of fingerling salmon reared at different densities may have substantial hatchery rearing and management implications.

Selected reproductive characteristics obtained during spawning of land-locked fall chinook salmon Oncorhynchus tshawytscha from Lake Oahe, South Dakota, were evaluated for their use as predictors of embryo survival to the eyed-egg stage. Spawn was categorized according to the presence or absence of observable overripe eggs. No significant differences in female length, female weight, the number of eggs per female, egg size, the amount of ovarian fluid released during spawning, and ovarian fluid specific gravity, pH, and conductivity, were observed between spawn containing overripe eggs versus spawn without overripe eggs. Conductivity was significantly positively correlated to embryo survival only in spawn without overripe eggs, while the total number of eggs per female was only positively correlated to embryo survival in spawn with overripe eggs. Spawning female weight, the number of eggs per female, and egg size were significantly different in spawn containing overripe eggs where no embryo survival was observed, compared to spawn containing overripe eggs with at least some embryo survival to the eyed-egg stage. Although no definitive predictors of subsequent embryo survival were detected, spawning personnel are probably justified in discarding land-locked fall chinook salmon spawn if more than 10% of the eggs are overripe and the female releasing the eggs is smaller than normal with relatively fewer, smaller eggs.

In the late 1990s, the State of South Dakota proposed site-specific water quality standards for 11 inorganic chemicals in several streams in the Northern Black Hills that receive acid mine drainage from gold mining operations. For nine inorganics, the proposed standards exceed current national acute and/or chronic water quality criteria. The chronic toxicity of a mixture of 11 inorganics combined at a ratio of their proposed Criterion Continuous (chronic) Concentrations (pCCC) was assessed by the Ceriodaphnia dubia survival and reproduction test. The acute toxicity of a mixture of the same inorganics combined at a ratio of their proposed Criterion Maximum (acute) Concentrations (pCMC) was assessed by the standard 96-h exposure test with fathead minnow. For the pCCC mixture, all C. dubia exposed to concentrations at or above the pCCC died within 24 h and survival at concentrations 0.125x-0.50x pCCC was 30-60% after 8 days. Reproduction of C. dubia was significantly reduced at all mixture concentrations compared to the control treatment. These results indicate that the proposed site-specific CCC for these 11 inorganics, if they occur simultaneously in the water, are not protective of C. dubia. For the pCMC mixture, there were no mortalities of fathead minnow at concentrations 1.0x pCMC and the 96-h LC50 of the mixture was 1.52x pCMC. These results indicate that the proposed site-specific CMC for a mixture of these 11 inorganics is protective of fathead minnow. Additional studies are needed to determine protective concentrations of these inorganics combined in mixtures to C. dubia on an acute and chronic basis.

Populations of the Topeka shiner, Notropis topeka, have declined throughout the historic Midwestern range of this species and it is currently listed as endangered by the U.S. Fish and Wildlife Service. Significant populations of Topeka shiners are now restricted to the Flint Hills in Kansas, tributaries of the Missouri River in Missouri, and the Vermillion, Big Sioux and James rivers in South Dakota. Eight microsatellite primers were developed and used to genotype individuals from each of 9 populations throughout South Dakota, Iowa, Kansas and Minnesota. Allele frequencies at each locus for each population were calculated and the data used to estimate the degree of genetic divergence among sampling locations by calculating F_st values. Multilocus F_st values indicate that moderate to high levels of genetic divergence exist between the South Dakota population and the Kansas populations. With relatively low levels of genetic differentiation between South Dakota populations and the populations from Iowa and Minnesota.

Genetic Analysis of South Dakota Populations of Walleye

DNA microsatellite markers were used to compare Park’s Pond walleye to three walleye populations in Lake Oahe. Previously, it was demonstrated that walleye in Park’s Pond displayed a sex ratio bias in favor of females. The genetic basis of this sex ratio bias was explored using a variety of DNA techniques. Sex ratio bias could have been the result of a feminization of genetically male fish, one of the consequences of this would be a 3:1 sex ratio of males to females in the progeny of Park’s Pond fish. To test this, a morphological analysis of the 2002 offspring of Park’s Pond females was conducted.

Preliminary analysis of microsatellite loci suggests that Park’s Pond walleye showed no evidence for a lack of genetic diversity or genetic differences when compared with Lake Oahe populations. RAPD analysis of male and female genomes did not yield any diagnostic differences that indicated the presence of a sex linked DNA marker. Known sex-linked DNA markers from related fish could not be used successfully in walleye. Development of a sex-specific DNA marker in walleye would require further research. A morphological analysis of 49 progeny of Park’s Pond females indicated a 3:1 male-biased sex ratio suggesting a feminization event of the original Park’s Pond cohort. The implications of these results will be discussed.

During rainstorms, urban streams typically have increased flows, high suspended sediment concentrations and poorer water quality as a result of changes within the watershed related to human activity. Between May and November of 2001 and 2002 water quality was monitored continuously at five sites along Rapid Creek within Rapid City. Water quality samples were collected for six baseflows (non-events) and six storm events. Blood samples were collected from wild adult brown trout (Salmo trutta) concurrently to determine if storm events could elicit physiological stress responses. Blood samples were also collected 24, 48 and 96 h after each storm event had started. Water monitoring results show significant increases in runoff volume and peak flows during storm events. Water quality parameters exceeding criteria for a coldwater fishery were total suspended solids and temperature.

Although minnows are best known for inhabiting small streams and lakes, there is a group of minnow species that characteristically occupies large rivers. Even though most big river minnows are widespread, their ecology is poorly known. However, it is known that several of these fishes share a unique reproductive strategy—they are pelagic, broadcast spawners. Pelagic, broadcast spawners have semi-buoyant, non-adhesive eggs that hatch in 24 to 48 hours. Their early (swimup) larvae are also pelagic for 48 to 72 hours. As a result, embryos and early larvae are highly susceptible to downstream displacement for 3 to 5 days post spawning. The spawning period is protracted and spawning peaks commonly coincide with descending flood flows. Pelagic, broadcast spawning of plains minnow and emerald shiner is well documented and there is evidence that western silvery minnow and sturgeon chub also use this reproductive strategy. The habits and phylogeny of sicklefin chub, silver chub, river shiner, and silverband shiner suggest they do as well. Evolutionary advantages of pelagic, broadcast spawning are presumably avoidance of burial in unstable sediment and wide dispersal via passive drift. However, this life history strategy may result in vulnerability to river channel degradation and river operations that reduce hydraulic retention and vulnerability to instream barriers that impede upstream dispersal. Western South Dakota streams are relatively pristine and native pelagic spawning species remain prevalent there, in contrast to rivers of the southern Great Plains.

Fieldwork on the decade-long project to update information on river fishes and habitat in South Dakota will be complete after tributaries to Cheyenne River are sampled. Preliminary surveys of Cheyenne River tributaries were made in 2003, and the purpose of this report is to summarize the fish communities and instream habitat of two, proximally confluent watersheds. Ten sites in Cherry Creek Basin were compared to six sites in Plum Creek Basin. Bankfull width-to-depth ratio ranged from 3.0 to 31.6 in Cherry Creek and 4.3 to 13.4 in Plum Creek. Discharge ranged from 0.0 to 1cm³/s (^ = 0.1 ± 0.4) in Cherry Creek and 0.0 to 0.4 cm³/s (^ = 0.4 ± 0.2) in Plum Creek. Cherry Creek had 15 fish species while Plum Creek had 16. Twelve species were found in both watersheds. Fish species richness ranged from 0 to 10 (^ = 4.3 ± 3.5) in Cherry Creek and from 5 to 15 (^ = 8.8 ± 3.7) in Plum Creek. Evenness varied from 0.0 to 1.9 (^ = 0.7 ± 0.6) in Cherry Creek, and from 0.4 to 1.7 (^ = 1.2 ± 0.5) in Plum Creek. Two species, Notemigonous crysoleucas and Etheostoma exile, were previously undiscovered in Cheyenne River Basin. Although watershed area of Cherry Creek was larger than Plum Creek and Cherry Creek had a larger channel in its lower reaches, Plum Creek had higher fish species diversity. Presence of stable flow, low width:depth, and beaver ponds in Plum Creek may account for this difference.

Optimal foraging theory suggests that predators should adopt a tactic of prey choice based on size, morphology, and behavior that will maximize the net energy gained per time spent foraging. For prey choice to be optimal, the ratio of energy gained to energy expended should be maximized. Activity costs associated with pursuit and capture are substantial and considered to be the most costly activity in free-swimming fish. Foraging behavior and fish activity have been linked to production of glycolytic (anaerobic) enzymes such as lactate dehydrogenase (LDH), in the axial, white musculature of fish. To examine the effect of prey size on anaerobic activity, we conducted a series of laboratory feeding trials with largemouth bass (Micropterus salmoides) predators (240-300 mm TL) and bluegill (Lepomis macrochirus) prey (35-85 mm). Prey selectivity trials, conducted in 800-L mesocosms, indicated that small (35-mm) to moderate sized (50-mm) prey were preferred (89%) over larger (60-85 mm) individuals (11%). Activity cost, as indexed by LDH, increased in largemouth bass with increasing prey size, with LDH activity 20% higher in bass feeding on large compared to small prey. Moreover, bioenergetics modeling revealed that consumption was appreciably under-estimated for larger prey sizes (65-80 mm), implying that activity costs increase for larger prey, consistent with LDH measurements. Future efforts are directed toward examining the linkage between LDH, and the activity component of bioenergetics modeling.

Routine metabolism of juvenile pallid sturgeon, Scaphirhynchus albus precursor to bioenergetics model development

Bioenergetics models are one method to explore trophic interactions between fishes and their prey and assess suitability of habitats for fish growth. These models estimate fish consumption using a balanced budget where consumption (as energy) equals the sum of total metabolic costs, waste products, and growth. Recovery of the endangered pallid sturgeon Scaphirhynchus albus in the Missouri River is predicated on hatchery reared juveniles released into four Recovery Priority Areas (RPAs) from Montana to Missouri, reaches that retain some riverine habitat qualities. Flow augmentation from the main stem dams has also been considered as a means to mimic pre-impoundment conditions (i.e. spring rises in water levels) which may cue spawning by remaining adult pallid sturgeon. How and when waters are released from these dams subsequently changes the thermal habitat available downstream. How these new thermal regimes in each RPA could affect juvenile pallid surgeon growth and condition can be assessed with bioenergetics models. In 2003, respiration experiments were conducted on juvenile pallid sturgeon to measure routine metabolic rates (i.e. oxygen consumption) as an initial step towards obtaining physiological data needed to parameterize a bioenergetics model. Currently, no metabolic data for any Scaphirhynchus species exists. Experiments were conducted to ascertain the influence of body size and temperature on metabolic rate and determine if routine metabolism changed ontogenetically. Preliminary results for pallid sturgeon metabolism were compared to those reported for Atlantic sturgeon (Acipenser oxyrinchus) and shortnose sturgeon (A. brevirostrum) to determine whether a single sturgeon model for routine metabolism is warranted.

Missouri River walleyes and saugers were tagged during spring of 2002 for the purpose of determining their exploitation and movement between Ft. Randall and Gavins Point Dams on the Missouri River. Most walleyes tagged were captured immediately below Ft. Randall Dam, and most saugers tagged were captured from Lewis and Clark Lake. From first year tag returns of angler caught fish, exploitation of walleye was determined to be 18 % and of sauger 7 %. The highest number of walleyes were caught and harvested in June. The highest number of saugers were caught and harvested in July or November. Most walleyes tagged were 380-509 mm in length, while the highest tag return rate was for walleyes 510-629 mm. Most saugers tagged were less than 380 mm in length, while the highest tag return rate was for saugers 380-529 mm. Most tagged walleyes and saugers were caught in the same vicinity as where they were tagged. Observed walleye movement that occurred was predominately downriver, and mostly within the river or within the reservoir. The longest distance a walleye moved upstream was 98 km and downstream was 109 km. Five walleyes and one sauger passed through Gavins Point Dam and were caught in the tailrace below the dam. Observed sauger movement that occurred was entirely between the river and reservoir or vice-versa. The longest distance a sauger moved upstream was 24 km and downstream was 12 km.

Gizzard shad Dorosoma cepedianum are an important prey fish in many Missouri River reservoirs. The abundance and availability (appropriate sizes) of gizzard shad may strongly influence growth and recruitment of predator fishes within these systems. To better understand how age-0 gizzard shad reproduction and growth influence predator-prey dynamics, we quantified hatching date distribution, daily growth, and size at the end of the growing season for gizzard shad in three Missouri River Reservoirs in South Dakota. We observed a gradient across reservoirs wherein gizzard shad in the most downstream reservoir (Lewis and Clark Lake) hatched later (early June), but grew slower than upstream reservoirs. Gizzard shad in Lake Sharpe (most upstream) hatched earlier (late May) and grew faster than gizzard shad in the other reservoirs. The middle reservoir (Lake Francis Case) was intermediate to the other reservoirs in both hatching date and daily growth. The combination of earlier hatching and faster growth likely contributed to the larger size that age-0 gizzard shad achieved at the end of the growing season in Lake Sharpe as compared to Lewis and Clark Lake. We predict that gizzard shad likely become available to predators earliest in Lake Sharpe, followed by Lake Francis Case, and latest in Lewis and Clarke Lake. Understanding the basic ecology of gizzard shad will improve management of predatory sport fish in Missouri River Reservoirs.

From May to September of 2003, larval fishes were collected at approximately 2-week intervals from surface waters of the Missouri River below Fort Randall and Gavins dams. These two stretches of the Missouri River represent unchannelized habitats that still encompass riverine characteristics. However, these reaches have different flow regimes due to operation of the respective dams; Fort Randall releases have high diel fluctuations (> 1 m) for power generation, whereas daily Gavins Point outflows are relatively constant. Two 0.5-m diameter conical plankton nets (length-width ratio 3:1, 500-um mesh) passively collected drift in flowing waters from 1 to 3 minutes depending on detritus loads. Three macrohabitats were sampled: inside bends (ISB), outside bends (OSB) and secondary connected channels (SCC). Densities of larval fishes will be compared between reaches and among macrohabitats. Due to highly variable flows exposing shallow water habitats and consequently any adhered fish eggs, I hypothesize that overall larval fish densities are lower below Fort Randall Dam in comparison to Gavins Point Dam.

During 1973, Silver carp Hypopthmichty molotrix, bighead carp Hypopthmichtys nobilis, and black carp Mylopharyngodon piceus were imported into the United States for evaluation as biological control agents for the aquaculture trade. Silver and bighead carp escaped from various facilities and are now well established throughout the Mississippi River Basin. Black carp are now also being documented in the wild although their abundance and range is poorly understood. The high fecundity and rapid growth of silver and bighead carp has created concern regarding the potential competition with native fishes such as paddlefish Polyodon spathula and bigmouth buffalo Ictiobus cyprinellus for limited phytoplankton and zooplankton resources in river systems. Black carp are mollucsivores that have the potential to severely impact native mollusk populations, one of our most declining native aquatic fauna. We will present information useful for developing public education programs and enforceable regulations, currently the only tools available for curtailing the spread of Asian carp into uninfested watersheds.

Walleye Sander vitreus tournament angling is a popular and growing component of many fisheries in the Midwest. However, there is concern from both non-tournament anglers and some fishery professionals that tournaments may negatively affect walleye populations. To examine some of these issues, we quantified delayed mortality of walleyes during three tournaments (April-June 2003) on Lake Francis Case, South Dakota. Weigh-in procedures (e.g., air exposure of fish during weigh-in, distance traveled, etc) and lake conditions (wind speed and wave height) were also measured to investigate how these factors affected delayed mortality. Walleyes were randomly chosen from each tournament during the weigh-in procedure, and placed in large (5,600 liter) round tanks at the American Creek Fisheries Station with an equal number of control fish captured the night before each tournament via electrofishing. Walleyes were monitored every 4 hr for 4 d following each tournament. Cumulative survivorship functions were determined for tournament and control fish and compared within each tournament. Mortality was similar for control and tournament fish during the April and May tournaments, but mortality was higher for tournament fish as compared to control fish during the June tournament. Tournament procedures were generally similar for all tournaments, except that anglers traveled further during the later tournaments. Higher mortality experienced by tournament-caught walleyes during the June tournament was likely due to warmer water temperatures (18-20ºC). These results will allow fisheries managers to better predict the effects of delayed mortality on tournament-caught walleyes in South Dakota waters.

Mining activity within the Bear Butte Creek watershed began with the gold rush of 1876 and concluded in 1998 when the Gilt Edge Mine ceased operation and subsequently placed on EPA’s Superfund National Priority List. Since 1997, the SDGF&P and the EPA have conducted fish population surveys within the Bear Butte Creek watershed to monitor the recovery of the longnose dace, mountain sucker and brook trout populations. Currently the State of South Dakota and the EPA are developing remedial objectives for the Gilt-Edge Mine that include objectives which will address native and non-native species within this watershed.

Radio telemetry was used to determine winter habitat use and movement patterns of bluegills Lepomis macrochirus in Enemy Swim Lake, South Dakota. Transmitters were attached externally to 40 adult bluegills (>200 mm) during late September. Tracking occurred from 7 October 2002 to 3 June 2003, and included pre-ice, ice-cover, and post-ice periods. Transmitter-bearing fish were located 3-4 times each week by boat, ATV, or snowmobile, and positions were recorded by handheld GPS. Overall mortality was 60%. Most mortality was believed to have occurred during the ice-cover period. Thirteen bluegills showed evidence of survival through the study period; three additional bluegills lost signal strength during the ice-cover period. Mean daily movement during pre-ice (73.3 m + 14.2 SE) was significantly higher (P=0.01) than during ice-cover (19.4 m + 12 SE) and post-ice (13.7 m + 12.9 SE). Mean distance from shore (160 m) was not different during any month (P=0.5), suggesting the importance of submergent vegetation to bluegills during cold-water periods.

We compared the removal and processing times required when scales and otoliths were used to estimate age in walleyes Sander vitreum and yellow perch Perca flavescens collected from three South Dakota lakes. On average, scales could be removed in less than half the time it took to remove otoliths in both walleyes and yellow perch. However, otoliths, which were viewed whole, required no additional processing time, while scales pressing required an additional 1.4 minutes per sample. When scale annuli were recorded on paper strips, scales and otoliths required a similar amount of time to read and total processing times were about a minute per sample less for otoliths. Without recording scale annuli, total processing times were similar for the two structures. The relative precision of ages assigned by 5 readers using scales and otoliths (20 walleye and 20 yellow perch samples) is currently being analyzed. Results will be presented in Pierre.

We investigated the effect of substrate type and location on yellow perch egg deposition in semi-permanent wetlands located in Eastern South Dakota. Mixed conifer tree reefs (three inshore and three offshore) were placed into two wetlands prior to the spawning season in 2002 and 2003. In 2002, the trees were placed in inshore and offshore locations to measure the effect of depth on egg deposition. In 2003, new trees were paired with older trees from the previous year to measure the combined effect of needle loss and periphyton growth on yellow perch usage. Trees were lifted every four to seven days throughout each spawning season and egg masses were counted. During 2002, yellow perch extruded egg masses on 93% (n = 27) of the inshore trees in both wetlands, but only 32% (n = 19) of the offshore trees were used for spawning. Similarly in 2003, yellow perch extruded egg masses on 96% (n = 28) of the inshore trees, but only 30% (n = 20) of the offshore trees. Inshore egg masses were found on 100% (n = 10) of the newly introduced trees and on 94% (n = 18) of the trees from the previous year. Offshore egg masses were found on 0% (n = 8) of the newly introduced trees and on 50% (n = 12) of the trees from the previous year. In these semi-permanent wetlands, yellow perch preferred to spawn in inshore locations, but did not prefer newly introduced conifer reefs over older reefs.

We examined sand shiner growth in relation to physical habitat in South Dakota wadeable streams during summer 2002 and 2003. Study sites represent all physiographic provinces in South Dakota and a variety of riverine conditions. Mean back-calculated length at age was derived from scales. Correlations were used to examine the relationship between 32 stream variables and mean annual growth increments (distance between annuli). Growth increments that correlated with several variables (P < 0.05) were further examined with stepwise-multiple regression. Few age-one fish were collected; analysis for growth increment one was not conducted. Growth increment two (n = 16) was correlated only with percent cobble (r = 0.50 and P = 0.05). Growth increment three (n = 19) was correlated with percent substrate embeddedness (r = 0.816; P < 0.01), bank angle (r = 0.58; P = .010), stream incised height (r = -0.52; P = 0.03), and percent fine gravel (r = -0.59; P = 0.01). Only percent substrate embeddedness contributed significantly to growth increment three (r² = 0.67; P < 0.01) when examined with stepwise-multiple regression. These data suggest substrate composition is an important factor influencing sand shiner growth.

Yellow perch (Perca flavescens) abundance can influence both angling success and prey supplies for predators. We evaluated relationships between climatological variables and abundance of larval yellow perch in eastern South Dakota lakes. Yellow perch were collected from seven glacial lakes over a 7-year period. Age-0 yellow perch were collected using a 0.75-m diameter ichthyoplankton net from May through mid-June at 7- to 10-d intervals. The number of years trawled varied from four to seven among lakes. Mean catch per unit effort (CPUE) was assessed volumetrically with peak abundance being related to climatological variables among years by lake. Highest correlation coefficients with larval yellow perch abundance were for April total precipitation (r=0.95-0.99; P=0.09-0.01; three lakes), mean March wind speed (r=-0.98 to -0.99; P=0.02-0.006; two lakes), mean of May average daily temperatures (r=0.78; P=0.12; one lake) and mean May wind speed (r=-0.82; P=0.02; one lake). Given the low number of years in some samples, individual years at times had undue influence on the relationship, resulting in high correlation coefficients. Multiple regression modeling resulted in improved models for only two of the seven lakes (R²=0.90,0.98; P=0.05,0.02). We caution that many of these relationships were developed with a low number of observations (4-7 years). However, March through May weather patterns in some combination were related to larval yellow perch abundance in all seven study lakes. Larval abundance tended to be higher in years with less wind, more precipitation, and warmer air temperatures. Whether wind, temperature, or precipitation were most influential seemed to vary by lake.

It has been over 30 years since most of North Dakota fishing waters have been bathymetrically surveyed. Methods employed then of running visual, timed depth transects and hand drawn contours were not entirely precise or accurate. With current availability of sub-meter accurate GPS, sonar technology and the use of GIS software products we now can produce highly accurate, georeferenced contour maps. Accurate area and volume statistics at any water-level along with average depth, max depths and shoreline miles are easily attained. These maps are valuable tools for lake improvement/rehabilitation projects, access and development issues and management of the fishery and also available to recreational lake users to promote the fisheries of ND.

Northern pike Esox lucius were first documented in West Long Lake, Nebraska in 1998. In 2002, a Peterson mark-recapture population estimate on northern pike revealed density and standing stock (i.e., biomass) estimates of 35.8 fish/ha (95% confidence interval= + 8.8) and 22.0 kg/ha (95% confidence interval= + 5.4), respectively. Consequently, West Long Lake was sampled in 2002 to compare relative abundance, size structure, and growth of bluegill Lepomis macrochirus, largemouth bass Micropterus salmoides, and yellow perch Perca flavescens prior to (1998) and after (2002) the establishment of a high-density northern pike population. Bluegill, largemouth bass, and yellow perch relative abundances were significantly lower in 2002 than 1998. Similarly, size structure of all three species was significantly different between years. Size structure declined for both bluegill and yellow perch, and increased for largemouth bass. Growth was significantly higher for bluegill, largemouth bass, and yellow perch in 2002 than 1998. While the fish community changes were expected, they occurred in a relatively short time period (i.e., 4 years).