Muskellunge Esox Masquinongy Research Articles

Turbidity‐induced changes in emergent effects of multiple predators with different foraging strategies

Abstract – In natural systems, prey frequently interact with multiple predators and the outcome often cannot be predicted by summing the effects of individual predator species. Multiple predator interactions can create emergent effects for prey, but how those change across environmental gradients is poorly understood. Turbidity is an environmental factor in aquatic systems that may influence multiple predator effects on prey. Interactions between a cruising predator (largemouth bass Micropterus salmoides) and an ambush predator (muskellunge Esox masquinongy) and their combination foraging on a shared prey (bluegill Lepomis macrochirus) were examined across a turbidity gradient. Turbidity modified multiple predator effects on prey. In clear water, combined predators consumed in total more prey than expected from individual predator treatments, suggesting risk enhancement for prey. In moderately turbid water, the predators consumed fewer prey together than expected, suggesting a risk reduction for prey. At high turbidity, there were no apparent emergent effects; however, the cruising predator consumed more prey than the ambush predator, suggesting an advantage for this predator. Understanding multiple predator traits across a gradient of turbidity increases our understanding of how complex natural systems function.

Factors Affecting Recruitment of Age‐0 Muskellunge in Escanaba Lake, Wisconsin, 1987–2006

AbstractWe modeled variation in recruitment (R) of age‐0 muskellunge Esox masquinongy to identify factors influencing their abundance in Escanaba Lake, Wisconsin. Muskellunge R declined over the study period and ranged from 0.00 to 1.85 age‐0 fish/km of shoreline (mean = 0.42 age‐0 fish/km of shoreline). A Ricker stock–recruitment model determined that the following factors explained 88% of the variation in annual R of age‐0 muskellunge between 1987 and 2006: abundance and age structure of the adult muskellunge population, abundance of bluntnose minnow Pimephales notatus, abundance of age‐3 and older (age‐3+) walleyes Sander vitreus, abundance of age‐0 white suckers Catostomus commersonii, and coefficient of variation (CV) of May water temperatures. Abundance of adult muskellunge (≥76.2 cm total length) accounted for only 1% of the variation in R and showed no significant relationship with R. Abundance of bluntnose minnow improved the model fit to 40% of the variation in R and indicated that higher R was achieved with greater numbers of bluntnose minnow. The average age of adult muskellunge further improved the model fit to 59% of the variation in R, suggesting that R increased when more young adults were present in the population. The abundance of age‐3+ walleyes enhanced the model fit to 69% of the variation in R and indicated that greater R occurred with high numbers of walleyes. The abundance of age‐0 white suckers improved the model to explain 77% of the variation in R and indicated that more recruits occurred when numbers of age‐0 white suckers were low. Finally, the CV of May water temperatures further improved the model to explain 88% of the variation in R and signified that lower variability in May water temperatures was beneficial to recruitment success. We interpret the model results to mean that muskellunge R in Escanaba Lake is regulated by the reproductive potential of the adult muskellunge population, forage availability, variation in May water temperatures, and other community dynamics.

Short‐ and Long‐Term Evaluation of Passive Integrated Transponder and Visible Implant Elastomer Tag Performance in Muskellunge

AbstractFisheries professionals charged with managing muskellunge Esox masquinongy frequently seek population information that requires the ability to identify cohorts as well as individuals; hence, reliable tagging methods are needed. Our approach was to simultaneously assess multiple marking techniques on different life stages of muskellunge over short and long time scales. We evaluated the short‐term detection of visible implant elastomer (VIE) and passive integrated transponder (PIT) tags in muskellunge fingerlings in experimental ponds. We compared survival (relative to that of control fish) and tag retention for two PIT tagging locations (the cheek and dorsal musculature) and one VIE location (the jaw). Overwinter survival did not differ between tagged and untagged fish (84–98%), but overwinter PIT tag retention was lower for the cheek (92%) than the dorsal musculature (100%). We also fin‐clipped and VIE‐tagged (jaw) 1,651 muskellunge fingerlings from 1997 to 2002 to evaluate long‐term tag retention in a broodstock lake. In addition, 125 adult muskellunge were captured and PIT‐tagged from 2003 to 2006. Muskellunge were sampled annually with trap nets and electrofishing during spring and fall. Only 2 VIE tags were detected in adults marked as fingerlings. The proportion of PIT‐tagged adults recaptured ranged from 52% to 84% during the sampling period. Our results indicate that both VIE and PIT tags are viable short‐term marks for muskellunge fingerlings, while PIT tags appear to be reliable long‐term tags when implanted in the dorsal musculature of adults.

Effects of Fin‐Clipping on the Foraging Behavior and Growth of Age‐0 Muskellunge

AbstractWe evaluated the effects of fin‐clipping on the foraging behavior and growth of age‐0 muskellunge Esox masquinongy. Fish were subjected to one of six fin‐clipping treatments (one or both pectoral and pelvic fins, all paired fins, and a nonclipped control) and allowed to forage on golden shiners Notemigonus crysoleucas in laboratory pools (1.7 m in diameter). Observations of foraging behavior showed that muskellunge required a similar number of stalks, follows, and strikes to capture prey regardless of fin clip. Capture efficiencies (56%) were also similar among treatments. In outdoor pools (1.5 m in diameter), the growth and food conversion efficiency of fin‐clipped muskellunge feeding on golden shiners over a 1‐month period did not differ from those of unclipped controls. Fin removal did not compromise foraging behaviors and growth for juvenile muskellunge foraging on moderately evasive prey, and fish showed immediate behavioral compensation.

Walleye and Muskellunge Movement in the Manitowish Chain of Lakes, Vilas County, Wisconsin

AbstractWe quantified within‐year and between‐year movement of walleyes Sander vitreus and muskellunge Esox masquinongy in the Manitowish Chain of 10 interconnected lakes in Vilas County, Wisconsin. Beginning in May 2004, we marked 7,427 walleyes (55–2,720 fish/lake) and 491 muskellunge (24–99 fish/lake) with T‐bar anchor tags and marked 33 walleyes and 36 muskellunge with radio tags. Tags were recaptured and recovered through October 2005 via fyke‐netting, electrofishing, angling, and spearing. Anchor tag loss averaged 2.9% for walleyes and 2.1% for muskellunge. Of 1,752 anchor‐tagged walleyes (19–555 fish/lake), 81% (54–90% per lake) were recovered in the same lake in which they were tagged. Of the 95 muskellunge tagged (1–18 fish/lake), 53% (0–100% per lake) were recovered in the same lake in which they were tagged. For radio‐tagged fish, 82% (27 of 33 fish) of walleyes and 50% (18 of 36 fish) of muskellunge were recovered in the same lake in which they were tagged. Of 1,153 anchor tag returns for walleyes (8–326 fish/tag group and 6–340 fish/lake) and 57 anchor‐tag returns for muskellunge (1–17 fish/tag group and 1–12 fish/lake), 76% of walleyes (37–98% per lake) and 45% of muskellunge (0–100% per lake) were found in the same lake in spring 2004 and spring 2005. Our results indicate that most walleyes remained in the same lake during the year of tagging and between years, whereas half of all muskellunge did not remain in the same lake during the tagging year or between years. We recommend that walleye angling and spearing fisheries be managed for individual lakes and that muskellunge fisheries be managed for the entire chain of lakes.

The Genetic Legacy of Stocking Muskellunge in a Northern Minnesota Lake

AbstractThe effects of stocked fish on native populations of the same species are poorly understood. During the 1960s‐1980s, the Minnesota Department of Natural Resources (MNDNR) stocked muskellunge Esox masquinongy derived from Shoepack Lake in the Hudson Bay drainage of northern Minnesota into Moose Lake in the Upper Mississippi River drainage. In the mid‐1980s, the MNDNR recognized that stocked Shoepack Lake‐strain fish (hereafter, Shoepack strain) were not attaining large sizes, and sources were switched statewide; subsequently, muskellunge from a Wisconsin hatchery were stocked once into Moose Lake. We used 14 microsatellite DNA markers to estimate the genetic contribution by each source population to muskellunge sampled in four different years from 1981 to 2004, and we evaluated the effects of Shoepack‐strain ancestry on fish size. Two samples in the 1980s had mostly fish with a single ancestry; thus, these fish were probably Shoepack‐strain fish stocked a few years earlier or native fish. By 2004, when most fish would have been naturally produced in the lake, contributions from all three source populations were detected, including admixed individuals from crosses among all ancestral sources. The estimated ancestry by source was 52% native Moose Lake ancestry, 29% Wisconsin strain, and 19% Shoepack strain, with 24% of the individuals having pure Moose Lake ancestry. Fish without Shoepack‐strain ancestry had a greater median length than did those with Shoepack‐strain ancestry and had a greater proportion of legal‐sized individuals (total length ≥ 1,016 mm) in the population. In contrast, Moose Lake and Wisconsin‐strain descendents were common among all sizes of fish. Management options include doing nothing, accepting that extensive introgression has already occurred, or manipulating the population by either stocking to dilute Shoepack‐strain ancestry or genetic screening to purge the population of Shoepack‐strain ancestry.

Novel Tools for Analyzing Proportional Size Distribution Index Data

AbstractProportional size distribution (PSD) indices are convenient measures for numerically summarizing size structure of fish populations. Several novel methods for analyzing PSD index data were examined as a means for potentially improving inferences of size structure: generalized linear mixed modeling, calculation of location quotients, and simultaneous construction of 100(1 − α)% confidence intervals for PSD indices through multinomial modeling. The methods are demonstrated using simulated and previously published PSD index data. Generalized linear mixed modeling was used to (1) conduct a model selection analysis of PSD index data relative to a change in harvest regulation for walleyes Sander vitreus, (2) partition the variance of PSD index data among spatial, temporal, and environmental attributes, and (3) nonlinearly relate PSD data to adult density for largemouth bass Micropterus salmoides. The location quotient, which is an index for describing relative concentration of proportional data, was used to describe spatial and temporal localization of largemouth bass and walleye PSD index data. Finally, a modified method of constructing simultaneous 100(1 − α)% confidence intervals for multinomial proportions was used to produce 95% confidence intervals for traditional and incremental PSD indices based on length frequency data from muskellunge Esox masquinongy. The approaches described herein can assist fishery biologists in size structure assessments of fish populations and ultimately aid in cost‐effective fisheries management.

Ecology and management of northern pike in Wisconsin

Northern pike (pike) Esox lucius Linnaeus are broadly distributed across Wisconsin and provide an important sport fishery for anglers. Historical management has included use of angling regulations, stocking, and protection of critical habitat areas. Pike management is often a lower priority in comparison to more intensively managed species such as muskellunge Esox masquinongy Mitchell and walleye Sander vitreous. Pike provide angling opportunities year around, with higher catch rates and live release during open water, and higher harvest rates during winter. While length of pike caught during the two seasons is generally similar, there is some evidence that larger fish are caught during winter months. Results from minimum length limit changes implemented in 1995 have been equivocal and warrant further monitoring using standardized protocol to better determine effects on populations. If natural recruitment is not limited, pike populations can reach high densities and stunting can result. Loss of nearshore habitat has continued at an increased rate as more lake homes are built and shorelines graded, and altered with riprap, sand blankets, or sea walls. If natural recruitment is lacking, fry or fingerling stocking sustains or rehabilitates populations. Most pike stocking occurs in the southeastern portion of the state where habitat loss has been extensive. Stocking in other areas is largely to re-establish populations following a chemical reclamation or from winterkill. Future management needs to establish sampling protocols to ensure comparable data on both a temporal and a spatial scale. Long-term monitoring with these methods is essential to help determine effects of various factors (e.g., regulations, habitat loss) on populations.

Survival, Growth, and Tag Retention in Age‐0 Muskellunge Implanted with Passive Integrated Transponders

AbstractMark–recapture studies are an important component of fisheries research and management. Underlying assumptions of such studies include minimal tag loss and negligible effects on the behavior, fitness, and survival of tagged individuals. Passive integrated transponder (PIT) tags are becoming increasingly commonplace, largely because of their small size, ease of implantation, longevity, and reportedly high rates of retention. We evaluated tag retention and survival and growth effects on age‐0 muskellunge Esox masquinongy marked with PIT tags at two implantation sites, the peritoneal cavity and the dorsal musculature, during overwinter trials in Illinois and Wisconsin. For both trials, no significant differences in survival (88.0–89.8%), relative daily growth (0.0006–0.00062 mm·mm−1·d−1), or tag retention (99.5–99.8%) were observed among the two implantation groups and a control group. Survival and tag retention were also similar between trials. Our findings suggest that PIT tags implanted either in the peritoneal cavity or the dorsal musculature are acceptable for use in marking age‐0 muskellunge.

Mortality event in freshwater drum Aplodinotus grunniens from Lake Ontario, Canada, associated with viral haemorrhagic septicemia virus, Type IV

A mortality event primarily affecting freshwater drum Aplodinotus grunniens was noted during April and May 2005 in the Bay of Quinte, Lake Ontario, Canada. A conservative estimate of the number of dead drum was approximately 100 metric tonnes. Large numbers of dead round goby Neogobius melanostomus were also seen, as well as a few muskellunge Esox masquinongy. In the drum, there was a consistent histological pattern of variably severe panvasculitis, a necrotising myocarditis, meningoencephalitis and a segmental enteritis. Moderate numbers of bullet-shaped viral particles consistent with a rhabdovirus were identified by transmission electron microscopy (TEM) in affected heart tissue. Following primary isolation from pooled tissues on fathead minnow (FHM) cells, a morphologically similar virus, approximately 165 x 60 nm in size, was visualised. Identification of the isolate as viral haemorrhagic septicemia virus (VHSV) was confirmed by enzyme immunoassay and by polymerase chain reaction. An appropriately sized product (468 bp) of the G-glycoprotein gene (nucleotides [nt] 340 to 807) was generated with RNA extracted from FHM cell supernatant. Analysis of a 360 nt partial glycoprotein gene sequence (nt 360 to 720) indicated a 96.4 to 97.2% nucleotide identity with known strains of North American (NA) VHSV. Analysis using Neighbour-joining distance methods assigned the isolate to the same lineage as the NA and Japanese isolates (Genogroup IV). However, there was sufficient sequence divergence from known NA VHSV isolates to suggest that this isolate may represent a distinct subgroup. The effects of ongoing mortality in freshwater drum and in multiple species during spring 2006 suggest that this newly recognised virus in the Great Lakes will have continued impact in the near future.

Population Dynamics and Angler Exploitation of the Unique Muskellunge Population in Shoepack Lake, Voyageurs National Park, Minnesota

AbstractA unique population of muskellunge Esox masquinongy inhabits Shoepack Lake in Voyageurs National Park, Minnesota. Little is known about its status, dynamics, and angler exploitation, and there is concern for the long‐term viability of this population. We used intensive sampling and mark–recapture methods to quantify abundance, survival, growth, condition, age at maturity and fecundity and angler surveys to quantify angler pressure, catch rates, and exploitation. During our study, heavy rain washed out a dam constructed by beavers Castor canadensis which regulates the water level at the lake outlet, resulting in a nearly 50% reduction in surface area. We estimated a population size of 1,120 adult fish at the beginning of the study. No immediate reduction in population size was detected in response to the loss of lake area, although there was a gradual, but significant, decline in population size over the 2‐year study. Adults grew less than 50 mm per year, and relative weight (W r) averaged roughly 80. Anglers were successful in catching, on average, two fish during a full day of angling, but harvest was negligible. Shoepack Lake muskellunge exhibit much slower growth rates and lower condition, but much higher densities and angler catch per unit effort (CPUE), than other muskellunge populations. The unique nature, limited distribution, and location of this population in a national park require special consideration for management. The results of this study provide the basis for assessing the long‐term viability of the Shoepack Lake muskellunge population through simulations of long‐term population dynamics and genetically effective population size.

Simulated Effects of Recruitment Variability, Exploitation, and Reduced Habitat Area on the Muskellunge Population in Shoepack Lake, Voyageurs National Park, Minnesota

AbstractThe genetically unique population of muskellunge Esox masquinongy inhabiting Shoepack Lake in Voyageurs National Park, Minnesota, is potentially at risk for loss of genetic variability and long‐term viability. Shoepack Lake has been subject to dramatic surface area changes from the construction of an outlet dam by beavers Castor canadensis and its subsequent failure. We simulated the long‐term dynamics of this population in response to recruitment variation, increased exploitation, and reduced habitat area. We then estimated the effective population size of the simulated population and evaluated potential threats to long‐term viability, based on which we recommend management actions to help preserve the long‐term viability of the population. Simulations based on the population size and habitat area at the beginning of a companion study resulted in an effective population size that was generally above the threshold level for risk of loss of genetic variability, except when fishing mortality was increased. Simulations based on the reduced habitat area after the beaver dam failure and our assumption of a proportional reduction in population size resulted in an effective population size that was generally below the threshold level for risk of loss of genetic variability. Our results identified two potential threats to the long‐term viability of the Shoepack Lake muskellunge population, reduction in habitat area and exploitation. Increased exploitation can be prevented through traditional fishery management approaches such as the adoption of no‐kill, barbless hook, and limited entry regulations. Maintenance of the greatest possible habitat area and prevention of future habitat area reductions will require maintenance of the outlet dam built by beavers. Our study should enhance the long‐term viability of the Shoepack Lake muskellunge population and illustrates a useful approach for other unique populations.

Effect of Discharge on Daytime Habitat Use and Selection by Muskellunge in the New River, Virginia

AbstractFor several fish species, increased river discharge has been linked to behavioral changes, including movement towards particular habitats. From 2000 to 2003, we used radiotelemetry to monitor habitat use by 42 muskellunge Esox masquinongy within a 17‐km reach of the New River, Virginia; to evaluate habitat selection; and to determine whether habitat use and selection were affected by discharge. Water depth, occurrence of aquatic vegetation, substrate type, and distance to riverbanks within the study reach were mapped with hydroacoustic and Global Positioning System technologies. Real‐time discharge measurements from an upstream U.S. Geological Survey stream gauge were used to classify fish locations into those made during periods of reduced (<75 m3/s) or increased (>75 m3/s) discharge. Seasonal habitat selection models for the different discharge levels were created using logistic regression. Differences in logistic regression coefficients between models were tested with multivariate chi‐square tests and Bonferroni‐corrected pairwise comparisons. Meta‐analytic averaging of Pearson's correlation coefficients was used to determine the overall effect size of discharge on habitat use by muskellunge. Overall, muskellunge exhibited a positive selection for deeper habitats; however, discharge was found to significantly affect both habitat use and selection. Habitat use was consistent with the hypothesis that fish moved to shallower habitats (both summer and winter) located closer to riverbanks (winter only) during periods of increased discharge. In terms of habitat selection, selection strengths for variables such as water depth (summer and winter) and distance to shoreline (winter only) generally weakened during periods of increased discharge, indicating that habitat use became more proportionate to availability. Increased movement as a result of increased discharge has been theorized to potentially reduce winter survival of fish because of seasonal energetic limitations. Thus, indirect effects on fish from dam operating modes (e.g., hydropeaking) may be as important as direct effects when evaluating biotic implications of water release schedules.

Evaluation of temperature-selection differences among juvenile muskellunge originating from different latitudes

Genetic differences among muskellunge Esox masquinongy populations are related to residence in major river drainages, suggesting the existence of divergent stocks. By use of radio-telemetry we compared different seasonal and diel temperature selection in a southern Illinois reservoir for three geographically and genetically distinct stocks of age-2 muskellunge from throughout the latitudinal range of the species. Muskellunge from the Upper Mississippi River drainage were represented by the Leech Lake, Minnesota, population and the Ohio River drainage was represented by the Cave Run Lake, Kentucky, population. Progeny from North Spring Lake, Illinois, an interstock, or mixed-origin stock, were also evaluated. No differences in temperature selection were observed among stocks of juvenile muskellunge across seasons or diel periods. The seasonal mean temperatures of the water varied significantly—spring 21.7°C, summer 28.4°C, and fall 14.8°C, with an overall average temperature of 24.1°C, in agreement with previously published values obtained in laboratory trials. This lack of different temperature-selection patterns among stocks is in contrast with other life-history characteristics, for example growth, metabolism, and conversion efficiency, which have been shown to differ among populations and stocks.

Capture Efficiencies of Two Hook Types and Associated Injury and Mortality of Juvenile Muskellunge Angled with Live Baitfish

AbstractStrict harvest regulations and a strong catch‐and‐release ethic among recreational anglers of muskellunge Esox masquinongy have led to interest in developing strategies for reducing injury and mortality of released fish. With many anglers using live baitfish to capture muskellunge, the use of circle hooks may reduce deep hooking and hence mortality. We contrasted the performance of circle hooks and J‐style aberdeen hooks when capturing juvenile muskellunge with actively fished live baitfish. The J hooks performed better than circle hooks in terms of capture efficiency. The J hooks were more efficient at hooking muskellunge than were circle hooks, but landing efficiency was similar between the two types. Interestingly, injury was judged to be low regardless of hook type. Neither anatomical hooking location nor hooking depth differed significantly between fish captured on J and circle hooks. No fish were hooked in potentially lethal locations (e.g., gullet or eye) during the use of either hook type. Ease of hook removal did not differ between hook types, and hooks were generally categorized as easy to remove. Bleeding was considered minor and did not differ between hooks. We observed no initial or delayed mortality for fish captured on J or circle hooks. Given that J hooks have a higher muskellunge capture efficiency and that the use of circle hooks did not provide any compelling conservation benefits, anglers will probably continue to use J hooks and avoid circle hooks. Nonetheless, use of circle hooks could be advantageous for other fishing styles (e.g., still fishing, where baitfish are often swallowed), other species, or different sizes of muskellunge.

Expulsion of miniature radio transmitters along with eggs of muskellunge and northern pike––a new method for locating critical spawning habitat

Identification and protection of critical spawning habitat for muskellunge Esox masquinongy and northern pike Esox lucius is important for preserving the reproductive potential of both species. In this study, we implanted miniature radio transmitters through the oviduct into the egg masses of female muskellunge and northern pike just prior to spawning. This non-surgical procedure was a novel approach for identifying spawning sites when transmitters were expelled with the eggs during egg deposition. Preliminary studies in three lakes showed that muskellunge and northern pike deposited many of the transmitters in likely spawning habitat. An inability to find eggs limited our validation of this method, but nevertheless, a relatively high proportion (70%) of northern pike larger than 690 mm (27.2 inches) expelled transmitters in a previously known spawning area in Willow Lake, Minnesota. Shoreline vegetation in that area consisted primarily of sedges Carex spp., and the adjacent water was shallow with substrate consisting of large mats of water bulrush Scirpus subterminalis. A lower proportion (50%) of muskellunge expelled transmitters in Elk Lake, Minnesota. Water depth at likely spawning sites averaged 1.1 m (3.6 feet) and vegetative cover was variable, but Chara spp. was common to most sites. In Moose Lake, Minnesota, containing sympatric populations of muskellunge and northern pike, 60% of muskellunge and 90% of pike expelled transmitters. Chara spp. beds were the predominant substrate where transmitters were expelled in Moose Lake, but the two species deposited transmitters on deepwater bars (3.7–5.2 m) in addition to shallow near-shore habitat. These results suggest more flexibility in depths used for spawning than typically reported for muskellunge and northern pike.

Sectioned pelvic fin ray ageing of muskellungeEsox masquinongyfrom a Virginia river: comparisons among readers, with cleithrum estimates, and with tag–recapture growth data

Abstract The potential utility of pelvic fin rays as ageing structures was evaluated for southern US muskellungeEsox masquinongyMitchill populations by comparing age estimates among three readers and against cleithrum estimates, and by comparing observed length changes of tagged fish with changes predicted from growth equations based on pelvic fin ray age estimates. Mean coefficient of variation in age estimates among all readers and between the two readers with prior ageing experience was 17.8% and 5.6%, respectively. Exact and within 1‐year agreement rates between pelvic fin rays and cleithra were 76% and 100%, respectively. Mean (± 2 SE) estimated absolute error between observed and predicted length changes for 13 tagged muskellunge was 30 ± 14 mm. This evaluation indicated that pelvic fin rays may prove to be a useful, non‐lethal method for ageing muskellunge in southern US waters. Validation studies are still needed to ensure that growth rings form consistently throughout fish's life span.

Retention of Coded Wire Tags by Age-0 Muskellunge

ABSTRACT Retention of coded wire tags implanted in three different locations (right cheek, left cheek, and dorsal fin) in age-0 muskellunge (Esox masquinongy) was monitored over 90 d. Survival over the course of the study was compared among the three groups and an untagged control group. Fish were held in 2082 L circular tanks and checked for tags 1, 3, 7, 30, 60, and 90 d post-tagging. Tag retention 1 d post-tagging was lowest in the left cheek (86%) and was different from both the right cheek and dorsal fin groups (>98%). These differences appeared to be a result of tag placement technique rather than anatomical location. Retention for all groups did not change after 30 d post-tagging. Survival during the experiment period was 2 75% for all groups, and survival for all groups declined after 7 d post-tagging. No differences in survival rates among tagged and control groups were observed.

Social Aspects of Muskellunge Management in Wisconsin

Public opinion plays an important part in the successful development of a fisheries management plan. We used a mail questionnaire to survey 1,400 anglers who fish for muskellunge Esox masquinongy in Wisconsin. The survey included defined groups of muskellunge anglers separated by muskellunge club affiliation and geographic location and general anglers selected from a random sample of angler license sales. The survey questions were designed to obtain opinions regarding muskellunge fishery and trophy management in Wisconsin in terms of angling behaviors, regulation options, and perceived problems. All anglers generally preferred fishing with artificial lures and practiced the voluntary live release of legal-length muskellunge. Muskellunge anglers considered a trophy muskellunge to be at least 40 in long, with a preferred length of 50 in or longer. Muskellunge anglers also supported regulations for muskellunge that were based on a water's biological potential, along with increased restrictions on regulations such as minimum length limits. General anglers were less supportive of restrictive regulations and were more likely to keep a legal muskellunge for consumptive purposes. The greatest perceived problems with muskellunge fishing were Native American spearing and conflicts with users of speedboats and jet skis. Opinion surveys such as this can help in formulating management strategies that satisfy most anglers within biological limits.

Statistical Properties of the Relative Weight (Wr) Index and an Alternative Procedure for TestingWrDifferences between Groups

Abstract Fishery managers commonly test for differences in relative weight (W r ) between or within populations using standard parametric or nonparametric statistical tests. However, the statistical properties of the W r index have not been studied; consequently, we cannot be certain that W r data satisfy the theoretical assumptions upon which many standard tests are based. In particular, we do not know if W r data are independent and identically distributed (i.i.d.), which is an assumption made by most standard statistical tests and which can increase the type I error rate of a statistical test when it is violated. We derived approximations to the expectation, variance, and covariance of the W r index using the Delta method and estimated these parameters with sample data for muskellunge Esox masquinongy, largemouth bass Micropterus salmoides, and black crappie Pomoxis nigromaculatus. Additionally, we devised a likelihood ratio test (R-test) that tests for differences in W r between groups and that does n...