Lake Fisheries Research Articles

Dependence of Water Quality and Fish Habitat on Lake Morphometry and Meteorology

The dependence of lake water temperatures, dissolved oxygen concentrations, and associated fish habitat characteristics on weather parameters and lake morphometry has been quantified from the output of verified water quality models. The models were applied to 27 Minnesota lake classes. Lake survey data for 3,002 lakes in the Minnesota Lakes Fisheries Database were used as a basis for the classification. The one-dimensional, deterministic, process-based water quality models used 25 years of daily meteorological data (1955–79) as input. The simulated characteristics of daily water temperatures, dissolved oxygen concentrations, and fish habitat during the open water season are correlated selectively with lake surface area, maximum depth, Secchi depth, annual normal air temperature, and saturated dissolved oxygen concentration. Annual normal air temperature and lake geometry ratio (the fourth root of lake surface area \iA\i\ds divided by the maximum lake depth \iH\dm\da\dx; \iA\i\ds\u0\u.²\u5/\iH\dm\da\dx) were found to be good predictors for simulated daily normal (25-year average) surface water temperatures, water temperatures near lake sediments, and volume-averaged water temperatures. Saturated dissolved oxygen concentration evaluated at maximum daily normal surface water temperature and lake geometry ratio were found to be good predictors for simulated daily normal surface and volume-averaged dissolved oxygen concentrations. Lakes with geometry ratios \iA\i\ds\u0\u.²\u5/\iH\dm\da\dx > 8 are well mixed, have high dissolved oxygen concentrations, and good fish habitat as long as the upper good growth water temperature limit is not exceeded. Lakes with geometry ratios \iA\i\ds\u0\u.²\u5/\iH\dm\da\dx <2 are seasonally stratified, have low dissolved oxygen concentrations near the bottom in summer, and only a fraction of their total lake volume available for good growth of fishes. Empirical formulas for indicators of lake water temperatures, dissolved oxygen, and associated fish habitat as functions of weather and morphometric lake parameters are formulated from the simulation results.

Factors effecting the demand for recreational fishing opportunities in Finnish lakes during the 1980s

Recreational fishing is one of the most popular leisure activities in Finland and an essential factor in the exploitation of Finnish lake fisheries resources. Fisheries resources are under private control, with a functioning market of fishing licences. In spite of this, empirical studies concerning the factors affecting the recreational fishery market are rare. During the years 1974–1991, which precede and follow the Finnish fisheries law reform of 1983, a total of 1584 sites were put on the market. In this study empirical single equation demand models were specified and estimated. Demand was measured by participation rate, i.e. by the total number of recreational fishermen and fishing days. By linear regression analysis models were found which explained up to 58–65% of the demand for recreational fishing. The results suggest that the average annual price index (FIM 25/a in 1991) for recreational fishing was so low that it did not affect the market behaviour of recreational fishermen. Neither was the pricing of recreational fishing licences related to the characteristics of fishing sites. The pricing policy seems to be rather a function of social values than economic forces and consequently provides only weak signals for creating improvements in recreational fishing opportunities.

Reply - Estimation of selection differentials from fish scales: a step towards evaluating genetic alteration of fish size in exploited populations

We developed a model to predict genetic response to selection imposed by a size-selective fishery. Use of our model provides estimates of selection as a function of heritability and overall selection differential imposed against a size-related trait, length of a scale radius from the focus to a given annulus (radius n). Selection differentials were estimated using data from the walleye (Stizostedion vitreum) fishery in Red Lakes, Minnesota. Overall selection differentials, incorporating selection differentials estimated by age and sex, and weighted by the contribution to spawning, were negative for the 1955 spawning population and positive for that of 1958. Directions of selection differentials, estimated by age and sex, generally corresponded to expected directions of selection based on the shape of the gillnet selectivity curve for walleye, suggesting that scale radii are useful for estimating selection against size traits. Results indicated that selective effects of gear may be surprisingly complex and...

Changing Economic Problems for Women in the Nile Perch Fishing Communities on Lake Victoria

Large-scale changes in the ecology of Lake Victoria have had a number of implications for the women in riparian households. It has proven difficult for them to take advantage of the economic opportunities that have arisen while their access to the lake fisheries has been dimin ished. This article reviews these changes at the levels of the lake, the community and the household. Fish-related economic activities are par ticularly important for women who are heads of households. These activ ities also afford married women greater independence than other activi ties. Women are responding to changes in access to the lake by working together at a community level.

Survival of vendace (Coregonus albula) escaping from a trawl cod end

Many young (0 group) vendace (Coregonus albula) are thought to die after passing through trawl cod ends during commercial vendace fishery in Finnish lakes. Survival of 2- to 4-month-old vendace (5–10 cm) after escaping from a 24-mm square mesh trawl cod end was therefore studied in Lake Puulavesi, Finland, during July–August 1993. Escapees were collected in a hooped netting cage that was released from the cod end after the tow, closed, and left at the depth of capture for 3–7 days. The data consist of 59 cagings. On average, 50% of the escaped vendace died, although mortality varied considerably. Most mortality occurred during the first day after escaping. Hauls conducted in the late evening and at night were accompanied by the highest mortality (60–80%). Mortality was 30–40% in the afternoon and early evening hauls. Generally, higher mortality was observed in August than in July. Comparisons with caged fish caught by a purse seine suggested that the experimental procedure did not substantially contribute to the observed total mortality of escapees. Scale loss and exhaustion experienced by vendace during trawl capture may have caused the rapid death of escapees through loss of osmoregulatory control.

Validation of a fish habitat model for lakes

Water temperatures and dissolved oxygen concentrations in 27 classes of lakes have been hindcast by simulation models and related to presence of coldwater, coolwater, and warmwater fishes in 3002 Minnesota lakes. A one-dimensional, dynamic water quality model driven by 25 years of daily weather data was used to model water temperature and dissolved oxygen profiles of these lakes. Fish presence data were available for these lakes from the Minnesota Lake Fisheries Data Base. Water temperature and dissolved oxygen criteria derived from a very large United States Environmental Protection Agency fish-temperature database and dissolved oxygen observations were used to define and link simulated water temperatures and dissolved oxygen conditions to suitability of habitats for coldwater, coolwater, and warmwater fish assemblages. Good agreement was found between fish presence and numerical simulations of fish habitat defined by water temperatures and dissolved oxygen concentrations. Generally water temperature and DO are good indicators of suitable fish habitat.

Fishery and Environmental Managers’ Attitudes About and Support For Lake Trout Rehabilitation in the Great Lakes

An ecosystem approach to Great Lakes lake trout rehabilitation requires explicit consideration of all stakeholders. Fishery and environmental resource managers are stakeholders whose views are critical to adopting and implementing lake trout rehabilitation program objectives.We used a self-administered mail questionnaire to census 919 Great Lakes fishery and environmental managers to (1) characterize the beliefs and attitudes of Great Lakes managers toward fishery management goals and lake trout rehabilitation; and (2) compare these variables based on level of government (provincial/state vs. federal), type of job responsibility (environmental management vs. fishery management), and, for fisheries agencies, country (Canada vs. United States). Provincial/state fishery managers expressed stronger support for artificial vs. natural systems, for utilitarian vs. ecological goals, and for placing relatively greater emphasis on anglers and economic benefits compared to federal fishery managers. Environmental managers assigned higher priority to goals associated with reestablishing native species, and lower priority to goals associated with satisfying anglers than did their fishery management counterparts. Differences observed for Canadian vs. U.S. fishery managers were similar to those between environmental vs. fishery managers. In addition, Canadian fishery managers tended to have a broader view of which groups were important stakeholders in lake trout management, placing less relative emphasis on anglers and more on other citizens in the Great Lakes Basin and on nonconsumptive fishery users. The challenge for the future of ecosystem management is to either recognize and accept these differences and work within their bounds, or to work to change the beliefs held by various stakeholders related to lake trout rehabilitation support or opposition.

Progress Toward Lake Trout Restoration in Lake Michigan

Progress toward lake trout restoration in Lake Michigan is described through 1993. Extinction of the native lake trout fishery by sea lamprey predation, augmented by exploitation and habitat destruction, resulted in an extensive stocking program of hatchery-reared lake trout that began in 1965. Sea lamprey abundance was effectively controlled using selective chemical toxicants. The initial stocking produced a measurable wild year class of lake trout by 1976 in Grand Traverse Bay, but failed to continue probably due to excessive exploitation. The overall lack of successful reproduction lakewide by the late 1970s led to the development and implementation in 1985 of a focused inter-agency lakewide restoration plan by a technical committee created through the Lake Committee structure of the Great Lakes Fishery Commission. Strategies implemented in 1985 by the plan included setting a 40% total mortality goal lakewide, creating two large refuges designed to encompass historically the most productive spawning habitat and protect trout stocked over their home range, evaluating several lake trout strains, and setting stocking priorities throughout the lake. Target levels for stocking in the 1985 Plan have never been reached, and are much less than the estimated lakewide recruitment of yearlings by the native lake trout stocks. Since 1985, over 90% of the available lake trout have been stocked over the best spawning habitat, and colonization of the historically productive offshore reefs has occurred. Concentrations of spawning lake trout large enough for successful reproduction, based on observations of successful hatchery and wild stocks, have developed at specific reefs. Continued lack of recruitment at these specific sites suggests that something other than stotk abundance has limited success. Poor survival of lake trout eggs, assumed to be related to contaminant burden, occurred in the late 1970s and early 1980s, but survival has since increased to equal survival in the hatchery. A recent increase in lamprey wounding rates in northern Lake Michigan appears to be related to the uncontrolled build-up of lampreys in the St. Marys River a tributary of Lake Huron. If left uncontrolled, further progress toward restoration in the Northern Refuge may be limited.

Lake Sturgeon Waters and Fisheries in New York State

Historic and contemporary records of lake sturgeon ( Acipenser fulvescens) occurrences in new York State have been assembled in this report to assist in planning and prioritizing the areas for restoration. This has become important because information about this threatened species is not easily assembled nor easily retrieved from the few remaining fishermen. Lake sturgeon were identified in 17 waters of New York State in the Great Lakes drainage including Lakes Erie, Ontario, Champlain, and the Niagara and St. Lawrence rivers. Two other rivers in the Laurentain Great Lakes drainage had self-sustaining populations, five others historically supported spawning runs, and five other waters had historical records of use or relict populations. Lake Erie provided the largest historic fishery for lake sturgeon in New York State (1,678 tonne reported in 1885) followed by Lake Ontario (292 tonne reported in 1890). All the major waters (the first five identified above) had large harvests, and two tributaries to the St. Lawrence River, the Grasse and Oswegatchie rivers, also provided commercial harvests. The Great Lakes fisheries were reduced to abandonment by the 1940s and the remaining ones were discontinued by the 1960s. Currently, lake sturgeon are self-sustaining at very low levels in the upper Niagara, St. Lawrence, and the Grasse rivers. The fish is protected from harvest in all areas but one.

Exotic Species and the Integrity of the Great Lakes

Edward L. Mills is a senior research associate in the Department of Natural Resources, Cornell University Biological Field Station, Bridgeport, NY 13030. Joseph H. Leach is a senior scientist at the Ontario Ministry of Natural Resources, Lake Erie Fisheries Station, Wheatly, Ontario, Canada NOP 2PO. James T. Carlton is a professor of marine sciences and the director of the Maritime Studies Program, Williams College-Mystic Seaport, Mystic, CT 06355, and Carol L. Secor is a graduate student in the Department of Biological Sciences, University of South Carolina, Columbia, SC 29208. Both Mills and Leach have served on a special task force on exotics for the Great Lakes Fishery Commission. Carlton's research examines the global movement of exotic species resulting from ship ballast introductions. ?1994 American Institute of Biological Sciences. Cumulative effects of

Estimation of Selection Differentials from Fish Scales: A Step Towards Evaluating Genetic Alteration of Fish Size in Exploited Populations

We developed a model to predict genetic response to selection imposed by a size-selective fishery. Use of our model provides estimates of selection as a function of heritability and overall selection differential imposed against a size-related trait, length of a scale radius from the focus to a given annulus (radius n). Selection differentials were estimated using data from the walleye (Stizostedion vitreum) fishery in Red Lakes, Minnesota. Overall selection differentials, incorporating selection differentials estimated by age and sex, and weighted by the contribution to spawning, were negative for the 1955 spawning population and positive for that of 1958. Directions of selection differentials, estimated by age and sex, generally corresponded to expected directions of selection based on the shape of the gillnet selectivity curve for walleye, suggesting that scale radii are useful for estimating selection against size traits. Results indicated that selective effects of gear may be surprisingly complex and population characteristics must be well understood before changes in fishery management are considered. We suggest that measurement of overall selection differentials alone may provide a useful management tool for indicating genetic risks of selective fisheries.

Management of inland fisheries in shallow eutrophic, mesotrophic and oligotrophic lakes in China

Optimizing fish yields in natural waters has long been the primary goal of lake management in China. Three different approaches that are used to increase fish yields are illustrated with reference ...

Motivations and Satisfactions of Lake Ontario Boating Salmonid Anglers

Declines in populations of forage fish are leading fisheries management agencies to predict declining growth and survivorship of some Lake Ontario salmonids in coming years. These expectations have stimulated additional interest in research that can help managers predict how changes in fish populations or other fishing conditions may influence participation in the open lake fishery. Managers need additional understanding of angler motivations and satisfactions to effectively predict rates of fishing participation. We utilized a study of Lake Ontario salmonid anglers to test hypotheses about the relative importance of catch-related motivations and satisfactions within two angler subgroups (fishing tournament and salmon snagging participants) and among anglers at two levels of personal investment (i.e., high and low). Anglers were identified through a randomized sample of boat registrants in five New York State counties bordering Lake Ontario. Data on motivations and satisfactions were gathered through a self-administered mail-back questionnaire. Tournament anglers, salmon snaggers, and highly invested anglers were found to hold a range of motivations and satisfactions. Nevertheless, results also led to acceptance of our hypotheses that tournament anglers, salmon snaggers, and highly invested anglers all place high personal importance on catch-related motivations and satisfactions. Based on these results it is reasonable to expect some decrease in fishing participation by these angler subgroups if fish size or abundance decreases. Findings related to highly invested anglers are particularly noteworthy, given the fact that this group accounts for the majority of angler days and angler expenditures on Lake Ontario.

Monitoring midlake water temperature in southern Lake Michigan for climate change studies

Recent studies of potential climatic change on Great Lakes fisheries (e.g. Meisner , 1987; Magnuson , 1990; Regieret al., 1990) and our general ignorance of the natural variability of the basic physical properties of the Great Lakes (McCormick, 1990) have demonstrated the need for a long-term observation program which is representative of the lake-wide environment. In April 1990 a site was established in Lake Michigan to continuously monitor the offshore thermal structure and vertical velocity profile. The site is located near the center of the lake's southern basin in 160 m of water. Temperature is measured at 16 depths (winter) to 28 depths (summer), and the horizontal velocity components are measured at 5 levels which allows us to characterize the offshore environment with high temporal resolution. The goals of this effort are to provide basic physical measurements to better describe the flow of energy through the lake ecosystem and to provide a basis against which future change can be better gauged.

Water Level Regulations and Fisheries in Rainy Lake and the Namakan Reservoir

The difference between the yearly maximum and minimum water levels (YMXR) is an index of lake dynamics: shoals are exposed and inundated, nutrients are oxidized and reduced, and the diversity and density of the aquatic plant community are affected. Shoals and emergent macrophytes provide spawning habitat for fish. The 5-yr moving variance of YMXR fluctuates regularly with periods of about 11.2 yr (periodicity of sunspot cycles). This reflects the effects of within-year consecutive periods of storms and dry spells. Water level regulations resulted in changes in both amplitudes and frequencies of YMXR compared with natural fluctuations. We established links between fluctuations in YMXR and fluctuations in fish populations. Water level regulations, through their effects on YMXR, corresponded to changes in interspecific interactions on Rainy Lake and the Namakan Reservoir. In both, walleye's (Stizostedion vitreum) fluctuations were synchronized with both those of lake whitefish (Coregonus clupeaformis) and northern pike (Esox lucius) more than those of either species with the other two. On the Namakan Reservoir, YMXR fluctuations were accentuated by water level regulation; on Rainy Lake, they were dampened. Regulations should consider frequencies and amplitudes of changes in water level and their effect on fish populations.

Fisheries and the evolution of resource management on the lower Amazon floodplain

Traditionally, the ribeirinhoeconomy has been based on strategies of multiple resource use including agriculture, fishing, and small-scale stock raising. In the last two decades though, ribeirinhostrategies of resource management have undergone major changes due to the decline of jute production (the principal cash crop), and the intensification of the commercial fisheries. As a result of these trends, there has been a shift of ribeirinholabor from agriculture to commercial fishing. Today, the diversity which once characterized ribeirinhosubsistence strategies is disappearing, and fishing has become the primary economic activity for the great majority of varzeafamilies. As pressure on varzeafisheries has increased, ribeirinhocommunities have attempted to assert control over local varzealakes and exclude fishermen from outside the community. In a number of cases, ribeirinhocommunities have closed lakes to outsiders and established informal lake reserves under local community management. These lake reserves are a promising strategy for managing lake fisheries on a sustainable basis.

An Economic Injury Level Approach to Establishing the Intensity of Sea Lamprey Control in the Great Lakes

Abstract Tightening budgetary constraints have forced the Great Lakes Fishery Commission to reevaluate the effectiveness of its program to control sea lamprey Petromyzon marinus in the Great Lakes. One rational option requires setting target levels of control for each of the Great Lakes. This paper is an analysis of an economic injury level approach to setting a target level of control for Lake Ontario. Using a decision support system for the integrated management of sea lamprey in Lake Ontario, we show that calculation of optimal levels of adult sea lamprey is feasible, We calculate that the economic injury level of adult sea lampreys in Lake Ontario is 30,000 fish (95% confidence interval, 16,400–43,600). We predict that this level of abundance could be achieved with an annual application of 9,400 kg of the lampricide TFM. Relative to this standard, Lake Ontario is currently undertreated for sea lamprey control. Implementation of this approach to setting target levels will require further work on estima...

Disputed Waters: Native Americans and the Great Lakes Fishery, Robert Doherty, Lexington, KY: University of Kentucky Press, 1990, viii + 172 pp.

Disputed Waters: Native Americans and the Great Lakes Fishery, Robert Doherty, Lexington, KY: University of Kentucky Press, 1990, viii + 172 pp.

Species richness, composition, and abundance of fish larvae and juveniles inhabiting natural and developed shorelines of a glacial Iowa lake

Young-of-the-year fish communities in naturally vegetated sites were compared with those inhabiting nearby sites where lakeshore development (i.e., construction of homes, boat docks, and beaches) reduced nearshore macrophyte species richness and abundance. The study was conducted in a 2266 hectare, glacially formed, eutrophic lake in northwestern Iowa during the summers of 1987 and 1988. Study sites were divided into 3 depth zones, and fishes were collected by seining (0–1 m), plexiglass traps (1–2 m), and a nonclosing Tucker trawl (2–3 m). Species richness and total fish abundance were consistently greater in natural than in developed sites in both nearshore (0–1 m) and intermediate (1–2 m) depth zones, but differed little between natural and developed sites in the offshore (2–3 m) depth zone. Nearly 50% of the species sampled, including yellow perch Perca flavescens and bluegill Lepomis macrochirus, inhabited limnetic areas as larvae before migrating inshore as juveniles. Eighteen of the 20 fish species collected as juveniles were in greater abundance in natural than in developed sites. Smallmouth bass Micropterus dolomieui was the only game species consistently found in equal or greater abundance in developed sites. Within all sites, juvenile fishes were generally most abundant where macrophyte abundance and species richness were greatest. Findings from this study demonstrate the importance of nearshore aquatic vegetation to fishes during their first summer of life. If nearshore vegetation beds of lakes continue to be regarded as a nuisance and indiscriminately removed, important fish nursery habitat will be lost. The short-term result will likely be reduced year-class strength of vegetation-dependent species. More importantly, the long-term effects will be changes in fish community richness and composition which will, in turn, alter the lake's fishery.

The Bioeconomics of Resource Rehabilitation: A Commercial-Sport Analysis for a Great Lakes Fishery

We construct a fishery model which simulates: (a) stochastic population fluctuations and (b) harvest shifts between commercial and sport user groups. This model then assesses, for both commercial and sport harvesters, the bioeconomic impact of an ongoing rehabilitation plan for the yellow perch fishery of Green Bay, Lake Michigan. Overall economic gains from this plan are positive, with sport anglers reaping sizeable benefits, while commercial harvesters lose moderately. Using probing exercises which approximate economic optimization, the efficient allocation of harvest between sport and commercial user groups is also explored. Uncertainties about sport effort levels greatly influence this optimal allocation.