David F. Clapp

Range, activity, and habitat of large, free-ranging brown trout in a Michigan Stream

Abstract Little is known about behavior patterns and habitat use of large (400+ mm total length) brown trout Salmo trutta. We used radio telemetry to monitor the movements of eight large (437–635 mm), free-ranging brown trout for up to 346 d. Total range of movement upstream and downstream varied from 370 m to 33,420 m. At some time during the year, six of the fish moved out of an area protected with no-kill fishing regulations, even though none of them were tagged and released closer than 2 km from its boundaries. However, four of five fish tracked during the height of the fishing season spent 87% of their time in the protected area. The fish appeared to have separate winter and summer ranges. Five of six fish tracked during autumn–winter moved upstream about 10 km to slower, deeper parts of the river between August and November, and remained there at least through the following April. The part of the river used as autumn–winter range was considered only marginal habitat for brown trout during summer due...

Biophysical Model of Larval Yellow Perch Advection and Settlement in Lake Michigan

ABSTRACT Potential for large-scale physical transport processes to affect recruitment of Lake Michigan yellow perch (Perca flavescens) was studied by examining the variation in larval distribution, growth rate, and settlement during June–August 1998–2003 using a 3D particle transport model linked with an individual-based bioenergetics growth model. In all years, virtual larvae were released nearshore in southwestern Lake Michigan, a known and important spawning region for yellow perch. For any given year, the same circulation pattern and water temperature either promoted or reduced yellow perch settlement depending on the consumption rates and settlement size chosen in the growth model. Increased consumption increased the number of settled larvae and expanded the total area where larvae settled, whereas increased settlement size reduced the number of settled larvae and reduced the overall settlement area. Interannual variability in circulation patterns and water temperature also resulted in contrasting larval settlement rates, settlement locations, and size of settlement areas between years. Model predictions were most consistent with field observations of age-0 yellow perch from Illinois and Michigan waters when settlement was assumed to occur at 50 mm. Moreover, our model suggests that larvae originating from southwestern Lake Michigan can recruit anywhere within the southern basin and even in the northern basin. Future model improvement will require information on the relative contribution of various sectors to the larval pool, their distribution with reference to the hydrodynamic landscape, the feeding and growth of yellow perch during their pelagic phase, and the size at transition to demersal stage.

Monitoring Round Goby (Neogobius melanostomus) Population Expansion in Eastern and Northern Lake Michigan

In the Great Lakes basin, round gobies (Neogobius melanostomus) were first reported from the St. Clair River in 1990. Reported here are the details of range extension and establishment of round gobies in eastern Lake Michigan at Grand Haven, Michigan and in northern Green Bay at Escanaba, Michigan. Round gobies were first collected in survey samples at Grand Haven in 1997 (0.0 to 0.5 fish per trawl hour). Catch rates increased in 1998 (1.5 to 3.0 fish/h) and 1999 (38.0 to 69.0 fish/h). Individuals collected by trawling (N = 207) ranged in total length from 18 to 94 mm. Round gobies were first collected in survey (trawl) samples at Escanaba in 1998 (7.5 fish/h; total length range 43 to 58 mm). Round gobies were also collected during 1999 in trawls at Muskegon and in gill nets at Grand Haven and Saugatuck. No round gobies were collected at five other eastern Lake Michigan ports sampled during this same time period (1995 to 1999). Numerous adult round gobies were captured by anglers at Grand Haven and Escanaba, indicating that these populations had been established for some time prior to being detected in survey sampling. Additional populations were verified from angler reports at Charlevoix (1998) and Kipling (1999), Michigan. Round gobies collected by anglers were generally larger, and taken in areas that are difficult to sample using conventional inshore sampling gear. These results indicate that survey and angler samples are complementary, but that up-to-date angler reports of exotic species that bite readily (round gobies) or are otherwise collected by anglers (Bythotrephes cederstroemi, Cercopagis pengoi) are critical to tracking the spread of these organisms.

Yellow Perch Dynamics in Southwestern Lake Michigan during 1986–2002

Abstract We examined the role of harvest in the collapse of the population of yellow perch Perca flavescens in southwestern Lake Michigan during the mid to late 1990s. After the great decrease in this population at that time, commercial fisheries in Illinois and Wisconsin were closed during 1996–1997 (and have remained closed), and stricter regulations were placed on recreational fisheries. Reproductive failure has been implicated as the primary cause of the population collapse, but the role of fishing in the collapse was not rigorously investigated in previous studies. We conducted an age-, size-, and sex-structured stock assessment of yellow perch to estimate population size and examine historical trends in fishing mortality in Illinois and Wisconsin waters of southwestern Lake Michigan. Model estimates indicated that yellow perch abundance in 2002 was less than 10% of the 1986 abundance in Wisconsin and about 20% of the respective population in Illinois. Annual mortality rates for females age 4 and old...

Hooking Mortality of Smallmouth Bass Caught on Live Minnows and Artificial Spinners

Abstract The success of no-kill regulations for salmonid fisheries has led to increased interest in applying them to warmwater fisheries. Hooking mortality often makes gear restrictions critical to the success of these regulations. The objective of this study was to determine the probability of death (hooking mortality) for smallmouth bass Micropterus dolomieui caught on live minnows and artificial spinners. We collected 55 wild smallmouth bass from 6.3 to 12.6 in long and tagged them for individual recognition. We divided them into approximately equal groups and released them into artificial stream channels. During four 2-week test periods, we hooked and released fish in one channel using live minnows on a single hook and in the other channel using a spinner with a treble hook. Some fish in each channel were not hooked during the study. Mortality was 11% for smallmouth bass hooked on minnows, 0% for those hooked on spinners, and 4% for those not hooked. Mortality of fish hooked with minnows was significa...

Yellow Perch Research and Management in Lake Michigan

Abstract Yellow perch (Perca flavescens) is an important component of near-shore freshwater fish communities. It plays an important role in energy cycling and transfer, and is available to nearly all segments of the angling public and to commercial fisheries. Beginning around 1990, yellow perch population density declined in Lake Michigan due in part to an almost complete lack of recruitment. In response to this dramatic decline, the Lake Michigan Yellow Perch Task Group (YPTG) was formed (under the auspices of the Great Lakes Fishery Commissions Lake Michigan Committee) to develop a multi-agency research initiative to identify the likely cause(s) for yellow perch recruitment failure. The multi-agency effort has made substantial progress in addressing this question, and serves as a model for agencies to work collaboratively to address important management questions with a sound research strategy. We highlight the work conducted during 1997–2001 to address five factors (predation, zooplankton availability...

The Influence of Alewife Year-Class Strength on Prey Selection and Abundance of Age-1 Chinook Salmon in Lake Michigan

Abstract We used growth and diet data from a fishery-independent survey of Chinook salmon Oncorhynchus tshawytscha, acoustic estimates of prey density and biomass, and statistical catch-at-age modeling to study the influence of the year-class strength of alewife Alosa pseudoharengus on the prey selection and abundance of age-1 Chinook salmon in Lake Michigan during the years 1992-1996 and 2001-2005. Alewives age 2 or younger were a large part of age-1 Chinook salmon diets but were not selectively fed upon by age-1 Chinook salmon in most years. Feeding by age-1 Chinook salmon on alewives age 2 or younger became selective as the biomass of alewives in that young age bracket increased, and age-1 Chinook salmon also fed selectively on young bloaters Coregonus hoyi when bloater density was high. Selection of older alewives decreased at high densities of alewives age 2 or younger and, in some cases, high densities of bloater. The weight and condition of age-1 Chinook salmon were not related to age-1 Chinook sal...

Estimating Seasonal Movements of Chinook Salmon in Lake Huron from Efficiency Analysis of Coded Wire Tag Recoveries in Recreational Fisheries

Abstract The decline of hatchery-reared Chinook salmon Oncorhynchus tshawytscha stocks in Lakes Huron and Michigan during the 1980s prompted mass-tagging programs to investigate reproduction, poststocking survival, and movements. In Lake Huron, millions of smolts implanted with coded wire tags (CWTs) were released in Michigan waters and recovered from charter and noncharter fisheries, surveys, and weirs. Using generalized linear models (GLMs), we investigated Chinook salmon seasonal movements based on the spatial and temporal distributions of recoveries by fishing trips in U.S. recreational fisheries and recovery efficiency. We used models incorporating area, month, year, and recovery source; creel-clerk and “headhunter” (CWT collection specialist) samples; and charter captain reports. We implemented models for recoveries regardless of release area and from one particular area. All model predictors and interactions between month and area were significant. The variation in recovery levels among recovery so...

Modeling Variation in Mass-Length Relations and Condition Indices of Lake Trout and Chinook Salmon in Lake Huron: a Hierarchical Bayesian Approach

Abstract Commonly used approaches to studying mass-length relations and condition indices often do not adequately address covariance between mass-length parameters, usually ignore heterogeneity in individual variance for body mass at a given length, and assume that length distributions of fish samples are similar across regions and years. We used body mass at selected lengths as condition indices based on statistical modeling and a hierarchical Bayesian approach to inferences, and our approach allowed us to avoid using restrictive assumptions. We estimated spatial and annual variation in mass-length relations, where the process errors in parameters are drawn from a multivariate distribution. We also estimated region-, year-, and size-group-specific variance for individual variation in mass at given lengths. We applied our approach to study mass-length relations of lake trout Salvelinus namaycush (1977-2005) and Chinook salmon Oncorhynchus tshawytscha (1983-2004) in U.S. waters of Lake Huron. We found that...

Lake Whitefish Relative Abundance, Length-at-Age, and Condition in Lake Michigan as Indicated by Fishery-independent Surveys

ABSTRACT In the mid 1990s, growth and condition of lake whitefish (Coregonus clupeaformis) declined within commercial catches in Lake Michigan. However, underlying mechanisms responsible for the declines have not been thoroughly explored. Using fishery-independent survey data, we examined growth and relative abundance of adult whitefish over historical (1980–1990) and recent (1996–2005) time periods in three regions of Lake Michigan: north, mid, and south. Relative abundance was assessed from catch-per-unit-effort (CPUE) of independent surveys, and changes in growth conditions were evaluated using size-at-age estimates. Relative abundance increased in the mid and south regions between the two time periods and decreased in the north region. Length-at-age significantly declined between the two time periods in the north, mid, and south regions; the north region consistently had the lowest length-at-age. Condition also declined between the two time periods in each region. The decline in growth and condition coupled with increases in relative abundance suggest density-dependent mechanisms are contributing to the observed population changes in the south region. The north region does not appear to be regulated by density, suggesting density-independent mechanisms, such as food web changes, are influencing stocks. Changes in the mid region are likely from a mixture of increased lake whitefish abundance and food web changes. Using fishery-independent population data, our results suggest that multiple factors are potentially contributing differentially within three Lake Michigan regions to cause similar declines in length-at-age and condition of whitefish. These factors (e.g., food web changes, lake whitefish density) should be considered when managing the commercial fishery.