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T25: Fisheries: Techniques [clear filter]
Wednesday, January 30
 

10:20am EST

(FISHERIES: TECHNIQUES) Using Measures of Precision and Catch to Estimate Sample Size Required to Meet Sampling Objectives for Standard Sport Fish Assessments
AUTHORS: Stephen M. Tyszko, Jeremy J. Pritt, Joseph D. Conroy –Ohio Division of Wildlife

ABSTRACT: Using standard sampling methods for sport fish assessment allows powerful comparisons across time and space, if sample size is adequate. Biologists have begun evaluating precision and catch of sport fish surveys using North American standard methods (NASM) and have used resample methods to estimates sample sizes required to meet precision and catch objectives. The Ohio Division of Wildlife has collected standard sport fish surveys since 2003, providing an opportunity to further understand the performance of these methods. We evaluated relative standard error (RSE) and catch of stock-length individuals for NASM Largemouth Bass Micropterus salmoides electrofishing surveys  and NASM crappie (Pomoxis spp.) fyke net surveys in Ohio reservoirs 2003–2017.  We then used resampling methods to estimates sample sizes required to meet two sampling objectives: (1) for CPUE, achieve an RSE = 25; and, (2) collect at least 100 stock-length fish. We found that Largemouth Bass and crappie surveys generally met sampling objectives.  Resample analysis showed that the median number of samples required to meet objectives for Largemouth Bass surveys was 12 or fewer and the median for crappie surveys was 20 or fewer.  Our results support literature that shows NASM electrofishing can be used to obtain precise Largemouth Bass samples that meet catch objectives with a reasonable sample size.  Our crappie survey results contrasted literature that shows NASM fyke net methods required prohibitively large sample sizes to meet precision and catch objectives.  This analysis advances our understanding of sample size requirements for standard methods and highlights the importance of estimating sample size when designing standard surveys. Furthermore, we propose a standard resampling method for estimating sample size requirements.    

Wednesday January 30, 2019 10:20am - 10:40am EST
CENTER STREET ROOM A

10:40am EST

(FISHERIES: TECHNIQUES) Use of Lake Michigan and Indiana Standard Trap Nets to Collect Crappie: A Comparison of Catch, Size Structure, and Cost Effectiveness
AUTHORS: Andrew Bueltmann, Sandra Clark-Kolaks – Indiana Department of Natural Resources

ABSTRACT: Two entrapment gears, the Indiana Standard trap net (INS) and the Small Lake Michigan trap net (LM), were compared to evaluate which was more efficient and more cost effective for collecting Crappie. Gears were deployed randomly at four total lakes, one in 2017 and three in 2018. Efficiency was measured by effort needed to collect a similar sample size between gears along with time required to run both nets. Further, cost effectiveness was measured by the individual cost of both nets and the number of cheap nets which could be purchased for the more expensive net. Specifically, a single LM costs ~$4,500 and a single INS costs ~$500; therefore, nine INS could be purchased for one LM. Cost effectiveness was then calculated as the ratio of estimated catch:estimated labor time to run the necessary number of nets so that individual costs were equivalent (i.e., one LM to nine INS). The larger the ratio, the more cost effective the gear type. All lake data were pooled for analysis and indicate that size distribution between nets does not differ and mean overnight catch rates were nearly triple the amount higher for LM (14.8) than INS (5.6). Further, labor time required to achieve equivalent catch rates were as follows: one LM net (~9.8 to 60.4 mins to run) to three INS nets (~10.5 to 58.8 mins to run). Although mean overnight catch rate was higher for LM, cost effectiveness indicates little to no difference between the gears with INS (0.7) being slightly more cost effective than LM (0.5).

Wednesday January 30, 2019 10:40am - 11:00am EST
CENTER STREET ROOM A

11:00am EST

(FISHERIES: TECHNIQUES) Evaluation of Gill Net Design to Sample Fishes in Kansas Impoundments: Year Two
AUTHORS: Nick Kramer, Kansas Department of Wildlife, Parks, and Tourism

ABSTRACT: Gill nets are one of the most popular gears implemented to assess fish populations in North America. Ease of construction and low maintenance has led to their success and widespread implementation in the field of fisheries management. The characteristics of a gill net, along with the size and shape of the fish affect how capture occurs (i.e., wedging, gilling, tangling, or a combination). Many studies have been completed on selectivity of various sizes of mesh. Despite the importance of mesh size, the shape of the mesh can also be altered by modifying the hanging ratio which in turn will affect the catchability of fishes with differing body shapes. Additional studies have demonstrated the effectiveness of hobbling or tying down gill nets. This creates more of a “baggy” net which studies have shown to capture a wider size range of fish and may increase catches of species that could easily become tangled due to external protrusions (e.g., Channel Catfish or Paddlefish). In recent years, Kansas Department of Wildlife, Parks, and Tourism biologists have become interested in managing Blue and Flathead Catfish and have placed an increased priority on sampling these species; however, the biologists currently have little insight into fully representative population parameters due to standardized sampling gear that does not capture larger individuals. Thus, the objective of this study is to evaluate the effectiveness of various gill net designs to sample fish populations in Kansas impoundments with special consideration given to species of interest for biologists (e.g., Blue Catfish, Flathead Catfish). Year one of this study found differences in catch rates for some commonly assessed species. These differences were further examined in year two of the study by expanding the sample size; in both number of sets and number of reservoirs.

Wednesday January 30, 2019 11:00am - 11:20am EST
CENTER STREET ROOM A

11:20am EST

(FISHERIES: TECHNIQUES) Comparison of Hydroacoustic Survey Designs for Coldwater Forage Assessment in a Missouri River Reservoir
AUTHORS: Nicholas B. Kludt, South Dakota State University; Mark J. Fincel, South Dakota Game, Fish & Parks; Brian D.S. Graeb, South Dakota State University

ABSTRACT: Rainbow Smelt Osmerus mordax and Cisco Coregonus artedi are the primary coldwater forage species in Lake Oahe, South Dakota. Understanding the dynamics of these species is an important aspect of Walleye Sander vitreus and Chinook Salmon Oncorhynchus tshawytscha management. As these coldwater species are pelagic and heterogeneously distributed throughout the stratified reservoir zone, they have been historically surveyed using hydroacoustics. Hydroacoustics offers the ability to efficiently survey large areas, but can be time consuming. We compared the traditional cross-sectional transects (2.5 ± 0.8 km) with an abbreviated longitudinal transect (0.5 ± 0.0 km) survey, using a paired design replicated over three months and two years (n=97). We then analyzed the observed target densities of Rainbow Smelt and Lake Herring using a mean square error (MSE) approach. Observed densities were highly correlated for both Rainbow Smelt (r = 0.91) and Cisco (r = 0.94). Decomposing MSE revealed random error components of 67.3% and 99.7% of Rainbow Smelt and Cisco, respectively, indicating no systemic differences between the paired estimates. In either case, estimates were statistically comparable to a 1:1 line with a zero intercept, indicating high observational agreement. These results show no discernible difference between survey designs. While travel time between sites remains constant, the difference between longitudinal (6 min) and cross sectional (30 min) transect scanning times equates to an 80% time savings (1 hr, 42 mins vs. 8 hr, 38 mins). We therefore recommend the adoption of the longitudinal design for future standardized sampling of Lake Oahe coldwater stocks.

Wednesday January 30, 2019 11:20am - 11:40am EST
CENTER STREET ROOM A

11:40am EST

(FISHERIES: TECHNIQUES) Growth Chronology and Population Characteristics of Channel Catfish and Freshwater Drum Across Six Illinois Rivers
AUTHORS: Sabina Berry, Jim Lamer – Western Illinois University; Jason DeBoer, Andrya Whitten – Illinois Natural History Survey; Rob Colombo, Cassi Carpenter – Eastern Illinois University; Neil Rude, Greg Whitledge – Southern Illinois University Carbondale; Ben Lubinski, Jerrod Parker – Illinois Natural History Survey

ABSTRACT: Channel catfish (Ictalurus punctatus) and Freshwater drum (Aplodinotus grunniens) are two prominent North American sportfishes occupying a similar ecological niche in many river systems. Comparison of historically validated ageing structures and length frequency data can reveal dynamics of fish populations, including their recruitment, mortality, and individual growth patterns. In addition, tracking years of strong and weak growth through biochronological inference can increase understanding of the biotic and abiotic factors affecting individual reaches and rivers. This collaborative project covers reaches of six major rivers spanning Illinois, including the Wabash, Ohio, Illinois, Kankakee, Iroquois, Pools 16, 19, 20, 21, and 25 of the upper Mississippi River, as well as a small section of the lower Mississippi River. All fish were caught in 2017 and 2018 using DC electrofishing gear as part of a long term survey submitted annually to the Illinois Department of Natural Resources. Preliminary results from 2017 revealed weak year classes in all reaches for drum from 2010 to 2014, but stronger classes in the following years. Catfish showed weak years before 2011 and after 2014, but stronger years in between. Drum had faster growth rates in the Ohio and Mississippi reaches and slower growth in the Illinois and Wabash, whereas the catfish initially had faster growth rates only in the Ohio River. Mortality rates were highest for drum in the upper Mississippi River in pools 16 & 19, but lowest in the Ohio River. Catfish mortality rates were low throughout all reaches. Incorporating chronology factors as well as the data collected in 2018 may reveal additional trends and the larger dataset will allow us to further compare pools and reaches within each river. Understanding population dynamics and growth chronology of two common predatory fish spanning Illinois waterways is important for creating potential management strategies and determining their initial necessity.

Wednesday January 30, 2019 11:40am - 12:00pm EST
CENTER STREET ROOM A