6/05/2017  |   14:00 - 14:15   |  306C

VELOCITY, PREY-CAPTURE, AND MICROHABITAT SELECTION IN ARCTIC GRAYLING (THYMALLUS ARCTICUS) Our knowledge of the factors affecting microhabitat selection and population size for drift feeding salmonids is incomplete. We examined the relationship between prey capture success, holding velocity, and reactive distance experimentally for three sets of resident Alaskan Arctic grayling (N1 = 13, N2 = 15, N3 = 12, NTotal = 40). Mean standard lengths of Arctic grayling (mm +/- SD) was 161.8 +/- 31.1, 184.3 +/- 18.6, and 153.2 +/- 30.8. Velocity significantly affected prey capture success in all experiments and the relationship was negative and curvilinear. Holding velocities for Arctic grayling were significantly lower than capture velocities for velocity treatments of 30 cm/s and greater (p = 0.01). Mean reactive distance in single-fish experiments averaged 39.8 cm, 40.7 cm, and 37.8 cm respectively, and was weakly and positively related to velocity. Reactive distances did not differ significantly between Experiments 1 – 3 (p = 0.38). The Grossman et al. (2002) model yielded an optimal focal-point velocity prediction of 37.2 cm/s, however focal-point velocities occupied by fish in Panguingue Creek averaged 24.3 cm/s.

Bryan Bozeman (Primary Presenter/Author), Warnell School of Forestry and Natural Resources, University of Georgia, bryanbozeman@uga.edu;


Gary Grossman ( Co-Presenter/Co-Author), Warnell School Forestry & Natural Resources, University of Georgia, grossman@uga.edu;


Presentation:
This presentation has not yet been uploaded.

6/05/2017  |   14:30 - 14:45   |  306C

THE ECOLOGICAL ROLE OF AMPHIDROMOUS FISH RECRUITMENT IN CARIBBEAN FRESHWATER–MARINE ECOTONES Amphidromous fishes are ubiquitous, ecologically important, and culturally significant components of tropical stream communities. In amphidromy, eggs are spawned in freshwater streams, and larvae drift to the ocean. After an oceanic pelagic larval phase, they transition to postlarvae, migrate back into and ascend rivers where they grow to adults and spawn. Postlarval recruitment (i.e., river ingress) of several Caribbean amphidromous fish species occurs as synchronous pulses that are periodic at annual and lunar scales. These mass recruitment events may be a subsidy to freshwater–marine ecotones as they could be a pathway for the transfer of biomass from the ocean to freshwater and estuarine ecosystems. In this study we quantify seasonal and lunar periodicity of recruit abundances to river mouths in Puerto Rico and determine the trophic role of amphidromous mass recruitment events with diet analysis of estuarine and riverine predatory fishes. We also identify the role of amphidromous fish recruitment in nutrient and pollutant dynamics across the freshwater–marine ecotone with stable isotope and contaminant analyses. Our results and conclusions are useful for understanding Caribbean fisheries and aquatic ecosystems.

Augustin Engman (Primary Presenter/Author), University of Tennessee, gusengman@gmail.com;


Thomas Kwak ( Co-Presenter/Co-Author), U.S. Geological Survey, North Carolina State University, tkwak@ncsu.edu ;


Jesse Fischer ( Co-Presenter/Co-Author), North Carolina State University, jessefischer@gmail.com;


Greg Cope ( Co-Presenter/Co-Author), North Carolina State University, gcope@ncsu.edu;


Presentation:
This presentation has not yet been uploaded.

6/05/2017  |   14:45 - 15:00   |  306C

JUVENILE CHINOOK SALMON: A NEED FOR POPULATION AND LIFE STAGE-SPECIFIC BIOENERGETICS MODELS? Growth of juvenile salmonids is a critical variable affecting survival and recruitment to successive stages. Consumption and temperature are key variables affecting growth for fishes in general. Growth is an ideal indicator of habitat suitability, which is very informative for river restoration projects. We focus on juvenile Chinook Salmon in the San Joaquin River Restoration Program, which represents the southern-most Chinook Salmon run. We used meta-analyses of growth rates, simulations with inSTREAM and bioenergetics models to compare observed growth rates across populations from various sources. We also use bomb calorimetry data to directly measure juvenile energy densities and very discrete levels of habitat temperatures to improve bioenergetic model accuracy. Results from these multiple lines of evidence suggest that juvenile Chinook Salmon growth rates in southern rivers are quite robust. The scope for growth and consumption rates differ by ~35% by using direct versus published energy densities of juveniles. Further, temperatures in the restoration reach varied by as much as 10C during the rearing season, which greatly affects the estimated consumption rates of prey, which is valuable for establishing the carrying capacity of the restoration reach.

Steve Blumenshine (Primary Presenter/Author), Fresno State University, sblumens@csufresno.edu;


Skylar Nguyen ( Co-Presenter/Co-Author), Fresno State University, huyentnguyen@mail.fresnostate.edu;


Taylor Spaulding ( Co-Presenter/Co-Author), Fresno State University, tspaulding@mail.fresnostate.edu;


Presentation:
This presentation has not yet been uploaded.

6/05/2017  |   15:00 - 15:15   |  306C

LARVAL FISH IN A TIME OF UNCERTAINTY: DENSITIES AND GROWTH RATES ACROSS LAKE MICHIGAN Changing ecosystem dynamics in Lake Michigan due to quagga and zebra mussel invasion have contributed to declines in nutrient availability, reduced primary production, and altered zooplankton community composition. Long-term declines in forage fish densities may be a result of reductions in growth and survival of larval fishes from this altered food web. We hypothesize that locations closer to tributaries with high phosphorus loads will have higher larval fish densities and faster growth rates, owing to greater prey resources. In July 2015, we sampled larval fish at nine nearshore-to-offshore transects throughout Lake Michigan near tributaries with a range of phosphorous loads. We collected larval fish using surface/oblique tows and extracted otoliths from a subset of alewife and bloater to determine age and estimate growth rate. Larval alewife growth rates were significantly slower than ten years ago. Results also indicate highest densities and fastest growth rates of larval alewife were found at the St. Joseph transect, which is adjacent to the highest phosphorous-loading tributary in southern Lake Michigan. This has geographic implications for prey fish survival, which can inform predator stocking strategies.

Drew Eppehimer (Primary Presenter/Author), University of Arizona, deppehimer@gmail.com;


David Warner ( Co-Presenter/Co-Author), USGS Great Lakes Science Center, dmwarner@usgs.gov;


Patricia Armenio ( Co-Presenter/Co-Author), USGS Great Lakes Science Center, parmenio@usgs.gov;


Lauren Eaton ( Co-Presenter/Co-Author), USGS Great Lakes Science Center, leaton@usgs.gov;


David Bunnell ( Co-Presenter/Co-Author), USGS Great Lakes Science Center, dbunnell@usgs.gov;


Carly Nowicki ( Co-Presenter/Co-Author), USGS Great Lakes Science Center, cnowicki@usgs.gov;


David Wells ( Co-Presenter/Co-Author), NOAA Great Lakes Environmental Research Laboratory , wellsdj@umich.edu;


Presentation:
This presentation has not yet been uploaded.

6/05/2017  |   15:15 - 15:30   |  306C

WHEN A BARRIER IS NOT A BARRIER: USING FIELD SURVEYS TO IMPROVE CONNECTIVITY MODELS OF MIGRATORY FISH PASSAGE IN LAKE MICHIGAN TRIBUTARIES A landscape-based predictive model has been used to predict that only 14% of the total tributary length in the Great Lakes Basin is available to migratory fish because of dams and road crossings. This model estimates fish passability for 268,818 road crossings and forms the core of an online decision support tool (greatlakesconnectivity.org) that evaluates alternative barrier removals to optimize habitat gain per removal cost at any scale within the Great Lakes Basin. However, a limitation of the model is that it had yet to be validated with field surveys of fish passage. We conducted surveys in Lake Michigan tributaries during fish spawning migrations to compare alternative perspectives on accessibility of spawning habitat upstream of a series of potential barriers. We also surveyed dams within the Lake Michigan Basin outside the spawning season for fish passage structures to evaluate dams that are more likely to block fish passage. Both types of field surveys have implications for interpreting modeled passability and for improving the management value of the decision support tool.

Allison Moody ( Co-Presenter/Co-Author), University of Wisconsin, atmoody@gmail.com;


Austin Milt ( Co-Presenter/Co-Author), Center for Limnology, University of Wisconsin-Madison, milt@wisc.edu;


Evan Childress ( Co-Presenter/Co-Author), U.S. Fish and Wildlife Service, evan.childress@gmail.com;


Matt Diebel ( Co-Presenter/Co-Author), Wisconsin Department of Natural Resources, Matthew.Diebel@wisconsin.gov;


Peter B. McIntyre ( Co-Presenter/Co-Author), Center for Limnology, University of Wisconsin-Madison, pmcintyre@wisc.edu;


John Rodstrom (Primary Presenter/Author), University of Wisconsin-Madison Center for Limnology, rodstrom@wisc.edu;


Presentation:
This presentation has not yet been uploaded.