Climate Change Impacts on Fishery and Wildlife Management


1:10PM Temperature and Hypoxia Modify Early Life Stage Fish Responses to Seawater Acidification
  Teresa Schwemmer
To quantify energetic costs of multiple environmental stressors, we reared Atlantic silverside (Menidia menidia) offspring in factorial combinations of temperatures, carbon dioxide (CO2), and dissolved oxygen (DO) and measured metabolic rates with respirometry, and ionoregulatory capacity by staining ionocytes on the skin surface of embryos and larvae. Some of the temperature experiments used a range of common temperatures silversides would normally experience during the spawning season, and others compared a normal temperature to an extreme high temperature. The DO experiments applied constant low oxygen concentrations of 4 and 2 mg/L plus a control level around 8 mg/L. CO2 rarely affected metabolic rates in isolation, but temperature and DO significantly interacted with CO2. Temperature reversed the effect of CO2 in embryos such that at low temperature acidification increased metabolic rates, but at high temperature it decreased them. Embryos in the DO experiments had higher metabolic rates when reared in elevated CO2 under normoxia, but low DO counteracted the CO2 effect. Growth, survival, and physiological results from these and other experiments were then used to parameterize a dynamic energy budget (DEB) model combined with a population model to estimate how the energetic costs of coping with multiple near-future stressors impact population growth.
1:30PM Evaluation of Elasmobranchs Caught By Sardine Purse Seines in the Gulf of California for Ecological Vulnerability Analysis (Fishing and Climate Change)
  Karla Garcés-García
This study analyses data from elasmobranchs caught during sardine catches by the National Fisheries Institute of Mexico between 2012–2017 in the Gulf of California. A total of 17 elasmobranch species were collected during 83 trips done at 5.51m–86.26m depth and surface temperature from 16°C to 32.5°C. The highest number of elasmobranch species (15 species) were recorded in 2015, whereas the lowest number of elasmobranch species (2 species) were recorded in 2012. No significant differences were detected between summer 2014 and 2015 (t= 5, p=0.12), between spring 2015 and 2016 (t=5, p=0.12), and between winter 2015 and 2016 (t=6, p=0.10), but some species may be present in our study area only during these seasons. The most frequent elasmobranchs species were Rhinoptera steindachneri, Aetobatus laticeps, Hypanus longus, Mobula mobular, Sphyrna lewini and Rhizoprionodon longurio. Full range of sizes were registered only for R. steindachneri (from 40 cm Disc width (DW) to 120 cm DW, H. longus (from 20 cm DW to 150 cm DW, Mobula mobular (from 70 cm DW to 100 cm DW), S. lewini (24 cm TL to 140 cm TL). We suggest much lower catchabilities for the sharks than for the rays.
1:50PM Is Climate Change Driving Changes in Groundfish Condition Factor on the Northeast US Continental Shelf?
  Laurel A. Smith
Climate change can affect the health of fish populations in many ways including increasing the energetic requirements to search for prey and to find suitable thermal habitat. Managed populations may experience declines in condition as habitats become less favorable, but before they alter their distribution. In this study, 27 years of relative condition factors (Kn) were analyzed for 40 finfish stocks commonly caught on the Northeast Fisheries Science Center’s autumn bottom trawl survey. A generalized additive model was used to test if indices of bottom temperature, stomach fullness, local population density, copepod size structure, or bottom trawling fishing effort contributed to the prediction of relative condition. Sexes were analyzed separately for species that showed sexually dimorphic growth rates. Declines in condition occurred around the year 2000 across many fish species on the Northeast US Continental shelf, with some species recovering around 2010. Temperature predicted relative condition for some stocks, indicating that these stocks may be particularly sensitive to thermal changes, whereas density dependence, food availability and other factors are likely the primary drivers for other stocks. These changes in condition have direct implications for stock assessments, catch quotas and management and may indirectly impact fish recruitment and mortality.
2:10PM El Niño Effects on Galapagos Artisanal Coastal Fin-Fish Fishery and Implications for Climate Change
  Jose Marin Jarrin
El Niño events heavily influence the Tropical Eastern Pacific and lead to a decrease in phytoplankton concentrations and variation in the composition of marine trophic web. The target species of the Galapagos coastal fishery include demersal fish, several of which are listed on the IUCN Red List of threatened species. At present it is unclear how El Niño events influence artisanal fisheries in the Galapagos. To study this influence, catch composition at Puerto Ayora, Santa Cruz Island was recorded during March and April in 2013, 2014 and the El Niño year 2016. Compositions were significantly different between 2016 and both 2013 and 2014, but not between 2013 and 2014. These differences were due to the appearance of Grape-eye Seabass Hemilutjanus macrophthalmos and Pacific Dog Snapper Lutjanus novemfasciatus in 2016. Sizes were also significantly larger for several species observed in 2016 when compared to 2013 or 2014. At present, the immediate mechanism behind the observed changes in fish communities is unclear; however, because many demersal fish have conservative life histories and there are no species-specific regulations governing the take of fin-fish within the GMR, fishing during El Niño events may have profound effects on such populations by eliminating the largest individuals.
2:30PM Long-Term Climate Ocean Oscillations Inform Seabird Bycatch from Pelagic Longline Fishery
  Rujia Bi
A large proportion of seabird species have experienced dramatic declines over past decades, with a key threat to most species recognized as bycatch associated with fisheries. Seabird bycatch often varies over time and space. Spatial and temporal restrictions on fishing, especially in areas where there is a higher probability of seabird bycatch or during periods of higher seabird abundance, are expected to improve seabird management and conservation. We predicted the spatial heterogeneity of seabird bycatch probability and its changes over time through an interactive Bayesian hierarchical model based on the observer data from the National Marine Fisheries Service Pelagic Observer Program. The integrated nested Laplace approximations methodology and stochastic partial differential equations approach were applied to fit the model. Seabird bycatch was found to have a hotspot of high bycatch probability in the Mid-Atlantic Bight in most years and the hotspot varied year by year. Long-term climate oscillations, such as North Atlantic Oscillation and Atlantic Multidecadal Oscillation, showed clear links with the changes of seabird bycatch hotspot, which provides basic support to mitigate bycatch. The model was then applied to the logbook data to obtain the estimates of seabird bycatch from the pelagic longline fishery.
2:50PM Refreshment Break
3:20PM Impacts of Extreme Weather Events on Growth of Two Caribbean Native Stream Fishes
  Bonnie J. E. Myers
Climate change is predicted to increase the intensity of weather events in the Caribbean region, such as drought and hurricanes. These disturbances impact freshwater fish directly and indirectly through alterations to habitat, including changes in flow, dissolved oxygen content, and sediment load. Fish can respond behaviorally, phenologically, physiologically, and morphologically following extreme disturbances. Caribbean fish assemblages in Puerto Rico are expected to be resilient to certain extreme weather events due to their diadromous life history and adaptation to periodic flooding. However, nuanced impacts to native species growth and overall success may occur . To test if acutely severe drought and hurricanes affect fish growth, we determined growth responses in two native, amphidromous species (Mountain Mullet Agonostomus monticola and Bigmouth Sleeper Gobiomorus dormitor) in the Río Mameyes, Puerto Rico, using empirical age and growth information from mountain mullet (N=185) and bigmouth sleeper (N=214) spines. Both the 2015 drought and Hurricane Maria in 2017 events were captured in the age and growth data. Documenting the impact of severe disturbance events will enhance efforts to project changes in native fish populations in Puerto Rico and elucidate native fish responses to climate change.
3:40PM Changing Diet in a Changing Climate: A Comparative Assessment
  Aaron Shultz
Across the Ceded Territories in the Midwest, many walleye (ogaa) populations are declining. In many lakes, fewer young walleye are surviving to age-1. Warmer water may be causing shifts in fish communities and habitat throughout the region. We compared the relative condition and stomach contents of age-1 walleye in a lake with declining recruitment to a lake with stable recruitment during the growing season. The Walleye population of Lac Vieux Desert (LVD) Lake (4,300 acre flowage) has declined in abundance and recruitment, and the fish community has shifted towards warmwater (Centrarchid) species in recent years. Conversely, the walleye population of Sherman Lake (123 acres lake) has been stable with regular recruitment despite relatively high exploitation rates. The fish community in Sherman Lake is dominated by yellow perch and walleye. Juvenile walleye in LVD Lake were in poorer condition than juvenile walleye in Sherman Lake. Prey availability may be playing a role in their condition. Young walleye in Sherman Lake consumed more fish (primarily perch) than young walleye in LVD Lake. Taken together, a fish community shift could decrease survival of juvenile walleye. Fish communities throughout the region will likely continue to change because of warmer temperatures, potentially exacerbating walleye declines.
4:00PM Winter Temperature Effects on Yellow Perch Reproduction at the Southern Edge of the Species Range.
  John Cannaday
Climate change is altering thermal regimes in aquatic systems worldwide, often impacting species on the southern edges of their ranges. Yellow Perch Perca flavescens, a cool water species, are sporadically distributed at the southern edge of their range in systems that provide coolwater refuges during summer months (e.g., tailwaters below hypolimnetic release dams). However, minimum winter temperatures are much warmer in these systems than in northern locations. In northern populations, egg quality is linked to overwinter thermal conditions, with long, cold winters resulting in higher quality eggs compared to short, warm winters. We explored if Yellow Perch from the Savannah River, SC required similar exposure to long, cold winters for proper reproductive development. We conducted controlled laboratory experiments to determine if fish exposed to colder (8⁰C) or longer (42 d) winters would have higher offspring quality (larger, higher energetic density), than those exposed to warmer (12⁰C) or shorter (21 d) winters. Successful reproduction (spawning, fertilization, and hatching) occurred in all treatments -17 to 33 days after spring warming began. Results for hatching success, egg and larval size, and energetic density will be presented. Our results will provide improved understanding of Yellow Perch reproduction at the southern edge of their range.
4:20PM Characterizing Resilience of Michigan Rivers Under a Changing Climate
  Erin Tracy
Michigan stream habitats and fishes they support are ecologically, economically, and culturally important, yet they are increasingly threatened by changing climate. To effectively prioritize conservation of streams, natural resource managers need information on how resilient habitats will be to changing climate, including changes in precipitation and air temperature. Our research will help to meet this need by providing managers with an estimate of stream habitat’s ability to resist changes in climate. Ecosystem resilience is a multi-faceted property affected by a variety of physical and biological habitat features, and because of this, we created three indices assessing various components of resilience based on natural landscape factors (e.g., catchment geology, groundwater delivery to streams), anthropogenic landscape stressors (e.g., agricultural and urban land use in catchments), and biological factors (e.g., fish assemblage richness and diversity). Our results show spatially-explicit maps for one or all stream reaches in Michigan, and we present approaches for considering indices with other variables, including reach-specific estimates of changes in air temperature and precipitation. The indices developed from this effort offer natural resource managers novel yet critical information to guide allocation of resources to streams based on their resiliency to changing climate.
4:40PM Warm-Tolerance May Already be in a Rainbow Trout’s Genome: A Study of Its Acclimation Potential in Australia
  Olivia Adams
Rainbow trout, Oncorhynchus mykiss, introduced to southern Western Australia in the late 1980’s, have gone through repeated generations of extreme mortality at the Pemberton Freshwater Research Centre (PFRC) with up to 90% during natural bouts of high water temperature (>26˚C). The rainbow trout strain currently at PFRC is thought to have been naturally selected during these bouts of warm temperature because the PFRC line can live at 26˚C, temperatures that would kill other rainbow trout populations that typically thrive up to only 20˚C. While physiological studies exist for 15˚C-acclimated fish, a study of their acclimation potential is lacking. Because aerobic performance can be plastic, depends on temperature acclimation and varies among different populations of the same species, I tested growth and aerobic performance of the PFRC rainbow trout acclimated for over one month to six temperatures (15, 17, 19, 21, 23 and 25˚C). The objective was to determine optimal and maximal temperatures for growth, digestibility, food conversion efficiency, respirometry performance and maximum heart rate. These combined physiological assessments allow for a large-scale consideration of performance indicators to look at the energetics and scope for the survival of this unusual strain of rainbow trout.
5:00PM Models for Adaptive Management in the Face of Climate Change
  Rich Bell
Changing ocean ecosystems are altering the distribution and abundance of fish populations and impacting the people whose well-being and livelihoods depend on them. An adaptive management framework based on a long-term climate strategy, effective monitoring, accountability on the water, predefined flexible regulations, and real-time infrastructure could mitigate the impacts of climate change. Scenario planning and risk assessments are promising approaches for developing climate adaptation strategies when faced with uncertainty. Ongoing technological progress brings the potential to turn fishing fleets into data collection platforms providing real-time information to feed indicator-based frameworks that reduce lags between signal detection and response. Dynamic permitting with full accountability (electronic monitoring), increases fisher’s ability to respond to the current conditions while ensuring they stay within regulations. Fishery managers can increase adaptive capacity by developing predefined responses to a wide array of potential future conditions through long-term planning that links management actions to indicator values provided via effective real-time monitoring systems. These are not new concepts and based on a literature review, all these components are currently in practice. The current frontier is designing and implementing integrated management systems that combine all these elements to sustain productive and economically viable fisheries in the face of climate change.

Organizers: Susan Farady
Supported by: Susan Farady

Location: Reno-Sparks CC Date: October 1, 2019 Time: 1:10 pm - 5:20 pm