@article{raabe_hightower_ellis_facendola_2019, title={Evaluation of Fish Passage at a Nature-Like Rock Ramp Fishway on a Large Coastal River}, volume={148}, ISSN={["1548-8659"]}, DOI={10.1002/tafs.10173}, abstractNote={Abstract}, number={4}, journal={TRANSACTIONS OF THE AMERICAN FISHERIES SOCIETY}, author={Raabe, Joshua K. and Hightower, Joseph E. and Ellis, Timothy A. and Facendola, Joseph J.}, year={2019}, month={Jul}, pages={798–816} }
 @article{ellis_hightower_buckel_2018, title={Relative importance of fishing and natural mortality for spotted seatrout (Cynoscion nebulosus) estimated from a tag-return model and corroborated with survey data}, volume={199}, ISSN={["1872-6763"]}, DOI={10.1016/j.fishres.2017.11.004}, abstractNote={The spotted seatrout (Cynoscion nebulosus) is one of the most economically important sportfish in the U.S. South Atlantic and Gulf of Mexico, including at its northern distributional extent in North Carolina and Virginia. The recent stock assessment for this region used an assumed fixed rate of natural mortality (M), obtained from a general life-history relationship based on weight. However, biased estimates of fishing mortality (F) could result if the life-history proxy failed to capture either the magnitude or temporal variation in M. Data from the first comprehensive tag-return study of spotted seatrout in this region were used in a Bayesian statistical modeling framework to estimate F and M. Both laboratory and field studies, including high-reward and double tagging, were conducted to obtain estimates of auxiliary parameters (i.e., tag-reporting rate, tag loss, and tagging mortality) necessary for the tag-return model. There was no measured mortality associated with tagging, but reporting rate and loss of internal anchor tags limited returns in this study. From 2008 to 2012, tag-return model estimates of bimonthly instantaneous mortality rates ranged from 0.003 to 0.067 2-mo−1 for F and from 0.002 to 2.850 2-mo−1 for M. Annual estimates of F were much lower than M for the three years studied, and annual M-estimates were higher than those used for spotted seatrout in this region’s recent stock assessment. Bimonthly estimates of total mortality rate (Z) from tag-return data were similar to bimonthly estimates of Z from an independent analysis of concurrent gill net survey data, which corroborates the variability and magnitude of mortality estimates determined from tagging. A strong seasonal influence (i.e., winter severity) on annual loss of spotted seatrout was observed, suggesting that future assessments and management measures for this stock would be improved by explicitly accounting for temporal variation in M in models of fishery population dynamics.}, journal={FISHERIES RESEARCH}, author={Ellis, Timothy A. and Hightower, Joseph E. and Buckel, Jeffrey A.}, year={2018}, month={Mar}, pages={81–93} }
 @article{ellis_buckel_hightower_poland_2017, title={Relating cold tolerance to winterkill for spotted seatrout at its northern latitudinal limits}, volume={490}, ISSN={["1879-1697"]}, DOI={10.1016/j.jembe.2017.01.010}, abstractNote={In the absence of winter thermal refugia, acute cold stress can lead to episodic mass mortality (winterkill) in fishes. Populations existing near the northern extent of a species' latitudinal range, such as spotted seatrout, Cynoscion nebulosus (Cuvier, 1830), in North Carolina, USA, are particularly vulnerable to winterkill. Information on cold tolerance for spotted seatrout is incomplete, which limits understanding of a likely important source of natural mortality for this species. In this study, two laboratory experiments for controlled exposure of spotted seatrout to dynamic decreases in water temperature were conducted in order to determine cold tolerance as affected by either rapid or prolonged exposure to low-temperature extremes across upper- (10) and lower-estuarine (30) salinities. Under rapid exposure, spotted seatrout were unable to maintain equilibrium at temperatures ≤ 4°C, with a small but measured mitigating effect of high salinity on the onset of observed physiological stress. No fish survived prolonged exposure (2 d) to 3 °C but spotted seatrout were tolerant of exposures to 5 °C for approximately 5 d, after which survival precipitously declined. Survival after 10-d exposure to 7 °C was high but not absolute. Salinity had no measured effect on mortality rates in the prolonged exposure trials. These empirical estimates of low-temperature thresholds, along with previously determined field estimates of instantaneous winter natural mortality rate (M), were used to develop models for predicting M. Historic daily water temperatures were used to estimate winter M of spotted seatrout from 1994 to 2015. Predictions of M suggest winterkill (≥ 50% population loss) in eight of the last 22 years; these years correspond to anecdotal and fishery-independent observations of winterkill events in North Carolina. The results of this study provide strong evidence for thermally-limited overwinter survival of spotted seatrout at its northern latitudinal limits, where winterkill events can have population-level impacts.}, journal={JOURNAL OF EXPERIMENTAL MARINE BIOLOGY AND ECOLOGY}, author={Ellis, Timothy A. and Buckel, Jeffrey A. and Hightower, Joseph E. and Poland, Stephen J.}, year={2017}, month={May}, pages={42–51} }
 @article{ellis_buckel_hightower_2017, title={Winter severity influences spotted seatrout mortality in a southeast US estuarine system}, volume={564}, ISSN={["1616-1599"]}, DOI={10.3354/meps11985}, abstractNote={MEPS Marine Ecology Progress Series Contact the journal Facebook Twitter RSS Mailing List Subscribe to our mailing list via Mailchimp HomeLatest VolumeAbout the JournalEditorsTheme Sections MEPS 564:145-161 (2017) - DOI: https://doi.org/10.3354/meps11985 Winter severity influences spotted seatrout mortality in a southeast US estuarine system Timothy A. Ellis1,*, Jeffrey A. Buckel1, Joseph E. Hightower2 1Center for Marine Sciences and Technology, Department of Applied Ecology, North Carolina State University, 303 College Circle, Morehead City, NC 28557, USA 2Department of Applied Ecology, North Carolina State University, Campus Box 7617, Raleigh, NC 27695, USA *Corresponding author: taellis@ncsu.edu ABSTRACT: Winterkill in spotted seatrout Cynoscion nebulosus is associated with extreme cold conditions throughout much of the species’ geographic range. However, rigorous study is needed to confirm longstanding but largely untested assumptions that acute cold stress drives overwinter loss. We provide the first direct field-based estimates of spotted seatrout survival relative to the severity of cold temperatures. Spotted seatrout overwintering in North Carolina, USA, estuaries were tagged with ultrasonic transmitters and monitored during 3 consecutive and variable winters from 2009 to 2012. Fates of telemetered fish were inferred from daily movements and used in a multistate capture-recapture model to estimate instantaneous rates of natural mortality (M), fishing mortality, and emigration. Natural death was inferred for 7 fish in 2009/2010 (n = 34 telemetered spotted seatrout at risk), 6 fish in 2010/2011 (n = 9 fish at risk), and 1 fish in 2011/2012 (n = 65 fish at risk), and when estimable, weekly M ranged from 0.001 to 0.187. Daily estimates of natural mortality increased quickly with declining water temperatures (T), M = 1/[1 + e-(-0.714-0.756T)], and indicated that cold-stun deaths occurred when water temperatures were below ~7°C. Our results provide direct evidence that winterkill in spotted seatrout at its northern limits of distribution is related to the severity of low water temperatures and demonstrate that the simultaneous monitoring of telemetry-tagged animals and abiotic conditions is an effective approach to determine lethal environmental limits. KEY WORDS: Cynoscion nebulosus · Telemetry · Multistate · Capture-recapture · Survival · Winterkill · Cold tolerance · Temperature-dependent mortality · Mortality rate Full text in pdf format Supplementary material PreviousNextCite this article as: Ellis TA, Buckel JA, Hightower JE (2017) Winter severity influences spotted seatrout mortality in a southeast US estuarine system. Mar Ecol Prog Ser 564:145-161. https://doi.org/10.3354/meps11985Export citation RSS - Facebook - Tweet - linkedIn Cited by Published in MEPS Vol. 564. Online publication date: February 03, 2017 Print ISSN: 0171-8630; Online ISSN: 1616-1599 Copyright © 2017 Inter-Research.}, journal={MARINE ECOLOGY PROGRESS SERIES}, author={Ellis, Timothy A. and Buckel, Jeffrey A. and Hightower, Joseph E.}, year={2017}, month={Feb}, pages={145–161} }
 @article{del toro-silva_miller_taylor_ellis_2008, title={Influence of oxygen and temperature on growth and metabolic performance of Paralichthys lethostigma (Pleuronectiformes : Paralichthyidae)}, volume={358}, ISSN={["1879-1697"]}, DOI={10.1016/j.jembe.2008.01.019}, abstractNote={In this study, we apply Fry's classification of environmental factors to demonstrate the limiting effects of oxygen and its interaction with temperature on the growth of juvenile P. lethostigma. We also evaluated the properties of two metabolic indices, marginal metabolic scope (MMS) and limiting oxygen concentration (LOC), as indicators of metabolic scope. We found that oxygen limitation has its greatest impact near the optimum temperature for growth of the species. At 29 °C a reduction from 6.00 mg/L to 4.00 mg/L caused a 50% reduction in growth rate while at 27 °C the reduction had no significant effect on growth rate. The results are particularly relevant because these temperatures and oxygen concentrations are commonly observed in nursery areas during summer months. At all temperatures fish from the lowest oxygen treatment (1.75 mg/L) had negative growth rates. Comparisons between daily oscillating oxygen treatments and constant treatments failed to demonstrate significant effects. At temperatures past the optimum, growth rates between the 6.00 mg/L and 4.00 mg/L treatments were not statistically different. LOC was significantly affected by temperature, oxygen, and their interaction. Estimates were positively correlated with oxygen treatment (R2 > 0.71) and negatively correlated with temperature at moderate and low oxygen concentrations (R2 > − 0.84). MMS was significantly affected by temperature and oxygen and was significantly correlated with oxygen treatment (R2 > − 0.91), but correlations with temperature were not as clear. In conclusion, oxygen and temperature interactions have significant effects on metabolic scope and growth rates of fish, well above the accepted hypoxia threshold of 2.00 mg/L and MMS has proved a useful estimator of the metabolic scope of the organism within an environment.}, number={2}, journal={JOURNAL OF EXPERIMENTAL MARINE BIOLOGY AND ECOLOGY}, author={Del Toro-Silva, F. M. and Miller, J. M. and Taylor, J. C. and Ellis, T. A.}, year={2008}, month={Apr}, pages={113–123} }