Hard-part microchemistry offers a powerful tool for inferring the environmental history and stock assignment of individual fishes. However, despite the applicability of this technique to a wide range of fisheries conservation and management issues, its use has been restricted to only a small fraction of North American species and inland waters. In this article, we provide freshwater fisheries professionals with an accessible review of methods and applications of hard-part microchemistry techniques. Our objectives are to (1) summarize the science of hard-part microchemistry; (2) provide guidelines for designing hard-part microchemistry studies, including sample sizes, laboratory analyses, statistical techniques, and inferential limitations; and (3) identify conservation and management applications where these techniques may be particularly useful. We argue that strategic use of hard-part microchemistry methods (specifically when they are used in concert with other indirect tracer techniques such as stable isotope chemistry and genetics) can advance fish management and conservation across all stages of fish life history. RESUMEN la microquímica de partes duras representa una herramienta poderosa para inferir la historia ambiental y la asignación de stocks en peces. No obstante, a pesar de la aplicabilidad de esta técnica a un amplio rango de aspectos de conservación y manejo de pesquerías, su utilización se ha restringido a sólo una pequeña fracción de especies de aguas continentales en Norte América. En este trabajo, se presenta una revisión accesible de los métodos y aplicaciones de técnicas de microquímica de partes duras, dirigida a los profesionales en pesquerías de aguas interiores. Los objetivos son: (1) resumir la ciencia de la microquímica de partes duras, (2) proporcionar guías para el diseño de estudios de microquímica de partes duras, incluyendo tamaños de muestra, análisis de laboratorio, técnicas estadísticas y limitaciones de orden inferencial, y (3) identificar aplicaciones para la conservación y manejo en las cuales estas técnicas puedan ser particularmente útiles. Se argumenta que la utilización estratégica de métodos de microquímica de partes duras (específicamente cuando éstos son usados en conjunto con otras técnicas de rastreo indirecto como química de isótopos estables y genética) puede abonar a la conservación y manejo de los peces durante todos los estadios de vida.

Alteration of rivers for human use has resulted in substantial biodiversity declines, particularly for species restricted to the largest rivers. Conservation and restoration efforts on large rivers often focus on the mainstem, but societal reliance on benefits derived from these alterations generally prevents complete restoration of the river. We propose that certain tributaries, by virtue of their lower degree of alteration, offer underappreciated opportunities for conserving large‐river biota. Using the distribution patterns of large‐river specialist fishes from the Mississippi River Basin, we identify a threshold discharge (166 cubic meters per second) beyond which tributaries support all or most of these species. We merge our macroecological analysis of assemblage structure with data on dam locations to identify tributaries where restoration efforts offer the highest potential conservation gains for 60 of the 68 large‐river specialist fish species that are of state, federal, or international conservation concern. Given the highly altered state of many mainstem rivers, this analytical approach could be used to select tributaries that will aid in the conservation of large‐river species worldwide.

Previous studies have evaluated fish injury and mortality at hydrokinetic (HK) turbines, but because these studies focused on the impacts of these turbines in situ they were unable to evaluate fish responses to controlled environmental characteristics (e.g., current velocity and light or dark conditions). In this study, we used juvenile hybrid Striped Bass (HSB; Striped Bass Morone saxatilis × White Bass M. chrysops; N = 620), Rainbow Trout Oncorhynchus mykiss (N = 3,719), and White Sturgeon Acipenser transmontanus (N = 294) in a series of laboratory experiments to (1) evaluate the ability of fish to avoid entrainment through an axial‐flow HK turbine, (2) evaluate fish injury and survival associated with turbine entrainment, and (3) compare the effects of different HK turbines on fish. We found that the probability of turbine entrainment was species dependent and highest for HSB. Across species, current velocity influenced entrainment probability. Among entrained fish, observed survival rates were generally >0.95. The probability of injury for surviving entrained fish only differed from that for nonentrained fish for Rainbow Trout and in general was not >0.20. The probability of injury following entrainment was greater only for HSB, although there were no differences in injury rates between fish that were turbine entrained and those that were not, suggesting that injuries were not turbine related. Taking turbine entrainment, survival, and injury estimates together allowed us to estimate the probability of a randomly selected fish in a population proximate to an HK turbine surviving passage or remaining uninjured after passage. For species and current velocities for which there was a significant effect due to entrainment, we estimated, for instance, that HSB had a survival probability of 0.95 and that Rainbow Trout and White Sturgeon had a >0.99 probability of survival. Similarly, by combining these estimates with those from previous studies, we derived total passage survival probabilities >0.90 but generally approaching 1.00 across different HK turbine types, fish species, and fish lengths. Received May 14, 2014; accepted October 23, 2014