Theodore Castro-Santos

United States Geological Survey | USGS · S.O. Conte Anadromous Fish Research Center

Swimming ability and performance are central to the ecology of aquatic species and to the design of structures intended to promote access to habitat. This is particularly important for migratory species traveling over significant distances. Here, we present results of a study of swimming behaviors of adult shortnose sturgeon (Acipenser brevirostrum...

Objective An assumption of biotelemetry is that animal performance is unaffected by the tagging process and tag burden, yet this assumption is often untested or not thoroughly explored. Our objective was to explore how transmitter implantation procedures influenced Atlantic Salmon Salmo salar smolt survival and migratory performance. Methods We mo...

Abstract Background Mobile radio tracking is an important tool in fisheries research and management. Yet, the accuracy of location estimates can be highly variable across studies and within a given dataset. While some methods are available to deal with error, they generally assume a static value for error across all detections. We provide a novel m...

Abstract Background Acoustic telemetry is a commonly used technology to monitor animal occupancy and infer movement in aquatic environments. The information that acoustic telemetry provides is vital for spatial planning and management decisions concerning aquatic and coastal environments by characterizing behaviors and habitats such as spawning agg...

Background Little is known about the transformer stage of the parasitic lampreys, a brief but critical period that encompasses juvenile out-migration from rivers to lakes or oceans to begin parasitic feeding. Information about this life stage could have significant conservation implications for both imperiled and invasive lampreys. We investigated...

Predicting and mitigating the impact of anthropogenic barriers on migratory fish requires an understanding of the individual and environmental factors that influence barrier passage. Here, the upstream spawning migrations of iteroparous twaite shad Alosa fallax were investigated over three successive spawning migrations in a highly fragmented river...

Locomotion is the act and process of moving from place to place, which is fundamental to the life history of all mobile organisms. While the field of biomechanics encompasses the study of the physical constraints of what animals are capable of, ecological contexts require an integrated view that includes ecology and behavior. This chapter provides...

Many aquatic animals swim by undulatory body movements and understanding the diversity of these movements could unlock the potential for designing better underwater robots. Here, we analyzed the steady swimming kinematics of a diverse group of fish species to investigate whether their undulatory movements can be represented using a series of interc...

Introduction Radio telemetry, one of the most widely used techniques for tracking wildlife and fisheries populations, has a false-positive problem. Bias from false-positive detections can affect many important derived metrics, such as home range estimation, site occupation, survival, and migration timing. False-positive removal processes have relie...

Significance Swimming ability has contributed to the evolutionary success of fishes, and its mechanics have been studied extensively. Most fishes swim primarily through undulation of their body and caudal fin (BCF) and have been historically divided into four major kinematic modes based on their morphology. Here, we compare kinematics of BCF locomo...

Alewife (Alosa pseudoharengus) and blueback herring (Alosa aestivalis) are iteroparous anadromous fish found throughout the East Coast of North America. The phenology of anadromous fish migrations is important for fitness, and the duration of spawning migrations has been compressed in recent years in response to climate change. Anthropogenic barrie...

Hatchery salmonid smolts are often reared using groundwater with elevated temperatures to maximize growth. Previous work has shown that rearing hatchery smolts in surface water with a more natural thermal regime resulted in increased return rates of adult landlocked Atlantic salmon (Salmo salar). We evaluated whether landlocked Atlantic salmon rear...

The construction of dams and tide gates on waterways has altered the physical structure of many coastal, estuarine, and freshwater systems. These changes have come at a cost to fish populations, most notably diadromous species, which rely on connectivity between marine and freshwater systems. These anthropogenic structures can have direct effects o...

River herring (Alosa spp.) are anadromous fish that enter North American Atlantic coastal rivers and lakes each spring to spawn. Anthropogenic structures such as dams and tide gates serve as physical obstacles that limit river herring access to spawning habitat. This study examined the physical and ecological components affecting herring passage th...

This presentation shows the results of a study on Short-nose sturgeon locomotion. swimming behavior, performance, and kinematics are discussed in the context of fish passage designs.

There is growing evidence that culverts at road-stream crossings can increase fish density by reducing stream width and fish movement rates, making these passageways ideal predator ambush locations. In this study, we used a combination of videography and δ13C stable isotope analyses to investigate predator–prey interactions at a road-stream crossin...

Anadromous alosines are widespread throughout the Northern Hemisphere. Juveniles of this clade are notoriously fragile animals that are at high risk of injury and death associated with passage at hydroelectric facilities. Although turbine mortality is a common concern, conditions encountered when bypassed around these routes may also be hazardous....

The ability to move between habitats has important implications for fitness in many species. In‐stream barriers such as culverts can impede movements of riverine fishes and thus reduce connectivity between habitats. The ability of fish to overcome barriers is related to the features of the environment and the barrier itself, but also to physiologic...

Currently, application of lampricides and installation of low-head barriers are the only proven means of sea lamprey (Petromyzon marinus) control in the Great Lakes. While sea lamprey cannot climb or jump over low-head barriers, many desirable migratory species also cannot traverse barriers and are unintentionally blocked. Recently, there has been...

How seasonal effects such as temperature increases and reduced lipid content affect the ability of anadromous fishes to traverse high-velocity barriers and sprint swimming is poorly understood. We evaluated American shad (Alosa sapidissima) swimming performance in a flume against high flow velocities (2.5–3.7 m·s⁻¹) during the upstream migration pe...

Fish are thought to exploit low velocity recirculation zones in the wakes of baffles to take refuge from challenging hydraulic conditions in baffled culverts. Here, we investigate how sediment deposition in the wakes of baffles affects passage and behaviors of juvenile rainbow trout in a baffled experimental flume. High temporal resolution 3D fish...

The northern diamondback terrapin (Malaclemys terrapin terrapin) is a saltmarsh-dependent turtle that occupies coastal habitats throughout much of the Atlantic coast of North America. We used a novel application of acoustic telemetry to quantify both mobility and occupancy of terrapins within a dredged harbor and surrounding habitats, and used thes...

El presente trabajo analiza la capacidad voluntaria de nado del barbo ibérico (Luciobarbus bocagei Steindachner, 1864) en un canal abierto durante su época de migración, relacionándola con factores ambientales y biométricos. La temperatura del agua, la velocidad de flujo y la longitud del pez fueron los factores de mayor importancia que condicionar...

There is much to learn about improving baffle designs to increase successful fish passage through culverts. A fish’s motivation to attempt entry into the culvert is essential. Upon entry, successful passage will largely depend on the physiological ability of the fish to navigate the entire culvert length. In this study, the motivation of brook trou...

Partial barriers to migration can affect migratory fish population dynamics and be influenced by many biotic, abiotic, and anthropogenic factors, including nutritional deficiencies. We investigated how such variables (including a thiamine deficiency) impact fine-scale movement of landlocked Atlantic salmon (Salmo salar) by treating returning spawne...

We evaluated the effectiveness of the fish ladder at Porto Primavera Dam in the severely regulated Upper Parana´ River, for two Neotropical migratory fish species. Overall, 564 fish (448 Megaleporinus obtusidens and 116 M. piavussu ) were PIT-tagged, released in upstream and downstream areas (on the left and right banks), and monitored continuously...

Much effort has been devoted to developing, constructing and refining fish passage facilities to enable target species to pass barriers on fluvial systems, and yet, fishway science, engineering and practice remain imperfect. In this review, 17 experts from different fish passage research fields (i.e., biology, ecology, physiology, ecohydraulics, en...

Culverts may restrict fish movements under some hydraulic conditions such as shallow flow depths or high velocities. Although swimming capacity imposes limits to passage performance, behaviour also plays an important role in the ability of fish to overcome velocity barriers. Corrugated metal culverts are characterized by unsteady flow and existence...

It is well known that human-caused alterations to the natural environment can have significant effects on wild fish migration, behavior and subsequently their populations. However, some of these effects may be difficult to quantify due to difficulties of making observations in coastal and estuarine environments where water visibility is typically p...

The purpose of this study was to investigate behavior and survival of radio-tagged wild- and hatchery-reared landlocked Atlantic salmon smolts as they migrated past three hydropower dams equipped with fish bypass solutions in the Winooski River, Vermont, USA. Among hatchery-released smolts, those released early were more likely to initiate migratio...

Radio‐tag signals from fixed‐position antennas are most often used to indicate presence or absence of individuals, or to estimate individual activity levels from signal strength variation within an antenna's detection zone. The potential of such systems to provide more precise information on tag location and movement has not been explored in great...

Considerable effort has been expended to construct culverts and fishways that allow for fish passage. However, the designs have seldom considered behaviour, energetics, and biomechanics of fish. In this study, we performed controlled experiments, in which upstream-migrating Alewife (Alosa pseudoharengus) and Brook Trout (Salvelinus fontinalis) were...

Crucial to the management of invasive species is understanding space use and the environmental features affecting space use. Improved understanding of space use by invasive sea lamprey (Petromyzon marinus) could help researchers discern why trap success in large rivers is lower than needed for effective control. We tested whether manipulating disch...

Culverts can restrict movement of stream-dwelling fish. Motivation to enter and ascend these structures is an essential precursor for successful passage. However, motivation is challenging to quantify. Here, we use attempt rate to assess motivation of 447 brook trout (Salvelinus fontinalis) entering three culverts under a range of hydraulic, enviro...

This article describes a study of PIT-tagged sea lamprey (Petromyzon marinus) ascending four fishways comprising three designs at two dams on the Connecticut River, USA. Migration between dams was rapid (median migration rate = 23 km·day⁻¹). Movement through the fishways was much slower, however (median = 0.02–0.33 km·day⁻¹). Overall delay at dams...

Passage of fish through hydropower dams is associated with mortality, delay, increased energy expenditure and migratory failure for migrating fish and the need for remedial measures for both upstream and downstream migration is widely recognised. A functional fish passage must ensure safe and timely passage routes that a substantial portion of migr...

Detailed re-examination of the datasets that were used for a meta-analysis of fishway attraction and passage revealed a number of errors that we addressed and corrected. We subsequently re-analysed the revised dataset, and results showed no significant changes in the primary conclusions of the original study; for most species, effective performance...

Under specific environmental and hydraulic conditions, culverts become barriers to upstream movements of fish. Motivation to stage an attempt is the first step towards successful passage. However, motivation is challenging to quantify. Here, we use attempt rate to assess motivation of 450 wild brook trout (85-230 mm) volitionally entering 3 culvert...

Passage performance of brown trout (Salmo trutta), Iberian barbel (Luciobarbus bocagei), and northern straight-mouth nase (Pseudochondrostoma duriense) was investigated in a vertical slot fishway in the Porma River (Duero River basin, Spain) using PIT telemetry. We analysed the effects of different fishway discharges on motivation and passage succe...

Culverts can restrict access to habitat for stream-dwelling fishes. We used passive integrated transponder telemetry to quantify passage performance of >1000 wild brook trout (Salvelinus fontinalis) attempting to pass 13 culverts in Quebec under a range of hydraulic and environmental conditions. Several variables influenced passage success, includi...

Quantifying fine-scale locomotor behaviours associated with different activities is challenging for free-swimming fish. Biologging and biotelemetry tools can help address this problem. An open channel flume was used to generate volitional swimming speed (Us) estimates of cultured lake sturgeon (Acipenser fulvescens Rafinesque, 1817) and these were...

Under specific hydraulic conditions, culverts may constitute velocity barriers impeding fish upstream movements. Motivation to stage attempts is the first step towards successful passage. However, once a fish entered a culvert, what is driving its success? Here, we present data from wild brook trout volitionally entering 13 culverts (length 9 to 45...

Traditional downstream bypass structures installed at hydroelectric projects have not been well studied for effectiveness of passage of adult downstream migrant eels. We quantified downstream movement and passage of telemetered migrant, silver-phase American eels at three consecutive hydroelectric projects on the Shetucket River, Connecticut, over...

When Brett first developed the protocols for measuring swimming performance in 1964, a primary goal was to develop velocity criteria for turbine intakes. Since then his techniques for Ucrit and fixed velocity tests have been widely repeated and have formed the basis for design of fishways and road crossings. The biology underlying many of these des...

Too often attempts to pass fish at dams or road crossings fail to meet performance expectations. Passage through engineered structures is often poor, and dam removals and stream simulation solutions can be expensive and slow, diverting resources that might be spent more efficiently on simpler solutions. Advocates for dam removal often promise that...

American shad historically conveyed millions of metric tons of biomass annually between rivers and the continental shelf. Whether the net nutrient flux was toward freshwater or toward the marine environment is unclear, and depends largely on the freshwater mortality of adults. Bioenergetics models suggest that mortality may be largely driven by del...

Under specific hydraulic conditions, culverts may constitute velocity barriers impeding fish upstream movements. The prediction of fish passage success is strongly linked to the knowledge of species swimming performance. Here, we present data from wild brook trout (Salvelinus fontinalis) volitionally entering culverts and swimming against moderate...

Migrations between different habitats are key events in the lives of many organisms. Such movements involve annually recurring travel over long distances usually triggered by seasonal changes in the environment. Often, the migration is associated with travel to or from reproduction areas to regions of growth. Young anadromous Atlantic salmon (Salmo...

We compared survival and tag retention of Alewives Alosa pseudoharengus tagged with PIT tags, using intraperitoneal (IP) surgical implants, gastric implants (GI), and untagged controls held for 38 d. Retention was 100% for IP‐tagged Alewives and 98% for GI‐tagged implants. No significant difference in survival was observed among any of these groups...

Sprinting behavior of free-ranging fish has long been thought to exceed that of captive fish. Here we present data from wild-caught brook trout (Salvelinus fontinalis) and brown trout (Salmo trutta), volitionally entering and sprinting against high-velocity flows in an open-channel flume. Performance of the two species was nearly identical, with th...

This paper describes a series of experiments designed to measure the effect of exposure to a full-scale, vertical axis hydrokinetic turbine on downstream migrating juvenile Atlantic salmon (N=175) and upstream migrating adult American shad (N=208). Controlled studies were performed in a large-scale, open-channel flume, and all individuals approache...

Improperly installed or poorly maintained culverts can pose a serious threat to fish by disrupting their habitat and endangering spawning success. Road culverts that are not designed for fish passage frequently can become obstacles. This can be especially problematic for migratory species, but can lead to fragmentation of resident populations as we...

The majority of the fish passages built in the Neotropical region are characterised by low efficiency and high selectivity; in many cases, the benefits to fish populations are uncertain. Studies conducted in the Canal da Piracema at Itaipu dam on the Parana River indicate that the system component designated as the Discharge channel in the Bela Vis...

Improperly installed or poorly maintained culverts can pose a serious threat to fish by disrupting their habitat and endangering spawning success. Road culverts that are not designed for fish passage frequently can become obstacles. This can be especially problematic for migratory species, but can lead to fragmentation of resident populations as we...

This paper presents results of a fishway evaluation performed at the Engenheiro Sérgio Motta Hydroelectric Power Plant (known as Porto Primavera) - CESP, Paraná River, Brazil. The evaluation was designed to quantify entry and passage proportions of 4 long-distance migratory fish species: Brycon orbignyanus (piracanjuba), Piaractus mesopotamicus (pa...

We synthesized evidence for unintended consequences and trade-offs associated with the passage of fishes. Provisioning of fish passageways at dams and dam removals are being carried out increasingly as resource managers seek ways to reduce fragmentation of migratory fish populations and restore biodiversity and nature-like ecosystem services in tri...

In this section, we illustrate the flexibility with which mark–recapture models and telemetry systems can be tailored to unique situations in aquatic environments. We describe simple to complex mark–recapture models and the associated telemetry system design needed to support each model. We simulate a tagged population of fish migrating downstream...

In this section, we illustrate the flexibility with which mark–recapture models and telemetry systems can be tailored to unique situations in aquatic environments. We describe simple to complex mark–recapture models and the associated telemetry system design needed to support each model. We simulate a tagged population of fish migrating downstream...

Attraction and passage efficiency were reviewed and compared from 19 monitoring studies that produced data for evaluations of pool-and-weir, Denil, vertical-slot and nature-like fishways. Data from 26 species of anadromous and potamodromous fishes from six countries were separated by year and taxonomic family into a matrix with 101 records. Attract...

Nature-like fishways have been designed with the intent to reconnect river corridors and provide passage for all species occurring in a system. The approach is gaining popularity both in Europe and North America, but performance of these designs has not been quantitatively evaluated in a field setting for any North American species. Two nature-like...

Human activities such as hydropower development, water withdrawals, and commercial fisheries often put fish species at risk. Engineered solutions designed to protect species or their life stages are frequently based on assumptions about swimming performance and behaviors. In many cases, however, the appropriate data to support these designs are eit...