Megalops Atlanticus Research Articles

Spectral Sensitivity Change May Precede Habitat Shift in the Developing Retina of the Atlantic Tarpon (Megalops atlanticus).

Fish that undergo ontogenetic migrations between habitats often encounter new light environments that require changes in the spectral sensitivity of the retina. For many fish, sensitivity of the retina changes to match the environmental spectrum, but the timing of retinal change relative to habitat shift remains unknown. Does retinal change in fish precede habitat shift, or is it a response to encountered changes in environmental light? Spectral sensitivity changes were examined over the development of the Atlantic tarpon (Megalops atlanticus) retina relative to ontogenetic shifts in habitat light. Opsin gene isoform expression and inferred chromophore use of visual pigments were examined over the course of M. atlanticus development. Spectral sensitivity of the retina was then determined by electroretinography and compared to the spectroradiometric measurements of habitat light encountered by M. atlanticus from juveniles to adults. These data, along with previously known microspectrophotometric measurements of sensitivity in M. atlanticus, indicate retinal spectral sensitivity that matches the dominant wavelengths of environmental light for juvenile and adult fish. For the intervening subadult stage, however, spectral sensitivity does not match the dominant wavelength of light it occupies but better matches the dominant wavelengths of light in the habitat of its forthcoming migration. These results first indicate that the relationship between environmental light spectrum and spectral sensitivity of the retina changes during M. atlanticus development and then suggest that such changes may be programmed to support visual anticipation of new photic environments.

Consistency of elemental and isotope-ratio patterns across multiple scales from individual fish.

Assays of elemental and stable-isotope ratios across growth increments of scales have the potential to provide a non-lethal alternative to otolith chemistry for identifying migration and ontogenetic trophic shifts. A central assumption when employing scales as otolith analogues is that any scale from an individual will provide equivalent information about the chemical history of that fish. This assumption was investigated with multiple scales from wild and captive euryhaline Atlantic tarpon Megalops atlanticus from the north-west Gulf of Mexico. Elemental (Sr:Ca) and isotope-ratio (δ13 C and δ15 N) life-history profiles were compared among multiple scales from each fish. All three chemical proxies showed highly consistent patterns among non-regenerated scales, while patterns in regenerated scales diverged, indicating rapid regrowth of interior scale material at the onset of regeneration. Patterns of Sr:Ca and δ13 C covaried, supporting their use as salinity proxies, while δ15 N patterns were consistent with ontogenetic diet shifts. Water samples taken from aquaria holding captive fish were used to calculate partition coefficients for a suite of elements in M. atlanticus scales for future quantification of migratory movements in the region. Together, these results support the assumption that non-regenerated scales from individual M. atlanticus provide equivalent chemical histories, further validating their use as a viable non-lethal alternative to otoliths.

Iron, Copper, and Zinc in Some Fish Species of the Atrato River Delta, Colombian Caribbean

ABSTRACTThe concentrations of iron (Fe), copper (Cu), and zinc (Zn) were evaluated in 96 samples of the following eight fish species: Centropomus undecimalis, Caranx hippos, Scomberomorus brasiliensis, Lutjanus purpureus, Caranx crysos, Megalops atlanticus, Elops saurus, and Epinephelus itajara collected in the Atrato River Delta in the Gulf of Urabá. Three fish were caught from each of the following common fishing grounds: Bahía Candelaria, Bahía Marirrío, Bocas del Roto, and Bocas del Atrato. Fish were captured during a one-year period, with one specimen per species in each climatic period: dry, transient, and wet. The quantification was performed by microwave plasma-atomic emission spectroscopy. The highest levels of Fe and Cu were found in Caranx crysos, and highest level of Zn in Megalops atlanticus. According to the percentage of the daily value per food serving, Caranx crysos and Caranx hippos are good sources of Fe, and Caranx crysos is a good source of Cu.

Low-temperature tolerance of juvenile tarpon Megalops atlanticus

The tarpon Megalops atlanticus is a tropical to subtropical species whose pole-ward distribution is thought to be limited by low water temperatures. In the western north Atlantic Ocean juvenile tarpon occur in estuaries of the South Atlantic Bight (SAB) north of Florida near the northern limit of its distribution, but it is currently unknown whether these individuals can survive winter, grow to maturity, and contribute to the adult population. As a first step to determine whether juvenile tarpon can survive winter conditions in the SAB, we conducted laboratory experiments to estimate minimum lethal temperatures of tarpon exposed to 1) ambient fluctuating winter water conditions and 2) a constant rate of temperature decline. Juvenile tarpon exposed to ambient winter water conditions had a mean ± standard deviation (SD) minimum lethal temperature of 13.7 ± 3.4 °C. When exposed to a constant rate of temperature decline (2 °C day−1), mean ± SD minimum lethal temperature (9.2 ± 0.8 °C) was lower than when tarpon were exposed to ambient fluctuating conditions. A combination of our results with all published data on the cold tolerance of juvenile tarpon resulted in an overall mean ± SD minimum lethal temperature of 12.0 ± 2.8 °C. Based on available long-term temperature records from SAB estuaries, overwinter survival of juvenile tarpon is unlikely in most aquatic habitats (e.g., tidal creeks, flats, open water). Similar to other estuarine transient fishes, juvenile tarpon likely exploit seasonably favorable nursery habitats and then migrate to other locations to overwinter.

Species-specific development of retinal architecture in elopomorph fishes: adaptations for harvesting light in the dark

Elopomorph fishes are distinguished in part by a shared leptocephalus larval form. These glass-clear, ribbon-like larvae are remarkably similar across the elopomorpha, yet they mature to radically different forms as adults. Along the timecourse of development, they transition through a variety of spectrally distinct habitats, occupying very different temporal niches as adults - some diurnal predators in high-light environments, others crepuscular, and others nocturnal. We found that in concert with these changes, the retinas of a variety of elopomorph fish change in similarly dramatic ways over the course of development. While the mature bonefish [Albula vulpes (Linnaeus,1758)] retina is specialized for visual tasks in a high-light environment, the Atlantic tarpon (Megalops atlanticus Valenciennes, 1847) and ladyfish (Elops saurus Linnaeus,1766) exhibit multiple specializations for function at night or otherwise in very dim light conditions. These include stacked rod photoreceptors that are gathered into massive bundles, retinomotor movement of photoreceptor outer segments, and a highly reflective tapetum. In the adult form, the speckled worm eel (Myrophis punctatus Lutken, 1852) maintains a retina with nearly all rods. The dramatic divergence among taxa over the course of development produces species with distinctly specialized visual capabilities. Moreover, the ability to change over the course of development may underlie the capacity for resilience in the face of anthropogenic insults, including light pollution in increasingly developed coastal zones. On the other hand, if light history can drive retinal change, exposure to artificial light at night may be detrimental to the survival of individuals that move between light-polluted and naturally dark locations.

Circadian rhythms of retinal sensitivity in the Atlantic tarpon, Megalops atlanticus

The Atlantic tarpon (Megalops atlanticus Valenciennes,1847) is a visually-guided marine predator that may be active at any time in the 24-hr light-dark cycle despite dramatic changes in light intensity over the course of the day. To test the hypothesis that retinal sensitivity changes with time of day in M. atlanticus, possibly under the influence of a circadian clock, populations of fish (three populations of 6 fish per lighting treatment for two treatments = 36 fish total) were exposed to different lighting treatments and sensitivity of the retina was measured periodically by electroretinography (ERG). The intensity of light required to elicit a half-maximal ERG response was significantly greater during the day than the night in fish held in 12L:12D light-dark cycles (LD). To determine whether this cycle of retinal sensitivity is driven by an internal timekeeping mechanism, ERG was performed at 4-hr intervals over the course of 24 hrs in constant darkness (DD). Sensitivity was significantly higher during subjective night than during subjective day, though the rhythm in DD was damped relative to the cycle in LD. These results show that retinal sensitivity is much higher at night than during the day in a light-dark cycle, and that this cycle of retinal sensitivity is driven at least in part by an internal biological clock. Such endogenous timekeeping mechanisms enhance survivability by allowing organisms to anticipate change in their external environments. Rhythms of retinal sensitivity are likely important for survival by supporting prey capture, predator avoidance, and reproduction, but they may be disrupted by abnormally-timed exposure to light, including artificial light at night.

Two new species of Elopicola (Digenea: Aporocotylidae) from Hawaiian ladyfish, Elops hawaiensis (Eastern Sea) and Atlantic tarpon, Megalops atlanticus (Gulf of Mexico) with a comment on monophyly of elopomorph blood flukes

Elopicola bristowi sp. n. infects the blood vascular system of Hawaiian ladyfish, Elops hawaiensis, in the Eastern Sea. It differs from the only nominal congener Elopicola nolancribbi by the combination of having rows of ventrolateral tegumental spines, a proportionally long oesophagus, anterior caeca, vasa efferentia coalescing ventral to the posterodextral margin of the testis, a post-testicular metraterm, a dextral common genital pore lateral to the oötype, and genitalia that are enantiomorphic relative to those of E. nolancribbi. Elopicola franksi sp. n. infects the heart and blood vascular system of Atlantic tarpon, Megalops atlanticus, in the Gulf of Mexico. It differs from its congeners by the combination of lacking ventrolateral tegumental spines and having an elongate body (6× longer than wide), a proportionally long oesophagus, a compact testis at level of the distal ends of the posterior caeca, and a post-testicular common genital pore at level of the oötype. Phylogenetic analyses based on the small subunit ribosomal DNA (18S), large subunit ribosomal DNA (28S), and internal transcribed spacer 2 (ITS2) genes revealed considerable genetic differences between these taxa. The 18S+28S tree showed a monophyletic Elopicola sister to all aporocotylids infecting fishes of Euteleosteomorpha. The ITS2 tree showed Paracardicoloides yamagutii as the sister taxon to Elopicola spp.

Ecological niche partitioning within a large predator guild in a nutrient‐limited estuary

AbstractWithin oligotrophic ecosystems, resource limitations coupled with interspecific variation in morphology, physiology, and life history traits may lead to niche partitioning among species. How generalist predators partition resources and their mechanisms, however, remain unclear across many ecosystems. We quantified niche partitioning among upper trophic level coastal and estuarine species: American alligators (Alligator mississippiensis), bull sharks (Carcharhinus leucas), common bottlenose dolphins (Tursiops truncatus), common snook (Centropomus undecimalis), and Atlantic tarpon (Megalops atlanticus) in the Shark River Estuary of the Florida Coastal Everglades, USA using acoustic telemetry, stable isotope analysis, and visual surveys, combined with published diet and life history demographic information. Spatial and isotopic niche overlap occurred among most species, with variability in partitioning among interspecific interactions. However, seasonal variability in habitat use, movements patterns, and trophic interactions may promote coexistence within this resource‐limited estuary. Beyond guild‐level niche partitioning, predators within the Shark River Estuary also exhibit partitioning within species through individual specializations and divergent phenotypes, which may lead to intraspecific variability in niche overlap with other predators. Niche differentiation expressed across multiple organizational levels (i.e., populations and communities) coupled with behavioral plasticity among predators in oligotrophic ecosystems may promote high species diversity despite resource limitations, which may be important when species respond to natural and human‐driven environmental change.

Guidelines for evaluating the suitability of catch and release fisheries: Lessons learned from Caribbean flats fisheries

Catch and release is receiving attention as a recreational fisheries conservation tool, but data are often lacking on: the suitability of target species; location-specific factors (e.g., predator field); likelihood of community support; infrastructure capabilities; availability of suitable habitat. This is especially true where C&R fisheries are being developed because they are perceived as economically valuable, automatically self-sustaining, with low environmental impact. However, resources to support research, management, and enforcement are often lacking, leading to fisheries that are de facto C&R, with little oversight or conservation planning. This can lead to fisheries that are not sustainable due to low post-release mortality, overfishing, loss of critical habitats. In locations with limited resources, a framework is needed to maximize these resources to provide sufficient information for fisheries management and evaluation. The “flats fishery” of the Caribbean, comprised of bonefish (Albula vulpes), Atlantic tarpon (Megalops atlanticus), permit (Trachinotus falcatus), and common snook (Centropomus undecimalis), supports an economically valuable recreational fishery that is C&R in many locations throughout its geographic range. Once a fishery that received little management attention, recent research has provided sufficient information to guide conservation and management. In this manuscript, the lessons learned from >10years of research and conservation of the Caribbean flats fishery are used to demonstrate how C&R Fishery Evaluation Guidelines (FEGs) can be applied to this and similar C&R fisheries. The FEG factors include: species suitability, habitat, water quality, fishery status, fishery capacity, socio-economics, enforcement and compliance, cultural factors, and education.

The natural armors of fish: A comparison of the lamination pattern and structure of scales

Fish scales exhibit a unique balance of flexibility, strength and toughness, which is essential to provide protection without encumbering locomotion. Although the mechanical behavior and structure of this natural armor are of recent interest, a comparison of these qualities from scales of different fish species has not been reported. In this investigation the armor of fish with different locomotion, size and protection needs were analyzed. Scales from the Arapaima gigas, the tarpon (Megalops atlanticus) and the carp (Cyprinus carpio) were compared in terms of the stacking sequence of individual plies and their microstructure. The scales were also compared with respect to anatomical position to distinguish site-specific functional differences. Results show that the lamination sequence of plies for the carp and tarpon exhibit a Bouligand structure with relative rotation of 75° between consecutive plies. The arapaima scales exhibit a cross-ply structure, with 90° rotation between adjacent plies. In addition, results indicate that the volume fraction of reinforcement, the number of plies and the variations in thickness with anatomical position are unique amongst the three fish. These characteristics should be considered in evaluations focused on the mechanical behavior.

A Contribution to the Life History of Tarpon (Megalops atlanticus) in the Northern Gulf of Mexico

Megalops atlanticus (Tarpon) is a highly migratory species that supports an economically important recreational fishery in the Gulf of Mexico. Despite this, little is known about Tarpon life history in the northern Gulf of Mexico. Collections of Tarpon leptocephali, young-of-the-year, juveniles, sub-adults, and adults from waters of southeastern Louisiana and the adjacent northern Gulf of Mexico suggest that the northern region may provide valuable habitats for the species at the present time, and potentially be of greater importance as climate change progresses.

Megalops atlanticus (Megalopidae), un nuevo pez en el océano Pacífico; información sobre su importancia pesquera

RESUMENObjetivo. Registrar la presencia de Megalops atlanticus (sábalo real) por primera vez en el Pacífico colombiano y dar un marco inicial de conocimiento acerca de su distribución, usos y apreciación por parte de las poblaciones locales. Materiales y métodos. Se llevaron a cabo 50 encuestas a pescadores de las comunidades de los municipios de Nuquí y Bahía Solano (departamento del Chocó) con el fin de recabar información acerca de los sitios de captura, características ecológicas y usos; adicionalmente se tomaron muestras donde se determinó sexo y estado de madurez gonadal. Resultados. A partir del conocimiento tradicional de los pescadores se establecieron los métodos de captura (línea de mano, arpón, caña de pescar y trasmallo), sitios de pesca: frente de los centros poblados de Jurubirá, Tribugá, Coquí y Bahía Solano (encontrándose en ambientes rocosos y ensenadas aledañas a estos) y usos que le dan al sábalo: consumo (65%), elaboración de artesanías (20%), venta (7%) y pesca deportiva (8%), adicionalmente en los ejemplares estudiados se evaluó el estado de madurez encontrándose todos en estadio III de maduración. Conclusiones. Este trabajo permite alcanzar un primer marco de conocimiento acerca de la distribución del sábalo en el Pacífico colombiano y su explotación en la región, sirviendo de base para estudios posteriores y planes de manejo que se realicen de esta especie en el Pacífico.

Otolith chemistry chimes in: migratory environmental histories of Atlantic tarpon (Megalops atlanticus) caught from offshore waters of French Guiana

The migratory life histories of 37 Atlantic tarpon (Megalops atlanticus) caught from offshore waters of French Guiana were quantified using otolith Sr:Ca and Ba:Ca ratios. In general Sr:Ca ratio was more informative marker for inferring movements along salinity gradients, but Ba:Ca ratio was used to infer movements to estuarine mixing zones with high Ba availability. All sampled individuals had made use of marine and brackish water but only 8 % had experienced fresh water and 24 % hypersaline water. The newly-hatched post-metamorphic larvae recruited to brackish (49 %), sea (43 %), fresh (5 %) and hypersaline (3 %) water nursery areas. Following the settlement to nursery areas Atlantic tarpon likely displayed facultative habitat selection and complex set of inter-habitat shifting among waters of various salinity. The combined use of both markers allowed us to conclude that brackish (estuarine) areas are likely the main habitat for Atlantic tarpon in French Guiana, and fresh water use is surprisingly rare. As no general migratory life-history emerged, and because Atlantic tarpon seemed rather facultative in its habitat use, it should be regarded as ‘euryhaline marine migrantʼ.

Effect of chemical composition and microstructure on the mechanical behavior of fish scales from Megalops Atlanticus

This paper presents an experimental study of the composition, microstructure and mechanical behavior of scales from the Megalops Atlanticus (Atlantic tarpon). The microstructure and composition were evaluated by Scanning Electron Microscopy (SEM) and RAMAN spectroscopy, respectively. The mechanical properties were evaluated in uniaxial tension as a function of position along the length of the fish (head, mid-length and tail). Results showed that the scales are composed of collagen and hydroxyapatite, and these constituents are distributed within three well-defined layers from the bottom to the top of the scale. The proportion of these layers with respect to the total scale thickness varies radially. The collagen fibers are arranged in plies with different orientations and with preferred orientation in the longitudinal direction of the fish. Results from the tensile tests showed that scales from Megalops Atlanticus exhibit variations in the elastic modulus as a function of body position. Additional testing performed with and without the highly mineralized top layers of the scale revealed that the mechanical behavior is anisotropic and that the highest strength was exhibited along the fish length. Furthermore, removing the top mineralized layers resulted in an increase in the tensile strength of the scale.

Advancing the science and management of flats fisheries for bonefish, tarpon, and permit

The fish of the sub-tropical and tropical flats including bonefish (Albula spp.), Atlantic tarpon (Megalops atlanticus), and permit (Trachinotus falcatus), capture the imagination of specialized coastal marine recreational anglers. Until recently, little was known about the biology and natural history of these iconic species. Flats ecosystems are under threat from coastal development and environmental change while basic information on demographics and population size is lacking. This makes it difficult to understand the consequences of these threats, or to formulate potential management strategies. Through extensive partnerships involving anglers, industry, conservation organizations, natural resource agencies, and academics, the mysteries surrounding these species are starting to be solved. Nonetheless, many challenges remain. The systematics of these fish is complex, particularly for the bonefish which include a number of cryptic species. Identifying the timing and habitats associated with reproduction remain high priority such that management efforts can target protecting that important life-history event. Information on the spatial ecology of flats fish at various spatial scales is being elucidated by electronic tagging studies and angler tagging programs. Habitat science for these fish continues to improve but there is still need to identify effective habitat restoration strategies. Catch-and-release science has improved dramatically (especially for A. vulpes in The Bahamas) although there is need to for additional work across regions and species. Targeted species-specific management strategies (e.g., catch-and-release regulations) as well as more ecosystem-level strategies (e.g., habitat protection and fishing effort management) are increasingly being used for active management of flats fish and their habitats. Partnerships will remain key to addressing outstanding research questions and in working cooperatively to ensure that evidence (both scientific and stakeholder knowledge) forms the basis for management decisions.

High resolution profiles of elements in Atlantic tarpon (Megalops atlanticus) scales obtained via cross-sectioning and laser ablation ICP-MS: a literature survey and novel approach for scale analyses

Fish scales may be used as nonlethal alternative structures to otoliths for establishing chemical time-series that trace migration and habitat use for euryhaline species such as Atlantic tarpon (Megalops atlanticus). We survey four decades of fish scale studies employing elemental analyses to show the wide diversity of aims, approaches and instrumentation. Analyses are mainly solution-based measurements of whole or subsampled scales or in situ solid-sampling techniques of specific growth regions. Although spot-based transects across scales have been employed for a handful of species, continuous elemental transects across scale growth increments are rare. Laser ablation based sampling methods that assay scale exteriors can be difficult to implement for species with natural topographic variations exceeding the focal range of the laser. These limitations may be overcome by performing laser ablation of scales in cross-section when scale thickness in the well-calcified external layer provides enough surface area for a laser transect. For this study, scales of Atlantic tarpon were embedded in epoxy and longitudinally cross-sectioned to expose the scale growth record of the external layer. Laser ablation ICP-MS was used to quantify continuous profiles of element:Ca ratios across scale growth increments. The analytes surveyed (Mg, P, Ca, Mn, Sr, and Ba) were consistently above the limits of detection (LODs) across each scale with the exception of Pb for one scale. Obtaining high resolution elemental life history profiles from scales will be essential for future efforts to use this structure as a non-lethal substitute for otoliths in Atlantic tarpon and other migratory fishes that possess scales with sufficiently thick calcified external layers to permit a cross-sectional approach.

A nationwide assessment of threats to bonefish, tarpon, and permit stocks and habitat in Belize

Although Belize has developed an international reputation as being a leader in environmental conservation given that approximately 26 % of its terrestrial and marine territories are designated as protected areas, there remains persistent threats to the country’s bonefish (Albula vulpes), tarpon (Megalops atlanticus), permit (Trachinotus falcatus), and associated habitats. While some of these threats resemble those found in other regions and countries such as pollution or overfishing, Belize’s fisheries also face unique threats because of its proximity to Guatemala and the rapid pace of development along the Belize coast. However, fishing guides and lodge owners have been instrumental in pursuing policies that protect and sustainably manage bonefish, tarpon, and permit stocks. This paper provides a nationwide assessment of some of the major threats facing bonefish, tarpon, permit and associated habitat in Belize, as well as some of the responses to counter these threats.

Trace elements and stable isotopes in Atlantic tarpon scales reveal movements across estuarine gradients

Atlantic tarpon, Megalops atlanticus, are large migratory fish that make use of a wide array of habitats during the course of their lifetime, including oceanic, coastal and upper estuaries. Many aspects of the migratory ecology of this species are poorly described, including the scope of individual variability in movements across estuarine gradients. Population abundances have declined precipitously in recent decades leading to its classification as “Vulnerable” under the IUCN, lethal methods of identifying migration patterns such as otolith analyses are not feasible. We therefore examined the non-lethal alternative method of combined stable isotope and trace element analysis in subsamples of scales removed from living fish collected in subtropical areas of the western Gulf of Mexico and Puerto Rico. We found significant differences in chemical signatures from edges of scales collected from separate geographic regions. Within scales, we observed consistent enrichments in δ15N values indicating ontogenetic trophic shifts and individual variation in the remaining proxies (Sr:Ca, Ba:Ca, and δ13C) that suggested differential patterns of movement between marine and fresh waters. Notably, values of δ13C were positively related to Sr:Ca in all geographic regions, suggesting that scale δ13C values primarily reflected movement across salinity gradients rather than fractionation associated with trophic increases. Multi-proxy chemical analysis of Atlantic tarpon scales therefore provides a non-lethal alternative to otolith geochemistry for identifying individual movement and trophic patterns of this highly mobile species.

A reliable game fish weight estimation model for Atlantic tarpon (Megalops atlanticus)

Rapid growth of popular and lucrative catch-and-release marine sportfisheries worldwide has highlighted the need for reliable weight estimation methods for use in fishing tournaments, pursuit of fishing records, and to support scientific research that allows captured fish to be released alive. This paper describes new methods to predict weight from measurements of body size of game fish. Here we also evaluated efficacy of a widely used historical model and compared this to several new statistical and analytical weight estimation models that we developed herein. We applied these candidate models to a unique morphometric data set on Atlantic tarpon (Megalops atlanticus) which contained information on body weight W as a function of fork length L and dorsal girth G for more than 1100 individuals from Florida, the Gulf of Mexico, Caribbean Sea and western Africa. A popular formula (W=G2L/800), developed more than a century ago specifically for tarpon was originally derived from geometric and physical relationships between fish body weight and shape. We found this model to be negatively biased >−15% (i.e., underestimates individual fish weights) across the tarpon's entire size range up to 130kg (the current world record). Bias for our “new” ellipsoid volumetric formulation, which extends the principles of allometry, was less than 1% across the entire range of observed sizes. Our new estimator was used by Texas Parks and Wildlife Department to assist fishery management in setting “minimum maximum” sizes for recreationally caught tarpon that have the potential to break the Texas State record. It has also supported catch-and-release tarpon fisheries and tournaments in Florida, Texas, Mexico, and Trinidad. It provides a reliable means to accurately estimate weights of tarpon of potential (world) record sizes.

Vertical movement rates and habitat use of Atlantic tarpon

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 467:167-180 (2012) - DOI: https://doi.org/10.3354/meps09957 Vertical movement rates and habitat use of Atlantic tarpon Jiangang Luo*, Jerald S. Ault University of Miami, Rosenstiel School of Marine and Atmospheric Science, Division of Marine Biology and Fisheries, 4600 Rickenbacker Causeway, Miami, FL 33149, USA *Email: jluo@rsmas.miami.edu ABSTRACT: We evaluated vertical depth and thermal habitat utilization of Atlantic tarpon Megalops atlanticus from high-resolution temporal data on 42 recovered pop-up archival transmitting (PAT) tags deployed and recovered from 2002 to 2010 to estimate vertical movement rates (swim speeds) during descents and ascents. All individuals strongly preferred shallow waters, spending >80% of their time in water depths <10 m. Diel vertical distributions followed 4 patterns, but there was substantial variation within and among individuals. Vertical descent and ascent rates, defined as changes in depths extending ≥2 m over time, were estimated from tag data with 1 s sampling intervals. Descent rates ranged from 0.01 to 2.74 m s−1, while ascent rates ranged from 0.01 to 4.5 m s−1. Relatively uncommon deep diving behaviors might be associated with spawning activity. The most preferred water temperature was ~26°C, particularly during the spring and fall migratory periods. However, these reached >29°C in summer when tarpon were at their feeding grounds at the northern extreme of their range. Peaks of ‘rolling and jumping’ behaviors inferred from relative conductivity sensor data occurred with greatest frequency just after sunset and sunrise. KEY WORDS: Megalops atlanticus · Satellite tracking · Thermal habitat · Rolling and jumping · Diel patterns Full text in pdf format PreviousNextCite this article as: Luo J, Ault JS (2012) Vertical movement rates and habitat use of Atlantic tarpon. Mar Ecol Prog Ser 467:167-180. https://doi.org/10.3354/meps09957 Export citation RSS - Facebook - Tweet - linkedIn Cited by Published in MEPS Vol. 467. Online publication date: October 25, 2012 Print ISSN: 0171-8630; Online ISSN: 1616-1599 Copyright © 2012 Inter-Research.