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Home Range of Juvenile Lemon Sharks, Negaprion brevirostris
Abstract
Manual acoustic telemetry techniques were used to study spatial and temporal patterns of movement of juvenile lemon sharks. Ultrasonic transmitters were implanted into the coelom of 38 sharks, yielding trackings totaling 2281 telemetry fixes. Activity space varied from 0.23 km2 to 1.26 km2 and was positively correlated with shark size. Three indices of site attachment demonstrated that juvenile lemon sharks establish a home range. An index of site defense and field observations indicated that no territoriality was observed against conspecifics.
... In Bimini, The Bahamas, juvenile and subadult lemon sharks, Negaprion brevirostris, use the nearshore nursery habitats around the islands year round (Chapman et al., 2009;Gruber et al., 1988;Guttridge et al., 2012;Morrissey & Gruber, 1993a, 1993b and tidal changes in predation risk have been shown to affect space use, with both juveniles and subadults using inshore areas during high tides and offshore areas during low tides (Guttridge et al., 2012). Despite this, there is no knowledge of how tidally mediated predation risk impacts the activity and behaviour of lemon sharks as they move through the habitat, and what this reveals about key behavioural trade-offs. ...
... Arthur et al., 2008;Komyakova et al., 2019;Lind & Welsh, 1994), including sharks (e.g. Franks, 2007;Knip et al., 2011;Matich & Heithaus, 2015;Morrissey & Gruber, 1993b;Wetherbee et al., 2007;Yeiser et al., 2008). Findings here show that, as predation risk diminished with increasing size of shark, core areas and home range sizes increased while overall activity and resting behaviour decreased. ...
Describing patterns in activity and behaviour of animals as they move through their environment helps to reveal fundamental aspects of their ecology and identify key habitat requirements. Nursery areas are used by many shark species and play an important role in maintaining the viability of populations. Although shark movements within nursery areas have been well studied, far less is known about how space use correlates with activity levels and specific behaviour. In the present study, we used combined accelerometer-acoustic transmitter tag packages to investigate fine-scale space use, activity and behavioural patterns of nursery-bound lemon sharks, Negaprion brevirostris. First, we constructed an ethogram to categorize specific behaviours from accelerometer data collected from seven sharks (97-122 cm total length) that were caught, tagged and observed in captivity for 3-6 days. Second, we conducted field trials with 19 sharks (78-169 cm total length), each tagged and actively tracked during 3-5 deployment days. We then used baited remote underwater video (BRUV) surveys to investigate potential overlap between shark foraging effort and prey distributions. Accelerometer and tracking data showed that the tidal phase significantly affected space use, activity and behaviour. Sharks used near- shore areas during the high tide periods where resting increased and activity levels were reduced. On falling tides, sharks moved farther from the shoreline and increased overall activity. Foraging effort peaked at low tide periods and foraging events overlapped with areas of disproportionately high preferred prey abundance. Ontogenetic patterns were also found in which larger sharks generally occupied larger home ranges, spent more time in areas farther offshore, rested less and foraged more than smaller individuals. These findings represent novel insights into nursery habitat use and behavioural trade-offs in lemon sharks and support more informed management for this threatened species.
... Minimum linear displacement (MLD) was used to estimate linear home range because the array was not designed for detection ranges to overlap. Comparing home range sizes among studies is difficult, due to differences in temporal scales and metrics used for home range analysis by different authors [90,[93][94][95][96], but while Caribbean reef sharks in Belize appeared not to exhibit ontogenetic expansion of home range size [2], such expansion has been observed in juvenile Caribbean reef [11,70] and other reef sharks elsewhere [65,79,93]. While these findings could be an artefact due to the greater detection range of V16 compared to that of V9 tags (used in very small sharks of < 110 cm TL), ontogenetic differences in space use are common in many sharks [9,10,28] and thought to be linked to individual energy requirements. ...
... Minimum linear displacement (MLD) was used to estimate linear home range because the array was not designed for detection ranges to overlap. Comparing home range sizes among studies is difficult, due to differences in temporal scales and metrics used for home range analysis by different authors [90,[93][94][95][96], but while Caribbean reef sharks in Belize appeared not to exhibit ontogenetic expansion of home range size [2], such expansion has been observed in juvenile Caribbean reef [11,70] and other reef sharks elsewhere [65,79,93]. While these findings could be an artefact due to the greater detection range of V16 compared to that of V9 tags (used in very small sharks of < 110 cm TL), ontogenetic differences in space use are common in many sharks [9,10,28] and thought to be linked to individual energy requirements. ...
Understanding how reef-associated sharks use coastal waters through their ontogeny is important for their effective conservation and management. This study used the horizontal movements of acoustically tagged Caribbean reef sharks (Carcharhinus perezi) to examine their use of coastal space around the Cayman Islands between 2009 and 2019. A total of 39 (59.1%) tagged sharks (male = 22, female = 17, immature = 18, mature = 21) were detected on the islands wide network of acoustic receivers. The detection data were used to calculate values of Residency Index (RI), Site-Fidelity Index (SFI) and minimum linear displacement (MLD), as well as for network analysis of individual shark movements to test for differences between demographics, seasons, and diel periods. Sharks were detected for up to 1,598 days post-tagging and some individuals showed resident behaviour but the majority of tagged individuals appear to have been one-off or only occasional transient visitors to the area. Generally, individuals showed strong site-fidelity to different areas displaying linear home ranges of < 20 km. The evidence indicates that there was no pattern of diel behaviour. Tagged sharks generally showed increased movements within and between islands during the summer (April–September), which may be related to breeding activity. Some individuals even made occasional excursions across 110 km of open water > 2,000 m deep between Grand Cayman and Little Cayman. One mature female shark showed a displacement of 148.21 km, the greatest distance reported for this species. The data shows that the distances over which some sharks moved, greatly exceeded the extent of any one of the islands’ marine protected areas indicating that this species may be more mobile and dispersive than previously thought. This study provides support for the blanket protection to all sharks throughout Cayman waters, which was incorporated within the National Conservation Act in 2015.
... To investigate inter-migratory spatial overlap, separate KUDs were calculated for the D. pastinaca that were present before and after their migration. Then an index of reuse was calculated following Morrissey and Gruber (1993), defined as the overlap (intersect) between both areas divided by the cumulative area occupied during both periods. ...
Aggregations and social interactions play an important role in the movement ecology of many animals, including elasmobranchs. Several of these species have shown the capability of carrying out complex social behaviours, and the importance of sociality in this taxon is being realized. Although it is a growing field of study in the case of these organisms, these processes still need to be better understood, especially to support management and conservation policies. In this study, a long-term acoustic telemetry data set collected on Dasyatis pastinaca in a coastal marine protected area was analysed. A co-occurrence network analysis was done to investigate preferential associations among individuals, revealing non-random associations among them. The analysis revealed a few strong and consistent associations that were maintained across inter-migratory periods, as this species performs seasonal migrations to a nearby estuary, suggesting temporal stability of the observed associations. Moreover, individuals had similar average positions and a generally high overlap of space use in both periods, indicating some level of site fidelity to the fully protected area. Groups of up to 64% of tagged individuals were co-detected at a same receiver, particularly in the western side of the array. Despite our limited sample size, likely underestimating associations, these results show that in addition to their large-scale movement pattern, D. pastinaca is likely to also present active partner preference and spatial structure at a finer spatial scale. The nature of such results is relevant to support the protection of these species.
... Thus, considering the small home ranges of these sharks (Bouyoucos et al. 2020), their continuous swimming patterns, and the negligible tidal variation, the probability of capturing neonates at Moorea can be expected to remain somewhat constant, irrespective of lunar phase. In contrast, adult reef sharks can move throughout the deeper parts of the fore reef and lagoons (Compagno 1984;Gruber et al. 1988;Mourier et al. 2013b) or even disperse to other reefs (Chin et al. 2013a;Mourier et al. 2013a) and, hence, are not confined to the small home ranges observed in neonates (Cortes & Gruber, 1990;Morrissey & Gruber 1993). In this case, lunar phase can potentially influence foraging behaviour and decisions of the adult sharks, where the adults move closer to the fringe reefs where prey may be more abundant (Papastamatiou et al. 2009) in anticipation of lunar-mediated foraging opportunities. ...
Elasmobranch (i.e. sharks, skates, and rays) behaviours have been found to align with moon phases; yet, it is not fully understood how the moon influences elasmobranchs’ foraging habits. In coastal ecosystems, tidal changes are typically seen as the primary influence on the behavioural rhythms of fishes, which are linked to the lunar cycle. Sharks have been documented to synchronise behaviours, such as foraging patterns, with the phases of the moon, but studies have yet to clearly separate and identify the mechanisms by which the lunar phase affects these patterns. The island of Moorea, French Polynesia, serves as a nursery habitat for neonatal blacktip reef and sicklefin lemon sharks within the South Pacific amphidromic system, which experiences minimal tidal ranges (~ 0.2 m). This setting provides a unique opportunity to isolate the lunar cycle’s effects from tidal influences. We compared catch rates of neonates of both shark species and foraging success, through stomach content analysis, of blacktip reef sharks across the lunar cycle. Our findings did not support the hypothesis of lunar-induced entrainment of foraging patterns for these neonatal reef sharks. However, understanding the environmental factors that shape the behavioural patterns and foraging strategies of neonatal reef sharks is becoming increasingly important against the backdrop of human disturbances.
... Female lemon sharks at Bimini are regionally philopatric and return to Bimini to pup on a biennial schedule, while the males with which they mate likely reproduce over a much larger area (Feldheim et al., 2002). Juveniles use the shallow waters surrounding Bimini as a nursery and remain in the area until 2-3 years of age or until they reach 90 cm in length (Morrissey & Gruber, 1993) and generally do not move between the North and South Islands . The Bimini nursery contributes to a larger Western Atlantic population that is classified as Vulnerable on the IUCN Red List Hansell et al., 2018Hansell et al., , 2021. ...
Obtaining robust estimates of population abundance is a central challenge hindering the conservation and management of many threatened and exploited species. Close-kin mark-recapture (CKMR) is a genetics-based approach that has strong potential to improve the monitoring of data-limited species by enabling estimates of abundance, survival, and other parameters for populations that are challenging to assess. However, CKMR models have received limited sensitivity testing under realistic population dynamics and sampling scenarios, impeding the application of the method in population monitoring programs and stock assessments. Here, we use individual-based simulation to examine how unmodeled population dynamics and aging uncertainty affect the accuracy and precision of CKMR parameter estimates under different sampling strategies. We then present adapted models that correct the biases that arise from model misspecification. Our results demonstrate that a simple base-case CKMR model produces robust estimates of population abundance with stable populations that breed annually; however, if a population trend or non-annual breeding dynamics are present, or if year-specific estimates of abundance are desired, a more complex CKMR model must be constructed. In addition, we show that CKMR can generate reliable abundance estimates for adults from a variety of sampling strategies, including juvenile-focused sampling where adults are never directly observed (and aging error is minimal). Finally, we apply a CKMR model that has been adapted for population growth and intermittent breeding to two decades of genetic data from juvenile lemon sharks (Negaprion brevirostris) in Bimini, Bahamas, to demonstrate how application of CKMR to samples drawn solely from juveniles can contribute to monitoring efforts for highly mobile populations. Overall, this study expands our understanding of the biological factors and sampling decisions that cause bias in CKMR models, identifies key areas for future inquiry, and provides recommendations that can aid biologists in planning and implementing an effective CKMR study, particularly for long-lived data-limited species.
... The neonates, which measure around 60 cm in length, will remain in these very shallow waters for the first few years of their life. As they grow, they gradually increase the area that they utilise, eventually moving away from the mangroves into deeper sand flats and seagrass areas, eventually joining the adult population offshore or around coral reefs (Morrissey and Gruber 1993). Many of the elasmobranchs that occur in UAE waters follow a similar life cycle as the lemon shark, including the closely related and almost identical sicklefin lemon shark (Negaprion acutidens). ...
The waters of the United Arab Emirates (UAE) are home to a wide variety of shark and ray species, many of which are unique to the region and about which relatively little is known. Research efforts to date have focused primarily on identifying the species that occur locally and their importance to fisheries, but further research is required to understand their inherent biological and ecological traits. Decades of heavy fishing pressure and coastal development have impacted shark and ray populations to the extent that some, once common species, are now considered rare. Encouragingly, the UAE has adopted a National Plan of Action for the Conservation of Sharks to guide researchers and policy makers in their efforts to ensure that the nation’s shark and ray populations are effectively managed and conserved.
Debido a que muchas especies de tiburones cuentan con poblaciones compartidas entre varios países del POT, resulta indispensable contar con programas estandarizados que permitan la comparación de datos en la región y ayuden a establecer políticas de manejo y conservación regionales adecuadas. En este sentido, los programas de marcaje y monitoreo de tiburones tienen el potencial de proporcionar información valiosa sobre la historia de vida y patrones de movimiento de los tiburones, contribuyendo a la toma de decisiones para su protección y manejo sostenible. Sin embargo, su efectividad depende en gran medida del diseño y la aplicación de buenas prácticas. Un programa de marcaje y monitoreo mal diseñado o ejecutado puede llevar a resultados inservibles, sesgados e incluso al daño irreversible de los tiburones marcados.
El presente documento tiene como objetivos: 1) describir los conceptos biológicos y ecológicos básicos de las áreas de crianza de tiburones; 2) describir las metodologías y técnicas utilizadas para el estudio de tiburones neonatos y juveniles; 3) generar un protocolo estandarizado para la caracterización y monitoreo de las potenciales áreas de crianza; y 4) promover las buenas prácticas que garanticen la calidad y comparabilidad de los datos obtenidos así como la supervivencia de los tiburones. Esperamos que este documento sea de utilidad tanto para investigadores como para las personas interesadas en el estudio y la conservación de las áreas de crianza de tiburones.
Use of a small tropical nursery in the Los Roques Archipelago by lemon sharks (Negaprion brevirostris) was investigated using acoustic telemetry. Twelve juvenile lemon sharks of three size classes were tracked between February 2014 and August 2015 in the Sebastopol Lagoon. Sharks were strongly site attached and remained in the lagoon for the duration of the study. Individuals in the smallest size class exhibited restricted movements within the innermost area of the lagoon in shallow water (< 1 m), over muddy substrate and along mangrove-lined shores. Sharks in the two larger size classes ranged further, in deeper water, over a wider range of substrates and more frequently near the lagoon entrance. Activity space varied among size classes, with home range (95% kernel utilization densities–KUD) of 0.42 km² and core area (50% KUD) of 0.13 km² for individuals in the smallest size class. For the medium and large size classes home ranges were 1.11 and 1.15 km² and core areas were 0.33 and 0.35 km² respectively. Space use as Minimum Convex Polygons differed among size classes, with overlap between the two largest size classes of 89%, compared with 40% between medium and smallest and 43% for largest and smallest size classes. Space use of lemon sharks in the Los Roques nursery illustrates variable use of habitat with varying environmental characteristics, likely reflecting a balance between predator avoidance and prey acquisition. Greater understanding of the use of nursery habitats for species such as lemon sharks, which use small, discrete nurseries over a broad geographical range can enhance our understanding of relationships between life history traits and environmental variability and management of populations.
Use of a small tropical nursery in the Los Roques Archipelago by lemon sharks (Negaprion brevirostris) was investigated using acoustic telemetry. Twelve lemon sharks (six female, six male, three each of age classes 0+, 1+, and 2+) were tracked between February 2014 and August 2015 in the Sebastopol Lagoon. Sharks were strongly site attached and remained in the lagoon for the duration of the study. Age 0+ individuals largely restricted their movements within the innermost area of the lagoon in shallow water (< 1 m), over muddy substrate and along mangrove-lined shores. Ages 1+ and 2+ sharks ranged further, in deeper water, over a wider range of substrates and more frequently to areas near the lagoon entrance. Activity space (home range = 95% kernel utilization densities - KUD) was 0.42, 1.11 and 1.15 km2 for age 0+, 1+ and 2+ sharks respectively. Core area (50% KUD) was 0.13, 0.33 and 0.35 km2 for age 0+, 1+ and 2+ sharks respectively. MCP overlap between ages 1+ and 2+ was 89%, in contrast to smaller overlap between ages 0+ and 1+ (40%) and 0+ and 2+ (43%). Abundance of potential prey was greatest along mangroves fringes, decreasing from the innermost lagoon to entrance. Space use of lemon sharks within nurseries of variable characteristics illustrates a consistent balancing of selective pressures on predator avoidance and prey acquisition among inconsistent nursery habitats. Understanding nursery area use aids informed management of lemon shark populations and incorporation of species-wide life history traits for sustainable management practices.
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