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Feldheim K.A.,Pritzker Laboratory for Molecular Systematics and Evolution | Gruber S.H.,Bimini Biological Field Station Foundation | Dibattista J.D.,King Abdullah University of Science and Technology | Kessel S.T.,Great Lakes Institute for Environmental Research | And 4 more authors.
Molecular Ecology | Year: 2014

Sharks are a globally threatened group of marine fishes that often breed in their natal region of origin. There has even been speculation that female sharks return to their exact birthplace to breed ('natal philopatry'), which would have important conservation implications. Genetic profiling of lemon sharks (Negaprion brevirostris) from 20 consecutive cohorts (1993-2012) at Bimini, Bahamas, showed that certain females faithfully gave birth at this site for nearly two decades. At least six females born in the 1993-1997 cohorts returned to give birth 14-17 years later, providing the first direct evidence of natal philopatry in the chondrichthyans. Long-term fidelity to specific nursery sites coupled with natal philopatry highlights the merits of emerging spatial and local conservation efforts for these threatened predators. © 2013 John Wiley & Sons Ltd.


Ashe J.L.,Marine Conservation Institute | Feldheim K.A.,Pritzker Laboratory for Molecular Systematics and Evolution | Fields A.T.,Marine Conservation Institute | Reyier E.A.,Kennedy Space Center Ecological Program | And 5 more authors.
Marine Ecology Progress Series | Year: 2015

Genetic diversity, population genetic structure and isolation by distance (IBD) were assessed in a viviparous coastal shark (the lemon shark Negaprion brevirostris) across 8 western Atlantic samples spaced between ∼150 and 7000 km apart. Juveniles (N = 325) were sequenced at 2 mitochondrial loci (1729 bp) and typed at 9 nuclear encoded microsatellite loci. Analysis of mitochondrial sequences revealed higher diversity at low-latitude island samples compared to highlatitude continental samples, consistent with an equatorial center-of-origin for this species. There were 5 distinct groups across our sampling areas (Brazil, Louisiana, Cape Canaveral, Gullivan Bay and the Florida Keys/Bahamas/Virgin Islands; pairwise ℙST = 0.07-0.87) and all but one pair of the 8 samples also exhibited significantly different haplotype frequencies (pairwise FST = 0.10-0.51). Bayesian analysis indicated that the Brazil and Louisiana samples were generally isolated from the others, but most of the rest were diverged although still connected or recently connected by migration. In contrast, structure was only detected between the most distant sample (Brazil) and all of the others using the microsatellite markers (pairwise FST = 0.03-0.06). There was a significant pattern of IBD for all markers and measures of genetic differentiation (r2 = 0.65-0.81, p < 0.05- 0.01), but not after removing the Brazil sample. There was evidence that glacial and post-glacial historical processes and sex-specific differences in philopatry affected IBD. Because of the relatively fine-scale population structure of this and other large coastal shark species more attention should be paid to local processes in the conservation and fisheries management of these species. © Inter-Research 2015.


Gledhill K.S.,South African Shark Conservancy | Kessel S.T.,University of Windsor | Guttridge T.L.,Bimini Biological Field Station Foundation | Hansell A.C.,University of Massachusetts Dartmouth | And 5 more authors.
Journal of Fish Biology | Year: 2015

A longline survey was conducted from 2004 to 2014 to investigate the demographic population structure and seasonal abundance of the blacktip shark Carcharhinus limbatus in the Bimini Islands, the Bahamas. All individuals sampled (n = 242) were sub-adult or adults [70·1-145·1 cm pre-caudal length (LPC) range] with no neonates or YOY recorded in Bimini. Carcharhinus limbatus abundance peaked in September, coincident with the largest ratio of female to male sharks and a peak in fresh mating wounds on females. Mitochondrial control region (mtCR) DNA sequences were obtained from C. limbatus at Bimini to test whether Bimini C. limbatus are most closely related to geographically proximate populations sampled on the south-eastern coast of the U.S.A., the closest known nursery areas for this species. Nine mtCR haplotypes were observed in 32 individuals sampled at Bimini [haplotype diversity (h) = 0·821, nucleotide diversity (π) = 0·0015]. Four haplotypes observed from Bimini matched those previously found in the northern Yucatan (Mexico)-Belize and two matched a haplotype previously found in the U.S.A. Four haplotypes were novel but were closely related to the northern Yucatan-Belizean haplotypes. Pair-wise ΦST analysis showed that Bimini was significantly differentiated from all of the populations previously sampled (U.S.A. Atlantic, U.S.A. Gulf of Mexico, northern Yucatan, Belize and Brazil). This indicates that C. limbatus sampled from Bimini are unlikely from the described, proximate U.S.A. nurseries. © 2015 The Fisheries Society of the British Isles.


Kessel S.T.,University of Windsor | Kessel S.T.,University of Cardiff | Chapman D.D.,State University of New York at Stony Brook | Franks B.R.,Bimini Biological Field Station Foundation | And 5 more authors.
Marine Ecology Progress Series | Year: 2014

Understanding how and why animals are distributed through time and space has always been a fundamental component of ecology and is an essential prerequisite for effective conservation and/or management. However, for highly mobile K-selected species, behavioural predictability is rarely considered over appropriate scales relative to life history. To address this point, a multidisciplinary approach combining telemetry, external tagging, physical assessment, environmental monitoring and genetic analysis was adopted to determine a spatial framework for the movements of adult lemon sharks Negaprion brevirostris at multiple spatial and temporal scales from 2007 to 2011. Lemon sharks (n = 83) were tracked with passive acoustic telemetry, revealing a winter residency in the southeast Florida region. Detections from individuals recorded within the core winter habitat for >20 d (n = 56) were incorporated into generalized linear mixedeffects models to investigate the influence of water temperature, photoperiod, moon phase, month and year on presence. The findings of this study suggest a temperature driven 'migrationresidency' model for mature lemon shark distribution across the USA eastern seaboard. Lemon sharks are distributed across a wide geographical area in the summer months and migrate south concentrating off southeast Florida in the winter, with this pattern repeated each year. From comparative genetic analysis and the absence of any evidence of mating behaviour during the winter residency period, mating and parturition most probably occur in May/June between northern Florida and the Carolinas. This study highlights the importance of determining the specific dynamics and proximate causes of animal movement and distribution over appropriate spatial and temporal scales relative to life history. © Inter-Research 2014.


PubMed | University of Windsor, Pritzker Laboratory for Molecular Systematics and Evolution, Bimini Biological Field Station Foundation, South African Shark Conservancy and 3 more.
Type: Journal Article | Journal: Journal of fish biology | Year: 2015

A longline survey was conducted from 2004 to 2014 to investigate the demographic population structure and seasonal abundance of the blacktip shark Carcharhinus limbatus in the Bimini Islands, the Bahamas. All individuals sampled (n = 242) were sub-adult or adults [701-1451 cm pre-caudal length (LPC) range] with no neonates or YOY recorded in Bimini. Carcharhinus limbatus abundance peaked in September, coincident with the largest ratio of female to male sharks and a peak in fresh mating wounds on females. Mitochondrial control region (mtCR) DNA sequences were obtained from C. limbatus at Bimini to test whether Bimini C. limbatus are most closely related to geographically proximate populations sampled on the south-eastern coast of the U.S.A., the closest known nursery areas for this species. Nine mtCR haplotypes were observed in 32 individuals sampled at Bimini [haplotype diversity (h) = 0821, nucleotide diversity () = 00015]. Four haplotypes observed from Bimini matched those previously found in the northern Yucatan (Mexico)-Belize and two matched a haplotype previously found in the U.S.A. Four haplotypes were novel but were closely related to the northern Yucatan-Belizean haplotypes. Pair-wise ST analysis showed that Bimini was significantly differentiated from all of the populations previously sampled (U.S.A. Atlantic, U.S.A. Gulf of Mexico, northern Yucatan, Belize and Brazil). This indicates that C. limbatus sampled from Bimini are unlikely from the described, proximate U.S.A. nurseries.


PubMed | University of Windsor, University of Massachusetts Dartmouth, University of Cardiff and Bimini Biological Field Station Foundation
Type: Journal Article | Journal: Journal of fish biology | Year: 2016

In Bimini, Bahamas, the consistent employment of longlines, beginning in 1982, provided a rare opportunity to explore population trends for large resident sharks. This study assessed three shallow water longline survey periods at this location; 1982-1989, 1992-2002 and 2003-2014, with the aim of determining trends in annual catch per unit effort (CPUE) for an IUCN listed near-threatened species, the lemon shark Negaprion brevirostris. A general additive model (GAM) was used to analyse the non-linear annual CPUE values over the entire 32-year research period. The GAM displayed high variability of annual CPUE, with a peak value of 0026 N. brevirostris per hook day (hooks day(-1) ) in 2000. The temporal pattern of CPUE indicated an abundance trend with a complete cycle, from trough to trough, occurring over a period of approximately 18 years. The 1982-1989 survey period saw the highest proportion of mature individuals (198%) and the smallest average pre-caudal length (LPC ; 1248 cm). The 1992-2002 survey period had the highest average annual CPUE (0018 hooks day(-1) ), while the 2003-2014 research period saw largest average LPC size (1348 cm) and the lowest average CPUE values (0009 hooks day(-1) ) of the entire research period. The long-term trend identified in this study provides a baseline for future assessment.


PubMed | Florida State University, Bimini Biological Field Station Foundation, National Oceanic and Atmospheric Administration, South African Shark Conservancy and 2 more.
Type: Journal Article | Journal: Journal of fish biology | Year: 2015

This study documents and discusses recent (2002-2015) sightings and captures of smalltooth sawfish Pristis pectinata in the Bahamas. Movement patterns and habitat preferences of five P. pectinata are examined: two tracked with acoustic telemetry in Bimini and three tagged with pop-up archival transmitting tags in Andros. Historically, P. pectinata may have been distributed throughout the Bahamas; however, since 2002 only 61 encounters were recorded including: Andros (30), Bimini (19) and a handful across other Islands (12). In Bimini, all P. pectinata were >225 cm (stretched total length, LST) suggesting that it is not used as a nursery area. Pristis pectinata in Andros ranged from c. 80 to 450 cm (LST) indicating that this island might be an important nursery and breeding habitat. Pristis pectinata tracked in both islands remained at depths <3 m, often adjacent to mangrove habitats, displaying residency from 42 days (Bimini) to 180 days (Andros). These preliminary findings confirm the Bahamas as an important habitat for P. pectinata and emphasize the urgent need for national protection and management of this population.


PubMed | University of New South Wales, Copenhagen University, Bimini Biological Field Station Foundation, CNR Institute for Coastal Marine Environment and 4 more.
Type: Journal Article | Journal: Biology open | Year: 2016

Billfishes are considered to be among the fastest swimmers in the oceans. Previous studies have estimated maximum speed of sailfish and black marlin at around 35ms


Bullock R.W.,Bimini Biological Field Station Foundation | Bullock R.W.,University of Hull | Guttridge T.L.,Bimini Biological Field Station Foundation | Cowx I.G.,University of Hull | And 3 more authors.
Journal of Fish Biology | Year: 2015

Behavioural responses of lemon sharks Negaprion brevirostris to a fin-mounted tag package (CEFAS G6A tri-axial accelerometer with epoxied Sonotronics PT4 acoustic transmitter) were measured in a controlled captive environment (n = 10, total length, LT range 80-140 cm) and in free-ranging sharks upon release (n = 7, LT range100-160 cm). No changes were detected in behaviour (i.e. swimming speed, tailbeat frequency, time spent resting and frequency of chafing) between control and tagged captive shark trials, suggesting that the tag package itself does not alter behaviour. In the free-ranging trials, an initial period of elevated swimming activity was found in all individuals (represented by overall dynamic body acceleration). Negaprion brevirostris, however, appeared to recover quickly, returning to a steady swimming state between 2 and 35 min after release. Post-release tracking found that all sharks swim immediately for the shoreline and remain within 100 m of shore for prolonged periods. Hence, although N. brevirostris are capable of quick adaptation to stressors and demonstrate rapid recovery in terms of activity, tracking data suggest that they may modify their spatial use patterns post release. This research is important in separating deviation in behaviour due to environmental stressors from artefacts caused by experimental techniques. © 2015 The Fisheries Society of the British Isles.


PubMed | University of Hull and Bimini Biological Field Station Foundation
Type: Journal Article | Journal: Journal of fish biology | Year: 2015

Behavioural responses of lemon sharks Negaprion brevirostris to a fin-mounted tag package (CEFAS G6A tri-axial accelerometer with epoxied Sonotronics PT4 acoustic transmitter) were measured in a controlled captive environment (n = 10, total length, LT range 80-140 cm) and in free-ranging sharks upon release (n = 7, LT range 100-160 cm). No changes were detected in behaviour (i.e. swimming speed, tailbeat frequency, time spent resting and frequency of chafing) between control and tagged captive shark trials, suggesting that the tag package itself does not alter behaviour. In the free-ranging trials, an initial period of elevated swimming activity was found in all individuals (represented by overall dynamic body acceleration). Negaprion brevirostris, however, appeared to recover quickly, returning to a steady swimming state between 2 and 35 min after release. Post-release tracking found that all sharks swim immediately for the shoreline and remain within 100 m of shore for prolonged periods. Hence, although N. brevirostris are capable of quick adaptation to stressors and demonstrate rapid recovery in terms of activity, tracking data suggest that they may modify their spatial use patterns post release. This research is important in separating deviation in behaviour due to environmental stressors from artefacts caused by experimental techniques.

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