The Center for Shark Research

Sarasota, FL, United States

The Center for Shark Research

Sarasota, FL, United States

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Aguilar C.,University of Habana | Aguilar C.,University of Guadalajara | Gonzalez-Sanson G.,University of Guadalajara | Hueter R.,The Center for Shark Research | And 6 more authors.
Latin American Journal of Aquatic Research | Year: 2014

Sharks have been important as seafood source and fisheries revenue in Cuba. Nevertheless, current information about this group of fishes in Cuba is scarce and in the last decades they have not been the focus of any organized research. From October 2009 to June 2011, fisheries and biological (229 sharks examined) data were collected at four landing sites in the northwest of Cuba. At present, there is no organized fishery specifically targeting only sharks along the northwest coast of Cuba, but they are caught as a component of multispecies fisheries on the insular shelf and as bycatch in longline fisheries targeting billfishes. We registered a total of 17 species, six in the commercial fishery, dominated by Carcharhinus perezii, Sphyrna mokarran, and Carcharhinus leucas, and 14 in the sport fishery (i.e., small-scale artisanal, not recreational properly), dominated by Isurus oxyrinchus, Isurus paucus, Carcharhinus longimanus, Carcharhinus falciformis, Galeocerdo cuvier and Prionace glauca. Mean CPUE by months in sport fishing varied from 0.43 to 4.44 number of sharks caught per ten fishing trips. Most oceanic sharks caught in the Cuban sport fisheries are highly migratory species and their populations show great ecological connectivity throughout the Gulf of Mexico and adjacent waters. This fact and the presence of a high proportion of individuals of C. longimanus and C. falciformis below maturity size are important results to be considered for regional conservation of sharks and planning rational use of shark fisheries.


Bassos-Hull K.,The Center for Shark Research | Bassos-Hull K.,c o Mote Marine Laboratory | Wilkinson K.A.,The Center for Shark Research | Wilkinson K.A.,Ziegler | And 7 more authors.
Environmental Biology of Fishes | Year: 2014

The spotted eagle ray, Aetobatus narinari, is listed on the IUCN Red List of Threatened Species as Near Threatened with a decreasing population trend, but many aspects of this ray's biology and population status are unknown. Aerial and on-water surveys were conducted in the eastern Gulf of Mexico off southwest Florida 2008-2013, to document seasonal occurrence and life history characteristics of this species. Aerial surveys documented spotted eagle rays mostly in spring, summer, and autumn months with larger aggregations observed near inlet passes. Boat-based surveys documented rays on 152 out of 176 survey days, mostly as solitary individuals but sometimes in aggregations of up to 60. More rays were observed when water temperatures were 23-31 oC. A total of 393 rays (231 males, 161 females, 1 unrecorded sex) were captured, measured, sampled, tagged, and released. Sizes ranged 41.4-203.0 cm disc width (DW) and weight 1.1-105.5 kg. Male size at 50 % maturity was 127 cm DW. Five percent (19) of tagged rays were recaptured after 5-1,293 days at liberty and recaptured rays exhibited faster growth than previously estimated from vertebral readings. Based on observations of rays relative to survey effort, numbers of observed rays declined after 2009 for reasons not yet understood. This observation, together with concerns about sustainability of fisheries targeting these rays in nearby Mexico and Cuba, underscore the need for investigations into stock structure, population trends, growth, and critical habitat of spotted eagle rays throughout the Gulf of Mexico, Caribbean Sea, and elsewhere in their range. © 2014 Springer Science+Business Media Dordrecht.


Mara K.R.,University of South Florida | Motta P.J.,University of South Florida | Martin A.P.,University of Colorado at Boulder | Hueter R.E.,The Center for Shark Research
Journal of Morphology | Year: 2015

The study of functional trade-offs is important if a structure, such as the cranium, serves multiple biological roles, and is, therefore, shaped by multiple selective pressures. The sphyrnid cephalofoil presents an excellent model for investigating potential trade-offs among sensory, neural, and feeding structures. In this study, hammerhead shark species were chosen to represent differences in head form through phylogeny. A combination of surface-based geometric morphometrics, computed tomography (CT) volumetric analysis, and phylogenetic analyses were utilized to investigate potential trade-offs within the head. Hammerhead sharks display a diversity of cranial morphologies where the position of the eyes and nares vary among species, with only minor changes in shape, position, and volume of the feeding apparatus through phylogeny. The basal winghead shark, Eusphyra blochii, has small anteriorly positioned eyes. Through phylogeny, the relative size and position of the eyes change, such that derived species have larger, more medially positioned eyes. The lateral position of the external nares is highly variable, showing no phylogenetic trend. Mouth size and position are conserved, remaining relatively unchanged. Volumetric CT analyses reveal no trade-offs between the feeding apparatus and the remaining cranial structures. The few trade-offs were isolated to the nasal capsule volume's inverse correlation with braincase, chondrocranial, and total cephalofoil volume. Eye volume also decreased as cephalofoil width increased. These data indicate that despite considerable changes in head shape, much of the head is morphologically conserved through sphyrnid phylogeny, particularly the jaw cartilages and their associated feeding muscles, with shape change and morphological trade-offs being primarily confined to the lateral wings of the cephalofoil and their associated sensory structures. J. Morphol. 276:526-539, 2015. © 2015 Wiley Periodicals, Inc.


Newby J.,College of Charleston | Darden T.,South Carolina Department of Natural Resources | Bassos-Hull K.,The Center for Shark Research | Shedlock A.M.,College of Charleston
Environmental Biology of Fishes | Year: 2014

Observations of elasmobranchs in groups suggest sociality in sharks and rays. However we currently lack a strong understanding of social structure and the role kinship has in structuring group organization in cartilaginous fishes. The spotted eagle ray, Aetobatus narinari (Euphrasen, 1790) frequents the shallow waters near Sarasota, FL, often in pairs or groups suggesting a social component to their behavior. In the present study, eight eagle ray-specific microsatellite markers were used to investigate relatedness in A. narinari groups, and used to determine if kin structure contributed to group organization. Using regression-based and maximum-likelihood approaches, relatedness was quantified and compared within and among groups of juveniles, and adults in mixed sex and same sex groups. Results showed a lack of kin-structured sociality in A. narinari, suggesting factors apart from relatedness shape social interactions among spotted eagle rays in the near-shore waters of Sarasota, FL. Our results add to the limited amount of published literature on elasmobranch kinship, which are important for understanding implications of anthropogenic disturbance on genetic variability for coastal populations. © 2014 Springer Science+Business Media Dordrecht.

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