Florida Museum of Natural History

Abstracts of AES Scientific Papers

American Elasmobranch Society 1999 Annual Meeting
State College, Pennsylvania
ABSTRACTS - Part 3: Manire through Purdy
*Manire, Charles A., Rasmussen, L. E. L.

(CAM) Mote Marine Laboratory, Mote Marine Laboratory, Sarasota, FL 34236; (LLR) Department of Biochemistry and Molecular Biology, Oregon Graduate Institute, Beaverton, OR 97006

Do shark reproductive steroid hormone concentrations exhibit a diurnal cyclical pattern?

Despite the recent increased understanding of the patterns and roles of steroid hormones in elasmobranch reproduction, little is known regarding short-term cycles in these animals. Diel cycles in reproductive steroid hormones have been described in a wide variety of vertebrates including mammals, reptiles, amphibians, and teleost fishes. To determine whether the bonnethead shark,  Sphyrna tiburo, undergoes a similar diurnal cycle, blood was collected from mature females from the wild at three hour intervals over a two day period. The serum derived from this blood was then analyzed for 17-beta estradiol, progesterone, testosterone, dihydrotestosterone and corticosterone. These hormone concentrations were determined using standard radioimmunoassay techniques. Results of these analyses and implications of the findings will be presented. 

*Manire, Charles A., Rasmussen, L. E. L., Tricas, Tim

(CAM) Mote Marine Laboratory, Sarasota, FL 34236; (LLR) Department of Biochemistry and Molecular Biology, Oregon Graduate Institute, Beaverton, OR 97006; (TT) Department of Biological Science, Florida Institute of Technology, Melbourne, FL 32901

Elasmobranch corticosterone concentrations: related to stress or sex or what?

The steroid 1-alpha hydroxycorticosterone is known to be the major stress hormone in elasmobranchs, but the related steroid corticosterone that serves as a stress hormone in many other groups of animals is also present in elasmobranch serum. To determine whether corticosterone might function as a secondary stress hormone, blood samples were collected from bonnethead sharks,  Sphyrna tiburo, in the wild when the exact time of first contact with the net for capture was known. Some of the sharks sampled in this way were taken into the laboratory for monitoring of hormone levels over a longer time frame as well. No change in corticosterone concentration was detected either for short term stress (acute stress) or for longer term stress (chronic stress) in these animals. To assess the possibility of a reproductive role for this steroid, samples were taken from immature and mature male and female bonnetheads in the wild, and a number held in the laboratory over a large portion of the reproductive cycle, as well as from mature male and female Atlantic stingrays,  Dasyatis sabina, from the wild. There was a significant difference between male and female corticosterone concentrations, but no difference between immature and mature sharks. There were also significant differences for both mature male and female sharks and stingrays at different reproductive stages. 

*Marshall, Allan, Smith, Mark, Correia, Joáo P., Oliveira, Miguel de Esplanada D. Carlos I.

Oceanário de Lisboa, Lisboa, 1998 Portugal

Development of elasmobranch transportation techniques

An overview of techniques utilized to transport elasmobranchs to the Oceanário de Lisboa is undertaken. Specifically, techniques to capture, restrain and transport elasmobranchs are examined. In addition, anaesthetic regimes and profilactic protocols are reviewed. The efficacy of different techniques is discussed. 

Martin, Andrew P.

Dept EPOB, University of Colorado, Boulder, CO 80309

Rates of organelle and nuclear gene evolution follow same rules: continuing lessons from sharks

Rates of nucleotide substitution for organelle and nuclear genes are thought to follow different sets of rules. Rates of nucleotide substitution for nuclear genes may be governed primarily by the number of germ line replication events (the so called "generation time" hypothesis) whereas rates of mitochondrial DNA evolution appear to be controlled primarily by DNA damage pathways of mutation mediated by mutagenic by-products of oxidative phosphorylation (the so called "metabolic rate" hypothesis). Comparison of synonymous substitution rates estimated for dlx, hsp70, and RAG-1 genes in mammals and sharks, two taxa with similar generation times but differing metabolic rates, shows that rates of molecular evolution in sharks are approximately an order of magnitude slower than mammals for both nuclear and mitochondrial genes. In addition, there is significant positive covariation of substitution rate for mitochondrial and nuclear genes within sharks. These results, interpreted in the light of differences in life history and metabolic rate between taxa, and coupled with increasing evidence for cross-genome activity of DNA repair enzymes, suggests that molecular clocks for mitochondrial and nuclear genes follow the same set of rules. 

*Mattos, Sérgio, Pereira, José, Ferreira, Beatrice

(SM) Pç Min Joáó Gonçalves de Souza, SUDENE, Renewable Natural Resources, Recife, Pernambuco 50670-900 Brazil; (JP, BF) Departamento de Oceanografia, Federal University of Pernambuco, Recife, Pernambuco 50670-901 Brazil

Growth parameters of the Caribean sharpnose shark  Rhizoprionodon porosus  (poey, 1861) off Pernambuco State (Brazil) continental shelf 

The Caribbean sharpnose shark,  Rhizoprionodon porosus  (Poey, 1861), is a tropical specie found in Caribbean waters, along all Brazilian coast, until Uruguay waters. The present paper aim to present a preliminary result of growth parameters of the Caribbean sharpnose shark, from specimens caught by the artisanal fishery of Pernambuco State-Brazil, relevant for the adequate resources administration. The growth curves for females as much as for males, in length and weight, demonstrate that females grow larger, but males grow faster, and that K, t and L(infinite) values, are close if compared to other genus species, and even if compared with other small and medium groups size sharks. The obtained growth curves in centimeters, from von Bertalanffy (1938) mathematics equation, are:

L = 87.13 [1 - e -0.42 (t + 1.10) ] (males) and

L = 106.82 [1 - e -0.30 (t + 1.12) ] (females).

There was a high significant difference among the growth curves in length for males and females. For the gutted weight / total length relationship for males and females, the mathematics equations are:

W = 0.0054 L2.8993  (males) and

W = 0.0017 L3.1666  (females).

It was observed a significant difference among gutted weight / total length relationship for males and females. From the mathematics expression of the growth curve in length and the gutted weight / total length relationship, it was obtained the growth curve in weight in grams, for males and females:

W = 2,277.9 [1 - e-0.42 (t + 1.10) ]2.8993  (males) and

W = 4,512.6 [1 - e -0.30 (t + 1.12) ]3.1666, (females).

*Mattos, Sérgio, Nunes, Danillo, Hazin, Fabio

(SM) Pç Min João Gonçalves de Souza, SUDENE, Renewable Natural Resources, Recife, Pernambuco 50670-900 Brazil; (DN, FH) Av Dom Manoel de Medeiros, s/n, Federal Rural University of Pernambuco, Recife, Pernambuco 52171-900 Brazil

Reproductive biology of the Caribean sahrpnose shark  Rhizoprionodon porosus  (Poey, 1861) off Pernambuco State (Brazil) Continental Shelf

The Caribbean sharpnose shark, Rhizoprionodon porosus (Poey, 1861), is a tropical specie found in the Caribbean waters, along all Brazilian coast, until the Uruguay waters. The present paper aim to describe the preliminary results on the reproductive biology of the Caribbean sharpnose shark. A total of 264 specimens were analysed, 161 been females, with total length (TL) ranging from 33.5 to 100.5 cm, and 103 been males, with TL ranging from 33.5 to 80.0 cm. The total body weight (TW) range from 128.0 to 5,010.0 g for females and from 131.5 to 1,907.0 g for males. Among the females, 80 were pregnant, with TL ranging from 63.0 to 100.5 cm. The Diameter of the largest ovarian follicle in these pregnant females showed a growth at the same rate of the embryos growth, indicating that probably they should be ready for another ovulation immediately after parturition. The sub-adult and pre-ovulatory females presented a TL near to the pregnant females. The actual data suggest that females first mature at approximately 65 cm in the Pernambuco State waters. Concerning males, the clasper length showed a sharp increase in the 60-65 cm length class, and together with the data on clasper calcification, suggest that male first mature at these length. 

*McCandless, Camilla T., Pratt, Harold L., Kohler, Nancy E.

(CTM) Department of Fisheries, Animal and Veterinary Sciences, University of Rhode Island, Kingston, RI 02881; (HLP, NEK) NOAA/NMFS/NEFSC Narragansett Lab, National Marine Fisheries Service, Narragansett, RI 02882

Preliminary Results of the 1998 Cooperative Atlantic States Shark Pupping and Nursery Survey (COASTSPAN)

Understanding coastal shark nursery habitat is critical to effective management and necessary for defining essential fish habitat (EFH). The Apex Predators Program (APP) formed the Cooperative Atlantic States Shark Pupping and Nursery Survey (COASTSPAN), an alliance of state cooperators to investigate shark nursery grounds along the east coast of the United States. Cooperative researchers in selected coastal states conducted a comprehensive and standardized investigation of putative shark nursery areas. North Carolina DMF, South Carolina DNR, Savannah State College with cooperation from Georgia DNR, Florida DEP and NMFS/University of Rhode Island in Delaware Bay all participated to sample a total of 1104 sharks in east coast waters in 1998. Seven hundred seventy three of these sharks were tagged with fin tags and released. Sharks commonly caught by these states were: sandbar,  Carcharhinus plumbeus, Atlantic sharpnose,  Rhizoprionodon terraenovae, smooth dogfish,  Mustelus canis, bonnethead,  Sphyrna tiburo, finetooth,  Carcharhinus isodon, spinner,  C. brevipinna, and bull shark,  C. leucas 

*Morris, Julie A., Wyffels, Jennifer, Snelson Jr., Franklin F.

(JAM) University of Central Florida, Winter Park, FL 32792; (JW) ADVSC Dept., Clemson University, Clemson, SC 29634; (FFS) Department of Biology, University of Central Florida, Orlando, FL 32816

Confirmation of embryonic diapause in the bluntnose stingray  Dasyatis say 

The female reproductive cycle of  Dasyatis say  has been confirmed for the Indian River Lagoon system population (Brevard County, FL).  D. say  exhibits embryonic diapause, arresting development of its embryos at the blastoderm stage. In the summer, mating activity immediately precedes ovulation and fertilization of the eggs. Encapsulated, diapausing embryos are maintained in the uterus for approximately 10 months. When embryogenesis resumes in the spring, development is rapid, lasting 10-12 weeks. Pupping is followed by ovulation and mating, then the cycle repeats. There is no period of reproductive inactivity. 

*Naylor, Gavin, Ryburn, Julie A., Fedrigo, Olivier, Lopez, Andres

Zoology and Genetics, Iowa State University, Ames, IA 50011

Toward a molecular phylogeny for Galeomorph sharks: A progress report.

Representatives of each of the eight orders of sharks were sequenced for 3 mitochondrial and one nuclear gene in an effort to determine the evolutionary branching order among the major lineages of sharks. Comparisons between mitochondrial and nuclear inferences are presented.

*Neal, Ashley E., Bodine, A. B., Wourms, John P.

(AEN, JPW) Clemson University, Clemson, SC 29634; (ABB) AVS Department, Clemson University, Clemson, SC 29634

Protein Analysis of the Uterine Histotrophe of Rays

Stingrays display a form of aplacental viviparity in which embryos develop  in utero  without connection to maternal tissues. In most species, yolk reserves are exhausted early in development and uterine fluid, termed histotrophe, is the putative source of nutrients for the remainder of gestation. Uterine fluid from several species of stingrays was analyzed for total protein content. Fatty acid components were removed and soluble and insoluble protein was isolated. The molecular weight of the proteins was determined using SDS-PAGE. The majority of the soluble protein present in histotrophe has a molecular weight of less than 10 KD, although a substantial amount has a weight that exceeds 100KD. Quantitative and qualitative comparisons were made of protein content at different phases of the reproductive cycle. In some species, protein content is low early in gestation and increases during mid-gestation. Work continues on the identification of specific proteins in histotrophe such as immunoglobulin M, vitellogenin, albumin, and transferrin or other iron-binding proteins.

*Neal, Ashley E., Wyffels, Jennifer T., Wourms, John P.

(AEN, JPW) Clemson University, Clemson, SC 29634; (JTW) AVS Department, Clemson University, Clemson, SC 29634

Virtual Embryology: 3D Reconstruction of Skate Embryos ( Raja erinacea )

The most notable use of 3 dimensional reconstruction of serial sections of elasmobranchs dates back to the 1911 monograph of Scammon on  Squalus acanthias  embryos. Since then few authors have attempted reconstructions because early methodologies were so labor intensive. Recent advances in computer technology, however, have made this form of morphological analysis more feasible. Our work represents one component in a comprehensive series of studies on the embryology of  Raja erinacea . Using a combination of video microscopy and computer techniques we seek to visualize development of this species in the three dimensions of space as well as the fourth dimension of time.

O'Donnell, Erin E.

Biology Department, University of Massachusetts Dartmouth, North Dartmouth, MA 02747

A comparative study of time-place learning in skates and stingrays

Few studies have been conducted on the learning abilities of elasmobranchs and fewer still have examined comparative learning abilities in these animals. Yet, distinctive differences in brain morphology and relative brain size suggest that differences in learning abilities may exist among them. The most disparate brains, in terms of relative size and morphological complexity are found in two groups of batoids - skates (Rajiformes) and stingrays (Myliobatiformes). This study compared the abilities of skates  Raja erinacea  and stingrays  Dasyatis sabina  in learning a simple time-place task. The results of four sets of experiments based upon the presence or absence of a light cue at a specific time of day provided evidence that  D. sabina  are capable of time-place learning. Under the same conditions in paired experiments,  R. erinacea  did not respond in a manner that statistically demonstrated their ability to make a time-place association.

*Pardini, Amanda T., Jones, Catherine S., Noble, Leslie R.

(ATP) Department of Aberdeen, University of Aberdeen, Aberdeen, Aberdeenshire AB24 2TZ United Kingdom; (CSJ, LRN) Department of Zoology, University of Aberdeen, Aberdeen, Aberdeenshire AB24 2TZ United Kingdom

Molecular population genetics of the Great white shark, Carcharodon carcharias 

The Great White Shark (GWS), Carcharodon carcharias, is considered a threatened species. However, the true conservation status of this predator is uncertain, due to its intractability as a research organism. Aside from the inherent problems of working in a marine environment GWS are elusive and uncommon. The difficulty of undertaking research on this species is evident from the paucity of information on most aspects of its biology, in particular population dynamics, encouraging speculation about its conservation status.

Molecular based approaches are now routinely used on a variety of organisms to address previously intractable questions pertaining to their population biology. Application of these approaches to GWS research promises to significantly improve our knowledge of shark population biology and behaviour. The potential to use minute tissue samples for identification of individuals will circumvent many of the problems current in GWS research programmes on natural populations, in addition to making fragmentary museum material susceptible to robust genetic analysis. 

*Piermarini, Peter M., Evans, David H.

University of Florida, Gainesville, FL 32611

Effect of salinity on Na,K-ATPase expression in the gills, rectal gland, and kidneys of the Atlantic stingray ( Dasyatis sabina )

The influence of environmental salinity on osmoregulatory mechanisms of elasmobranch fishes has not been well studied. One of the most important enzymes associated with ion balance is the sodium, potassium-ATPase (Na-pump). The goal of this study was to describe and/or quantify the branchial, rectal gland, and renal expression of the Na-pump, using immunocytochemistry and Wesern blotting, in the euryhaline Atlantic stingray ( Dasyatis sabina ). In fresh water, the Na-pump was localized to both filamental and lamellar cells of the branchial epithelium, but was only localized to cells of the filament in marine ( D. sabina ). Results from Western blots demonstrated that the overall branchial expression of the Na-pump was lower in sea water animals. Rectal glands from marine ( D. sabina ) were larger and expressed more overall Na-pump than those from freshwater animals. Western blots of kidney tissue showed a similar amount of expression for the Na-pump in fresh and sea water animals. We suggest that the differential expression of the Na-pump in the gills and rectal gland of ( D. sabina ) may be a key component to its euryhaline life style. Supported by American Elasmobranch Society Student Research Award (PMP), EPA STAR Grant U-915419-01-0 (PMP) and NSF Grant IBN-9604824 (DHE). 

*Prodóhl, Paulo A., Stanhope, Michael J., Shivji, Mahmood S.

(PAP, MJS) School of Biology and Biochemistry, The Queen's University, Belfast, Northern Ireland BT9 7BL UK; (MSS) Oceanographic Center, Nova Southeastern University, Dania, FL 33004

Microsatellite DNA profiling in the blue shark  Prionace glauca : development and potential application for population studies.

The world-wide increase in shark fisheries is thought to be resulting in declining population numbers of many species. The blue shark ( Prionace glauca ), possibly the most abundant of the larger pelagic sharks, is no exception. In addition to a directed fishery, large numbers of blue sharks make up the bycatch in the tuna and swordfish fishery. Increased fishing pressure and inadequate management strategies have prompted concerns about the sustainable health of blue shark populations. The main reason for inadequate management measures is the paucity of information on population genetic structure and life history strategy for this species. Traditional methods used to gather this type of information such as allozyme electrophoresis and RFLP analysis of mitochondrial DNA have proved to be only of limited use due to the apparent low rate of molecular evolution in this and other shark species. Recently, microsatellite DNA profiling techniques have been proposed as an alternative source of highly informative molecular makers. This new class of markers has not yet been fully exploited for shark population studies. Here we report on the development of blue shark microsatellite markers from an enriched library. Their potential for blue shark population genetic studies with examples is also discussed. 

*Purdy, Robert W., Applegate, Shelton P.

(RWP) National Museum of Natural History, Smithsonian Institution, Washington, DC 20560; (SPA) Universidad Nacional Autonoma de Mexico, Instituto de Geologia, Mexico City, Mexico D. G. 04510 Mexico

The Phylogenetic Importance of Fossil Shark Teeth

Since the classic work of Louis Agassiz (1835-1843), paleontologists have given much attention to the taxonomic description and interpretation of fossil shark teeth, which occur mainly as isolated teeth. Most of this work has been done without the benefit of knowledge of the great variation present in the teeth of living sharks. Although Leriche recommended reconstructing fossil shark dentitions as means of reducing the number of unneeded taxonomic names, his advice has gone unheeded. As a result of this, for fossil lamniform sharks close to 1000 names alone exist in the literature. Recently the importance of fossil shark teeth to our understanding of their phylogenetic history has been questioned. We review briefly dental variation in lamnid sharks, discuss its impact on the taxonomy of fossil forms, demonstrate the usefulness of reconstructed dentitions to taxonomic studies, and discuss their strengths and weaknesses. Finally we discuss the importance of selecting the correct outgroup for the cladistic analysis of shark dental characters.