CTA Human Genome Center, L-452 Lawrence Livermore National Laboratory, Livermore, California 94550 USA; JPR, MH, RTL and GWL Department of Pediatrics, University of South Florida, Florida USA; MJS, Center of Marine Biotechnology, University of Maryland, Maryland USA
Organization of Immunoglobulin Genes in the Chondrichthyes.
Chrondrichthyans are the most phylogenetically primitive ver- tebrate group to exhibit heat-stable, heterodimeric antibody molecules (immunoglobulins). With little exception, these anti- body molecules are structurally and functionally identical to those of their higher vertebrate (mammalian) counterparts. The genes encoding chrondrichthyan immunoglobulins, however, differ greatly in their genomic configuration. Whereas “recombinations” of immunoglobulin gene segments [that give rise to combinatorial antibody diversity] in mammals also occur in chondrichthyan fishes, the latter possess a unit, “cluster”-type gene organiza- tion that closely resembles that of the mammalian T-cell receptor loci. This clustered immunoglobulin genomic organization is seen in genes encoding both the heavy and light chains in chondrichthyans. Actinopterygian fishes, on the other hand, appear to possess a mammalian-type immunoglobulin gene organization. The clustered immunoglobulin gene organization seen in cartilaginous fishes has both immunological and phylogenetic implications. KEYWORDS: cartilaginous fishes; immunoglobulin; gene; T- cell receptor, PRESENTATION: ORAL, SESSION: AES IMMUNE
AFA, CAA Divisao de Pesca Maritima, Instituto de Pesca, Av. Bartolomeu de Gusm_o, 192,11030-906 Santos-SP, Brasil; FMSB Departamento de Zoologia, Instituto de Biociéncias, UNESP, Rio Claro.
Blue shark (Prionace glauca) reproduction off South and Southeast of Brazil.
This study is based on the longliners settles in Santos city, S|a|o Paulo state, that catch blue sharks all year round off South-Southeast of Brazil (20-33 S and 39-50 W). It was the most caught species of this boats from 1983 to 1992, representing 30% of their catches. The highest blue shark yield and CPUR occurred from May to July (sex ration 7:1) and the lowest from December to January (sex ratio 1:1). In this area all the blue shark reproductive cycle was verified. No specimens in juvenile stages were found in this area. However, specimens of small size (over 3 kg and probably 6 months old) were caught in small number, usually from June to August. Scars in female, probably made by male at mating season, were observed from November to March (summer). Generally in January, 80% of the females between 177 and 226 cm fork length (FL) had these scars. This proportion decreased through the months and in April it was about 14%. In March and April all females with scars had embryos: females with recent scars had embryos ranging from 5 to 40 mm total length (TL) and the others with old scars had larger embryos measuring till 157 mm TL, and it was the largest size of embryos, still envolved by ooteca. These females ranged from 172 to 216 cm FL in March, and from 167 to 211 cm FL in April. The embryos found in November/December were around 50 cm TL, close to birth length. The sex ratio of embryos was 1:1. KEYWORDS: Chondrichthyes, Prionace glauca, blue shark, reproduction, embryos, Brazilian coast, PRESENTATION: ORAL, SOCIETY: AES
Institute of Geology. Universitdad Nacional Autonoma de Mexico, Apodo Postal 70-296, Mexico D.F. 04510
The use of tooth sets in mexican species of the genus Carcharhinus with comments on the fossil history of this genus in Mexico.
The tooth sets of the 16 known mexican species that are known are discussed in relationship to their dental formula, tooth morphology and fossil record. Specific variation, interspecific and tooth abnormalities are dealt with. Special attention is given to the anterior teeth. With the possible exception of C. signatus which may be present as far back as the middle or upper Eocene most of the species seem to be no older then the lower part of the middle Miocene. This occurrence is at La Cocina IGM 283 in Baja California Sur. At this locality the species recognized are C. leucus, C. brachylus and C. falciformes. The first occurrences of the other species are also mentioned. The validity of tooth sets with certain caution is equal to that of the lamniform sharks. KEYWORDS: sharks’ teeth; carcharhiniformes; Carcharhinus; tooth sets; relationships. PRESENTATION: ORAL SOCIETY: AES
Divisao de Pesca Maritima, Instituto de Pesca, Av. Bartolomeu de Gusm|a|o, 192, 11030-906 Santos-SP, Brasil
Notes on the white shark (Carcharodon carcharias) caught off Cananéia São Paulo – Brazil
A great white shark was caught by a gill net 30 miles off Cananéia (25° 08′ 88″ S and 47° 15′ 05″ W) in water about 40 m deep, in December 8, 1992. The specimen was a female, 530 cm total length (503 cm fork length) and over 2.5 t (total weight). According to the fishermen the specimen was moribund when it was found. The dental formula of this specimen was 25/22 = 6-717-5 / 5-616-5. Some teeth were missing but the heighest found was 48.3 mm. The perimeter of upper jaw was 1065 mm. In the stomach, weighting about 200 kg, was found six shark’s heads discarded by fishermen, in different stages of digestion: two of Carcharhinus plumbeus (the largest was 30 cm head width-HDW), two probably also of C. plumbeus, Sphyrna lewini (60 cm HDW), Prionace glauca (25 cm HDW), pieces of two dolphins and of a bony fish. The weight of the liver, intestinal valve, uterus, ovary, pancreas, heart and spleen were respectively 674, 15, 13, 12, 3, 3 and 1.8 kg. Based on jaw, tooth and picture there were ten records of this species in Brazilian waters. Nevertheless, this is the first whole specimen examined. This shark is now displayed at the Victor Sadowsky Museum in Cana|e|ia. KEYWORDS: Chondrichthyes, Carcharodon carcharias, white shark, stomach contents, Brazilian coast, register, PRESENTATION: ORAL, SOCIETY: AES
Perry R. Bass Marine Fisheries Research Station, Texas Parks and Wildlife Department, HC 2, Box 385, Palacios, Texas 77465 USA
Identification of members of the genus Sphyrna utilizing isoelectric focusing.
Sarcoplasmic proteins were isolated from skeletal muscle of three species of the genusSphyrna utilizing isoelectric focusing techniques. Diagnostic banding patterns were readily discernable using a low resolution pH gradient (pH 3-10). Intraspecific comparisons were made between individuals collected from the Atlantic coast of North America and the Gulf of Mexico. A graphical representation of differences in banding patterns among the three species was provided by densitometric tracings. The library of protein profiles generated in this study provides a powerful tool for shark identification and may help to further shark conservation efforts. KEYWORD: elasmobranchs; species identification; Sphyrnidae; sharks, PRESENTATION: ORAL, SOCIETY: AES
ABB, MER, and JTW Department of Animal, Dairy, and Veterinary Sciences , Clemson University, Clemson, South Carolina 29634-0361 USA; CAL and CJW Mote Marine Laboratory, Sarasota, Florida USA; MBD Governor’s School for Science and Mathematics, Hartsville, South Carolina USA
Production and partial characterization of an Interleukin 1-like factor from the epigonal organ of the nurse shark (Ginglymostoma cirratum).
Cells from epigonal tissue of the Atlantic nurse shark (Ginglymostoma cirratum) were incubated quiescently for 9 days in modified serum-free RPMI 1640 medium at 25°C, 5% CO2. Following incubation, the culture supernatant (conditioned medium, CM ) was concentrated by pervaporation against 20% polyvinyl pyrrolidone containing 0.1 mM benzamidine HCl and extensively dialyzed against elasmobranch-modified phosphate-buffered saline (~ 970 mOsM, pH 7.0 ). The conditioned medium was assayed for protein by the microBradford procedure using bovine IgG as standard. The CM was assessed for proliferative factor(s) by use of a chick thymocyte/concanavalin A, co-mitogenic assay ( interleukin-1 like activity ) and by a co-culture growth response assay with mouse embryos. In co-mitogenic assays, conditioned medium in the presence of the mitogen induced a greater than three-fold increase in tritiated thymidine incorporation compared to control Con A cultures. In the growth response assay, conditioned medium was shown to increase significantly the number of mouse embryos reaching the blastocyst stage. Sodium dodecyl sulfate polyacrylamide gel electrophoresis, and agarose gel isoelectric focusing of epigonal conditioned medium revealed several proteins of which the major constituents had a molecular weight range of 15-19 kD and isoelectric points of 4.1-4.8 . KEYWORDS : AESIMMUNE; interleukin-1; epigonal organ; chick thymocyte; nurse shark; concanavalin A; co-mitogenic assay, PRESENTATION : ORAL, SOCIETY : AES
SB – Gulf and South Atlantic Fisheries Development Foundation, Lincoln Center, Suite 997, 5401 W. Kennedy Blvd., Tampa, Florida 33609 USA; JAM – Virginia Institute of Marine Science
Findings from a long-term fishery-independent analysis of shark abundance in the Chesapeake Bight region of the U.S. mid-Atlantic coast.
In 1991, we presented preliminary results that the abundance, as measured by catch-per-unit- effort (CPUE), of shark species that seasonally inhabit the Chesapeake Bay and adjacent coastal waters had declined by as much as 60-80% since 1974. The completion of an intensive three- year field sampling program (1990-1992) confirms these preliminary conclusions. For some species, CPUE declined on an order of magnitude. Recent stock assessments indicate that the combination of recreational and commercial fishing efforts have overexploited the resource, but a yet unimplemented management plan optimistically estimates that the stock can be rebuilt to its 1989 level in only two years. Based on our data, catch rates for several species inhabiting the mid-Atlantic region must increase five-fold to equal catch rates of the late-1980’s. If our catch rates are indicative of local abundance and stock condition, then local stock abundance must then also increase five-fold. Given the known life history characteristics of these shark species, such a large recruitment increase in two years is highly unlikely. Based on findings by other researchers that carefully considered the life history characteristics of sharks, such recuperation may require decades. KEYWORDS: sharks, shark fishery, CPUE, Virginia, Chesapeake Bay, PRESENTATION: ORAL SOCIETY: AES
JCC, Department of Biology, Albion College, Albion, Michigan 49224 USA E-Mail:JCARRIER@ALBION.BITNET; HLP, NOAA/NMFS, Narragansett Laboratory; LKM, Monterey Bay Aquarium.
Group mating behaviors in free living nurse sharks, Ginglymostoma cirratum: I. Precoupling and coupling behaviors.
Fifty mating events in free-living nurse sharks, Ginglymostoma cirratum were observed, videotaped, and photographed over a nine-day period in the southern Florida Keys. Four stages of mating were identified and recorded: precoupling, coupling, positioning and alignment, and insertion and copulation. Precoupling behaviors were categorized on the basis of whether females were stationary or moving, and, in the latter case, were often ac- companied by “following behaviors” lasting for as long as 90 minutes. Coupling began when a female’s fin was grasped by one or more males, often aggressively, and the grasp was maintained for the entire duration of copulation. The degree to which the fin was grasped strongly influenced the success of the mating attempt, and determined whether an event would progress to the last two stages, culminating with copulation. This study indicated that there is a relatively high proportion of multiple males involved in mating events and that proper alignment and positioning is more likely to occur when numerous males were involved. KEYWORDS: mating; reproduction; nurse shark; behavior; group mating; copulation; PRESENTATION: ORAL, SESSION: AES
JCC, Department of Biology, Albion College, Albion, Michigan 49224 USA E-Mail:JCARRIER@ALBION.BITNET; *HLP, NOAA/NMFS, Narragansett Laboratory; LKM, Monterey Bay Aquarium.
Group mating behaviors in free living nurse sharks, Ginglymostoma cirratum: II. Positioning and alignment, and insertion and copulation.
Fifty mating events in free-living nurse sharks, Ginglymostoma cirratum were observed, videotaped, and photographed over a nine-day period in the southern Florida Keys. Four stages of mating were identified and recorded: precoupling, coupling, positioning and alignment, and insertion and copulation. Following the grasping behavior, females were rolled by the male(s) into a ventral-side-up position, a maneuver which required several aggressive techniques by the male(s). The positioning was more likely to succeed if the water depth was greater than 0.5m. Additionally the presence of multiple males seemed to reduce the effectiveness of escape attempts by females. Copulation began with insertion of the males’s clasper and was accompanied by copulatory movements, mostly by the male. Copulatory behavior terminated with removal of the clasper. Seminal fluids were observed in several instances and samples were collected and stained, revealing individual (non-packaged) spermatozoa. KEYWORDS: mating; reproduction; nurse shark; behavior; sperm; group mating; copulation; PRESENTATION: ORAL, SESSION: AES
Department of Fisheries, National Taiwan Ocean University, 2 Pei-Ning Road, Keelung, Taiwan, R.O.C.
Age and growth of sandbar shark, Carcharhinus plumbeus, in northeastern Taiwan waters
Age and growth of the sandbar shark, Carcharhinus plumbeus, caught by longline in northeastern Taiwan waters from 1989 to 1992, were determined from annulus counts from 427 individuals. Translucent and opaque zones on vertebral centra were formed twice a year, in June and December. The von Bertalanffy growth curves parameters obtained using a nonlinear regression based on age and back-calculated length were as follows: asymptotic length (L_00_ )=216.3 cm total length (TL), growth coefficient (K)=0.280, age at zero length (t_0_)=-1.259 yr for females; and L_00_ =200.7 cm TL, K=0.312, t_0_ =-1.493 yr for males. Growth was apparently fast and varied among individuals. The growth rate during the first year was estimated to be 37.1 cm for females and 33.76 cm for males, then the 28.06 cm/yr-12.12 cm/yr for females and 24.71 cm/yr-9.69 cm/yr for males for years 2-5, and 9.15 cm/yr-2.98 cm/yr for females and 7.09 cm/yr-2.04 cm/yr for males for years 6-10. Holden’s method was applied to estimate growth parameters for purposes of comparison. Estimated age at maturity was 5.12 yr (180 cm TL) for females and 4.52 yr (170 cm TL) for males, based on the von Bertalanffy growth equation from back-calculated data. The largest female (225 cm TL) was 19 yr old at least. KEYWORDS: elasmobranch; age and growth PRESENTATION: ORAL SOCIETY: AES
DAC, Department of Biological Sciences, Florida Institute of Technology, 150 West University Drive, Melbourne, Florida 32901 USA E-mail INTERNET: 103255@ROO.FIT.EDU
Diet overlap of the Atlantic stingray, Dasyatis sabina, with recreational and commercial fishes in the Indian River Lagoon, Florida.
Although all dasyatid stingrays are known benthic carnivores, no information exists on their potential dietary overlap with sympatric commercial and recreational fishes. The Atlantic stingray, Dasyatis sabina is the most common elasmobranch in Indian River Lagoon. The stomach contents of 140 rays sampled from a sand flat habitat were examined over a one year period to determine 1) prey types, 2) seasonal shifts in diet, and 3) potential dietary overlap with commercial and sport fishes. The dominant prey were infaunal crustaceans, polychaetes, and echinoderms. Amphipod and mysid crustaceans were the most frequent prey taken by both sexes. A seasonal shift in prey among stomachs was reflected by a high diversity in fall and winter months that successively decreased to a minimum diversity in June when amphipods were often the exclusive prey. D. sabina has a gross diet similarity to commercial and sport species such as juvenile black drum, red drum, and pompano. Dietary overlap among D. sabina and fishery species indicate that these species may exploit similar habitats and food resources in estuarine environments. KEYWORDS:Dasyatis sabina; Atlantic stingray; diet overlap; estuary; food habits; prey diversity PRESENTATION: ORAL, SOCIETY: AES, AWARD:GRUBER; STOYE-EE,
SFC Argus-Mariner Consulting Scientists, 6427 SE 94th Avenue, Portland, Oregon 97266-5255 USA; LJVC Shark Research Center, South African Museum
Non-Predatory Behavior in White Sharks
White sharks are known to seize and release other species ranging from common prey (pinnipeds) to those which are not normal prey (birds, humans, otters, etc.). It has been assumed that one of two reasons explained this behavior: 1) for prey species that whites were disabling large animals and retreating to allow the prey to die before consumption; 2) for non-prey, as well as inanimate objects, that mistaken identification was involved. However, another factor which could account for seize-and-release or other behaviors in which there is no follow-up interaction has received little attention…displacement. Displacement has been well-studied for many non-marine animals. Dogs and cats are well-known examples. Both undergo resting periods when potential to enact certain behaviors builds then, at threshold, they’re acted out. This may take several forms including stalking, pursuing, batting at, pouncing, evading or seizing objects or other animals. Displacement apparently serves several functions including honing hunting skills, stress relief, or development of skills necessary to socialization or hierarchical order. Once enacted displacement tends to dissipate rapidly and the animal displaying the behavior appears to become sated. White sharks may exhibit one or more similar behaviors in addition to others, such as intraspecific threat displays, not of a displacement nature. Observations of non-predatory behavior will be examined including “seize-and-release”, “bouncing”, “bashing”, and “gaping” involving white sharks and other species. KEYWORDS: white sharks; displacement; nonpredatory; Lamnidae; intraspecific; interspecific; Carcharodon carcharias; behavior PRESENTATION: ORAL SESSION: AES
Center for Shark Research, Mote Marine Laboratory, 1600 Thompson Parkway, Sarasota, Forida 34236 USA
Demographic analysis of the Gulf of Mexico population of the Atlantic sharpnose shark, Rhizoprionodon terraenovae.
The Atlantic sharpnose shark, Rhizoprionodon terraenovae, is a small coastal species caught in recreational fisheries and as discarded bycatch in the shrimp trawl fishery in the Gulf of Mexico. Demographic analyses incorporating the best available information on validated age and growth, age at maturity, maximum age, and age-specific mortality and fecundity were performed. Age- specific natural mortality was kept constant throughout these analyses, but first year survivorship was varied. The life history table/Leslie matrix model yielded net reproductive rates (R_o_) ranging from 0.844 to 1.282, constant generation lengths (G) of 5.7 years, and instantaneous rates of population increase (r) ranging from -0.029 to 0.043. Further simulations were performed to test the sensitivity of the computed results to input parameter values. The estimated mean fishing mortality from 1986 to 1989 (F=0.428) was then added to natural mortality in selected cases and the analyses were rerun. The implications of this study for the management of the Atlantic sharpnose shark fishery are discussed in the context of the Federal Management Plan (FMP) for sharks of the Atlantic Ocean. KEYWORDS: life history table; fisheries; mortality; bycatch; shark, FMP., PRESENTATION: ORAL, SOCIETY: AES
JCC Department of Wildlife and Fisheries Sciences, 210 Nagle Hall, Texas A&M University, College Station, Texas 77843 USA
Systematics of the Bathyraja and Rhinoraja species of the Bering Sea.
Despite the facts that the skates of the Bering Sea and adjacent waters in the North Pacific Ocean have been well collected and the subject of several recent studies, they remain poorly known. The confusion concerns Bathyraja and Rhinoraja. Twelve species ofBathyraja and one or two species of Rhinorajanbsp;have been recorded from the Bering Sea. Of these, only three are clearly distinct: B. abyssicola, B. aleutica, and B. parmifera. However, while the primary diagnostic character for B. aleutica and B. parmifera does not distinguish them, several other meristic and morphological characters are diagnostic. The single character that distinguishes Bathyraja and Rhinoraja is of questionable validity. However, the one or two Rhinoraja and several Bathyraja species constitute a monophyletic group. KEYWORDS:systematics; Rajidae; Bering Sea; morphometrics, PRESENTATION: ORAL SESSIONS: AES, AWARD: GRUBER; STOYE-ICH
KAD and JFM Department of Biology, Gittleson Hall, Room 130, 114 Hofstra University, Hempstead, New York 11550-1090 USA
Higher phylogeny of elasmobranchs inferred from 12S rDNA
Recent preliminary investigations of the molecular phylogeny of elasmobranchs have yielded intriguing results. However, all such studies were deficient due to the absence of representative species from several major lineages. This study presents the first investigation of the molecular phylogeny of all elasmobranch lineages. We have extracted, amplified, and sequenced the 12S mitochondrial gene from Pristiophorus, Pristis, Heptranchias,Chlamydoselachus, Squalus, Heterodontus, Alopias, Carcharodon, Carcharhinus,Triakis, Squatina, Ginglymostoma, Hemiscyllium, Torpedo, Narcine, Raja,Urolophus, Potamotrygon, Rhinobatos, and Platyrhinoidis. Phylogenetic comparisons of the above sequences were performed using a holocephalan outgroup. The resulting phylogenetic hypothesis will be presented and compared with all contemporary hypotheses. KEYWORDS: molecular phylogeny; elasmobranchs, PRESENTATION: ORAL, SESSION: AES, AWARD: GRUBER
Department of Fisheries, Humboldt State University, Arcata, California 95521 USA
Food habits, occurence, and population structure of the bat ray, Myliobatis californica, in Humboldt Bay, California
The bat ray, Myliobatis californica, is the most common elasmobranch in Humboldt Bay, CA. Local oyster growers harvest this species to prevent predation on oyster beds. A thirteen month study was conducted in north Humboldt Bay in close proximity to oyster beds to examine the seasonal abundance, population structure, and feeding ecology of bat rays. Rays enter the bay in early spring, and remain throughout the summer and fall. Smaller rays appear earliest (late February) and remain longest (until November). Adult rays use the bay as a spawning ground and pupping area. As water temperatures decrease below 10-12 C, all rays leave the shallow bay waters. Predominant food items for juvenile rays (disc width (DW) <40 cm) include small clams and shrimp, Crangon spp. Larger rays (DW 40-80 cm) feed heavily on clams and shrimp, but also prey upon crabs,Cancer spp., and polychaetes. The largest rays (DW >80 cm) feed primarily on crabs and adult clams, including Tresus spp. and Saxidomus spp. Lesser numbers of blue mud shrimp, Upogebia pugettensis, innkeeper worms, Urechis caupo, and polychaetes are also taken. Predation on oysters was rare. KEYWORDS: bat rays; feeding habits; population structure; Humboldt Bay; California, PRESENTATION: POSTER, SOCIETY: AES
College of William and Mary/VIMS
What is a holocephalan, anyway? Why… an ethmoid canal?
Within Chondrichthyes the ethmoid canal is considered to be a uniquely holocephalan character. The origin of this canal has been strongly debated with particular reference to the nature of a holocephalan:selachian relationship (Kappers 1912, Allis 1926, DeBeer and Moy-Thomas 1935, Holmgren 1942, Patterson 1965, Stahl 1967). My research examines the features of the ethmoidal region in the extant Selachii and Holocephali. Examinations have also been performed on the Mississippian (Namurian E2B) Selachii:Paraselachii:Holocephali clade of Bear Gulch, Montana to trace changes in chondrichthyan cranial dimensioning which may influence the development of an ethmoid canal. Patterns of cranial vascularization and mode of suspensorium provide vital clues to morphological shifts which can result in ethmoid canal formation. The data are presented in view of the major theories for canal formation and are used to formulate a novel interpretation for development of this cranial structure. KEYWORDS: Selachii; Holocephali; Paraselachii; ethmoid canal; hyostyly; autodiastyly; vasculature, PRESENTATION: ORAL, SESSION: AES, AWARD: STOYE-ICH; AES
College of William and Mary/VIMS
Field Techniques for the Collection of Chondrichthyan Immunologic Tissues and Preliminary Comparative Observations on Selachian and Chimaeroid Immune Systems.
Field sampling of chondrichthyan tissues for the purpose of in vitro immunologic analyses can be a difficult task and, therefore, few researchers in this area have an active field program. Over the past six years I have experimented with variations in the collection process so as to optimize cell recovery and reactivity in the laboratory. My techniques are presented and observations are made on variables believed to influence the efficacy of sampling. Information is presented for collection of both shark and holocephalan tissues and followed up with early stage analysis of samples in the lab. These primary stage analyses include cell separation, identification, and attempts to establish successful in vitro cultures. KEYWORDS: AESIMMUNE; Techniques; selachian; holocephalan; immune system, PRESENTATION: ORAL, SESSION: AES
Department of Biology, San Francisco State University, and California Academy of Sciences, Steinhart Aquarium, Golden Gate Park, San Francisco, California 94118 USA
Temperature, swimming depth, and diel movements of a white shark (Carcharodon carcharias) at the South Farallon Islands, Central California, and comments on thermal physiology.
Stomach temperature (T_s_), swimming depth, and diel movements of an adult male white shark (Carcharodon carcharias) were intermittently recorded by acoustic telemetry over an eight day period at the South Farallon Islands, off the Central California coast. Temperature profiles of the water column (T_w_) were also obtained. The maximum elevation of T_s_ over T_w_ was 13.7 ^o^C, while the daily mean swimming depth ranged between 13.9 m and 32.1 m. Trackings of short term movements show that both near island movements and excursions away from and back to the islands are along the sites where large numbers of attacks on pinnipeds, their primary prey, occur. The ability to maintain a warm body may provide an increase in neural, digestive, and muscle activity/function, any of which might be advantageous to this large predator in searching for and attacking prey, and converting assimilated food into reserves. It may also have played an important evolutionary role in the white sharks ability to live in cool temperate and cold waters circumglobally. KEYWORDS: Stomach temperature; diel movements; acoustic telemetry; rete mirabile; thermoregulation; physiology; evolution PRESENTATION: ORAL SOCIETY: AES AWARD: GRUBER
Virginia Institute of Marine Science, Gloucester Point, Virginia 23062 USA Email:EDWARD@ches.cs.vims.edu
Cosmopolitan population genetics of the shortfin mako shark Isurus oxyrinchuswith comparison to the sandbar shark Carcharhinus plumbeus.
The shortfin mako shark Isurus oxyrinchus is a large active species that supports commercial and recreational fisheries throughout the temperate, subtropical, and tropical oceans. Because of its great vagility and pelagic occurrence, gene flow throughout the world-wide range of this species may prevent genetic differentiation between widely separated locations. Mitochondrial DNA restriction fragment length polymorphism analysis was used to estimate the degree of gene flow between mako shark populations from the Mid-Atlantic Bight and California Pacific coast, two apparent endpoints in the species distribution, as well as samples from an intermediate location in Australia. A comparison was made with the sandbar shark, Carcharhinus plumbeus, a species with a similar range but restricted primarily to neritic waters. KEYWORDS: population genetics; DNA; mtDNA, PRESENTATION:ORAL, SOCIETY: AES, AWARD:STOYE-GDM;GRUBER
Department of Husbandry, National Aquarium in Baltimore, Pier 3, 501 E. Pratt Street, Baltimore, Maryland 21202 USA
Tonic Immobility in Elasmobranchs: preliminary results on 11 species and its use as an aid in their captive husbandry.
Tonic immobility (TI), or animal hypnosis has been observed in a wide variety of taxa. It has been reported in all vertebrate classes with the exception of Agnatha. To date, TI has been reported to occur in six species of elasmobranchs. Preliminary results are presented here for five species of Galeomorph sharks, one species of Squalomorph shark, and five species of batoids. Depending upon the species involved, TI may be used as an aid in a few husbandry and medical procedures in captive elasmobranchs. KEYWORDS: tonic immobility; elasmobranch, PRESENTATION: ORAL, SOCIETY: AES
Department of Biology, University of Massachusetts-Dartmouth, North Dartmouth, Massachusetts 02747 USA
Metabolic rate and rhythmicity in the little skate Raja erinacea, Mitchill
The standard (SMR) and routine (RMR) metabolic rates of the little skate were estimated from oxygen consumption measurements. Data were gathered from a computerized, flow-through respirometry system. Individual trials were done over 96 hours at 10^o^C. The resulting rates, SMR = 20.1 (+/- 1.99 SE) and RMR = 48.3 (+/- 2.5 SE) mgO_2_/kg/hr, for a skate of 0.5 kg standardized weight are the lowest reported for any elasmobranch or comparable teleost fish. Periodogram analysis revealed a significant exogenous, circadian component to the oxygen consumption of these fish, indicating a pattern of nocturnal and crepuscular activity. The use of low dosage MS-222 in conjunction with the respirometry trials provided positive preliminary evidence that this technique may be useful in giving quick, accurate estimates of SMR in the more intractable elasmobranch fishes. KEYWORDS: Metabolic rate; Respirometry; Circadian rhythm; Anesthesia PRESENTATION: ORAL SESSION: AES, AWARD: GRUBER
President, American Elasmobranch Society, Director, Center for Shark Research, Mote Marine Laboratory, Sarasota, Florida 34236 USA
Elasmobranchs (and all other organisms) as biotic resources
As it approaches its tenth year, the American Elasmobranch Society today is a robust, growing organization of nearly 450 members, including about 85 international members and 100 student members. The diversity in background of the AES membership, together with its close affiliation with ASIH, have fortified both the society’s professionalism and the relevance of the organization’s aggregate activities in today’s world community. Increasingly, AES members are being pressed by the public, funding agencies, administrators, and colleagues to justify this societal relevance. This, of course, is not unique to AES, and so the AES responses have application to other fields of biology. In this age of bottom-line accountability, the response that hits home with many audiences is that of the “resource value” of elasmobranchs. This goes beyond traditional views of the resource concept and touches on the current debate among preservationists, conservationists, user groups, and others with an interest in resource allocation. For the elasmobranchs, their role as a resource can be divided artificially into at least three categories: 1) ecological resources; 2) research and development resources; and 3) fishery resources. Lack of study (i.e., understanding) and/or depletion of these elasmobranch resources commonly have negative impacts on society, and specific examples of such effects are available for all three categories. This may be consumerism at work, but at the very least it raises the question of “what’s in it for me?” up to the level of “what’s in it for the earth?” in a very down-to- earth way. From this perspective, which ultimately feeds back positively into biological research, the elasmobranchs are but a banner group representing nothing more, and nothing less, than the indispensable nature of all living organisms. KEYWORDS: elasmobranch; AES; resources, PRESENTATION: ORAL, SESSION: AES, OTHER: Schedule in Plenary Session for 20 min.
Department of Wildlife and Fisheries Sciences, Texas A&M University, College Station, Texas 77843-2258 USA
The systematics and reproductive biology of the marbled catshark Galeus arae
The Galeus arae complex contains three recognized subspecies: G. a. arae, G. a. antillensis, and G. a. cadenati. Galeus a. arae occurs from South Carolina to the Mississippi Delta, the northern coast of Cuba, the Caribbean coasts of Honduras, Nicaragua, and Costa Rica, and some of the neighboring islands. Galeus a. antillensis is found in the Straits of Florida, along the northern coasts of Cuba, Hispaniola and Puerto Rico, and off many of the Leeward Islands. Galeus a. cadenati is found off the Caribbean coasts of Panama and Columbia. While there is no reproductive information available forG. a. cadenati, G. a. arae is considered to be aplacental viviparous and G. a. antillensisoviparous. A review of the literature and an examination of the specimens suggests that the distribution of subspecies may overlap. A study of the reproductive biology has shown that all three subspecies have encapsulated eggs and are therefore considered to be oviparous. A systematic study based on morphometrics and meristics suggests that this complex may be made up of at least two species. KEYWORDS: reproductive biology; Scyliorhinidae; systematics PRESENTATION: ORAL, SESSION: AES, AWARD: GRUBER
Dept. of Zoology, University of Hawaii, Honolulu, Hawaii 96822 USA
Swimming performance of juvenile scalloped hammerhead sharks.
Swimming performance of juvenile hammerhead sharks was measured using a swim tunnel located at the Hawaii Institute of Marine Biology. Critical swim speed (Ucrit), tail beat frequency, stride length, and tail beat amplitude were recorded from seven sharks. Sharks exhibited Ucrit values (0.91 – 1.38 L/sec) slightly lower than those observed in the leopard shark, Triakis semifasciata (1.42 – 1.74 L/sec) of equivalent total lengths (52 – 65cm). Tail beat frequency and stride length increased linearly with increases in relative swimming speeds, while tail beat amplitude slightly decreased. Tail beat frequency also decreased linearly with the total length of sharks swimming at the same relative speed, while stride length increased. Differences in swimming performance between hammerhead shark pups (obligate swimmers) and other species of non-obligate swimming sharks may suggest adaptations for a more continuously active lifestyle. KEYWORDS: Sphyrna lewini; swimming performance, tail beat frequency; critical swim speed, PRESENTATION: ORAL, SOCIETY: AES
CAL, CJW, Mote Marine Laboratory, 1600 Thompson Parkway, Sarasota, Florida 34236 USA; ABB, JTW, Department of Animal, Dairy, and Veterinary Sciences, TRS, CK, Department of Poultry Science, Clemson University, Clemson, South Carolina USA
Identification and partial characterization of the major hematopoietic tissues; in elasmobranch fish.
Elasmobranch fish (sharks, skates and rays) possess a cartilaginous skeleton, and lack true bone marrow and lymph nodes. Consequently, the primary tissue sites involved in hematopoiesis (formation of blood cells) in most vertebrates are not present. Alternative sites for hematopoiesis in elasmobranchs are not well understood. Lymphoid organs in common with higher vertebrates, including spleen and thymus, are involved with lymphocyte production, but do not account for the total blood cell population. Tissues unique to elasmobranch fish, such as Leydig organ, epigonal organ and rectal gland, have been investigated for their potential hematopoietic function, with the documentation that both Leydig and epigonal organs contribute significantly to both lymphocyte and granulocyte production. The role of the rectal gland in hematopoiesis is unclear, although lymphocytes have been found associated with this tissue. An additional site worthy of mention is the peripheral circulation, where significant blood cell replication, differentiation, and maturation have been observed. Cell flow cytometric analysis of unstimulated peripheral blood lymphocytes (PBL) from three nurse sharks (Ginglymostoma cirratum) sampled weekly for eight weeks confirms that 20-23% of the PBL’s are actively synthesizing DNA (S phase), and 2-7% are in some stage of mitosis (G_2_/M phase). KEYWORDS: elasmobranch; hematopoiesis; lymphoid organs; spleen; thymus; Leydig organ; epigonal organ; rectal gland; peripheral blood lymphocytes. PRESENTATION: Oral, SOCIETY: AES
Center for Shark Research , Mote Marine Laboratory , 1600 Thompson Parkway , Sarasota, Florida 34236 USA
Distribution and seasonal movements of sharks in Tampa Bay and Charlotte Harbor, Florida
Estuarine areas of Florida’s Gulf coast provide nursery grounds and/or juvenile habitat for numerous shark species. A study is underway to examine the neonate, juvenile, and small adult shark populations of two such estuaries of Florida’s southwest coast. Sharks are captured in gill nets and with hook-and-line gear. Sharks surviving capture are identified, measured, tagged and released. Those not surviving are examined for stomach contents, reproductive stage and other factors. As of mid-March 1993, a total of 346 sharks of eleven different species have been captured in the Tampa Bay and Charlotte Harbor systems, with 261 tagged and released. The numerically predominant species are blacktip (Carcharhinus limbatus), blacknose (C. acronotus), and bonnethead (Sphyrna tiburo) with lesser numbers of sharpnose (Rhizoprionodon terraenovae), lemon (Negaprion brevirostris), bull (C. leucas), sandbar (C. plumbeus), finetooth (C. isodon), nurse (Ginglymostoma cirratum), scalloped hammerhead (S. lewini) and Florida smoothhound (Mustelus norrisi). Capture data collected thus far indicate definite seasonal movements into and out of the estuaries which vary by species. Data will be presented to demonstrate these movement patterns and their correlation with water temperature. KEYWORDS: elasmobranch; sharks; nursery grounds; tagging; estuaries; Gulf of Mexico; juvenile; neonate PRESENTATION: ORAL SESSION: AES
JJM, and SFS Department of Microbiology and Immunology, University of Arizona, College of Medicine, Tucson, Arizona 85724 USA; JJM E-mail:MARCHALONIS@biosci.arizona.edu
Immunoglobulin production in sharks; Biological and molecular genetic studies.
Shark immunoglobulins resemble mammalian IgM in structure and gene similarity. IgM comprises as much as 50% of serum proteins in sharks, compared to less than 5% in humans. To compare their natural antibodies, we carried out a study of the capacity of IgM from unimmunized sharks and humans (normals and patients suffering from autoimmune diseases) to react against a panel of antigens, including some usually considered indicative of autoantibodies such as thyroglobulin and single-stranded DNA. Sharks and humans possess IgM antibodies that react with thyroglobulin and single-stranded DNA, although these constitute small fractions of total IgM. The shark antibodies show extensive cross-reactivity comparable to that shown by polyspecific IgM autoantibodies produced by human B cells that appear early in ontogeny. Immunoglobulin gene arrangement in sharks is radically different from that in mammals. In the sandbar shark, light chain gene segments are distributed as apparently independent clusters consisting of variable, joining and constant region gene elements. For many of these clusters, the segments encoding the variable and joining regions are fused in the germline. These results suggest that the mechanisms for the generation of diversity and for the regulation of gene expression may be quite distinct in the shark. KEYWORDS: AESIMMUNE; Carcharhinus plumbius; sandbar shark; immunoglobulins; natural antibodies; gene arrangement, PRESENTATION: ORAL
Smithsonian Tropical Research Institute, Unit 0948, APO, AA 34002-0948
Counterintuitive direction of morphological innovation: the hammerhead of sharks
Knowledge of macroevolutionary sequences provides important insight into the origin of biological innovation and the nature of selective forces responsible for the evolution of adaptations. Hammerhead sharks are characterized by the presence of a remarkable innovation: a laterally-expanded head (termed the cephalofoil) in which there has been substantial reorientation of olfactory, optical and electromagnetic sense organs. Because head shapes across contemporary species differ markedly in the extent of lateral elaboration, knowledge of phylogenetic relationships among species allows reconstruction of cephalofoil evolution. Previous phylogenetic analysis of morphology suggested that species with different head widths represent stages in the process of progressive evolution for increased lateral expansion. Analysis of 915 base pairs of mitochondrial DNA refutes the progressive evolution hypothesis. Evidence for cephalofoil diminution, lateral-expansion, and stasis in different lineages suggests that diverse selective pressures are at work. KEYWORDS: Hammerhead sharks; cephalofoil evolution; mitochondrial DNA; phylogenies; selection, PRESENTATION: ORAL, SOCIETY: AES
Biology Department, University of Massachusetts Dartmouth, North Dartmouth, Massachusetts 02747 USA E-mail: SMOSS@UMASSD.BITNET
Notes on reproduction in the porbeagle, Lamna nasus (Bonnaterre).
Three female porbeagles captured off southeastern Massachusetts in December, 1992, provide information on the reproductive biology of this oophagous species. One female, 232.0 cm in total length (TL) and from which measurements were taken, was sexually immature. A total of 6 embryos were obtained from two additional females (not measured, but that were approximately 274 cm TL) Two of these embryos (from a single female) were 401 (male) and 407 (female) mm TL. The remaining four embryos (three males and one female) were obtained from another shark caught in the same week, and ranged from 231 mm to 252 mm TL, indicating temporal variation in reproductive activity in this species. The morphometrics of these embryos are compared with those of eleven others (including two Lamna ditropis embryos) known from the literature. In addition, data on the populations of nutritive eggs and uterine morphology from the adults are discussed. KEYWORDS: reproduction; oophagy; Lamnidae; embryo PRESENTATION: ORAL SESSION: AES
JAM, Virginia Institute of Marine Science, Gloucester Point, Virginia 23062 USA; SB, Gulf and South Atlantic Fisheries Development Foundation, Inc.
Increased survival in juvenile sand bar sharks – response to decline in large predatory sharks?
Subtropical and tropical galeoid sharks were collected by the VIMS long-line program in the Chesapeake Bight from 1973 to 1992. A total of 481 sets comprised of 44,378 hooks were fished, yielding 3,329 sharks. Sandbar sharks were the most abundant large coastal species, along with dusky, sand tiger, blacktip and tiger sharks. In addition, lower Chesapeake Bay served as a major pupping and nursery ground for sandbar sharks. All coastal species on the continental shelf declined over the period to about 20% of their original abundance. Surprisingly, juvenile (1-4 year old) sandbar sharks in the Chesapeake Bay nursery have not declined in abundance. This apparent contradiction of the well-documented parent-stock recruitment relationship in sharks may be explained by much lower predation and higher survival of Y-O-Y sharks associated with the decline in large predatory sharks. KEYWORDS: Sandbar shark recruitment; shark stock decline; juvenile survival; predation PRESENTATION: ORAL, SESSION: AES, AWARD:
Department of Biological Sciences, Florida Atlantic University, Boca Raton, Florida 33431 USA
Cell lines from the silky shark (Carcharhinus falciformis) and the nurse shark (Ginglymostoma cirratum)
The present study described the first cell lines produced from members of the class Chondrichthyes. Explants of brain tissue from an embryonic silky shark and a juvenile nurse shark were incubated in a mammalian medium modified with the addition of urea, trimethylamine N-oxide, NaCl, and bovine serum. Primary monolayers were passaged with 0.025% trypsin in a modified saline solution. Silky shark cells grew optimally at 29C as determined by MTT dye conversion. The population doubling time for (C. falciformis) cells at passage 29 was 67 hrs. For (G. cirratum) cells at passage 6 the population doubling was 84 hrs. Silky shark cells grew over a broad range of osmolalities from 315 mOsm to 1664 mOsm with optimal growth at 650 mOsm. A medium containing 10% dimethylsulfoxide allowed for cryopreservation with greater than 65% viability upon recovery. Current theories of elasmobranch osmoregulation are discussed in light of experimental data collected from studies conducted on the silky shark cell line. The silky shark cell line has been passaged over 50 times. KEYWORDS: AESIMMUNE; chondrichthyes; shark; cell line; elasmobranch; osmoregulation, PRESENTATION: ORAL, SOCIETY: AES, AWARD: AES SAMUEL GRUBER
EKR and SHG Rosenstiel School of Marine and Atmospheric Science, University of Miami, 4600 Rickenbacker Causeway, Miami, Florida 33149-1098 USA
Factors affecting the carrying capacity of young lemon sharks (Negaprion brevirostris) in a semi-enclosed, sub-tropical lagoon
Carbon flux studies in ecosystems are important for understanding estimates of the energetic content of different trophic levels, and for an overall understanding of the carbon flux through food webs. We have examined the North Sound of Bimini, Bahamas. This semi-enclosed 3 km^2^ shallow lagoon a well known nursery ground for lemon sharks,Negaprion brevirostris, was monitored to find out the amount of energy that has to be provided by the ecosystem to support the resident shark population of about 100 animals. We used the following parameters for creating a model of energy flux in the sound: Size composition and abundance of the teleost species, energy fluctuation caused by teleosts migrating through lagoon’s entrance, energy stored in unavailable forms, predatory influence by species other than lemon sharks, stomach content analyses and average daily food consumption of the young lemon sharks, and the primary productivity of the dominant turtle grass in this lagoon, Thalassium testudinum. Assuming constant survival rates for the young lemon sharks, the North Sound has been shown to provide energy to support the existing lemon shark population for less than 200 days. KEYWORDS: lemon shark: ecosystem: carbon flux; trophic levels. PRESENTATION: ORAL, SOCIETY: AES
Department of Ecology and Evolutionary Biology, The University of Connecticut, Storrs, Connecticut 06269-3043 USA
Some tetraphyllidean tapeworm species and their shark hosts: A phylogenetic look at their associations.
As part of a study of the tetraphyllidean tapeworms of elasmobranchs, a monophyletic species group, including the genera Orygmatobothrium and Paraorygmatobothrium, was identified using light and electron microscopy. These species were generally parasitic in carcharhiniforms. This study was undertaken to more broadly survey host distributions for this tapeworm lineage. Elasmobranchs from seven orders were sampled for their cestodes. A phylogenetic hypothesis for these tapeworms was generated with morphological evidence and compared to the biology and systematics of the corresponding host species. Three elasmobranch orders (Carcharhiniformes, Lamniformes, and Squaliformes) harbored tapeworm species belonging to this lineage. The majority of these tapeworm species were found parasitizing carcharhiniforms; each species was host specific. Cladistic analysis indicated that the genus Orygmatobothrium and Phyllobothrium squali form sister elements to Paraorygmatobothrium. This tapeworm lineage appears to have evolved from parasitism of squaliform and triakid host species to parasitism of carcharhinids and sphyrnids. Within Paraorygmatobothrium, some species are parasitic in larger oceanic shark hosts, including Alopias vulpinus. This preliminary study supports a general model of coevolution between a group of tapeworms and their shark hosts, although there is a lack of parasite data from a broad taxonomic sample of hosts. KEYWORDS: elasmobranchs; cestodes; coevolution; host/parasite relationships; phylogeny, PRESENTATION: ORAL, SESSION: AES
Moss Landing Marine Laboratories, P.O. Box 166, Moss Landing, California 95039-0166 USA
Gastric Evacuation and Daily Ration of the gray smoothhound Mustelus californicus shark in Elkhorn Slough, California.
Gastric evacuation was studied on four gray smoothhounds at a temperature of 15 ° C. Results were obtained by stomach eversions at prescribed times following a meal of shore crabs. Gastric evacuation proceeds exponentially and the gut is emptied in about 95 hours. The instantaneous rate of gastric evacuation was -0.04. Caloric content of whole prey, prey at various stages of digestion, and fecal material were quantified using bomb calorimetry. The change in caloric value of the meal with time suggests higher energy components are digested first. The fecal material contained no measurable caloric value. This suggests that gray smoothhound digestion is an orderly and efficient process resulting in maximum utilization of prey. No pattern in the diel feeding activity was found. Feeding in the population was asynchronous and intermittent. Five methods were applied to estimate daily ration. Four methods were based upon collection of data on stomach contents of sharks caught in the wild. The other was based on the Winberg (1966) bioenergetics model. Estimates of daily ration ranged from approximately 1.5 to 2.5% of the shark’s wet body weight. KEYWORDS: gastric evacuation; daily ration; feeding, PRESENTATION: ORAL SESSION: AES
Department of Biology, California State University, Long Beach, Long Beach, California 90840 USA
Effect of molecular structure on the shark repellent potency of anionic surfactants.
Sodium octyl sulfate, sodium decyl sulfate, and sodium dodecyl sulfate were tested to determine the relationship between shark repellent potency and length of the alkyl chain in anionic surfactants. Swim-through trials were conducted in a roundabout test tank using juvenile swell sharks, Cephaloscyllium ventriosum. Swimming sharks were directed through the tank’s test chamber which contained uniform concentrations of chemical. Two levels of unconditioned behavioral responses were observed. Level 1 was the minimal noticeable response – “coughing” (explusion reflex) and headshaking with slight acceleration. Level 2 represented a more vigorous repellent response consisting of headshaking, mouth gaping, and rapid acceleration. Effective concentration thresholds (EC50s) for sodium dodecyl sulfate were 40 ppm (Level 1) and 75 ppm (Level 2). EC50s for sodium decyl sulfate were 184 ppm (Level 1) and 368 ppm (Level 2). EC50s for sodium octyl sulfate were 1470 ppm (Level 1) and inconclusive at up to 5120 ppm (Level 2).; The shark repellent mode of action of anionic surfactants and the role of their monomeric versus micellic activity is discussed. KEYWORDS: Repellency, PRESENTATION: ORAL, SOCIETY: AES, AWARD: GRUBER
Massachusetts Division of Marine Fisheries, Martha’s Vineyard Research Station, P.O. Box 68, Vineyard Haven, Massachusetts 02568 USA
The ecology of the sandbar shark, Carcharhinus plumbeus, in the neritic waters of Chappaquiddick Island, Massachusetts.
The waters off Martha’s Vineyard and Nantucket Islands mark the northern limit to the western Atlantic distribution of the sandbar shark, Carcharhinus plumbeus. During the summer months, this species is commonly taken by recreational surf fishermen from the eastern and southern beaches of Chappaquiddick Island. To better understand the coastal ecology of this species, 72 sandbar sharks (37 male, 27 female, 8 unknown), 91-124cm in fork length, were sampled from the neritic waters of Chappaquiddick Island with rod and reel and bottom longline gear from 1990-1992. Eight sandbar sharks were taken in Cape Pogue Bay, a salt pond on the island’s north shore. Age estimates ranged from 8 to 24 years and all were determined to be sexually immature. Sandbar sharks occurred in the island’s nearshore waters from early July through early September of each year when water temperatures ranged from 19-27¯C. Based on landings, peak abundance was from mid to late July. The stomach contents of 19 sandbar sharks consisted of teleosts (66.7%), crustaceans (44.4%), elasmobranchs (22.2%), and cephalopods (11.1%); no single teleost species dominated. It is hypothesized that juvenile sandbar sharks travel in mixed schools opportunistically feeding in the productive and protective neritic waters of these islands. KEYWORDS: sandbar shark; surf fishing; ecology; age; maturity; food habits, PRESENTATION: ORAL, SESSION: AES
FFS and MRJ Department of Biology, University of Central Florida, Orlando, FL 32816 USA; LELR Department of Chemical and Biological Sciences, Oregon Graduate Institute of Science & Technology; DLH Department of Reproductive Sciences, Oregon Regional Primate Center
Serum concentrations of steroid hormones during reproduction in the stingrayDasyatis sabina.
The Atlantic stingray, Dasyatis sabina, has a well-defined annual reproductive cycle in Florida. We collected adult specimens over 12 months and evaluated reproductive parameters and serum levels of five steroid hormones (17 beta-estradiol — E_2_, progesterone–P, testosterone–T, dihydrotestosterone–DHT, and corticosterone–CS). Female E_2_ peaked twice, once in mid-March to early April in association with ovulation, and again in mid-June to mid-July in association with the enlargement of a second group of ovarian eggs. Female P peaked in early March and early April, coincident with the peak in E_2_. Female DHT was variable but exhibited a pattern not clearly associated with known events in the reproductive cycle. Female T and CS levels did not vary significantly though time. In males, T, DHT, and CS increased progressively through winter and spring, peaking in March when females were ovulating and when copulation probably took place. DHT concentrations were usually at least twice T levels. These three hormones peaked long after the November/December peak in gonadosomatic index. E_2_ was measurable in males and was highest during the period of testicular development. Male P varied in a pattern not clearly associated with known reproductive events. KEYWORDS: hormone; steroid; estradiol; testosterone; dihydrotestosterone; progesterone; reproduction; Florida; stingray; elasmobranch; batoid; Dasyatidae PRESENTATION: ORAL SOCIETY: AES, AWARD: NONE
Present address: College of Marine Studies, U. of Delaware, 700 Pilottown Road, Lewes, Delaware 19958 USA; and Department of Biology, California State University Long Beach. E-MAIL: email@example.com
Age and growth of the shovelnose guitarfish Rhinobatos productus.
Seventy-five shovelnose guitarfish were collected between 1988 and 1991 to determine their age and growth rate by examination of bands within the vertebral centra. Terramycin was injected into 10 shovelnose in captivity and three of the 10 received a second injection at a later date. The three shovelnose with double injections showed subsequent growth beyond the first Terramycin mark and indicated that bands were produced annually. Shovelnose were aged to a maximum of 11 years. Females matured at seven years and males matured at eight years. The shovelnose is best described as a slow growing species typified by linear growth. KEYWORDS: shovelnose guitarfish; age and growth; sexual maturity. PRESENTATION: ORAL SESSION: AES AWARD: STOYE-ICH; GRUBER
KT and SLS Department of Medical Laboratory Sciences, Florida International University, Tamiami Trail at S.W. 107th Avenue, Miami, Florida 33199 USA; AWD and ACW MRC Immunochemistry Unit, Oxford University, U.K.
Immunochemical and protein structural analysis of a C3-like complement protein in nurse shark serum.
Studies were carried out on a previously described early component of the classical complement pathway of the nurse shark. When shark serum is activated with zymosan an activated complement component binds to zymosan. Immunochemical studies have shown that a serum protein, eluted from zymosan, shows similar molecular structure to mammalian C3. In Western blots this protein reacts with antisera to human C3 when PAGE is carried out under nondenaturing, nonreducing conditions. Shark complement activity has been shown to be methylamine sensitive and using ^14^C-methylamine incorporation and SDS-PAGE analysis, a thiolester-containing protein has been identified and isolated from shark serum which resembles mammalian C3 in molecular composition. Isolation procedures included initial serum fractionation by low ionic strength precipitation followed by chromatography of the supernatant, first on Q Sepharose then on a Mono Q gradient column. Preliminary aminoacid sequence data on the two chains of the molecule show the beta chain to be 50% identical to human C3 over 26 residues of the N terminus. The alpha chains show 28% identity over 25 residues. This is the first study which provides evidence for the existence of a C3-like protein in an elasmobranch. KEYWORDS: shark complement, shark C3, PRESENTATION: ORAL, SOCIETY: AES
CJW, CAL, Mote Marine Laboratory, 1600 Thompson Parkway, Sarasota, Florida 34236 USA; ABB, JTW, Department of Animal Dairy and Veterinary Sciences, SV, Department of Aquaculture, Fisheries, & Wildlife, TRS, Department of Poultry Science, Clemson University, Clemson, South Carolina.
Functional characterization of elasmobranch thymus.
Histologically, elasmobranch thymus appears to possess most of the structural features characteristic of vertebrate thymus. Studies to investigate cell replicative activity and presence of cell surface markers in thymic tissue from several elasmobranch species indicate that many functional similarities with mammalian and avian thymus also exist. Cell flow cytometry indicates that from 10-14% of unstimulated elasmobranch thymocytes are actively synthesizing DNA (S phase), while ^3^H-TdR incorporation in quiescent thymocyte culture was maximal during the initial 4-12 h, and declined over the next 36 h. Confirmation of replicative activity was obtained through visual identification of mitotically active cells in thymic imprints. Elasmobranch thymocytes also display cytochemical enzyme profiles characteristic of mammalian thymocytes undergoing maturation, testing positive for acid phosphatase, -naphthyl butyrate esterase, and terminal deoxynucleotidyl transferase, but negative for _-glucuronidase. In addition, elasmobranch thymocytes readily bind the lectin, peanut agglutinin (PNA), a cell surface marker commonly utilized to identify mammalian thymocytes. A consistent observation in thymic imprints from elasmobranchs is the presence of macrophage-like cells similar to mammalian thymic nurse cells. These large cells, whose speculative role in mammals includes processing thymic cells to functional T-lymphocytes, contain 1 to 4 thymocytes within their cytoplasm, and are positive for _-glucuronidase activity. KEYWORDS: AESIMMUNE; elasmobranch; thymus; cell flow cytometry; cell surface markers; thymic nurse cell, PRESENTATION: Oral, SOCIETY: AES
Perry R. Bass Marine Fisheries Research Station, Texas Parks and Wildlife Department, HC-2, Box 385, Palacios, Texas 77465 USA
Identification of members of the genus Carcharhinus by isoelectric focusing.
Sarcoplasmic proteins were isolated from skeletal muscle of 9 members of the genusCarcharhinus collected from the Atlantic coast of North America and the Gulf of Mexico. Members of each of the 9 species were distinguishable utilizing isoelectric focusing. Intraspecific comparisons were made between individuals collected from different regions. Densitometric tracings provided a graphical representation of differences in banding patterns among the members of the genus. Development and potential uses of a protein profile library is discussed in terms of species identification and conservation. KEYWORDS: species identification; Carcharhinidae; sharks, PRESENTATION: ORAL, SOCIETY: AES
BMW, MR and SLS Department of Medical Laboratory Sciences, Florida International University, Tamiami Trail at S.W. 107th Avenue, Miami, Florida 33199 USA; SDO and CJW Southeastern University of the Health Sciences.
Further characterization of complement activity in the nurse shark,Ginglymostoma cirratum.
Recent studies in our laboratory have provided evidence for the existence of anaphylatoxins and components of the alternative complement pathway in the nurse shark. Nurse shark serum (NSS) was heated at temperatures ranging from 38 – 56^o^C for 15 and 30 minutes and assayed for residual classical (CCP) and alternative (ACP) complement activity. Whereas heating NSS for 30 min at 56^o^C abolished CCP activity, ACP activity was lost in 15 min at 48^o^C. Serum fractions from a Sephadex G-100 column were tested for their ability to restore hemolytic activity to heated NSS (48^o^C, 30 min). One hemolytically inactive serum fraction did restore activity to the heated sample. NSS when activated with zymosan (10mg/ml for 3 hr at 30^o^C) and fractionated by gel filtration yielded fractions which exhibited anaphylactic and chemotactic activity. Using human peripheral blood leucocytes a significant migratory response was obtained with some serum fractions tested. One low molecular weight fraction, in addition to chemotactic activity also induced muscle contraction of iso lated rat ileum. These results suggest that (a) NSS contains a heat labile component(s) which is essential for ACP activity but not CCP activity and which maybe functionally analogous to mamma lian factor B, and (b) activated shark serum may contain a C5a and/or C3a-like peptide. KEYWORDS: shark complement, chemotaxis, anaphylatoxin, factor B, PRESENTATION: POSTER, SOCIETY: AES
JTW and ABB Department of Animal, Dairy, and Veterinary Sciences, Clemson University, Clemson, South Carolina 29634-0361 USA; CAL and CJW Mote Marine Laboratory, Sarasota, FL; TRS Department of Poultry Science, Clemson University, Clemson, SC 29634-0361
Examination of the lymphoid tissues of the Atlantic nurse shark (Ginglymostoma cirratum) by tissue-imprinted lectin analysis (TILA).
A tissue-imprinted lectin analysis ( TILA ) was performed on fixed cell preparations from the spleen, thymus, epigonal organ, and rectal gland of Atlantic nurse sharks (Ginglymostoma cirratum). One to two mm cross- sections of the tissues were gently imprinted on the surface of a glass slide and fixed in cold methanol for five minutes. A panel of 20 biotinylated lectins was tested on imprints from several sharks( N=6 ) with appropriate controls for endogenous activity and specificity of binding . The cells which showed positive lectin binding appeared purplish-blue in contrast to those cells which remained colorless or stained brown due to endogenous peroxidase activity . The results revealed different lectin-binding profiles for each tissue, indicative of the differences among resident cells . Lectins bind to carbohydrate moieties with a specificity rivaling that of a monoclonal antibody. Lectin-binding profiles obtained by TILA are useful for characterizing cell types based on their glycoprotein-rich surface and cytoplasmic receptors. KEYWORDS: AESIMMUNE; lectins; nurse shark; tissue-imprint, PRESENTATION: ORAL SOCIETY: AES, AWARD: GRUBER
Seikai National Fisheries Research Institute, Shimonoseki Branch, Fisheries Agency of Japan, 2-5-20 Higashiyamato-machi, Shimonoseki 750, Japan
Reproductive biology of the black dogfish, Centroscyllium fabricii, collected from West Greenland waters
The reproductive biology of 1129 males (165-760 mm TL) and 1479 females (175-898 mm TL) of black dogfish, Centroscyllium fabricii, collected from West Greenland waters was examined. The sharks were caught with bottom otter trawls. Size at maturity was about 550 mm TL in males and 650 mm TL in females. Ovarian ova do not continue to develop during gestation. The ratio of embryonic males to females was 1:1. Litter size ranged from 4 to 40, with an average of 16.4. Total number of mature ova, fertilized ova and embryos tended to increase with size of the female. The near-term embryos (152-192 mm TL) has completely absorbed their external yolk sacs. The smallest free-swimming specimens collected in this study were 165 mm TL. This species displayed a well defined pattern of depth segregation by size. KEYWORDS: squalidae; black dogfish; size at maturity; sex ratio; litter size; embryo; depth segregation; West Greenland, PRESENTATION: ORAL, SOCIETY: AES