DOCSLIB.ORG

Fishery Biology on Pelagic Stingray Pteroplatytrygon Violacea Caught Off Southern Brazil by Longliners Settled in Sao Paulo State (2006-2007)

Total Page：16

File Type：pdf, Size：1020Kb

Download full-text PDF Read full-text
Fishery Biology on Pelagic Stingray Pteroplatytrygon Violacea Caught Off Southern Brazil by Longliners Settled in Sao Paulo State (2006-2007) SCRS/2007/173 Collect. Vol. Sci. Pap. ICCAT, 62(6): 1883-1891 (2008) FISHERY BIOLOGY ON PELAGIC STINGRAY PTEROPLATYTRYGON VIOLACEA CAUGHT OFF SOUTHERN BRAZIL BY LONGLINERS SETTLED IN SAO PAULO STATE (2006-2007) C.C. Ribeiro-Prado1, A.F. Amorim2 SUMMARY The pelagic stingray (Pteroplatytrygon violacea) is cosmopolitan and it is usually caught by Sao Paulo longliners as bycatch. The species is considered Least Concern by the IUCN Red List. From August to September 2006 and January to September 2007, 157 specimens (77% male and 23% female) were received from the mentioned fleet that operates off Southern Brazil. A total of 157 stomachs were analyzed. From that total, 99 stomachs were empty and 58 presented some content. Mollusca was the most common group, with predominance of Loligo sp. Actinopterygii was present in 19% and Crustacea in 17% of stomach contents. The male matures from 43.5 cm DW and 10.4 cm CL, and female from 46 cm DW on. According to Gonadosomatic Index, the females were larger in January, and it could indicate that they were near birth period. Two females were caught with embryos in different developing stages, in January 1992 and in April 2002. Females were most frequently caught near the surface and the males in deeper water. New areas of occurrence were registered. This paper aims to study the biological aspects of the P. violacea as a contribution for its conservation. RÉSUMÉ La Pastenague violette (Pteroplatytrygon violacea) est une espèce cosmopolite, généralement capturée par les palangriers de Sao Paulo en tant que prise accessoire. Cette espèce est considérée comme Préoccupation mineure par la Liste rouge de l’IUCN. Du mois d’août jusqu’au mois de septembre 2006 et de janvier à septembre 2007, 157 spécimens (77% mâles et 23% femelles) ont été reçus de la flottille susmentionnée opérant au sud du Brésil. Au total, 157 estomacs ont été analysés. Parmi ceux-ci, 99 estomacs étaient vides et 58 présentaient un contenu. Les mollusques étaient le groupe le plus répandu, avec une majorité de Loligo sp. Les contenus stomacaux se composaient d’actinoptérygiens (19%) et de crustacés (17%). Les mâles étaient matures à partir de 43,5 cm en poids manipulé et de 10,4 cm de longueur à la fourche, et les femelles à partir de 46 cm en poids manipulé. D’après l’indice gonadosomatique, les femelles étaient plus grandes au mois de janvier et cela pourrait indiquer qu’elles étaient proches de leur période de procréation. Deux femelles ont été capturées avec des embryons se trouvant dans diverses phases de développement, en janvier 1992 et en avril 2002. Les femelles étaient capturées le plus fréquemment près de la surface et les mâles plus en profondeur. Leur présence a été enregistrée dans de nouvelles zones. Ce document vise à étudier les aspects biologiques de la P. violacea afin de contribuer à sa conservation. RESUMEN La raya látigo violeta (Pteroplatytrygon violacea) es cosmopolita y por lo general los palangreros de Sao Paulo la capturan como captura fortuita. Esta especie es considerada de mínima inquietud por la Lista Roja de IUCN. Desde agosto hasta septiembre de 2006 y de enero a septiembre de 2007, 157 ejemplares (77% machos y 23% hembras) fueron recibidos de la mencionada flota que opera frente al sur de Brasil. Se analizó un total de 157 estómagos. De estos, 99 estómagos estaban vacíos y 58 presentaban algún contenido. El grupo más común eran los moluscos, con predominancia de Loligo sp. Actinopterygii estaba presente en el 19% y crustáceos en el 17% de los contenidos estomacales. Los machos maduran desde los 43,5 cm DW y 10,4 cm CL, y las hembras desde 46 cm DW en adelante. De acuerdo con el índice gonadosomático, las hembras eran más grandes en enero, lo que podría indicar que estaban cerca del periodo de parto. Dos hembras fueron capturadas con embriones en diferentes etapas de desarrollo, en enero de 1992 y abril de 2002. Las hembras se capturan con más frecuencia cerca de la superficie y los machos en aguas más profundas. Se registraron nuevas zonas de presencia. Este documento tiene como objetivo estudiar los aspectos biológicos de la P. violacea como una contribución a su conservación. 1 M.Sc. Student. Instituto de Pesca - APTA/SAA. Santos, SP. [email protected] 2 Instituto de Pesca - APTA/SAA. Santos, SP. [email protected] 1883 KEYWORDS Pteroplatytrygon violacea, incidental catches, longline, pelagic stingray, reproduction, stomach content 1. Introduction The pelagic ray, Ptheroplatytrygon violacea (Bonaparte, 1832) is considered cosmopolitan and is present in tropical and subtropical areas of the Atlantic, Pacific and Indian Oceans (Wilson and Beckett, 1970; Sadowsky and Amorim, 1977; Lamilla et al., 1995; Menni et al., 1995; McKinnell e Seki, 1998; Benson et al., 2001; Chapman, 2001; McEachran e Carvalho, 2002; Bromhead et al., 2003; Dávalos-Dehullu e González-Navarro, 2003; Letourneur et al., 2004; Domingo et al., 2004; FIP, 2004; Francis et al. 2005; Molina et al., 2005; Ward and Myers, 2005). It is incidentally caught by the tuna longliner fleet settled in São Paulo State that operates off Southern Brazil (Sadowsky and Amorim, 1977). The pelagic stingray was included on the Red List of the Threatened Species, considered as “Least Concern”, although its conservation status must be carefully monitored, because the fishing effort was intensified in the area of ray’s occurrence. So its conservation status can be changed to threatened species, if fishermen keep fishing the rays and discarding the dead animals in the ocean (Chapman, 2001; Otway et al., 2004; IUCN, 2007). There are a few studies on fisheries biology of this species (Rosenberger, 2001; Mollet and Cailliet, 2002; Musick, 2004; Peach and Rouse, 2004; Schwartz, 2005), that are important source of data for the species conservation. This paper intends to study the biological aspects of P. violacea, as long as to contribute to data related to its distribution in the Southern Brazil, aiming at the species conservation. 2. Material and methods One hundred and fifty-seven specimens of pelagic rays Pteroplatytrygon violacea (Bonaparte, 1832) were collected in August and September 2006 and from January to September 2007, from the longliners fishing companies from Santos and Guarujá Cities, in Sao Paulo State. Fisheries information were also collected, including numbers of fishing days, number of sets, kind of bait used and the area where the capture of rays occurred. For each exemplar the following data were taken: sex, total length (TL), total weight (TW), gonad weight (GW) and Liver Weight (LW). The Gonadossomatic Index (GSI) and Liversomatic Index (LSI) were calculated according to Vazzoler (1981): GSI=GW/TW*100; LSI=LW/TW*100. The stomach content was identified according to Figueiredo (1988), Dávalos-Dehullu and González-Navarro (2003), Thomas (1993) and Pineda et al. (2002). 3. Results and discussion According to the fishermen, Pteroplatytrygon violacea is always present in the longliner fisheries that aim swordfish, tunas and sharks. The total of P. violacea on sampling represents a small part of the total catch. The rays are discarded alive, although the fisherman injures the animals, in order to get rid of the hooks, what can lead to death. The fishermen also mentioned the preference of the rays for light stick and squids, which occur in waters with higher temperatures. It was also observed the prevalence of females in sets where the hooks were closer to the surface and the males in deeper sets. From 157 specimens caught up to now, 121 were males and 36 were females. The smallest sampling specimen was a female of 87 cm TL, 36.5 cm DW, 1,082 g Wt, with the left uterus weighing 2.0 g, caught in June of 2007 at 25°10’S and 44°30’W, in the area about 800 meters deep. The largest specimen was a female with 129 cm TL, 68.5 DW and 7,780 g TW, presenting only the left uterus developed (87 g), without embryos, caught in August 2007, at 28°00’S and 44º30’W. 1884 The females, although less frequently captured, presented higher disc width average than the males (Figure 1). Capapé (1993) reports the same variation of sizes between sexes on stingray Dasyatis centroura. Concerning to the sexual maturity, the studied males presented L50= 43.5 cm DW and 10.4 cm of Clasper Length, when the structure is rigid (Table 1), and the females probably from 46.0 cm on, where the left uterus was significantly more developed than the right one. Studying recent female maturity, it was not observed the presence of embryos. It was observed just one uterus with flaccid appearance, weighing 196 g and 160 cm long by 10.0 cm wide, caught in January 2007 that suggests a recent spawning (Vazzoler, 1981; Querol et al., 2002). The females were larger in January, when high values could indicate that they were near birth period. Nevertheless, two females were caught with embryos in different developing stages. According to Amorim (personal communication) there is a report of a female with three embryos (two females and one male) about five centimeters long without pigmentation pattern (yellowish white). It was brought by Taihei Maru longliner in January 1992, caught off 24°14’–24°59’S and 43°14’-41°33’W. According to Oddone (personal communication), in April 2002, a female with two embryos was found on a boat near Cape Santa Marta Grande (28°46’S-48°40’W). These embryos were about 15 cm long and had a dark color similar to a newborn (Figure 2). Probably the parturition period can occur around April. According to the Gonadosomatic Index, the females presented higher average in January.
Load more

Recommended publications
  • A New Stingray from South Africa
    Nature Vol. 289 22 January 1981 221 A new stingray from South Africa from Alwyne Wheeler ICHTHYOLOGISTS are accustomed to the regular description of previously un­ recognized species of fishes, which if not a daily event at least happens so frequently as not to cause great comment. Previously undescribed genera are like­ wise not infrequently published, but higher categories are increasingly less common. The discovery of a new stingray, which is so different from all known rays as to require both a new family and a new suborder to accommodate its distinctive characters, is therefore a remarkable event. A recent paper by P.e. Heemstra and M.M. Smith (Ichthyological Bulletin oj the J. L.B. Smith Institute of Ichthyology 43, I; 1980) describes this most striking ray as Hexatrygon bickelli and discusses its differences from other batoid fishes. Surprisingly, this remarkable fish was not the result of some organized deep-sea fishing programme, but was found lying on the beach at Port Elizabeth. It was fresh but had suffered some loss of skin by sand abrasion on the beach, and the margins of its fins appeared desiccated in places. The way it was discovered leaves a tantalising question as to its normal habitat, but Heemstra and Smith suggest that it may live in moderately deep water of 400-1,000m. This suggestion is Ventral view of Hexatrygon bickelli supported by its general appearance (small eyes, thin black dorsal skin, f1acid an acellular jelly, while the underside is chimaeroids Rhinochimaera and snout) and the chemistry of its liver-oil. richly supplied with well developed Harriota, and there can be little doubt The classification of Hexatrygon ampullae of Lorenzini.
    [Show full text]
  • Coral Reef Monitoring in Kofiau and Boo Islands Marine Protected Area, Raja Ampat, West Papua. 2009—2011
    August 2012 Indo-Pacific Division Indonesia Report No 6/12 Coral Reef Monitoring in Kofiau and Boo Islands Marine Protected Area, Raja Ampat, West Papua. 2009—2011 Report Compiled By: Purwanto, Muhajir, Joanne Wilson, Rizya Ardiwijaya, and Sangeeta Mangubhai August 2012 Indo-Pacific Division Indonesia Report No 6/12 Coral Reef Monitoring in Kofiau and Boo Islands Marine Protected Area, Raja Ampat, West Papua. 2009—2011 Report Compiled By: Purwanto, Muhajir, Joanne Wilson, Rizya Ardiwijaya, and Sangeeta Mangubhai Published by: TheNatureConservancy,Indo-PacificDivision Purwanto:TheNatureConservancy,IndonesiaMarineProgram,Jl.Pengembak2,Sanur,Bali, Indonesia.Email: [email protected] Muhajir: TheNatureConservancy,IndonesiaMarineProgram,Jl.Pengembak2,Sanur,Bali, Indonesia.Email: [email protected] JoanneWilson: TheNatureConservancy,IndonesiaMarineProgram,Jl.Pengembak2,Sanur,Bali, Indonesia. RizyaArdiwijaya:TheNatureConservancy,IndonesiaMarineProgram,Jl.Pengembak2,Sanur, Bali,Indonesia.Email: [email protected] SangeetaMangubhai: TheNatureConservancy,IndonesiaMarineProgram,Jl.Pengembak2, Sanur,Bali,Indonesia.Email: [email protected] Suggested Citation: Purwanto,Muhajir,Wilson,J.,Ardiwijaya,R.,Mangubhai,S.2012.CoralReefMonitoringinKofiau andBooIslandsMarineProtectedArea,RajaAmpat,WestPapua.2009-2011.TheNature Conservancy,Indo-PacificDivision,Indonesia.ReportN,6/12.50pp. © 2012012012201 222 The Nature Conservancy AllRightsReserved.Reproductionforanypurposeisprohibitedwithoutpriorpermission. AllmapsdesignedandcreatedbyMuhajir. CoverPhoto:
    [Show full text]
  • Species Bathytoshia Brevicaudata (Hutton, 1875)
    FAMILY Dasyatidae Jordan & Gilbert, 1879 - stingrays SUBFAMILY Dasyatinae Jordan & Gilbert, 1879 - stingrays [=Trygonini, Dasybatidae, Dasybatidae G, Brachiopteridae] GENUS Bathytoshia Whitley, 1933 - stingrays Species Bathytoshia brevicaudata (Hutton, 1875) - shorttail stingray, smooth stingray Species Bathytoshia centroura (Mitchill, 1815) - roughtail stingray Species Bathytoshia lata (Garman, 1880) - brown stingray Species Bathytoshia multispinosa (Tokarev, in Linbergh & Legheza, 1959) - Japanese bathytoshia ray GENUS Dasyatis Rafinesque, 1810 - stingrays Species Dasyatis chrysonota (Smith, 1828) - blue stingray Species Dasyatis hastata (DeKay, 1842) - roughtail stingray Species Dasyatis hypostigma Santos & Carvalho, 2004 - groovebelly stingray Species Dasyatis marmorata (Steindachner, 1892) - marbled stingray Species Dasyatis pastinaca (Linnaeus, 1758) - common stingray Species Dasyatis tortonesei Capapé, 1975 - Tortonese's stingray GENUS Hemitrygon Muller & Henle, 1838 - stingrays Species Hemitrygon akajei (Muller & Henle, 1841) - red stingray Species Hemitrygon bennettii (Muller & Henle, 1841) - Bennett's stingray Species Hemitrygon fluviorum (Ogilby, 1908) - estuary stingray Species Hemitrygon izuensis (Nishida & Nakaya, 1988) - Izu stingray Species Hemitrygon laevigata (Chu, 1960) - Yantai stingray Species Hemitrygon laosensis (Roberts & Karnasuta, 1987) - Mekong freshwater stingray Species Hemitrygon longicauda (Last & White, 2013) - Merauke stingray Species Hemitrygon navarrae (Steindachner, 1892) - blackish stingray Species
    [Show full text]
  • Chondrichthyes: Dasyatidae)
    1 Ichthyological Exploration of Freshwaters/IEF-1089/pp. 1-6 Published 16 February 2019 LSID: http://zoobank.org/urn:lsid:zoobank.org:pub:DFACCD8F-33A9-414C-A2EC-A6DA8FDE6BEF DOI: http://doi.org/10.23788/IEF-1089 Contemporary distribution records of the giant freshwater stingray Urogymnus polylepis in Borneo (Chondrichthyes: Dasyatidae) Yuanita Windusari*, Muhammad Iqbal**, Laila Hanum*, Hilda Zulkifli* and Indra Yustian* Stingrays (Dasyatidae) are found in marine (con- species entering, or occurring in freshwater. For tinental, insular shelves and uppermost slopes, example, Fluvitrygon oxyrhynchus and F. signifer one oceanic species), brackish and freshwater, and were only known from five or fewer major riverine are distributed across tropical to warm temperate systems (Compagno, 2016a-b; Last et al., 2016a), waters of the Atlantic, Indian and Pacific oceans though recent surveys yielded a single record of (Nelson et al., 2016). Only a small proportion of F. oxyrhynchus and ten records of F. signifier in the dasyatid rays occur in freshwater, and include Musi drainage, South Sumatra, indicating that obligate freshwater species (those found only in both species are more widely distributed than freshwater) and euryhaline species (those that previously expected (Iqbal et al., 2017, 2018). move between freshwater and saltwater) (Last et Particularly, the dasyatid fauna of Borneo al., 2016a). Recently, a total of 89 species of Dasy- includes the giant freshwater stingray Urogymnus atidae has been confirmed worldwide (Last et al., polylepis. The occurrence of U. polylepis in Borneo 2016a), including 14 species which are known to has been reported from Sabah and Sarawak in enter or live permanently in freshwater habitats of Malaysia and the Mahakam basin in Kaliman- Southeast Asia [Brevitrygon imbricata, Fluvitrygon tan of Indonesia (Monkolprasit & Roberts, 1990; kittipongi, F.
    [Show full text]
  • Stingray Injuries
    Stingray Injuries FINDLAY E. RUSSELL, M.D. inflicted by stingrays are com¬ the integumentary sheath surrounding the INJURIESmon in several areas of the coastal waters spine is ruptured and the venom escapes into of North America (1-4). Approximately 750 the victim's tissues. In withdrawing the spine, people a year along our coasts are stung by the integumentary sheath may be torn free and these elasmobranchs. The largest number of remain in the wound. stings are reported from southern California, Unlike the injuries inflicted by many venom¬ the Gulf of California, the Gulf of Mexico, and ous animals, wounds produced by the stingray the south Atlantic coast (5). may be large and severely lacerated, requiring Of 1,097 stingray injuries reported over a 5- extensive debridement and surgical closure. A year period in the United States (5, tf), 232 sting no wider than 5 mm. may produce a were seen by a physician at some time during wound 3.5 cm. long (#), and larger stings may the course of the recovery of the victim. Sixty- produce wounds 7 inches long (7). Occasion¬ two patients were hospitalized; the majority of ally, the sting itself may be broken off in the these required surgical closure of their wounds wound. or treatment for secondary infection, or both. The sting, or caudal spine, is a bilaterally ser¬ At least 10 of the 62 victims were hospitalized rated dentinal structure located on the dorsal for treatment for overexuberant first aid care. surface of the animal's tail. The sharp serra¬ Only eight patients were hospitalized for the tions are curved cephalically and as such are treatment of the systemic effects produced by responsible for the lacerating effects as the sting the venom.
    [Show full text]
  • Biology, Husbandry, and Reproduction of Freshwater Stingrays
    Biology, husbandry, and reproduction of freshwater stingrays. Ronald G. Oldfield University of Michigan, Department of Ecology and Evolutionary Biology Museum of Zoology, 1109 Geddes Ave., Ann Arbor, MI 48109 U.S.A. E-mail: [email protected] A version of this article was published previously in two parts: Oldfield, R.G. 2005. Biology, husbandry, and reproduction of freshwater stingrays I. Tropical Fish Hobbyist. 53(12): 114-116. Oldfield, R.G. 2005. Biology, husbandry, and reproduction of freshwater stingrays II. Tropical Fish Hobbyist. 54(1): 110-112. Introduction In the freshwater aquarium, stingrays are among the most desired of unusual pets. Although a couple species have been commercially available for some time, they remain relatively uncommon in home aquariums. They are often avoided by aquarists due to their reputation for being fragile and difficult to maintain. As with many fishes that share this reputation, it is partly undeserved. A healthy ray is a robust animal, and problems are often due to lack of a proper understanding of care requirements. In the last few years many more species have been exported from South America on a regular basis. As a result, many are just recently being captive bred for the first time. These advances will be making additional species of freshwater stingray increasingly available in the near future. This article answers this newly expanded supply of wild-caught rays and an anticipated increased The underside is one of the most entertaining aspects of a availability of captive-bred specimens by discussing their stingray. In an aquarium it is possible to see the gill slits and general biology, husbandry, and reproduction in order watch it eat, as can be seen in this Potamotrygon motoro.
    [Show full text]
  • Reproductive Biology of the Stingray Hypanus Marianae , an Endemic
    ReproduCtive Biology of the stingray Hypanus marianae, an endemic species from Southwestern Tropical Atlantic Ocean Biologia Reprodutiva da raia Hypanus marianae, uma espécie endêmica do SudOeste do Oceano Atlântico Tropical Biología reproductiva de la raya Hypanus marianae, una especie endémica del suROeste del Océano Atlántico Tropical Ana Rita Onodera Palmeira Nunes1 Getulio Rincon1,2 Ricardo de Souza Rosa3 Jorge Luiz Silva Nunes1 Abstract The Brazilian Large-eyed stingray Hypanus marianae is the smallest species of the family Dasyatidae in Brazil. This study aims to provide data on the reproductive biology of this species captured in artisanal fisheries from Ceará State. A total of 299 individuals of H. marianae were recorded at monitoring landings and adult male to female sex ratio was significantly different (1:2.9), indicating a possible spatial segregation between males and females. The size range was from 13.0 to 36.2cm in disc width (DW). Females reached greater size and body mass (36.2cm DW and 1855g) than males (29.3cm DW and 915g). The reproductive system analyses were based on 81 preserved specimens. The DW50 parameter was estimated at 26.1cm DW for females, and 23.8cm DW for males. Only the left uterus is functional, and birth size was estimated at 13.0–14.0cm DW. Vitellogenesis occurred concurrently with a short gestation (shorter than 6 months) and uterine fecundity is only one embryo per reproductive cycle, which seems to be asynchronous. Keywords: maturity, fecundity, birth, embryos, Dasyatidae. Resumo A raia Mariquita Hypanus marianae é a menor espécie da família Dasyatidae no Brasil e este trabalho tem como objetivo reportar informações acerca da sua biologia reprodutiva a partir de capturas da pesca artesanal no estado do Ceará.
    [Show full text]
  • An Overview of the Hooking Mortality of Elasmobranchs Caught in a Swordfish Pelagic Longline fishery in the Atlantic Ocean
    Aquat. Living Resour. 25, 311–319 (2012) Aquatic c EDP Sciences, IFREMER, IRD 2012 DOI: 10.1051/alr/2012030 Living www.alr-journal.org Resources An overview of the hooking mortality of elasmobranchs caught in a swordfish pelagic longline fishery in the Atlantic Ocean Rui Coelho1,2,a, Joana Fernandez-Carvalho1,PedroG.Lino1 and Miguel N. Santos1 1 Instituto Português do Mar e da Atmosfera, I.P. (IPMA), Avenida 5 de Outubro s/n, 8700-305 Olhão, Portugal 2 Centro de Ciências do Mar (CCMAR), Universidade do Algarve, Campus de Gambelas FCT Ed.7, 8005-170 Faro, Portugal Received 6 February 2012; Accepted 24 September 2012 Abstract – Hooking (or “at-haulback”) fishing mortality was analysed in elasmobranchs captured by Portuguese long- liners targeting swordfish in the Atlantic Ocean. Information was collected by on-board fishery observers who moni- tored 834 longline fishing sets between August 2008 and December 2011, and recorded information on 36 067 elasmo- branch specimens from 21 different taxa. The hooking mortality proportions were species-specific, with some species having relatively high percentages of live specimens at time of haulback (e.g., blue shark, crocodile shark, pelagic stingray, manta, devil and eagle rays), while others had higher percentages of dead specimens (e.g., smooth hammer- head, silky shark, bigeye thresher). For the most captured species (Prionace glauca, Pseudocarcharias kamoharai, Isurus oxyrinchus and Alopias superciliosus), logistic generalized linear models (GLMs) were carried out to compare the mortality rates between sexes, specimen sizes and the regions of operation of the fleet. The sex-specific proportions of hooking mortality were significantly different for blue and crocodile sharks, with the males of both species having higher proportions of hooking mortality than the females.
    [Show full text]
  • Class Wars: Chondrichthyes and Osteichthyes Dominance in Chesapeake Bay, 2002-2012
    Class Wars: Chondrichthyes and Osteichthyes dominance in Chesapeake Bay, 2002-2012. 01 July 2013 Introduction The objective of this analysis was to demonstrate a possible changing relationship between two Classes of fishes, Osteichthyes (the bony fishes) and Chondrichthyes (the cartilaginous fishes) in Chesapeake Bay based on 11 years of monitoring. If any changes between the two Classes appeared to be significant, either statistically or anecdotally, the data were explored further in an attempt to explain the variation. The Class Osteichthyes is characterized by having a skeleton made of bone and is comprised of the majority of fish species worldwide, while the Chondrichthyes skeleton is made of cartilage and is represented by the sharks, skates, and rays (the elasmobranch fishes) and chimaeras1. Many shark species are generally categorized as apex predators, while skates and rays and some smaller sharks can be placed into the mesopredator functional group (Myers et al., 2007). By definition, mesopredators prey upon a significant array of lower trophic groups, but also serve as the prey base for apex predators. Global demand for shark and consequential shark fishing mortality, estimated at 97 million sharks in 2010 (Worm et al., 2013), is hypothesized to have contributed to the decline of these apex predators in recent years (Baum et al., 2003 and Fowler et al., 2005), which in turn is suggested to have had a cascading effect on lower trophic levels—an increase in mesopredators and subsequent decrease in the prey base (Myers et al., 2007). According to 10 years of trawl survey monitoring of Chesapeake Bay, fish species composition of catches has shown a marked change over the years (Buchheister et al., 2013).
    [Show full text]
  • Ray by Design Stingray
    Sponsored by Blue Lagoon Island & Vendors from Nassau Dolphin Encounters - Project BEACH Contest Deadline: March 4th, 2016 Beautifully graceful underwater, Southern The unique hunting abilities of a stingray – stingrays choose the turquoise waters of digging, sucking, and crushing – also benefit The Bahamas as their home. Like many other reef animals looking for lunch. These other reef animals, stingrays play an gentle winged fish are key predators in a important role in our marine ecosystem. healthy, marine habitat, so it’s time to “Rays the Roof” and start protecting our stingrays! When a stingray hunts along the bottom, it mixes the sand and stirs up hidden Learn more about this unique animal and the creatures in search of food. Sea birds challenges it faces from the MEPC 2016 Info will often follow the path of a stingray Sheet and express your feelings through art hoping to make a meal from the animals in the Marine Education Poster Contest 2016. disturbed by the ray. Call for a FREE Marine Assembly Program at your school to introduce you to the marine topic “Rays the Roof!” Ray By Design Southern stingrays can be gills As masters of disguise Stingray 101 found in tropical and (camouflage), stingrays can subtropical waters of the completely bury themselves in Animal Type: Boneless Fish southern Atlantic Ocean, the sand or soft seafloor. Caribbean and Gulf of When swimming, if viewed Diet: Carnivore Mexico. These rays have been ventral side mouth from below, the bright belly Ave. Lifespan: 15-25 years found in depths of up to 180 of the ray matches the bright feet and are usually found Unlike sharks, rays crush their sky above, helping to escape Maximum Width: 4 feet roaming the ocean alone or in food -- prey such as conch, large predatory fish such as Maximum Weight: 200+ lbs.
    [Show full text]
  • Pacific Currents | Summer 2009 Pre-Registration and Pre-Payment Required on All Programs Unless Noted
    summer 2009 | volume 12 | number 4 member magazine of the aquarium of the pacific Learn about these graceful and magnificent animals that keep our ocean healthy! Focus on Sustainability GLOBAL WARMING’S EVIL TWIN One aspect of global climate change that has received far less attention than many others, but may be among the most important to ocean life, is ocean acidification. By Jerry R. Schubel EARLY EVERYONE has heard of global warming, and most believe that it is happening and that humans are a major driving force because of our use of fossil fuels. The AA N O more expansive term is global climate change, which OFT/N includes an array of effects caused by warming. These include sea R level rise, coral bleaching, loss of biodiversity, an increase in the frequency and intensity of tropical storms, and so on. One aspect of HOPC RUSS global climate change that has received far less attention than many Planktonic snails known as pteropods (Limacina helicina) are at high risk from ocean acidification, as the surface seawater of the polar regions is projected to become others, but may be among the most important to ocean life, is referred corrosive to their shells within decades. to by some scientists as “Global Warming’s Evil Twin.” The evil twin robs many animals with calcareous skeletons—both internal and external—of their ability to secrete calcium carbonate shells from sea Since increasing acidity lowers carbonate ion concentration—a water. The evil twin is ocean acidification. component of calcium carbonate used by many organisms to build Most of the carbon dioxide that is added to the atmosphere from their shells, skeletons, and coral reef structures—those organisms, the burning of fossil fuels remains in the atmosphere for an average including plankton (such as pteropods and coccolithophores), of about a century and then is transferred into the ocean where it benthos (such as clams, oysters, and mussels), and coral reefs, remains, on average, for a thousand years or longer.
    [Show full text]
  • Atlantic Sharks at Risk
    RESEARCH SERIES JUNE 2008 Risk Assessment Prompts No-Take Recommendations for Shark Species ATLANTIC SHARKS AT RISK SummARY OF AN EXPERT WORKING GROup REPORT: Simpfendorfer, C., Heupel M., Babcock, E., Baum, J.K., Dudley, S.F.J., Stevens, J.D., Fordham, S., and A. Soldo. 2008. Management Recommendations Based on Integrated Risk Assessment of Data-Poor Pelagic Atlantic Sharks. POpuLATIONS OF MANY of the world’s pelagic, or open ocean, shark and ray species are declining. Like most sharks, these species are known to be susceptible to overfishing due to low reproductive rates. Pelagic longline fisheries for tuna and swordfish catch significant numbers of pelagic sharks and rays and shark fisheries are also growing due to declines in traditional target species and the rising value of shark fins and meat. Yet, a lack of data has prevented scientists from conducting reliable population assessments for most pelagic shark and ray species, hindering effective management actions. Dr. Colin Simpfendorfer and the Lenfest Ocean Program convened an international expert working group to estimate the risk of overfishing for twelve species caught in Atlantic pelagic longline fisheries under the jurisdiction of the International Commission for the Conserva- tion of Atlantic Tunas (ICCAT). The scientists conducted an integrated risk assessment designed for data-poor situations for these sharks and rays. Their analysis indicated that bigeye thresher, shortfin mako and longfin mako sharks had the highest risk of overfishing while many of the other species had at least moderately high levels of risk. Based on these results, the scientists developed recommendations for limiting or prohibiting catch for the main pelagic shark and ray species taken in ICCAT fisheries.
    [Show full text]