DOCSLIB.ORG

Effects of Fishing During the Spawning Period: Implications for Sustainable Management

Total Page：16

File Type：pdf, Size：1020Kb

Download full-text PDF Read full-text
Effects of Fishing During the Spawning Period: Implications for Sustainable Management See discussions, stats, and author profiles for this publication at: https://www.researchgate.net/publication/271919728 Effects of fishing during the spawning period: implications for sustainable management ARTICLE in REVIEWS IN FISH BIOLOGY AND FISHERIES · MARCH 2014 Impact Factor: 2.73 · DOI: 10.1007/s11160-014-9370-x CITATIONS READS 5 58 2 AUTHORS, INCLUDING: Adriaan D. Rijnsdorp Wageningen UR 240 PUBLICATIONS 6,659 CITATIONS SEE PROFILE All in-text references underlined in blue are linked to publications on ResearchGate, Available from: Adriaan D. Rijnsdorp letting you access and read them immediately. Retrieved on: 28 January 2016 Rev Fish Biol Fisheries DOI 10.1007/s11160-014-9370-x REVIEWS Effects of fishing during the spawning period: implications for sustainable management Harrie¨t M. J. van Overzee • Adriaan D. Rijnsdorp Received: 12 February 2014 / Accepted: 22 August 2014 Ó Springer International Publishing Switzerland 2014 Abstract While fishery closures during the spawn- exploitation of specific spawning components. The ing season are commonplace, direct evidence for their contribution of spawning closures to sustainable benefit is mainly restricted to species forming large fisheries will differ among species and depends on spawning aggregations. This paper analyses the con- the complexity of the spawning system, the level of ditions under which spawning closures could contrib- aggregation during spawning and the vulnerability of ute to sustainable fisheries management by reviewing the spawning habitat. The importance of these closures how fishing during spawning may affect the physiol- depends on the degree of population depletion but ogy, behaviour and ecology of individuals and how does not cease when populations are ‘healthy’ (i.e. no this may influence the dynamics and the genetics of the sign that recruitment is impaired). population. We distinguish between the effects of fishing activities in relation to mortality, disturbance Keywords Spawning closures Á Fish Á Invertebrates Á of spawning activity, and impact on spawning habitat. Reproduction Á Spawning aggregations Á Fisheries Spawning closures may be of benefit it they: (1) reduce the fishing mortality of the large and older spawners; (2) avoid negative effects on spawning habitats; (3) reduce the risk of over-exploitation in species which Introduction form large spawning aggregations; (4) reduce the evolutionary effects on maturation and reproductive There is great concern internationally about the effects investment; and (5) reduce the risk of over- of fisheries on populations of exploited species and the ecosystem in which they live (Coleman and Williams 2002; Jackson et al. 2001; Pauly et al. 2002). Although Electronic supplementary material The online version of this article (doi:10.1007/s11160-014-9370-x) contains supple- the exploitation rate has started to decline in some mentary material, which is available to authorized users. well-studied ecosystems, the majority of the assessed stocks worldwide still require rebuilding (Worm et al. & H. M. J. van Overzee Á A. D. Rijnsdorp ( ) 2009). In addition, fisheries may have an adverse IMARES, Wageningen UR, PO Box 68, 1970 AB Ijmuiden, The Netherlands effect on the ecosystem due to the bycatch of e-mail: [email protected] undersized fish or organisms of no commercial value, by changing or adversely impacting habitats through A. D. Rijnsdorp towed bottom gear, and evolutionary changes (Dayton Aquaculture and Fisheries Group, Wageningen University, PO Box 338, 6700 AH Wageningen, et al. 1995; Jennings and Kaiser 1998; Jørgensen et al. The Netherlands 2007). 123 Rev Fish Biol Fisheries Fisheries management faces the difficult task of the population dynamics and sustainable management developing scenarios for sustainable exploitation are used, such as studying the population dynamics while, at the same time, protecting biodiversity and before and after the establishment of a spawning the livelihood of the fishing communities. Generally, closure (Russell et al. 2012), applying a comparative fisheries management applies a combination of mea- approach across species or populations (Sadovy de sures such as landing quota, effort quota, gear Mitcheson and Erisman 2012), or applying a simula- restrictions, size limits and closed areas or seasons. tion approach (Gru¨ss et al. 2014; Gwinn and Allen The establishment of closed areas has gained support 2010). as contributors to the protection of biodiversity Here we analyse the conditions under which (Agardy 1994). Closed areas may also promote spawning closures could make a contribution to the sustainable exploitation through the protection of sustainable fisheries management of fish and inverte- spawning or nursery areas (Murawski et al. 2000; brate species. We apply a mechanistic approach in Pastoors et al. 2000; Russ and Alcala 1996; Sadovy de which the effect of fishing during the spawning period Mitcheson and Colin 2012). on the physiology, behaviour, population dynamics Fishery closures during the spawning season are and genetics is considered and compared to the effect commonplace. Table 1 presents a selection of spawn- of fishing during the non-spawning period. We ing closures illustrating their wide-spread use in terms distinguish between the primary effect of fishing on of location and species, and the differences in the target species (mortality, disturbance of spawning) objectives. First, spawning closures have been estab- and the secondary effect of fishing on the spawning lished successfully to reduce the fishing mortality in habitat. Thereafter, population biological conse- fisheries targeting large spawning aggregations that quences of fishing during the spawning period are are particularly vulnerable to over-exploitation (Sa- discussed. Finally, implications for management are dovy de Mitcheson et al. 2013) (e.g. reef fish; Table 1, considered by presenting a scoring system to infer the #1–2). A review of spawning closures for spawning vulnerability of species to fisheries during the spawn- aggregating reef fish is presented by Russell et al. ing period and by discussing the ecosystem based (2012). Secondly, spawning closures have been approach. implemented successfully in semelparous or short- living species to allow a sufficient proportion of the spawning stock to be able to shed their eggs before Fishing effects during the spawning period dying (e.g. Southern calamary and Chokka squid; versus the non-spawning period Table 1, #3–4). Thirdly, spawning closures have been put into place to protect spawning populations in order To evaluate the effect of fishing during the spawning to enhance the reproductive output of spawning fish period, we analyse the effect of (1) fishing mortality, and hence improve the number of recruits in the (2) spawning disturbance and (3) impact on spawning exploited stock (e.g. European spiny lobster, Pacific habitat separately. As these factors are not restricted to halibut, cod, herring and haddock; Table 1, #5–10). the spawning period, the effects of fishing during the However, none of the latter studies provide compel- spawning period in comparison to the effect of fishing ling evidence to demonstrate that spawning closures during the non-spawning period are discussed are in fact achieving their stated objectives. (Table 2). Opinions in the scientific community about the usefulness of spawning closures are divided (Horwood Fishing mortality et al. 1998; Russell et al. 2012; Sadovy de Mitcheson and Erisman 2012; Sauer 1995). Although the concept Spawning is generally limited to specific areas and of spawning closures may be appealing as it is easy to times (Cushing 1990). Therefore, fishing during the understand, it is hard to study their effectiveness spawning period may target different components of because it is very difficult, if not impossible, to carry the population than during the non-spawning period. out replicated experiments in real fisheries systems The chance of catching the older (and larger) age (but see (Hamilton et al. 2011)). Therefore, alternative classes may be higher during the spawning period as approaches to study the effect of spawning closures on they gather on the spawning grounds, which are often 123 Rev Fish Biol Fisheries Table 1 Several examples of spawning closures for different exploited species around the world S. Species Area Closure Goal Effectiveness No. 1 Red hind (Epinephelus St. Thomas, U.S Closure fishery during spawning Protection of Increase average length, normalization sex ratio, guttatus) Virgin Islands, Red period (December until end spawning and increased fish abundance all indicated that Hind Bank Marine February, implemented in 1990)1,2 aggregations curtailment of fishing at the spawning locale has Conservation contributed to recovery of red hind around St. District Thomas1 Permanent closure (since 1999)3 Protection of Increase in average density, biomass, spawning spawning density3 aggregations and large area of critical fish habitat 2 Brown-marbled grouper Coral triangle (Papua Two spawning aggregation sites were Sustainable fisheries Densities of E. fuscoguttatus and E. (Epinephelus New Guinea) protected by the establishment of and protection of polyphekadion increased at both MPAs, but not fuscoguttatus), Camouflage community-based MPA in 2004 biodiversity at the site that remained open to fishing4 grouper (Epinephelus polyphekadion) 3 Southern calamary Great Oyster Bay, Two short closures in two-week Protect spawning The closure was successful in providing (Sepioteuthis australis) Tasmania blocks
Load more

Recommended publications
  • Crappie and Crappie Fishing
    Crappie & Crappie Fishing Crappie are among the most popular sport fishes in Texas. They are known by various names including white perch, sac-a-lait, calico bass, and paper-mouth. Two species are found in Texas, the white crappie (Pomoxis annularis) and black crappie (P. nigromaculatus). Black crap­ pie have irregular dark speck­ les and blotches on their sides. On white crappie, the dark markings consist of regularly arranged vertical bars. When in doubt, count the number of sharp dorsal spines at the front of a crappie’s dorsal fin. Black crappie have seven or eight spines while white crappie Young crappie feed on microscopic crustaceans called have five or six. During the spawning season, males of zooplankton. Juveniles and adults feed primarily on both species develop dark markings over most of the small threadfin and gizzard shad and insect larvae, es­ body, causing many anglers to misidentify male white pecially mayflies. Their diet also includes minnows, crappie as black crappie. silversides, other crappie and any other fish small enough to swallow. Black crappie are more numerous in the clear, acidic to slightly alkaline waters of East Texas. White crappie are found state­ In lakes with low bass populations, crappie often wide. Fish of both species may live up to eight years and overpopulate and become stunted. For crappie to reach become sexually mature at one to two years. Crappie belong larger sizes, populations must experience high total mor­ to the same family as the sunfishes and black basses; like tality to keep their numbers within the carrying capacity their cousins, crappie are nest builders.
    [Show full text]
  • Fish Spawning Aggregations
    Fish Spawning Aggregations a focal point of fisheries management and marine conservation in Mexico Photo: Octavio Aburto Authorship Brad Erisman – Coastal Fisheries Research Program, University of Texas Marine Science Institute, 750 Channel View Drive, Port Aransas, TX 78373 William Heyman – LGL Ecological Research Associates, Inc., 4103 S. Texas Avenue, Bryan TX 77802 Stuart Fulton – Comunidad y Biodiversidad, Isla del Peruano 215, Lomas de Miramar, Guaymas, Sonora, Mexico Timothy Rowell – Gulf of California Marine Program, Scripps Institution of Oceanography, 9500 Gilman Drive, La Jolla, CA 92037 Illustrations – Larry Allen and Madeline Wukusick Graphic Design – Madeline Wukusick | www.communique.design Photography – Octavio Aburto, Richard Barnden, Douglas David Seifert, Walt Stearns, Cristina Limonta, Alfredo Barroso Citation – Erisman, B., W.D. Heyman, S. Fulton, and T.Rowell 2018. Fish spawning aggregations: a focal point of fisheries management and marine conservation in Mexico. Gulf of California Marine Program, La Jolla, CA. 24 p. Email Contact: Brad Erisman, [email protected] Fish Spawning Aggregations // 2 Contents > Introduction .................................................................................................................................................................. 4 > What are fish spawning aggregations (FSAs)? ............................................................................................................ 5 > What kinds of fishes form FSAs? ................................................................................................................................
    [Show full text]
  • Spatial and Temporal Distribution of the Demersal Fish Fauna in a Baltic Archipelago As Estimated by SCUBA Census
    MARINE ECOLOGY - PROGRESS SERIES Vol. 23: 3143, 1985 Published April 25 Mar. Ecol. hog. Ser. 1 l Spatial and temporal distribution of the demersal fish fauna in a Baltic archipelago as estimated by SCUBA census B.-0. Jansson, G. Aneer & S. Nellbring Asko Laboratory, Institute of Marine Ecology, University of Stockholm, S-106 91 Stockholm, Sweden ABSTRACT: A quantitative investigation of the demersal fish fauna of a 160 km2 archipelago area in the northern Baltic proper was carried out by SCUBA census technique. Thirty-four stations covering seaweed areas, shallow soft bottoms with seagrass and pond weeds, and deeper, naked soft bottoms down to a depth of 21 m were visited at all seasons. The results are compared with those obtained by traditional gill-net fishing. The dominating species are the gobiids (particularly Pornatoschistus rninutus) which make up 75 % of the total fish fauna but only 8.4 % of the total biomass. Zoarces viviparus, Cottus gobio and Platichtys flesus are common elements, with P. flesus constituting more than half of the biomass. Low abundance of all species except Z. viviparus is found in March-April, gobies having a maximum in September-October and P. flesus in November. Spatially, P. rninutus shows the widest vertical range being about equally distributed between surface and 20 m depth. C. gobio aggregates in the upper 10 m. The Mytilus bottoms and the deeper soft bottoms are the most populated areas. The former is characterized by Gobius niger, Z. viviparus and Pholis gunnellus which use the shelter offered by the numerous boulders and stones. The latter is totally dominated by P.
    [Show full text]
  • Published Estimates of Life History Traits for 84 Populations of Teleost
    Summary of data on fishing pressure group (G), age at maturity (Tm, years), length at maturity (Lm, cm), length-at-5%-survival (L.05, cm), time-to-5%-survival 3 (T.05, years), slope of the log-log fecundity-length relationship (Fb), fecundity the year of maturity (Fm), and egg volume (Egg, mm ) for the populations listed in the first three columns. Period is the period of field data collection. Species Zone Period G Tm Lm L.05 T.05 Fb Fm Egg Data sources (1) (1) (2) (3) (4) (4) (5) (1) (2) (3) (4) (5) Clupeiformes Engraulis capensis S. Africa 71-74 2 1 9.5 11.8 1.8 3.411 4.856E+04 0.988 118 119 137 118 138 Engraulis encrasicholus B. Biscay 87-92 2 1 11.5 14 1.4 3.997 9.100E+04 1.462 125 30, 188 170, 169 133, 23 145 Medit. S. 84-90 1 1 12.5 13.4 2.3 4.558 9.738E+04 0.668 161 161 160 161, 120 120 Sprattus sprattus Baltic S. 85-91 1 2 12 13.8 6.2 2.84 2.428E+05 1.122 15 19 26 184, 5 146 North S. 73-77 1 2 11.5 14.3 3 4.673 8.848E+03 0.393 8 107 106 33 169 Clupea harengus Baltic S. 75-82 1 3 16 24 4.9 3.206 4.168E+04 0.679 116 191 191 116 169 North S. 60-69 3 3 22 26.9 2.7 4.61 2.040E+04 0.679 52 53, 7 52 39 169 Baltic S.
    [Show full text]
  • Largemouth Bass Biology and Life History
    SRAC Publication No. 200 August 1997 VI PR Revision Largemouth Bass Biology and Life History James T. Davis and Joe T. Lock* The largemouth bass (Micropterus Largemouth bass will eat a variety salmoides) is one of several “bass- of live fish, but bluegill are partic- es” that are actually members of ularly important in ponds and the sunfish family. There are two small lakes because they repro- recognized subspecies, the duce throughout the warm Florida and the Northern, which months. This furnishes a continual will blend genetically. Although supply of different size forage. the two subspecies differ slightly Tilapia* and/or goldfish are com- in body structure, behavior, and monly used as forage on fish growth, biochemical tests are nec- farms and in intensively managed essary to positively identify them. Largemouth bass. lakes because more can be pro- duced at lower cost. About 5 Food and growth reflex action toward anything that pounds of live forage are required moves. (The bass motto: If food is for annual maintenance, and 10 Largemouth bass are valued by there, eat it.) pounds of forage are required to fishermen chiefly because of their add 1 pound of gain to large- The availability of adequate size fighting ability. They are vora- mouth bass. cious predators that readily strike live food (baitfish or forage) usu- artificial baits. Bass begin to eat ally limits bass growth. With ade- The swimming speed of large- fish when they are about 2 inches quate forage, largemouth bass can mouth bass has not been studied long. They swallow live fish and surpass 2 pounds the first year, in depth.
    [Show full text]
  • Coral Reef Fish Spawning Periodicity and Habitat in New Caledonia: a Multi-Faceted Approach in a Data-Deficient Environment
    Coral Reef Fish Spawning Periodicity and Habitat in New Caledonia: a multi-faceted approach in a data-deficient environment Adrian FLYNN1*, Sébastien SARRAMEGNA2 and Michel KULBICKI3 1Hydrobiology Pty Ltd. 47 Park Rd. PO Box 2050 Milton 4064 Queensland, Australia 2 Falconbridge NC SAS, 9, rue d'Austerlitz BP MGA08 98802 Nouméa Cedex, Nouvelle-Calédonie 3 Institut de recherche pour le développment, BP A5 98848 Nouméa Cedex, Nouvelle-Calédonie *Corresponding Author: A. Flynn e-mail: [email protected] Abstract An Environmental Impact Assessment Introduction (EIA) for a proposed mining project on the west coast While most temperate fishes have a well-defined of Northern Province, New Caledonia, required an breeding season that is regulated by hormonal changes understanding of coral reef fish spawning/aggregation and a variety of environmental cues such as periodicity and habitat utilisation in New Caledonia in temperature and photoperiod (Scott 1979; Lam 1983; order to describe and mitigate the potential impacts of Bye 1984; Stacey 1984), tropical species generally the development. A study was undertaken that have a protracted breeding season and the specific encompassed literature review, interpretation of cues regulating spawning periodicity are not well oceanographic data, analysis of gonad index data known, although photoperiod, sea temperature and spanning some 18 years, analysis of commercial currents are often quoted as the most influential fisheries production data, interpretation of sales data (Munro et al. 1973; Thresher 1984; Walsh 1987). from the Nouméa fish market, interviews with Although the timing of spawning can occur commercial and subsistence fishermen and personal randomly in tropical environments, spawning is more communication with researchers at University of New commonly synchronised within a population Caledonia regarding unpublished records and (Johannes 1978; Colin and Clavijo 1988).
    [Show full text]
  • Grade 3 Unit 2 Overview Open Ocean Habitats Introduction
    G3 U2 OVR GRADE 3 UNIT 2 OVERVIEW Open Ocean Habitats Introduction The open ocean has always played a vital role in the culture, subsistence, and economic well-being of Hawai‘i’s inhabitants. The Hawaiian Islands lie in the Pacifi c Ocean, a body of water covering more than one-third of the Earth’s surface. In the following four lessons, students learn about open ocean habitats, from the ocean’s lighter surface to the darker bottom fl oor thousands of feet below the surface. Although organisms are scarce in the deep sea, there is a large diversity of organisms in addition to bottom fi sh such as polycheate worms, crustaceans, and bivalve mollusks. They come to realize that few things in the open ocean have adapted to cope with the increased pressure from the weight of the water column at that depth, in complete darkness and frigid temperatures. Students fi nd out, through instruction, presentations, and website research, that the vast open ocean is divided into zones. The pelagic zone consists of the open ocean habitat that begins at the edge of the continental shelf and extends from the surface to the ocean bottom. This zone is further sub-divided into the photic (sunlight) and disphotic (twilight) zones where most ocean organisms live. Below these two sub-zones is the aphotic (darkness) zone. In this unit, students learn about each of the ocean zones, and identify and note animals living in each zone. They also research and keep records of the evolutionary physical features and functions that animals they study have acquired to survive in harsh open ocean habitats.
    [Show full text]
  • Atlantic "Pelagic" Fish Underwater World
    QL DFO - Library / MPO - Bibliothèque 626 U5313 no.3 12064521 c.2 - 1 Atlantic "Pelagic" Fish Underwater World Fish that range the open sea are Pelagic species are generally very Atlantic known as " pelagic" species, to dif­ streamlined. They are blue or blue­ ferentiate them from "groundfish" gray over their backs and silvery­ "Pelagic" Fish which feed and dwell near the bot­ white underneath - a form of tom . Feeding mainly in surface or camouflage when in the open sea. middle depth waters, pelagic fish They are caught bath in inshore travel mostly in large schools, tu. n­ and offshore waters, principally with ing and manoeuvring in close forma­ mid-water trawls, purse seines, gill tion with split-second timing in their nets, traps and weirs. quest for plankton and other small species. Best known of the pelagic popula­ tions of Canada's Atlantic coast are herring, but others in order of economic importance include sal­ mon, mackerel , swordfish, bluefin tuna, eels, smelt, gaspereau and capelin. Sorne pelagic fish, notably salmon and gaspereau, migrate from freshwater to the sea and back again for spawning. Eels migrate in the opposite direction, spawning in sait water but entering freshwater to feed . Underwater World Herring comprise more than one­ Herring are processed and mar­ Atlantic Herring keted in various forms. About half of (Ctupea harengus) fifth of Atlantic Canada's annual fisheries catch. They are found all the catch is marketed fresh or as along the northwest Atlantic coast frozen whole dressed fish and fillets, from Cape Hatteras to Hudson one-quarter is cured , including Strait.
    [Show full text]
  • Field Identification of Major Demersal Teleost Fish Species Along the Indian Coast
    Chapter Field Identification of Major Demersal Teleost 03 Fish Species along the Indian Coast Livi Wilson, T.M. Najmudeen and P.U. Zacharia Demersal Fisheries Division ICAR -Central Marine Fisheries Research Institute, Kochi ased on their vertical distribution, fishes are broadly classified as pelagic or demersal. Species those are distributed from the seafloor to a 5 m depth above, are called demersal and those distributed from a depth of 5 m above the seafloor to the sea surface are called pelagic. The term demersal originates from the Latin word demergere, which means to sink. The demersal fish resources include the elasmobranchs, major perches, catfishes, threadfin breams, silverbellies, sciaenids, lizardfishes, pomfrets, bulls eye, flatfishes, goatfish and white fish. This chapter deals with identification of the major demersal teleost fish species. Basic morphological differences between pelagic and demersal fish Pelagic Demersal Training Manual on Advances in Marine Fisheries in India 21 MAJOR DEMERSAL FISH GROUPS Family: Serranidae – Groupers 3 flat spines on the rear edge of opercle single dorsal fin body having patterns of spots, stripes, vertical or oblique bars, or maybe plain Key to the genera 1. Cephalopholis dorsal fin membranes highly incised between the spines IX dorsal fin spines rounded or convex caudal fin 2. Epinephelus X or XI spines on dorsal fin and 13 to 19 soft rays anal-fin rays 7 to 9 3. Plectropomus weak anal fin spines preorbital depth 0.7 to 2 times orbit diameter head length 2.8 to 3.1 times in standard length Training Manual on Advances in Marine Fisheries in India 22 4.
    [Show full text]
  • Forage Fish Management Plan
    Oregon Forage Fish Management Plan November 19, 2016 Oregon Department of Fish and Wildlife Marine Resources Program 2040 SE Marine Science Drive Newport, OR 97365 (541) 867-4741 http://www.dfw.state.or.us/MRP/ Oregon Department of Fish & Wildlife 1 Table of Contents Executive Summary ....................................................................................................................................... 4 Introduction .................................................................................................................................................. 6 Purpose and Need ..................................................................................................................................... 6 Federal action to protect Forage Fish (2016)............................................................................................ 7 The Oregon Marine Fisheries Management Plan Framework .................................................................. 7 Relationship to Other State Policies ......................................................................................................... 7 Public Process Developing this Plan .......................................................................................................... 8 How this Document is Organized .............................................................................................................. 8 A. Resource Analysis ....................................................................................................................................
    [Show full text]
  • Scenario Calculations of Mercury Exposure
    VKM Report 2019:3 Scenario calculations of mercury exposure from fish and overview of species with high mercury concentrations Opinion of the Panel on Contaminants of the Norwegian Scientific Committee for Food and Environment Report from the Norwegian Scientific Committee for Food and Environment (VKM) 2019:3 Scenario calculations of mercury exposure from fish and overview of species with high mercury concentrations Opinion of the Panel on Contaminants of the Norwegian Scientific Committee for Food and Environment 05.04.2019 ISBN: 978-82-8259-319-9 ISSN: 2535-4019 Norwegian Scientific Committee for Food and Environment (VKM) Po 4404 Nydalen N – 0403 Oslo Norway Phone: +47 21 62 28 00 Email: [email protected] vkm.no vkm.no/english Cover photo: Colourbox Suggested citation: VKM, Heidi Amlund, Kirsten Eline Rakkestad, Anders Ruus, Jostein Starrfelt, Jonny Beyer, Anne Lise Brantsæter, Sara Bremer, Gunnar Sundstøl Eriksen, Espen Mariussen, Ingunn Anita Samdal, Cathrine Thomsen and Helle Katrine Knutsen (2019). Scenario calculations of mercury exposure from fish and overview of species with high mercury concentrations. Opinion of the Panel on Contaminants of the Norwegian Scientific Committee for Food and Environment. VKM report 2019:3, ISBN: 978-82-8259-319-9, ISSN: 2535-4019. Norwegian Scientific Committee for Food and Environment (VKM), Oslo, Norway. Scenario calculations of mercury exposure from fish and overview of species with high mercury concentrations Preparation of the opinion The Norwegian Scientific Committee for Food and Environment (Vitenskapskomiteen for mat og miljø, VKM) appointed a project group to answer the request from the Norwegian Food Safety Authority. The project group consisted of three VKM-members, and three employees, including a project leader, from the VKM secretariat.
    [Show full text]
  • Blue Water Spawning by Moorish Idols and Orangespine Surgeonfish in Palau: Is It a “Suicide Mission”?
    aqua, International Journal of Ichthyology Blue Water Spawning by Moorish Idols and Orangespine Surgeonfish in Palau: Is it a “Suicide Mission”? Mandy T. Etpison1 and Patrick L. Colin2 1) Etpison Museum, PO Box 7049, Koror, Palau 96940. Email: [email protected] 2) Coral Reef Research Foundation, PO Box 1765, Koror, Palau 96940. Email: [email protected] Received: 13 December 2017 – Accepted: 05 March 2018 Keywords am Morgen zu den Laichplätzen, schlossen sich zu Gruppen Predation, aggregation, feeding frenzy, gray reef shark, zusammen und bewegten sich über der Rifffläche auf und lunar periodicity. ab und zogen dabei die Aufmerksamkeit von Beutegreifern auf sich. Um die Mittagszeit steigen sie vom Riff auf und Abstract begeben sich ins freie Wasser jenseits vom Riff. Graue Spawning aggregations of the moorish idol (MI) and or- Riffhaie folgen ihnen, greifen sie an der Oberfläche an und angespine surgeonfish (OSS) were found on the western verzehren viele von ihnen in einem Fressrausch. Ein hoher barrier reef of Palau. MI aggregated around the first quar- Prozentsatz der aufsteigenden erwachsenen HF wird von ter moon from Dec. to Mar., with largest groups in Jan. den Haien gefressen, nur wenige können in die sichere Zone and Feb. Fish arrived near the sites in the morning, des Riffs zurückkehren. KD versammeln sich in denselben grouped together and moved up and down the reef face up Monaten, aber in der Zeit des letzten Mondviertels – wobei in late morning attracting the attention of predators. At es hierüber weniger Berichte gibt. Die Beobachtungen bei mid-day they ascend from the reef out into open water beiden Fischarten, dass sie weit nach oben steigen und sich away from the reef.
    [Show full text]