DOCSLIB.ORG

Shark Aggregation in Coastal Waters of British Columbia

Total Page：16

File Type：pdf, Size：1020Kb

Download full-text PDF Read full-text
Shark Aggregation in Coastal Waters of British Columbia Vol. 414: 249–256, 2010 MARINE ECOLOGY PROGRESS SERIES Published September 13 doi: 10.3354/meps08718 Mar Ecol Prog Ser Shark aggregation in coastal waters of British Columbia Rob Williams1, 2,*, Thomas A. Okey3, 4, S. Scott Wallace5, Vincent F. Gallucci6 1Marine Mammal Research Unit, Room 247, AERL, 2202 Main Mall, University of British Columbia, Vancouver, British Columbia V6T 1Z4, Canada 2The Henry M. Jackson School of International Studies, University of Washington, Box 353650, Seattle, Washington 98195-3650, USA 3School of Environmental Studies, University of Victoria, PO Box 3060 STN CSC, Victoria, British Columbia V8W 3R4, Canada 4West Coast Aquatic, #3 4310 10th Avenue, Port Alberni, British Columbia V9Y 4X4, Canada 5David Suzuki Foundation, 2211 West 4th Avenue, Vancouver, British Columbia V6K 4S2, Canada 6School of Aquatic and Fishery Sciences, University of Washington, Box 355020, Seattle, Washington 98195-5020, USA ABSTRACT: A concentration of pelagic sharks was observed in an area of western Queen Charlotte Sound, British Columbia, during systematic shipboard line-transect surveys conducted (2004 to 2006) for marine mammals throughout coastal waters of British Columbia. Surveys allowed only brief observations of sharks at the surface, providing limited opportunity to confirm species identity. Observers agreed, however, that salmon sharks Lamna ditropis (Lamnidae) were most common, fol- lowed by blue sharks Prionace glauca (Carcharhinidae). Both conventional and model-based dis- tance sampling statistical methods produced large abundance estimates (~20 000 sharks of all species combined) concentrated within a hotspot encompassing ~10% of the survey region. Neither statisti- cal method accounted for submerged animals, thereby underestimating abundance. Sightings were made in summer, corresponding with southern movement of pregnant salmon sharks from Alaska. The previously undocumented high density of these pelagic sharks in this location has implications for understanding at-sea mortality of returning Pacific salmon Oncorhynchus spp. (Salmonidae) and for assessing conservation status of sharks in Canada and beyond. We recommend that a dedicated Canada-US sightings and biological sampling programme be considered, perhaps under the UN Transboundary Species Fishery programme. KEY WORDS: Abundance · Density · Distance sampling · Distribution · Elasmobranch · Line transect · Salmon mortality · Shark · Spatial model Resale or republication not permitted without written consent of the publisher INTRODUCTION caught in unmanaged global fisheries (Stevens 2005). As a generalisation, stock assessments of shark popula- Shark populations in Canada’s Pacific waters are tions are usually not practical except for those few spe- poorly understood, and information on their population cies for which catch-effort data exist. Risk analyses may size and status is required to understand the role of top nevertheless be possible (Aires-da-Silva & Gallucci predators in marine ecosystems and to inform conser- 2007) as a substitute to estimate the probability of pop- vation and management efforts. Status assessments ulation declines below e.g. 50% of pre-exploitation lev- have not been pursued in Canada for many species due els or the estimation of a reference point of interest. Es- to insufficient information. On a global scale, salmon timates of abundance are especially difficult to obtain sharks Lamna ditropis are considered ‘data deficient’ and any information towards this end is valuable. by the International Union for Conservation of Nature Salmon sharks are distributed throughout the sub- (IUCN), and blue sharks Prionace glauca are currently arctic North Pacific Ocean and north temperate Pacific listed as ‘near threatened’ due to large numbers being Ocean waters. They inhabit the Gulf of Alaska and *Email: [email protected] © Inter-Research 2010 · www.int-res.com 250 Mar Ecol Prog Ser 414: 249–256, 2010 even parts of the Bering Sea at least during summer marine mammals and sharks, but predation effects and autumn (Hulbert et al. 2005, Weng et al. 2005, have received relatively little attention due to the 2008, Okey et al. 2007, Gallucci et al. 2008). Individu- challenges in studying them (Groot & Margolis 1991). als tagged in Alaska during July and August migrated A systematic, shipboard, sightings survey was from summer coastal habitat (about 60° N latitude) designed (Thomas et al. 2007) and conducted southward throughout the northeast Pacific Ocean to (Williams & Thomas 2007) to estimate summertime about 28° N latitude and as far south as 22° N latitude abundance and distribution of marine mammals in near Hawai’i (Hulbert et al. 2005, Weng et al. 2005, coastal waters of British Columbia. Line-transect sur- 2008), though migration timing and routes varied con- veys are widely used to estimate abundance of wildlife siderably. Northward return apparently occurs during (Buckland et al. 2001), and have been used recently to spring through autumn along the North American estimate abundance of basking sharks Cetorhinus coast via British Columbia (BC). Tagged migrants were maximus off Canada’s Atlantic coast to inform a con- all female and likely to pup in productive waters south servation status assessment for the species (Campana of the oceanic transition zone (Goldman 2003, Hulbert et al. 2008). Sightings of sharks were recorded in the et al. 2005, Gallucci et al. 2008), including California BC marine mammal survey (Williams & Thomas 2007, coastal areas and offshore areas. In California waters, 2009), but have not been reported previously. Here we neonates apparently feed and grow for 1 or 2 yr, after describe an area of high shark density identified from which they begin to travel northward towards coastal that survey. We present 2 methods for generating ten- BC and Alaska. Little is known about this stage of the tative abundance estimates for sharks from the effort life cycle or the true distribution of pupping. It is possi- and sightings data, and consider hypotheses for this ble that salmon shark populations have increased in observed aggregation including resting, reproductive recent decades in the North Pacific, at least in particu- activity and feeding. Improving our understanding of lar areas (Okey et al. 2007), and they have the potential abundance and diet of marine predators, including to consume large numbers of returning Pacific salmon sharks, is fundamental for conservation and ecosys- (Nagasawa 1998, Hulbert & Rice 2002, Hulbert et al. tem-based management of Pacific marine ecosystems. 2005, DeMaddalena et al. 2007, Okey et al. 2007). Despite the recent opening of a recreational salmon shark fishery in Alaska, basic demographic and related MATERIALS AND METHODS information about the species is unknown, some of which may be more easily or cost-effectively collected Study design and field methods. Shipboard surveys in areas in which sharks are found reliably in high for marine mammals for coastal waters of British Co- numbers. lumbia were conducted during the summers of 2004 to Some BC Coho and Chinook salmon stocks (On- 2006 and spring 2007. Field protocols required ob- corhynchus kisutch and O. tshawytscha, respectively) servers to record all sightings of sharks. The survey fol- appear to have declined relatively suddenly (i.e. since lowed a systematic design, which has been described the early 1990s), while stocks of these species in Wash- previously (Thomas et al. 2007), and observers followed ington, Oregon and California have declined gradually standard line-transect survey field protocols (Williams (i.e. over an 83 yr time period) (based on catch data in & Thomas 2007). Unlike mark-recapture methods, dis- Eggers et al. 2005). Sockeye salmon O. nerka have also tance sampling methods make no assumption about the recently exhibited signs of distress in BC; e.g. the sock- identity of individuals, but rather estimate the average eye returns in the Fraser River were unexpectedly low number of animals in the study area at the time the sur- in 2009. Explanations for declines in BC salmon stocks vey was being conducted. In the unlikely event that a include changes in climate and oceanography (e.g. shark was seen on 2 transects, it is assumed that there is BCMWALP 2002, Brodeur et al. 2006, Battin et al. an equal probability of another shark being missed on 2007, BCME 2007, Crozier et al. 2008), increased both transects (Buckland et al. 2001, p. 253; Thomas et hatchery production (e.g. Hilborn 1992, NRC 1996, al. 2010). Waples 1999), increased open-net farming of Atlantic The survey was completed as planned in the sum- salmon in coastal BC and the associated transmission mers of 2004 and 2005, but not in 2006 due to funding of parasitic salmon lice (e.g. Lepeophtheirus salmonis, constraints. The survey was also completed in May and Caligidae) (e.g. Krkosek et al. 2006, 2007), degradation June 2007, but no sharks were seen during the spring of spawning habitat, poorly managed fisheries, and in- survey, and so that season’s effort was excluded from creased predation. A better understanding of factors the analysis. Consequently, the field effort resulted in a influencing at-sea survival of salmon is needed; this is ‘design-unbiased’ (Buckland et al. 2001) sample for the central question of the ongoing Pacific Ocean Shelf 2004 and 2005, but an unrepresentative sampling de- Tracking Project. At-sea predators of salmon include sign for 2006. Consequently, (1) a conventional distance Williams et al.: Summertime shark
Load more

Recommended publications
  • Fishing in the Seward Area
    Southcentral Region Department of Fish and Game Fishing in the Seward Area About Seward The Seward and North Gulf Coast area is located in the southeastern portion of Alaska’s Kenai Peninsula. Here you’ll find spectacular scenery and many opportunities to fish, camp, and view Alaska’s wildlife. Many Seward area recreation opportunities are easily reached from the Seward Highway, a National Scenic Byway extending 127 miles from Seward to Anchorage. Seward (pop. 2,000) may also be reached via railroad, air, or bus from Anchorage, or by the Alaska Marine ferry trans- portation system. Seward sits at the head of Resurrection Bay, surrounded by the U.S. Kenai Fjords National Park and the U.S. Chugach National Forest. Most anglers fish salt waters for silver (coho), king (chinook), and pink (humpy) salmon, as well as halibut, lingcod, and various species of rockfish. A At times the Division issues in-season regulatory changes, few red (sockeye) and chum (dog) salmon are also harvested. called Emergency Orders, primarily in response to under- or over- King and red salmon in Resurrection Bay are primarily hatch- abundance of fish. Emergency Orders are sent to radio stations, ery stocks, while silvers are both wild and hatchery stocks. newspapers, and television stations, and posted on our web site at www.adfg.alaska.gov . A few area freshwater lakes have stocked or wild rainbow trout populations and wild Dolly Varden, lake trout, and We also maintain a hot line recording at (907) 267- 2502. Or Arctic grayling. you can contact the Anchorage Sport Fish Information Center at (907) 267-2218.
    [Show full text]
  • Migration and Habitat Utilization in Lamnid Sharks
    MIGRATION AND HABITAT UTILIZATION IN LAMNID SHARKS A DISSERTATION SUBMITTED TO THE DEPARTMENT OF BIOLOGICAL SCIENCES AND THE COMMITTEE ON GRADUATE STUDIES OF STANFORD UNIVERSITY IN PARTIAL FULFILLMENT OF THE REQUIREMENTS FOR THE DEGREE OF DOCTOR OF PHILOSOPHY Kevin Chi-Ming Weng May 2007 © Copyright by Kevin Chi-Ming Weng 2007 All Rights Reserved ii Abstract Understanding the movements, habitat utilization, and life history of high trophic level animals is essential to understanding how ecosystems function. Furthermore, large pelagic vertebrates, including sharks, are declining globally, yet the movements and habitats of most species are unknown. A variety of satellite telemetry techniques are used to elucidate the movements and habitat utilization of two species of lamnid shark. Salmon sharks used a subarctic to subtropical niche, and undertook long distance seasonal migrations between subarctic and subtropical regions of the eastern North Pacific, exhibiting the greatest focal area behavior in the rich neritic waters off Alaska and California, and showing more transitory behaviors in pelagic waters where productivity is lower. The timing of salmon shark aggregations in both Alaska and California waters appears to correspond with life history events of an important group of prey species, Pacific salmon. The enhanced expression of excitation-contraction coupling proteins in salmon shark hearts likely underlies its ability to maintain heart function at cold temperatures and their niche expansion into subarctic seas. Adult white sharks undertake long distance seasonal migrations from the coast of California to an offshore focal area 2500 km west of the Baja Peninsula, as well as Hawaii. A full migration cycle from the coast to the offshore focal area and back was documented.
    [Show full text]
  • Alaska Salmon Shark Assessment Project
    Alaska Salmon Shark Assessment Project Project Number: 02396 Restoration Category: Research Proposer: Dr. Stan Rice and Lee Hulbert NMFS, Auke Bay Laboratory ABL Program Manager, Dr. Stan Rice Lead Trustee Agency: NOAA Cooperating Agencies: Alaska Department of Fish and Game Alaska Sea Life Center: no Duration: Closeout of 2 year project Cost FY 02: $29.4K Cost FY 03: $0.0 Geographic Area: Prince William Sound Injured Resource/Service: Pacific salmon, Pacific herring, rockfish ABSTRACT This project will fund a closeout year of data analysis and manuscript preparation for this two- year study of salmon sharks in Prince William Sound. There will not be a field work component to the project in FY 02. Funding will cover analysis and final write-up of (a) Data transmitted from satellite tags deployed on salmon sharks that will be scheduled to transmit during winter and spring of 2002, and (b) Data transmitted from satellite tags deployed on salmon sharks that will transmit when the sharks frequent surface waters during summer, (c) Stomach samples collected during 2001 field sampling and pre-arranged stomach sample collections from the Copper River gillnet fleet and the Prince William Sound salmon seine fleet during the 2001 commercial fishing season. The funding will also cover FY 02 Argos time, NOAA Joint Tariff Agreement costs for satellite tag data recovery, and contracted data analysis. The final report will describe salmon shark movements, habitat utilization, regional fidelity, and diet composition from data collected during the project. INTRODUCTION The salmon shark, Lamna ditropis, is one of the predominant shark species in coastal Gulf of Alaska (GOA), yet very little is known of their movements, regional fidelity, or diet composition.
    [Show full text]
  • SALMON SHARK MA,Xl.'AE
    AKU-B-86-00l C3 SALMON SHARK MA,xl.'AE. 7 hoDD c'l pE tMa'tlat 0 l a CEEHt rEt.'rt.'E J.lStE,I 1'tEE.E iE.,ah it i k, l. c'!>!a' t I"ii! Et.'IX' 1EEllEC 4 .E t Il f~'ti'tl I ' Brian Paust ta't and i,,'~Pgr at RonaldSmith:Xlaaka<ca Rt',porthara!'.t Unl~ersity of .alaska Xlat. l9S6 Alaska Sea Grant College Program 590 University Avenue, Suite 'l02 Fairbanks, AK 99709-1046 SALHON SHARK HANUAL by Brian Paust Marine Advisory Program University of Alaska Petersburg, Alaska and Rona id Sml th University of Alaska Institute of Harine Science Fairbanks, Alaska T. Frady Editor NATIGliALSEAGRANE DEPOSITORY PELLLIBRARY BUlLOlll6 UR1,NARRAGAHMTT SAYCAVPUS NAiNAGANSETT,RlG2INZ ~K- S G-86-0 l University of Alaska Hay l986 ACKHOWLEOGEHE ITS Thispublication is the resul t of worksponsored by the Alaska Sea Grant College Program, Project numbers A/71-01 and A/75-01, Grant number NA82AA-D- OOO44F,TheAlaska Sea Grant Program is cooperat ively sponsoredbylslOAA Offf ceof SeaGrant and Extra-Hura i Programs, U.S .Depa rtment of Cormerce; and bythe University of Alaskawi th fundsappropriated by the state. Theauthors would l ike to thankDick Reynolds of the Alaska Department of Coy~erceandEconomic Development Office of Commercial Fisheries Development forproviding the financial support to conduct the Southeast Alaska Salmon Sharkproject experimental fishery ~ Thanksalso to KyleSchlecta who volun- tariiyserved asofficial documentor duringthat project and to f/V ~Lesie Ann ownerand skipper Dale Bosworth for his assi stance and the use of several milesof halibutlongl ine during the experimental f ishery.
    [Show full text]
  • Porbeagle Shark (Pos)
    685 PORBEAGLE SHARK (POS) (Lamna nasus) 1. FISHERY SUMMARY Porbeagle shark were introduced into the QMS on 1 October 2004 under a single QMA, POS 1, with allowances, TACC, and TAC in Table 1. Table 1: Recreational and Maori allowances, TACCs and TACs for porbeagle shark. Fishstock Recreational Allowance (t) Maori customary Allowance (t) Other mortality (t) TACC (t) TAC (t) POS 1 10 2 22 215 249 Porbeagle shark was added to the Third Schedule of the 1996 Fisheries Act with a TAC set under s14 because porbeagle shark is a highly migratory species and it is not possible to estimate MSY for the part of the stock that is found within New Zealand fisheries waters. Porbeagle shark was also added to the Sixth Schedule of the 1996 Fisheries Act with the provision that: “A commercial fisher may return any porbeagle shark to the waters from which it was taken from if – (a) that porbeagle shark is likely to survive on return; and (b) the return takes place as soon as practicable after the porbeagle shark is taken.” Management of the porbeagle shark throughout the western and central Pacific Ocean (WCPO) will be the responsibility of the Western and Central Pacific Fisheries Commission (WCPFC). Under this regional convention New Zealand will be responsible for ensuring that the management measures applied within New Zealand fisheries waters are compatible with those of the Commission. However, it is not expected that WCPFC will attempt to actively manage porbeagle shark in the first years of the Commission. (a) Commercial fisheries About half of the commercial catch of porbeagle sharks is taken by tuna longliners, and most of the rest by mid-water and bottom trawlers.
    [Show full text]
  • Migration of an Upper Trophic Level Predator, the Salmon Shark Lamna Ditropis, Between Distant Ecoregions
    Vol. 372: 253–264, 2008 MARINE ECOLOGY PROGRESS SERIES Published December 9 doi: 10.3354/meps07706 Mar Ecol Prog Ser Migration of an upper trophic level predator, the salmon shark Lamna ditropis, between distant ecoregions Kevin C. Weng1, 3,*, David G. Foley2, James E. Ganong1, Christopher Perle1, George L. Shillinger1, Barbara A. Block1 1Hopkins Marine Station, Stanford University, Pacific Grove, California 93950 USA 2Environmental Research Division, NOAA Fisheries Service, Pacific Grove, California 93950, USA 3Present address: School of Ocean and Earth Science and Technology, University of Hawaii at Manoa, Honolulu, Hawaii 96822, USA ABSTRACT: Knowledge of how animals move through heterogeneous environments is essential to understanding the ecological functions they fulfill in each habitat and their responses to environmen- tal change. Upper trophic level organisms exert structural influences through the food web, so infor- mation on their range, migration and foraging strategy is necessary to understanding ecosystem function. Recent technological advances have enabled researchers to follow individual animals over seasonal and multi-year timescales, revealing long-distance migrations in a variety of taxa. We used satellite telemetry to monitor female salmon sharks Lamna ditropis and remote sensing to character- ize their environment. Salmon sharks ranged throughout the entire eastern North Pacific Ocean dur- ing a seasonal migration cycle. During long-distance migrations, quantitative movement analyses of speed, path straightness and first passage time (FPT) revealed area-restricted search (ARS) behaviors in northern and southern regions, with transiting behaviors at mid-latitudes. Individuals migrating to a highly productive southern region displayed more ARS behaviors than those moving to a low pro- ductivity region.
    [Show full text]
  • And Chinook Salmon Age Structure
    Exploring the potential role of late stage predation and Chinook salmon age structure Item Type Thesis Authors Manishin, Kaitlyn A. Download date 28/09/2021 05:14:32 Link to Item http://hdl.handle.net/11122/10301 EXPLORING THE POTENTIAL ROLE OF LATE STAGE PREDATION AND CHINOOK SALMON AGE STRUCTURE By Kaitlyn A. Manishin A Thesis Submitted in Partial Fulfillment of the Requirements for the Degree of Master of Science in Fisheries University of Alaska Fairbanks December 2018 APPROVED: Andrew C. Seitz, Committee Chair Peter A.H. Westley, Committee Member Curry J. Cunningham, Committee Member Kenneth J. Goldman, Committee Member Milo D. Adkison, Chair Department of Fisheries S. Bradley Moran, Dean College of Fisheries and Ocean Sciences Michael A. Castellini, Dean of the Graduate School Abstract Chinook salmon (Oncorhynchus tshawytscha) populations across the North Pacific have displayed a decrease in body size-at-return resulting from declines both in age- and body size-at-maturity. These changes have precipitated the loss of the oldest age classes in some populations and have occurred throughout the range of this species, suggesting a shared - yet currently unknown - driver in the common marine environment. A hypothesis for the cause of these changes is intense and/or selective predation marine mortality after the first winter in the ocean, potentially from predators selectively removing relatively large sub-adult Chinook salmon. Here I consider the question: under what circumstances could predation on large sub-adult individuals by salmon sharks (Lamna ditropis) change the age structure of a Chinook salmon population? To address this question, I first estimated total per capita prey consumption by salmon sharks - an increasingly acknowledged predator of salmon on the high seas - using three methods: 1) daily ration requirement, 2) bioenergetic mass balance, 3) and a von Bertalanffy growth model.
    [Show full text]
  • Common Name Scientific Name Bycatch Pounds Bycatch Ratio Pounds Ratio Landings Total Notes
    Figure 7.4.1b PACIFIC ISLANDS REGION FISH BYCATCH BY STOCKS AND SPECIES (2014) Species bycatch ratio = total regional bycatch of a species / (total regional landings of the species + total regional bycatch of the species). Landings data were not available at the stock level. Bycatch ratio cells are left blank when landings = 0. DEAD BYCATCH DEAD BYCATCH COMMON NAME SCIENTIFIC NAME BYCATCH POUNDS BYCATCH RATIO POUNDS RATIO LANDINGS TOTAL NOTES ALBACORE Albacore - North Pacific Thunnus alalunga 8,572.70 5,837.20 Albacore - South Pacific Thunnus alalunga 29,380.00 28,457.50 Albacore - landings Thunnus alalunga <0.01 <0.01 3,779,936.00 ALBACORE (Subtotal) 37,952.70 34,294.70 3,779,936.00 BIGEYE SAND TIGER SHARK Bigeye sand tiger shark Odontaspis noronhai 345.20 345.20 Bigeye sand tiger shark - landings BIGEYE SAND TIGER SHARK (Subtotal) 345.20 345.20 0.00 BIGEYE THRESHER Bigeye thresher Alopias superciliosus 1,353,344.30 336,237.90 a Bigeye thresher - landings BIGEYE THRESHER (Subtotal) 1,353,344.30 336,237.90 0.00 BIGEYE TUNA Bigeye tuna - Pacific Thunnus obesus 251,708.80 63,149.60 Bigeye tuna - landings Thunnus obesus 0.02 <0.01 13,727,193.00 BIGEYE TUNA (Subtotal) 251,708.80 63,149.60 13,727,193.00 BILLFISHES (GROUP) Billfishes (group) Istiophoridae 59,987.70 52,111.60 Billfishes (group) - landings Istiophoridae BILLFISHES (GROUP) (Subtotal) 59,987.70 52,111.60 0.00 BLACK GEMFISH Black gemfish Nesiarchus nasutus 1,127.20 455.00 Black gemfish - landings BLACK GEMFISH (Subtotal) 1,127.20 455.00 0.00 BLACK MACKEREL Black mackerel Scombrolabrax
    [Show full text]
  • Dear Teacher
    Dear Teacher: During the Shark Shenanigans assembly program an Aquarium educator will introduce students to sharks and their adaptations using puppets, a PowerPoint presentation, song and dance, shark teeth and skin, egg cases, and a life-sized inflatable great white shark! After this program your students will understand the characteristics of sharks as cartilaginous fish. Before your assembly program: Define adaptations for your students. Give examples of human adaptations. Ask your students to list the characteristics of fish. Give examples. Compare fish adaptations to human adaptations. Color the Leopard and Whale shark coloring sheets. Conduct the Measuring Sharks activity. Using a tape measure, have your students see how they measure up to some of the ocean’s greatest predators. Tiger shark After your assembly program: Review shark adaptations and diversity using the Leopard and Whale Shark fact sheets. Make paiper-mache sharks and hang them from your classroom ceiling. Match shark teeth with what they eat with the Wheel of Gorgin’ craft. Participating in this program and using the pre and post curriculum will help your students meet Oregon science standards and Ocean Literacy Principles. Shark Shenanigans assembly program: Grades K-2 Goal: To understand that sharks are important animals that have special adaptations for survival in the ocean. Cognitive Objectives: 1. Explain that sharks have adaptations that help them survive in the ocean environment. 2. Name 3 shark body parts and describe how they are helpful to their survival. 3. Understand that most species of sharks are not dangerous to humans. Affective Objectives: 1. Students will value sharks as worthy of protection and conservation.
    [Show full text]
  • Estimation of Ratio of Fin Weight to Body Weight of Sharks in the Eastern Pacific Ocean in 2006
    Estimation of ratio of fin weight to body weight of sharks in the eastern Pacific Ocean in 2006 Soon-Song Kim, Doo-Hae An, Dae-Yeon Moon and Seon Jae Hwang National Fisheries Research and Development Institute (NFRDI), Republic of Korea The survey area . 9°13’S~1°36’N and 126°00’ ~138°21’W from September 20 to October 23, 2006 . Korean longliner : 416 GRT . Monitoring : 28 set (one set per day) . No. of hooks used : 62,464 - each set : 2,240 (560 of each type) Catch and species composition of shark species Shark species Weight Number (%) (%) (kg) Scientific name English name Alopias superciliosus Bigeye thresher shark 83 20.1 3,151 28.4 Lamna ditropis Salmon shark 59 14.3 2.048 18.5 Prionace glauca Blue shark 43 10.4 2,442 22.0 Isurus oxyrinchus Mako shark 3 0.7 470 4.2 Carcharhinus longimanus Oceanic white-tip shark 48 11.6 883 8.0 Sphyrna zygaena Smooth hammerhead shark 7 1.7 494 4.5 Scalloped hammerhead Sphyrna lewini 14 3.47 888 8.0 shark Pseudocarcharias kamoharai Crocodile shark 142 34.4 669 6.0 Smallmouth velvet dogfish Scymnodon sqamulosis 14 3.4 48 0.4 shark Total 413 100 11,093 100 Shark species Bigeye thresher shark Salmon shark Blue shark Longfin mako shark Shark species Smooth hammerhead shark Oceanic white-tip shark Crocodile shark Scalloped hammerhead shark Smallmouth velvet dogfish Catch per unit effort by bait CPUE by bait (no./1,000 hooks) Species (number) Chub Jack Sardine Squid Milk fish mackerel mackerel Large-sized sharks (257) 2.4 2.8 2.6 2.0 0.6 Small-sized sharks (156) 2.6 2.6 2.8 2.2 1.4 Total(413) 5.1 5.4 5.4
    [Show full text]
  • The Conservation Status of Pelagic Sharks and Rays
    The Conservation Status of The Conservation Status of Pelagic Sharks and Rays The Conservation Status of Pelagic Sharks and Rays Pelagic Sharks and Rays Report of the IUCN Shark Specialist Group Pelagic Shark Red List Workshop Report of the IUCN Shark Specialist Group Tubney House, University of Oxford, UK, 19–23 February 2007 Pelagic Shark Red List Workshop Compiled and edited by Tubney House, University of Oxford, UK, 19–23 February 2007 Merry D. Camhi, Sarah V. Valenti, Sonja V. Fordham, Sarah L. Fowler and Claudine Gibson Executive Summary This report describes the results of a thematic Red List Workshop held at the University of Oxford’s Wildlife Conservation Research Unit, UK, in 2007, and incorporates seven years (2000–2007) of effort by a large group of Shark Specialist Group members and other experts to evaluate the conservation status of the world’s pelagic sharks and rays. It is a contribution towards the IUCN Species Survival Commission’s Shark Specialist Group’s “Global Shark Red List Assessment.” The Red List assessments of 64 pelagic elasmobranch species are presented, along with an overview of the fisheries, use, trade, and management affecting their conservation. Pelagic sharks and rays are a relatively small group, representing only about 6% (64 species) of the world’s total chondrichthyan fish species. These include both oceanic and semipelagic species of sharks and rays in all major and Claudine Gibson L. Fowler Sarah Fordham, Sonja V. Valenti, V. Camhi, Sarah Merry D. Compiled and edited by oceans of the world. No chimaeras are known to be pelagic. Experts at the workshop used established criteria and all available information to update and complete global and regional species-specific Red List assessments following IUCN protocols.
    [Show full text]
  • Seasonal Foraging Movements and Migratory Patterns of Female Lamna Ditropis Tagged in Prince William Sound, Alaska
    Journal of Fish Biology (2005) 67, 490—509 doi:10.1111/j.1095-8649.2005.00757.x,availableonlineathttp://www.blackwell-synergy.com Seasonal foraging movements and migratory patterns of female Lamna ditropis tagged in Prince William Sound, Alaska L. B. HULBERT*†, A. M. AIRES- DA-SILVA‡, V. F. GALLUCCI‡ AND J. S. RICE‡ *NOAA Fisheries Auke Bay Laboratory, Juneau, Alaska 99801, U.S.A. and ‡University of Washington, School of Aquatic and Fishery Sciences, Seattle, Washington 98195, U.S.A. (Received 22 July 2004, Accepted 24 February 2005) Conventional and electronic tags were used to investigate social segregation, distribution, movements and migrations of salmon sharks Lamna ditropis in Prince William Sound, Alaska. Sixteen salmon sharks were tagged with satellite transmitters and 246 with conventional tags following capture, and were then released in Prince William Sound during summer 1999 to 2001. Most salmon sharks sexed during the study were female (95%), suggesting a high degree of sexual segregation in the region. Salmon sharks congregated at adult Pacific salmon Oncorhynchus spp. migration routes and in bays near Pacific salmon spawning grounds in Prince William Sound during July and August. Adult Pacific salmon were the principal prey in 51 salmon shark stomachs collected during summer months in Prince William Sound, but the fish appeared to be opportunistic predators and consumed sablefish Anoplopoma fimbria, gadids, Pacific herring Clupea pallasi, rockfish Sebastes spp. and squid (Teuthoidea) even when adult Pacific salmon were locally abundant. As Pacific salmon migrations declined in late summer, the salmon sharks dispersed; some continued to forage in Prince William Sound and the Gulf of Alaska into autumn and winter months, while others rapidly moved south-east thousands of kilometres toward the west coasts of Canada and the U.S.
    [Show full text]