DOCSLIB.ORG

Aspects of the Life History of California's Two Cowshark Species, Notorynchus Cepedianus and Hexanchus Griseus

Total Page：16

File Type：pdf, Size：1020Kb

Download full-text PDF Read full-text
Aspects of the Life History of California's Two Cowshark Species, Notorynchus Cepedianus and Hexanchus Griseus ASPECTS OF THE LIFE HISTORY OF CALIFORNIA'S TWO COWSHARK SPECIES, NOTORYNCHUS CEPEDIANUS AND HEXANCHUS GRISEUS A Thesis Presented to The Faculty of the Department of Biology San Jose State University In Partial Fulfillment of the P~quirernents for the Degree Master of Arts By David A. Ebert August , 19 84 ABSTRACT Life history information was gathered on 128 sevengill sharks (Notorynchus cepedianus) and 24 sixgill sharks (Hexanchus griseus) from the coastal waters of California during a 20 month period from November 1981 through June 1983. The majority of sevengill sharks (96) were collected during the spring and summer in Humboldt and San Francisco Bays, while most sixgills (6) were collected from Honterey Bay. Year- round sampling in San Francisco B~y indicated peak shark catches in the spring and surrnner. Leopard sharks (Triakis semifasciata) dominated these catches suggesting a shift may have occurred in the species composition of elasmobranchs. Gonad character­ istics and scarring in adult male and female sevengills captured in bays during the spring and summer suggest a possible breeding season. Cartilaginous and bony fishes were the major prey items of sevengills captured in bays. A distinct back­ ground color was observed for sevengills from different geographic regions. Only a limited amount of life history information was collected on the sixgill shark. The only \ mature sixgill recorded was a female (420 em TL) containing 51 near-term embryos, ranging in size from 68 to 73 em TL. Prey items were found in five of eleven sixgill stomachs iii examined with each occurring only once. Several age deter- mination techniques using vertebrae from both species were tested but proved unsuccessful. The ecosystem of several northern-California bays play an important role in the life h~story of sevengill sharks, while sixgills prefer· a deep water coastal habitat. ,. ; ; - . ' ~ . iv TABLE OF CONTENTS Page ABSTRACT ... iii LIST OF TABLES vii LIST OF FIGURES ........•........... viii ACKNOWLEDGEMENTS x INTRODUCTION . 1 METHODS AND l-i..ATERIALS Collection Techniques 4 General Elasmobranch Observations 5 Reproductive Biology 5 Food Habits . 7 Age Determination 8 Miscellaneous Hexanchid Observations . 8 RESULTS ·General Elasmobranch Observations . 10 Sevengill Shark General . .. .. , . .. 12 Reproductive Biology ..........•..•.• 12 Food Habits . , 15 Age Determination 16 Miscellaneous Sevengill Observations . •. 17 v ' Sixgill Shark General . .. .. .. .. .. .. .. .. 19 Reproductive Biology . • . • . 19 Food Habits 20 Parasites 20 DISCUSSION General Elasmobranch Observations . 21 Sevengill Shark General . .. .. .. .. .. .. .. .. .. .. .. .. 25 Reproductive Biology ................ 27 Food Habits . 30 Age Determination .. 31 Sixgill Shark General 33 Reproductive Biology ................ 33 Food Habits 35 Parasites 35 CONCLUSION 36 LITERATURE CITED 37 TABLES .. 43 FIGURES . • . • . • 48 vi f I ! LIST OF TABLES Table Page 1. Elasrnobranch catch and effort data, according to gear type, from San Francis co Bay. 43 2. Rod and reel catch/effort data by month of all elasmobranch species in San Francisco Bay, from November 1981 through May 1983. 44 3. Nurrber, percent, and sex of seven elasmobranch species caught in San Francisco Bay on rod and reel from November ·1981 through Hay 1983. 45 4. The percent number, volume,_ frequency of occurrence, and index of relative irrportance values for 38 sevengill shark stomachs that contained prey items. 46 5. Tagging records for five sevengill sharks. 47 I ' \ Vii LIST OF FIGURES Figure Page 1. Map of San Francisco Bay showing gear type and the areas fishes. 48 2. External measurements recorded for hexanchid sharks along the California coast. 49 3. The inner clasper length versus length for 60 sevengill sharks collected from November 1981 through June 1983. 50 4. Total length versus weight" for 22 male sevengill sharks collected from November 1981 through June 1983. 51 5. Total length versus weight for 17 female sevengill sharks collected from November 1981 through June 1983. 52 6. Scarring patterns observed on sevengi11 sharks. 53 7. Index of relative importance for the prey groups taken from the stomachs of 38 sevengill sharks collected from November 1981 through June 1983. 54 80 Index of relative importance graph for the prey items found in the stomachs of 38 sevengill sharks collected from November 1981 through June 19830 55 90 Total length versus 1o1eight for 12 sixgill sharks recorded from November 1981 through June 19830 0 0 o 0 0 o 0 0 0 0 0 0 56 100 A schematic diagram of the developmental stages and their proposed timing in the sev-engill shark (Notorynchus cepedianus) 0 57 ix ACKN OWLE DGEHENTS I would like to thank the following people for their time and consideration throughout this research. Ken Bates, Dennis Kittredge, and Bret Van Gorp for their fishing efforts in providing the numerous sevengills I examined. The following people provided additional specimens from their respective institutions, Leonard Campagna of the Tiburon Center for Enviromrental Studies, Robert Lavenberg and Jeffery Seigel of The Los Angeles County Museum of Natural History, and John McCosker of The California Academy of Sciences. The members of my thesis corrnnittee Greg Cailliet, Mike Foster, and John HcCosker for their helpful suggestions and comments in review- ing this manuscript. Leonard Campagna, Earl Ebert, Robert Lea, and Susan Smith provided many helpful ideas and suggestions. Mike Moser for identifing the parasites, Matt Kittredge for his fine work in illustrating the figures. General assistance in various portions of this study was given generously by Thomas Ebert, N. J. Haas, Kent Hauge, Kevin Lohman, Feney Matthews, Lisa .Natanson, and Steve Willis. George and Patricia Schmidt and Bill and Joanne Willis for the gracious hospitality they extended me on my numerous journeys to the bay area. I would like to express sincere appreciation to my parents, Earl and Peggy Ebert, for their constant support and encour­ agel!Ent in helping me to achieve my educational goals. X I INTRODUCTION Interest in elasmobranchs as a food resource has in- creased in California (Cailliet and Bedford 1983 and Pleschner 1983). Among the more commonly marketed species are the sixgill shark, Hexanchus griseus (Bonnaterre 1788), and the sevengill shark, Notorynchus cepedianus Peron 1807 (Frey 1971). Both these sharks are known to frequent bays (Miller and Lea 1972), including San Francisco Bay (Herald and Ripley 1951), where they support a small fishery and are a popular target species of sportfishermen (Cuanang 1981). Unfortnnately, the elasmobranch assernb 1age of San Francisco Bay is poorly understood and the importance of larger sharks, like the sixgill and sevengill, to the bay environment is not well dnown. Therefore, additional ; infoootion is needed to assess the shark populations and i their fisheries in San Francisco Bay. I The sixgill and sevengill sharks are members of the family Hexanchidae (cowsharks), which Compagno (1973, 1977, 1981) lists as having three genera and four living species. There are several nominal species of Notdrynchus, however, they all appear referable to N. cepedianus. The two most commonly referred to species N. maculatus Ayres 1855 and N. cepedianus are synonymous (L. J. V. Compagno, Tiburon Center I . 1 1-·.·. 2 t.;; for Environrrental Studies, pers. comm.). In the ·eastern North Pacific both species range from southeast Alaska, southward to central Baja California (Clemens and Hilby 1946, 1961, Knaggs, Sun ada, and Lea 1975, Miller and Lea 1972, and •{;I Roedel and Ripley 1950). Their distribution is notable because both occur in temperate regions, while the only other two members of the family; Heptranchias pe:do and H. vitulus, are tropical and subtropical (Bass et al. 1975, Bigelow and Schroeder 1948, Castro 1983, Garrick and Paul 1971, Pequeno 1979, Roedel and Ripley 1950, and Springer and Haller 1969). Since many elasmobranch species including sixgill and sevengill sharks are mobile ·and reach a relatively large size, life history studies have been difficult (Holden 1974). Members of the Hexanchidae are ovoviviparous (Breder and Rosen 1966 and Gilbert 1981), but further information on I their reproductive biology is limited. Springer and Haller (1969), based on the examination of a few large specimens, estimated that female H.· griseus reach maturity at 450 em total length. Herald and Ripley (1951) examined a number ·of sevengill sharks between 54 and 228 ern TL cought at shark derbies, and reported that all se\rengills examined were sexually immature. Herald (.1961) estimated that se"Vengills reached maturity at a length ·of 306 ern TL. ·However, Herald 7 3 (1968) revised this estimate after examination of a male (197.4 em TL) and female (264 em TL) sevengill that were both mature. Information on the feeding habits of the sixgill and sevengill is rather incomplete. Hart (1973) reported that sixgills ingest a wide variety of fishes and crustaceans, and noted that the sevengill' s diet included smaller sharks. Herald and Rip ley (l951) examined a few sevengill stomachs and found them to be either empty or to contain only bait. The objectives of this research were to investigate the elasmobranch assemblage in San Francisco Bay and the life history of the sixgill and sevengill sharks in California. Life history aspects include the reproductive biology, length-weight relationships, food habits, examination of possible age determination techniques, color variation, parasites, and moverrent
Load more

Recommended publications
  • Sharks for the Aquarium and Considerations for Their Selection1 Alexis L
    FA179 Sharks for the Aquarium and Considerations for Their Selection1 Alexis L. Morris, Elisa J. Livengood, and Frank A. Chapman2 Introduction The Lore of the Shark Sharks are magnificent animals and an exciting group Though it has been some 35 years since the shark in Steven of fishes. As a group, sharks, rays, and skates belong to Spielberg’s Jaws bit into its first unsuspecting ocean swim- the biological taxonomic class called Chondrichthyes, or mer and despite the fact that the risk of shark-bite is very cartilaginous fishes (elasmobranchs). The entire supporting small, fear of sharks still makes some people afraid to swim structure of these fish is composed primarily of cartilage in the ocean. (The chance of being struck by lightning is rather than bone. There are some 400 described species of greater than the chance of shark attack.) The most en- sharks, which come in all different sizes from the 40-foot- grained shark image that comes to a person’s mind is a giant long whale shark (Rhincodon typus) to the 2-foot-long conical snout lined with multiple rows of teeth efficient at marble catshark (Atelomycterus macleayi). tearing, chomping, or crushing prey, and those lifeless and staring eyes. The very adaptations that make sharks such Although sharks have been kept in public aquariums successful predators also make some people unnecessarily since the 1860s, advances in marine aquarium systems frightened of them. This is unfortunate, since sharks are technology and increased understanding of shark biology interesting creatures and much more than ill-perceived and husbandry now allow hobbyists to maintain and enjoy mindless eating machines.
    [Show full text]
  • Beringraja Binoculata) and Longnose Skate (Raja Rhina)
    Bomb Dating and Age Estimates of Big Skate (Beringraja binoculata) and Longnose Skate (Raja rhina) Jacquelynne King, Fisheries and Oceans Canada David Ebert, Moss Landing Marine Laboratories Craig Kastelle, Alaska Fisheries Science Center Thomas Helser, Alaska Fisheries Science Center Christopher Gburski, Alaska Fisheries Science Center Gregor Cailliet, Moss Landing Marine Laboratories ABSTRACT MATERIALS AND METHODS RESULTS Age and growth curve estimates have been produced for big skate Bomb radiocarbon analyses Big skate (Beringraja binoculata [formerly Raja binoculata]) and longnose skate 1. Big skate (n=12) and longnose skate (n=33) vertebrae were collected • the estimated birth years ranged from 1965-1970 (Raja rhina) populations in the Gulf of Alaska, British Columbia and during the early 1980s off California. These fishes were estimated to • there were no low ∆14C values for big skate California. Age estimation for these two skate species relies on growth be alive during the atmospheric testing of atomic bombs which resulted Longnose skate band counts of sectioned vertebrae. However these studies have not in the rapid increase in oceanic radiocarbon (14C). • the ∆14C values for longnose skate overlapped with mid to top portion of the produced similar results for either species, highlighting the need for age 2. Vertebrae where thin (0.7-1.0 mm) sectioned and mounted on ∆14C reference curve for Petrale sole (Fig. 3) validation. Archived large specimens of big skate and longnose skate microscope slides. • these skate were not as old as originally estimated but there were early collected in 1980 and 1981 had minimum age estimates old enough to 3. Ages were estimated based on vertebral band counts (Fig.
    [Show full text]
  • First Record of Swimming Speed of the Pacific Sleeper Shark Somniosus
    Journal of the Marine First record of swimming speed of the Pacific Biological Association of the United Kingdom sleeper shark Somniosus pacificus using a baited camera array cambridge.org/mbi Yoshihiro Fujiwara , Yasuyuki Matsumoto, Takumi Sato, Masaru Kawato and Shinji Tsuchida Original Article Research Institute for Global Change (RIGC), Japan Agency for Marine-Earth Science and Technology (JAMSTEC), 2-15 Yokosuka, Kanagawa 237-0061, Japan Cite this article: Fujiwara Y, Matsumoto Y, Sato T, Kawato M, Tsuchida S (2021). First record of swimming speed of the Pacific Abstract sleeper shark Somniosus pacificus using a baited camera array. Journal of the Marine The Pacific sleeper shark Somniosus pacificus is one of the largest predators in deep Suruga Biological Association of the United Kingdom Bay, Japan. A single individual of the sleeper shark (female, ∼300 cm in total length) was 101, 457–464. https://doi.org/10.1017/ observed with two baited camera systems deployed simultaneously on the deep seafloor in S0025315421000321 the bay. The first arrival was recorded 43 min after the deployment of camera #1 on 21 July 2016 at a depth of 609 m. The shark had several remarkable features, including the Received: 26 July 2020 Revised: 14 April 2021 snout tangled in a broken fishing line, two torn anteriormost left-gill septums, and a parasitic Accepted: 14 April 2021 copepod attached to each eye. The same individual appeared at camera #2, which was First published online: 18 May 2021 deployed at a depth of 603 m, ∼37 min after it disappeared from camera #1 view. Finally, the same shark returned to camera #1 ∼31 min after leaving camera #2.
    [Show full text]
  • Stomach Content Analysis of Short-Finned Pilot Whales
    f MARCH 1986 STOMACH CONTENT ANALYSIS OF SHORT-FINNED PILOT WHALES h (Globicephala macrorhynchus) AND NORTHERN ELEPHANT SEALS (Mirounga angustirostris) FROM THE SOUTHERN CALIFORNIA BIGHT by Elizabeth S. Hacker ADMINISTRATIVE REPORT LJ-86-08C f This Administrative Report is issued as an informal document to ensure prompt dissemination of preliminary results, interim reports and special studies. We recommend that it not be abstracted or cited. STOMACH CONTENT ANALYSIS OF SHORT-FINNED PILOT WHALES (GLOBICEPHALA MACRORHYNCHUS) AND NORTHERN ELEPHANT SEALS (MIROUNGA ANGUSTIROSTRIS) FROM THE SOUTHERN CALIFORNIA BIGHT Elizabeth S. Hacker College of Oceanography Oregon State University Corvallis, Oregon 97331 March 1986 S H i I , LIBRARY >66 MAR 0 2 2007 ‘ National uooarac & Atmospheric Administration U.S. Dept, of Commerce This report was prepared by Elizabeth S. Hacker under contract No. 84-ABA-02592 for the National Marine Fisheries Service, Southwest Fisheries Center, La Jolla, California. The statements, findings, conclusions and recommendations herein are those of the author and do not necessarily reflect the views of the National Marine Fisheries Service. Charles W. Oliver of the Southwest Fisheries Center served as Contract Officer's Technical Representative for this contract. ADMINISTRATIVE REPORT LJ-86-08C CONTENTS PAGE INTRODUCTION.................. 1 METHODS....................... 2 Sample Collection........ 2 Sample Identification.... 2 Sample Analysis.......... 3 RESULTS....................... 3 Globicephala macrorhynchus 3 Mirounga angustirostris... 4 DISCUSSION.................... 6 ACKNOWLEDGEMENTS.............. 11 REFERENCES.............. 12 i LIST OF TABLES TABLE PAGE 1 Collection data for Globicephala macrorhynchus examined from the Southern California Bight........ 19 2 Collection data for Mirounga angustirostris examined from the Southern California Bight........ 20 3 Stomach contents of Globicephala macrorhynchus examined from the Southern California Bight.......
    [Show full text]
  • BETTER DATA COLLECTION in SHARK FISHERIES LEARNING from PRACTICE Cover Image: Cacaodesign.It FAO Fisheries and Aquaculture Circular No
    NFIF/C1227 (En) FAO Fisheries and Aquaculture Circular ISSN 2070-6065 BETTER DATA COLLECTION IN SHARK FISHERIES LEARNING FROM PRACTICE Cover image: cacaodesign.it FAO Fisheries and Aquaculture Circular No. 1227 NFIF/C1227 (En) BETTER DATA COLLECTION IN SHARK FISHERIES LEARNING FROM PRACTICE by Monica Barone Fishery Resources Consultant FAO Fisheries Department Rome, Italy and Kim Friedman Senior Fishery Resources Officer FAO Fisheries Department Rome, Italy FOOD AND AGRICULTURE ORGANIZATION OF THE UNITED NATIONS Rome, 2021 Required citation: FAO. 2021. Better data collection in shark fisheries – Learning from practice. FAO Fisheries and Aquaculture Circular No. 1227. Rome. https://doi.org/10.4060/cb5378en The designations employed and the presentation of material in this information product do not imply the expression of any opinion whatsoever on the part of the Food and Agriculture Organization of the United Nations (FAO) concerning the legal or development status of any country, territory, city or area or of its authorities, or concerning the delimitation of its frontiers or boundaries. The mention of specific companies or products of manufacturers, whether or not these have been patented, does not imply that these have been endorsed or recommended by FAO in preference to others of a similar nature that are not mentioned. The views expressed in this information product are those of the author(s) and do not necessarily reflect the views or policies of FAO. ISBN 978-92-5-134622-8 © FAO, 2021 Some rights reserved. This work is made available under the Creative Commons Attribution-NonCommercial-ShareAlike 3.0 IGO licence (CC BY-NC-SA 3.0 IGO; https://creativecommons.org/licenses/by-nc-sa/3.0/igo/legalcode).
    [Show full text]
  • Stock Assessment and Fishery Evaluation of Skate Species (Rajidae)
    16. Gulf of Alaska Skates by Sarah Gaichas1, Nick Sagalkin2, Chris Gburski1, Duane Stevenson1, and Rob Swanson3 1NMFS Alaska Fisheries Science Center, Seattle WA 2ADF&G Commercial Fisheries Division, Kodiak AK 3NMFS Alaska Fisheries Science Center, Kodiak AK Executive Summary Summary of Major Changes Changes in the input data: 1. Total catch weight for GOA skates is updated with 2004 and partial 2005 data. 2. Biomass estimates from the 2005 GOA bottom trawl survey are incorporated. 3. Life history information has been updated with recent research results. 4. Information on the position of skates within the GOA ecosystem and the potential ecosystem effects of skate removals are included. Changes in assessment methodology: There are no changes to the Tier 5 assessment methodology. Changes in assessment results: No directed fishing for skates in the GOA is recommended, due to high incidental catch in groundfish and halibut fisheries. Skate biomass changed between the last NMFS GOA trawl survey in 2003 and the most recent survey in 2005, which changes the Tier 5 assessment results based on survey biomass. The recommendations for 2005 based on the three most recent survey biomass estimates for skates and M=0.10 are: Western Central GOA Eastern GOA GOA (610) (620, 630) (640, 650) Bathyraja skates Gulfwide Big skate ABC 695 2,250 599 ABC 1,617 OFL 927 3,001 798 OFL 2,156 Longnose skate ABC 65 1,969 861 OFL 87 2,625 1,148 Responses to SSC Comments SSC comments specific to the GOA Skates assessment: From the December, 2004 SSC minutes: The SSC is grateful to samplers with ADF&G who collected catch data and biological samples for Kodiak landings.
    [Show full text]
  • Tiger Shark (Galeocerdo Cuvier) on the East Coast of Australia
    The biology and ecology of the tiger shark (Galeocerdo cuvier) on the east coast of Australia. Bonnie Jane Holmes BSc (Hons) A thesis submitted for the degree of Doctor of Philosophy at The University of Queensland in 2015 School of Biological Sciences ABSTRACT The tiger shark (Galeocerdo cuvier) (Péron and Lesueur 1822) is the largest of the carcharhinids, with a circumglobal distribution in both tropical and warm temperate coastal and pelagic waters. In the western Pacific, G. cuvier movements are wide-ranging, encompassing the east coast of Australia and south Pacific Islands. Throughout the region, G. cuvier is exposed to a range of commercial, recreational, artisanal and illegal foreign fishery impacts, as both a target and by-product species. Listed as ‘near threatened’ on the International Union for Conservation of Nature (IUCN) Red List, suitable long term species-specific catch, catch rate and biological data are seldom available for large shark species like G. cuvier, particularly where historical commercial fishery logbook reporting has been poor. Shark control programs targeting large sharks along Australia’s east coast have been in operation for over 60 years, using relatively standardised fishing gear in nearshore waters all year round, with historical catch and effort data recorded by shark contractors. Historical catch, catch rate and biological data collected through the Queensland Shark Control Program (QSCP) since 1993 were investigated, which revealed significant declines (p < 0.05) in catch rates of G. cuvier at some tropical and all sub-tropical locations along the Queensland coast. Significant temporal declines in the average size of G. cuvier also occurred at four of the nine locations analysed (p < 0.05), which could be indicative of fishing reducing abundance in these areas.
    [Show full text]
  • Download the Full Article As Pdf ⬇︎
    LocalLockdown Diving — Dives Found in Contributors' Backyards Text and photos by Andrey Bizyukin, Larry Cohen, Brent Durand, Dmitry Efremychev, Jennifer Idol, Kate Jonker, Matthew Meier, Pete Mesley, Don Silcock, Olga Torrey and Martin Voeller As many divers face travel restrictions during the coronavi- rus pandemic, our contributors highlight the often overlooked or unsung yet intriguing div- ing that can be found in one's own backyard. X-Ray Mag contributors share their favorite local haunts—from a spring-fed Texan lake to a quarry and a sinkhole in Russia to the tem- perate waters off New Zealand, Japan, South Africa, New Jersey and Northern California to the subtropical waters of Southern California and Sydney, Australia—where they captured compelling underwater images. 58 X-RAY MAG : 101 : 2020 EDITORIAL FEATURES TRAVEL NEWS WRECKS EQUIPMENT BOOKS SCIENCE & ECOLOGY TECH EDUCATION PROFILES PHOTO & VIDEO PORTFOLIO MATTHEW MEIER feature Local Dives School of opaleye and garibaldi among sea grass and feather boa kelp. PREVIOUS PAGE: School of juvenile senorita fish in the kelp and sea grass beds Bat Ray Cove, San Clemente Island, Soupfin (tope) sharks can be seen swimming in California, USA the shallows and among the giant kelp, along with schools of blacksmith and jack mackerels. Text and photos by Matthew Meier California sea lions will swoop through intermittently, and the occasional harbor seal Thankfully, local diving is still possible during will play peak-a-boo in the kelp. the pandemic, and while this dive site requires Under the boat is a sandy bottom where boat access, it is still one of my favorites.
    [Show full text]
  • Pacific, Northeast
    536 Fish, crustaceans, molluscs, etc Capture production by species items Pacific, Northeast C-67 Poissons, crustacés, mollusques, etc Captures par catégories d'espèces Pacifique, nord-est (a) Peces, crustáceos, moluscos, etc Capturas por categorías de especies Pacífico, nordeste English name Scientific name Species group Nom anglais Nom scientifique Groupe d'espèces 2012 2013 2014 2015 2016 2017 2018 Nombre inglés Nombre científico Grupo de especies t t t t t t t White sturgeon Acipenser transmontanus 21 76 64 27 21 23 36 26 Pink(=Humpback) salmon Oncorhynchus gorbuscha 23 107 935 327 085 146 932 278 246 62 659 228 336 61 591 Chum(=Keta=Dog) salmon Oncorhynchus keta 23 74 254 78 418 44 746 68 310 61 935 86 782 62 944 Sockeye(=Red) salmon Oncorhynchus nerka 23 100 038 81 848 141 311 135 474 132 554 132 610 120 341 Chinook(=Spring=King) salmon Oncorhynchus tshawytscha 23 7 543 9 067 11 894 9 582 6 991 5 251 3 203 Coho(=Silver) salmon Oncorhynchus kisutch 23 11 470 19 716 23 167 12 241 14 699 17 170 13 100 Pacific salmons nei Oncorhynchus spp 23 ... ... ... ... ... ... 17 586 Eulachon Thaleichthys pacificus 23 - - 9 6 2 1 ... Smelts nei Osmerus spp, Hypomesus spp 23 335 213 280 261 162 162 159 Salmonoids nei Salmonoidei 23 1 1 0 1 1 - 1 American shad Alosa sapidissima 24 152 23 52 51 94 95 179 Pacific halibut Hippoglossus stenolepis 31 19 048 17 312 14 098 14 718 15 033 15 707 13 207 English sole Pleuronectes vetulus 31 202 367 295 319 393 204 304 Greenland halibut Reinhardtius hippoglossoides 31 4 621 1 394 1 397 2 084 2 156 2 733 1 760
    [Show full text]
  • Humboldt Bay Fishes
    Humboldt Bay Fishes ><((((º>`·._ .·´¯`·. _ .·´¯`·. ><((((º> ·´¯`·._.·´¯`·.. ><((((º>`·._ .·´¯`·. _ .·´¯`·. ><((((º> Acknowledgements The Humboldt Bay Harbor District would like to offer our sincere thanks and appreciation to the authors and photographers who have allowed us to use their work in this report. Photography and Illustrations We would like to thank the photographers and illustrators who have so graciously donated the use of their images for this publication. Andrey Dolgor Dan Gotshall Polar Research Institute of Marine Sea Challengers, Inc. Fisheries And Oceanography [email protected] [email protected] Michael Lanboeuf Milton Love [email protected] Marine Science Institute [email protected] Stephen Metherell Jacques Moreau [email protected] [email protected] Bernd Ueberschaer Clinton Bauder [email protected] [email protected] Fish descriptions contained in this report are from: Froese, R. and Pauly, D. Editors. 2003 FishBase. Worldwide Web electronic publication. http://www.fishbase.org/ 13 August 2003 Photographer Fish Photographer Bauder, Clinton wolf-eel Gotshall, Daniel W scalyhead sculpin Bauder, Clinton blackeye goby Gotshall, Daniel W speckled sanddab Bauder, Clinton spotted cusk-eel Gotshall, Daniel W. bocaccio Bauder, Clinton tube-snout Gotshall, Daniel W. brown rockfish Gotshall, Daniel W. yellowtail rockfish Flescher, Don american shad Gotshall, Daniel W. dover sole Flescher, Don stripped bass Gotshall, Daniel W. pacific sanddab Gotshall, Daniel W. kelp greenling Garcia-Franco, Mauricio louvar
    [Show full text]
  • Leopard Sharks Arc Commonly Taken from Piers and Jettics, and Are Knom to Congregate Around the Warm Water Outfalls of Powcr Plants
    tionally caught rctums, 54.5 percent came from slu&ipri\atc boat anglers, 40.9 perccnt camc from shore anglers, and only 4.5 percent camc from pattjboat anglcrs. Leopard sharks arc commonly taken from piers and jettics, and are knom to congregate around the warm water outfalls of powcr plants. A \aricty of fishing methods and gear tjpcs are used in thc fisheries for leopard sharks: angling with baited hooks, spearfishing by divers, gillnetting along the coast, and somc commercial longlining. Recreational spearing reportedly oc- curs in Humboldt Bay in shallow water. Gillnct catches will probably continue to decline with increasing legislation re- strictingwofthcsenctsincoastal waters. Someleopardsharks arc also taken incidcntally in ocean bottom trawl catches. &caw of its slow growih ratc, latc sexd maturity, low fccundity, and cas). accessibility to fishcrmcn, this spccics is considcrcd susccptiblc to fishing pressurc. Fishing mortality ratcs and lifc history paramctcrs indmtc that with the current amount of fishing prcssurc, somc mcasurc of protcction would LEOPARD SHARK bc ncccssary to assurc population rcplcnishmcnt. History of the Fishery Thc lcopard shark (Triokissemijaraota) is valucd as both a focd and gamc fish in Califomja; it is not uncommon in frcsh fish markcts and has a firm, mild-tasting flah. Thc distinctivc 4 markings and hardincss of this fish also make it dcsirablc for aquarium displays. Thc scope of thc fishcries for lcopard shark is dillicult to Lcopard shark. Triaku stmi/osciara cstimatc for two reasons: an unknown portion of thc commcr- cial catch may bc landcd undcr the gcncral catcgory "shark, unspcciilcd; and statistics on lmpard sharks caught by mc- Status of Biological Knowledge ational anglcrs havcbccn inadcquatcuntil thc bcginning ofthc Thc lcopard shark, also known as "tigcr shark" and "cat last dccadc.
    [Show full text]
  • UC Davis UC Davis Previously Published Works
    UC Davis UC Davis Previously Published Works Title Use of a hydrodynamic model to examine behavioral response of broadnose sevengill sharks (Notorynchus cepedianus) to estuarine tidal flow Permalink https://escholarship.org/uc/item/23q9c0bz Journal Environmental Biology of Fishes, 102(9) ISSN 0378-1909 Authors McInturf, AG Steel, AE Buckhorn, M et al. Publication Date 2019-09-15 DOI 10.1007/s10641-019-00894-3 Peer reviewed eScholarship.org Powered by the California Digital Library University of California Environ Biol Fish https://doi.org/10.1007/s10641-019-00894-3 Use of a hydrodynamic model to examine behavioral response of broadnose sevengill sharks (Notorynchus cepedianus) to estuarine tidal flow Alexandra G. McInturf & Anna E. Steel & Michele Buckhorn & Philip Sandstrom & Christina J. Slager & Nann A. Fangue & A. Peter Klimley & Damien Caillaud Received: 17 February 2019 /Accepted: 13 June 2019 # Springer Nature B.V. 2019 Abstract Innovative telemetry and biologging technol- hydrodynamic model of the estuary and calculated cur- ogy has increased the amount of available movement rent vectors along each track. We hypothesized that the data on aquatic species. However, real-time information sharks would adjust their swimming speed and direction on the environmental factors influencing animal move- depending on current strength when passing through the ments can be logistically challenging to obtain, particu- channel underneath the Golden Gate Bridge. Our results larly in habitats where tides and currents vary locally. indicate that sharks did tend to follow the current flow in Hydrodynamic models are capable of simulating com- the channel, but their overall displacement did not sig- plex tidal flow, and may thus offer an alternative method nificantly correlate with tidal amplitude.
    [Show full text]