DOCSLIB.ORG

Cephalopod Remains from Stomachs of Sperm Whales

Total Page：16

File Type：pdf, Size：1020Kb

Download full-text PDF Read full-text
Cephalopod Remains from Stomachs of Sperm Whales CEPHALOPOD REMAINS FROM STOMACHS OF SPERM WHALES THAT MASS-STRANDED ON THE OREGON COAST A Thesis Presented to the Faculty of Califomia State University, Stanislaus through Moss Landing Marine Laboratories In Partial Fulfillment of the Requirements for the Degree of Master of Science in Mmine Science By Theresa Friend January 2004 DEDICATION To my partner and source of strength and love, without whose constant support and patience this project would not have happened. Thank you for believing in me. iii ACKNOWLEDGMENTS In an undertaking such as this there are so many people to thank. First, I sincerely thank my committee members, Dr. James Harvey, Dr. Pamela Roe, Dr. Gregor Cailliet and Dr. Stacy Kim for their guidance, support, helpfi.1l comments and encouragement. Jim, thank you for the second chance when my first project fell through. I especially thank Dr. Roe for her countless trips to the graduate office to ensure that all of the proper paperwork was in place and for the many phone calls of encouragement when I was sure that this project would not happen. A very special thanks goes to Bill Walker for his immense generosity in helping to identify and verify cephalopod beaks and in training me to identify beaks. It was a tremendous experience. My deepest appreciation goes out to my mom, dad and brother for their constant support and love. Much love and thanks also go out to my extended family (Autumn, Jane, Tam, Kat, and Tom) without whose encouragement and many, many hours of beak measurements, data entry and library searches this project would not have happened. Thank you to Joan Parker and the entire library staff for their assistance in obtaining reference materials. Thank you to Josh Adams and Mike Weise for assistance with questions regarding beak identification and data analysis. iv Many thanks go to Jeff Rutter for his invaluable assistance with the statistics, graphs and pivot tables. Finally, to my partner and best friend, Lisa Scheff, I owe you the world. Your constant support, encouragement, patience and work on this project kept me motivated and on track. You rarely complained about the never-ending piles of squid beaks, papers, books, calipers, microscopes and computer equipment that covered our second bedroom and kitchen table. I can't even begin to thank you for the hours of beak identification and editing you undertook for me. This project was made possible by funding from the David and Lucile Packard Foundation, the Ray Cannon Scholarship, and the Graduate Equity Fellowship from CSU-Stanislaus. v TABLE OF CONTENTS PAGE Dedication ll1 Acknowledgments .................................................................................................... IV List of Tables ........................................................................................................... VII List of Figures ......................................................................................................... IX Abstract ................................................................................................................... x Introduction .............................................................................................................. 1 Current Study ........................................................................................................... 8 Methods.................................................................................................................... 10 Results ...................................................................................................................... 14 Discussion ................................................... ............................................................. 22 Literature Cited ....................................................................................................... 39 Tables ....................................................................................................................... 48 Figures ...................................................................................................................... 61 vi LIST OF TABLES TABLE PAGE 1 Sex, age and number of lower beaks in the stomach contents ......... 49 of 32 sperm whales (ages from Rice et al., 1986) stranded off the Oregon coast. 2 Regression equations used in estimating body lengths and ............. 50 masses of cephalopod prey species in the diet of sperm whales stranded off the Oregon coast. 3 Number and frequency of cephalopodoccurrence of prey recovered 51 from 32 stomachs of 41 sperm whales that stranded off the Oregon coast. 4 Two-dimensional indices of relative importance (IRI) calculated .... 52 by multiplying averaged %N by %FO of cephalopod prey items recovered from 32 stomachs of 41 sperm whales stranded off the Oregon coast. 5 Percentage contribution by mass including minimum, maximum, ... 53 and mean mass of cephalopod prey recovered from 32 stomachs of sperm whales stranded off the Oregon coast. 6 Two-dimensional indices of relative importance (IRI) for each ...... 54 sex and age group of sperm whales, calculated by multiplying averaged %N by %FO of cephalopod prey items recovered from the stomach contents of 32 sperm whales stranded off the Oregon coast. 7 Minimum, maximum and mean dorsal mantle lengths (DML) ....... 56 of cephalopod prey recovered from 32 stomachs of sperm whales stranded off the Oregon coast. 8 Small, medium, med-large and large size classes of cephalopods .... 57 recovered from the stomach contents of 32 sperm whales stranded off the Oregon coast. vii 9 Statistical results for One-Way ANOVA comparison of mean ....... 58 lengths for twelve prey species of cephalopod prey. 10 Cephalopod species recovered from the stomach contents .............. 59 of sperm whales from the Northeastern Pacific Ocean. viii LIST OF FIGURES FIGURE PAGE 1 Location of mass stranding of sperm whales, June 16, 1979, that.. .. 62 stranded off the Oregan coast near the Siuslaw River mouth. 2 Cumulative species curves for 32 spetm whales stranded off the ..... 63 Oregon coast. 3 Total number of beaks for each cephalopod prey item averaged ...... 64 within each whale to detetmine a percentage representation of the prey item for the whole group of whales. 4 Length distributions for 6 cephalopod species recovered from ........ 65 stomach contents of 32 sperm whales stranded off the Oregon coast. 5 Length distributions for 4 cephalopod species recovered from ........ 66 stomach contents of 32 sperm whales stranded off the Oregon coast. 6 Length distributions for Moroteuthis robusta recovered from .......... 67 stomach contents of 32 sperm whales stranded off the Oregon coast. 7 Length distributions for Taningia danae recovered from ................. 68 stomach contents of 32 sperm whales stranded off the Oregon coast. 8 Comparison of the %N represented by the major cephalopod prey .. 69 items consumed by male and female sperm whales. 9 Distribution in the water column of the major cephalopod species .. 70 eaten by the 32 sperm whales that stranded off the Oregon coast. ix ABSTRACT On 16 June 1979, a school of 41 sperm whales stranded on a shallow sloping beach near the mouth of the Siuslaw River in Florence, Oregon. A sample of the stomach contents from 32 of the whales was collected, identified, enumerated, and measured. In the 32 stomachs, 20,247 cephalopod lower beaks were recovered. These beaks represented 24 species from 14 different families. The most numerous species represented were Histioteuthis lwylei (24.4%), Galiteuthis phyllura (13.1 %), Taonius borealis (12.1 %), Moroteuthis robust a (11.1 %), and Gonatopsis/Berryteuthis type (10.9% ). Estimations of contribution by mass to the sperm whales' diets indicated that the dominant species were M. robust a (42.98 % V) followed by Gonatopsis/Benyteuthis type (20.0 1 % V) and H. lwylei (12.26% V). Statistical analysis determined that there was no difference in the overall lengths of the dominant species eaten by male and female sperm whales, however, there was a significant difference in the importance of different species between the diets of male sperm whales (ages 15 to 21), and female sperm whales (ages 11 to 21) and between females of different age groups (ages 11 to 21 and 22 to 58). Based on species composition the sperm whales in this study were feeding in the lower mesopelagic to bathypelagic zones off the Oregon coast. X INTRODUCTION The sperm whale (Physeter macrocephalus Linnaeus, 1758) is an odontocele cetacean (toothed whale) in the family Physeteridae. The family Physeteridae is comprised of two genera: Physeter (sperm whale) and Kogia (pygmy sperm whale; Berzin, 1972). Although there is no doubt that sperm whales are monotypic (Thomas, 1911; Berzin, 1972) there has been some confusion as to the correct species name. Currently, the more widely used name for sperm whales has been P. macrocephalus (Rice, 1998). The body of the sperm whale is streamlined and massive in comparison with other members of the order Cetacea (Berzin, 1972). The species is easily distinguished from other whales by its gigantic and distinctive head. The head is box-like and can constitute from one quarter to one third of the length of the body (Berzin, 1972; Leatherwood & Reeves, 1983; Gordon, 1998). The lower jaw of the sperm whale has up to 30 pairs of conical teeth, whereas the upper jaw has up to 18 pairs of teeth that are rudimentary stumps and no longer functional (Berzin, 1972; Kawakami, 1980; Gordon, 1998). The bottom teeth are firmly attached within sockets in the mandible,
Load more

Recommended publications
  • A Review of Southern Ocean Squids Using Nets and Beaks
    Marine Biodiversity (2020) 50:98 https://doi.org/10.1007/s12526-020-01113-4 REVIEW A review of Southern Ocean squids using nets and beaks Yves Cherel1 Received: 31 May 2020 /Revised: 31 August 2020 /Accepted: 3 September 2020 # Senckenberg Gesellschaft für Naturforschung 2020 Abstract This review presents an innovative approach to investigate the teuthofauna from the Southern Ocean by combining two com- plementary data sets, the literature on cephalopod taxonomy and biogeography, together with predator dietary investigations. Sixty squids were recorded south of the Subtropical Front, including one circumpolar Antarctic (Psychroteuthis glacialis Thiele, 1920), 13 circumpolar Southern Ocean, 20 circumpolar subantarctic, eight regional subantarctic, and 12 occasional subantarctic species. A critical evaluation removed five species from the list, and one species has an unknown taxonomic status. The 42 Southern Ocean squids belong to three large taxonomic units, bathyteuthoids (n = 1 species), myopsids (n =1),andoegopsids (n = 40). A high level of endemism (21 species, 50%, all oegopsids) characterizes the Southern Ocean teuthofauna. Seventeen families of oegopsids are represented, with three dominating families, onychoteuthids (seven species, five endemics), ommastrephids (six species, three endemics), and cranchiids (five species, three endemics). Recent improvements in beak identification and taxonomy allowed making new correspondence between beak and species names, such as Galiteuthis suhmi (Hoyle 1886), Liguriella podophtalma Issel, 1908, and the recently described Taonius notalia Evans, in prep. Gonatus phoebetriae beaks were synonymized with those of Gonatopsis octopedatus Sasaki, 1920, thus increasing significantly the number of records and detailing the circumpolar distribution of this rarely caught Southern Ocean squid. The review extends considerably the number of species, including endemics, recorded from the Southern Ocean, but it also highlights that the corresponding species to two well-described beaks (Moroteuthopsis sp.
    [Show full text]
  • In the Weddell
    View metadata, citation and similar papers at core.ac.uk brought to you by CORE provided by OceanRep Antarctic Science 6 (2):235-239 (1994) Distribution and lipid composition of early life stages of the cranchiid squid Galiteuthis glacialis (Chun) in the Weddell Sea, Antarctica UWE PIATKOWSKIl and WILHELM HAGEN2 'Institut fiir Meereskunde, Universitat Kiel, Diisternbrooker Weg 20,D-24105Kiel, Germany 'Institut fir Polarohdogie, Universitat Kiel, Wischhofstr. 1-3,Gebuude 12,D-24148Kiel, Germany Abstract: The relatively small numbers of pelagic cephalopods caught in the RMT-8 samples (0-300 m) in FebruaryMarch 1983 in the Weddell Sea were dominated by early life stages of the cranchiid squid Galiteuthis glacialis. A total of 48 specimens were caught with dorsal mantle length (ML) ranging from 4-36 mm. They occurred with amean density of 0.15 ind. x 1000 mJ and were present in 38% of 33 RMT-8 samples. G. glacialis was the only cranchiid squid found in the Weddell Sea between 66" and 74"s. Its early life stageswere concentrated in the layers below the summer thermocline (>50 m) and body sizes appeared to increase towards deeper water layers. For biochemical analyses, nine specimens of G. glacialis (ML 6-18 mm) were sampled in the eastern Weddell Seabetween 185-520mwater depth in JanuaryFebruaIy 1985. Totallipidcontentsrangedfrom8%-11% dry weight (DW) with phospholipids being the main lipid component (43-56% of total lipid). Storage lipids (triacylglycerols) made up 18-26% of total lipid. The relatively low lipid contents may reflect the early developmental stage of the specimens examined. The data presented give the first information on geographical and vertical distribution patterns of early life stages of G.
    [Show full text]
  • Technical Report No. 447 1974 •
    FISHERIES RESEARCH BOARD OF CANADA TECHNICAL REPORT NO. 447 1974 • ... FISHERIES RESEARCH BOARD OF CANADA Technical Reports FRB Technical Reports are research documents that are of sufficient importance to be preserved, but which ·for some reason are not appropriate for primary scientific publication. No restriction is placed on subject matter and the series should reflect the broad research interests of FRB. These Reports can be cited in publications, but care should be taken to indicate their manuscript status. Some of the material in these Reports will eventually appear in the primary scientific literature. Inquiries concerning any particular Report should be directed to the issuing FRB establishment which is indicated on the title page. FISHERIES AND MARINE SERVICE TECHNICAL REPORT NO. 44 7 THE SQUID OF BRITISH COLUMBIA AS A POTENTIAL FISHERY RESOURCE - A PRELIMINARY REPORT by S.A. Macfarlane and M. Yamamoto Fisheries and Marine Service Vancouver Laboratory Vancouver, B.C. TABLE OF CONTENTS Page No. I. INTRODUCTION 1 II. BIOLOGICAL ASPECTS 3 III. COMMERCIAL ASPECTS 8 A. Fishing Methods 8 B. International Squid Fisher,y 15 c. Status of Squid in British Co1uabia 19 IV. NUTRITIONAL ASPECTS 27 v. PROCESSING 28 VI. DISCUSSION 30 VII. ACKNOWLEDGMENTS 32 VIII. REFERENCES 33 1. I. INTRODUCTION Available catch statistics from 1965 through 1971 indicate • that world-wide landings of squid totalled roughly 700,000 metric tons annually. An additional 100,000 metric tons of cuttlefish and about 160,000 metric tons of octopus were also landed annually. Apart from the well-established squid fishery in the Monterey area of California and the relatively minor inshore squid fishery off Newfoundland, the North American fishing industry has tended to ignore the possibility of further exploitation and utilization of this resource.
    [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]
  • ICES Marine Science Symposia
    ICES mar. Sei. Symp., 199: 459-467. 1995 Genetic differentiation in Berryteuthis magister from the North Pacific O. N. Katugin Katugin, O. N. 1995. Genetic differentiation in Berryteuthis magister from the North Pacific. - ICES mar. Sei. Symp., 199: 459-467. Berryteuthis magister is a widespread quasibenthic commercial squid from the North Pacific. Intraspecific genetic differentiation was determined by allozyme electrophore­ tic analysis. Eighteen sample lots (2100 individuals) from geographically separated North Pacific regions were subjected to allozyme electrophoretic analysis using a total of 14 enzymes and unidentified ganglion protein spectra with polymorphic zones. Four loci with variant allele frequencies greater than 0.05 were found to be useful for population studies. No significant violations of the Hardy-Weinberg equilibrium were found at any loci in the samples. There was no evidence of genetic differences between sexes. Analysis of genetic differentiation using Wright’s F-statistics, cluster analysis of genetic distances, and contingency chi-square analysis suggested that there are popu­ lation differences between squids from the three major geographical localities: the Sea of Japan, the Kurile-Komandor region, and the Gulf of Alaska. Genetic divergence between squid from the Kurile-Komandor part of the species range probably reflects subpopulation differentiation of local stocks from successive generations. O. N. Katugin: Pacific Research Institute o f Fisheries and Oceanography (TINRO), Vladivostok, 690 600, Russia [tel: (+7) 4232 25 7790, fax: (+7) 4232 25 7783], been investigated electrophoretically. This family is con­ Introduction sidered to be the most abundant group of cephalopods in During the last two decades biochemical genetic tech­ the subarctic waters of the Pacific Ocean where it pre­ niques based on electrophoretic separation of multiple sumably originated and diverged (Nesis, 1973).
    [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]
  • Aspects of the Natural History of Pelagic Cephalopods of the Hawaiian Mesopelagic-Boundary Region 1
    Pacific Science (1995), vol. 49, no. 2: 143-155 © 1995 by University of Hawai'i Press. All rights reserved Aspects of the Natural History of Pelagic Cephalopods of the Hawaiian Mesopelagic-Boundary Region 1 RICHARD EDWARD YOUNG 2 ABSTRACT: Pelagic cephalopods of the mesopelagic-boundary region in Hawai'i have proven difficult to sample but seem to occupy a variety ofhabitats within this zone. Abralia trigonura Berry inhabits the zone only as adults; A. astrosticta Berry may inhabit the inner boundary zone, and Pterygioteuthis giardi Fischer appears to be a facultative inhabitant. Three other mesopelagic species, Liocranchia reinhardti (Steenstrup), Chiroteuthis imperator Chun, and Iridoteuthis iris (Berry), are probable inhabitants; the latter two are suspected to be nonvertical migrants. The mesopelagic-boundary region also contains a variety of other pelagic cephalopods. Some are transients, common species of the mesopelagic zone in offshore waters such as Abraliopsis spp., neritic species such as Euprymna scolopes Berry, and oceanic epipelagic species such as Tremoctopus violaceus Chiaie and Argonauta argo Linnaeus. Others are appar­ ently permanent but either epipelagic (Onychoteuthis sp. C) or demersal (No­ totodarus hawaiiensis [Berry] and Haliphron atlanticus Steenstrup). Submersible observations show that Nototodarus hawaiiensis commonly "sits" on the bot­ tom and Haliphron atlanticus broods its young in the manner of some pelagic octopods. THE CONCEPT OF the mesopelagic-boundary over bottom depths of the same range. The region (m-b region) was first introduced by designation of an inner zone is based on Reid et al. (1991), although a general asso­ Reid'sfinding mesopelagic fishes resident there ciation of various mesopelagic animals with during both the day and night; mesopelagic land masses has been known for some time.
    [Show full text]
  • Fishery Bulletin/U S Dept of Commerce National Oceanic
    Abstract.- Gastrointestinal tract contents were evaluated from Prey selection by northern fur seals 73 female andjuvenile male north­ ern fur seals (Callorhinus ursinus) fCallorhinus ursinusJ in the eastern for analysis of their diet in the Bering Sea. Fur seals were col­ Bering Sea lected from August to October of 1981, 1982, and 1985. Juvenile Elizabeth Sinclair walleye pollock (Theragra chalco­ gramma) and gonatid squid were Thomas Loughlin the primary prey. Pacific herring National Marine Mammal Laboratory. Alaska Fisheries Science Center; (Clupea pallasi) and capelin National Marine Fisheries Service. NOM <Mallotus villosus), considered im­ 7600 Sand Point Way. N.E., Seattle, Washington 98115 portant fur seal prey in previous reports, were absent from the diet. Prey species and size varied William Pearcy among years and between near­ College of Oceanography, Oregon State University shore and pelagic sample loca­ Oceanography Administration Building 104 tions. Interannual variation in the Corvaflis, Oregon 9733 J importance ofpollock in the diet of fur seals was positively related to year-class strength of pollock. Midwater (n=23) and bottom (n=116) trawls were conducted at The Pribilof Island population (St. were conducted prior to the 1975­ the location of fur seal collections George and St. Paul Islands) of 81 population decline and prior to to determine availability of fish northern fur seals (Callorhinus the 1970's development of a com­ and squid relative to prey species eaten by fur seals. The species and ursinus) represents approximately mercial walleye pollock (Theragra size composition of prey taken by 75% of the total species breeding chalcogramma) fishery in the fur seals was similar to midwater population.
    [Show full text]
  • 16. Bering Sea and Aleutian Islands Squids
    16. Bering Sea and Aleutian Islands Squids Olav A. Ormseth and Elaina Jorgenson NMFS Alaska Fisheries Science Center Executive Summary Summary of Major Changes Changes in the input data: Total catch data for Bering Sea and Aleutian Islands (BSAI) squids is updated with 2006 and partial 2007 data. Changes in assessment methodology: There are no changes in the assessment methodology. Changes in assessment results: There are no changes in assessment results because BSAI squids remain in Tier 6, as they have for the past several years. The recommended allowable biological catch (ABC) for squids in 2008 and 2009 is calculated as 0.75 multiplied by the average catch from 1978-1995, or 1,970 t; the recommended overfishing level (OFL) for squid in the years 2008-2009 is calculated as the average catch from 1978- 1995, or 2,624 t. We continue to lack reliable squid biomass information that would allow a Tier 5 or higher assessment. 2008-2009 Tier 6 harvest specifications for BSAI squids 2008-2009 ABC 1,970 t 2008-2009 OFL 2,624 t Responses to SSC Comments From the December 2006 SSC minutes: 1) For squid, it would be useful to see an analysis of the spatial distribution of catches for consideration in devising alternative tier 6 approaches. Response: Spatial analyses for 2000-2006 have not been completed, but we anticipate that this will be done in 2008. Introduction Description, scientific names, and general distribution Squids are marine molluscs in the class Cephalopoda (Group Decapodiformes). Squids are considered highly specialized and organized molluscs, with only a vestigial mollusc shell remaining as an internal plate called the pen or gladius.
    [Show full text]
  • During 1979-1997
    ICES CM/1988M:39 (Poster) 38.13 4 Interannual Variability in the Neon Flying Squid Abundance and Oceanographic Conditions in the Central North Pacific Ocean during 1979-1997 A. Yatsu*, J. Mori*, T. Watanabe*, T. Meguro", Y. Kamei", and Y. Sakurai" Abstract The neon flying squid, Ommastrephes bartrami, was the target species of the Japanese squid driftnet fishery in the Central North Pacific Ocean during 1979- 1992. Interannual variation in the neon flying squid catch-per-unit-effort (CPUE) in this fishery was highly correlated with that of the Hokkaido University's research driftnet surveys since 1979 along 175' 307Ein July which coincided with the peak of the commercial fishery. While productivity in the northern North Pacific Ocean was high during the 1970's and declining to the present days, the research net CPUE of 0. bartrami was higher in 1979 and in 1994-97 than in other years, suggesting effect of fishing on the stock abundance. The distributions and CPUE variability in 0. bartarmi were also affected by water temperature and salinity structures around the Subarctic Boundary. During the intensive driftnet fishing, three squid species (0. bartrami, Gonatopsis borealis and Onchoteuthis borealijaponica) may have, to some extent, filled throphic niche that was occupied by pelagic fishes. National Research Institute of Far Sear Fisheries, Shimizu 424-8633, Japan " Faculty of Fisheries, Hokknido University, Hakodate 041-8611, Japan Introduction end of 1992 according to the bycatch problem. Since 1993, fishing mortality The neon flying squid, Ommastrephes of the autumn cohort has been derived bartrami, is one of the most dominant only by jig fishing whose annual catch nekton in the epipelagic subtropical and has been less than approximately 10,000 subpolar waters of the world oceans, and tons for this cohort.
    [Show full text]
  • Full Text in Pdf Format
    MARINE ECOLOGY PROGRESS SERIES Vol. 177: 115-131, 1999 Published February 11 Mar Ecol Prog Ser Diet, provisioning and productivity responses of marine predators to differences in availability of Antarctic krill J. P. Croxall*, K. Reid, P. A. Prince British Antarctic Survey, Natural Environment Research Council. High Cross, Madingley Road. Cambridge CB3 OET. United Kingdom ABSTRACT: Knowledge of relationships between prey availability and predator performance is the key to using predators as indicators of the state of marine systems and to assessing potential conse- quences of competition between natural predators and man for common resources. Fluctuations in the abundance of Antarctic knll are beiieved to have a substantial influence on the reproductive perfor- mance of krill-dependent top predator species in the Southern Ocean; few quantifications of such inter- actions exist. At South Georgia, for 2 years in which acoustic surveys revealed a major difference in knll abundance, we compared diet, prov~sioningof offspring and breeding success in 4 main predator species (2 penguins, 2 albatrosses, with supporting data from Antarctic fur seal) whose dependence on krd typically ranges from 20 to 90%. The 4-fold difference in krill biomass between 1986 (ca 30 g m-2) and 1994 (ca 7 g m-2)was accompanied by (1) an 88 to 90% reduction in the mass of krill in predator dlets (and some increase in the fish component), (2) greater prey diversity for most species, (3) reduced diet overlap between species and (4) a switch from krill to amphipods in macaroni penguin but no major dietary change in other species.
    [Show full text]
  • Long-Term Fluctuations in Gonatid Squid (Gonatidae) Abundance in the Okhotsk Sea
    Pacific Research Institute of Fisheries and Oceanography (TINRO-Centre) Long-term fluctuations in gonatid squid (Gonatidae) abundance in the Okhotsk Sea Mikhail A. Zuev Nikolai S. Vanin Oleg N. Katugin Gennady A. Shevtsov The main goal reveal annual distribution patterns of squids of the family Gonatidae in the Sea of Okhotsk basing on data collected in TINRO-Centre research surveys with a purpose to estimate the role of these cephalopods in pelagic communities Methods: – analyze database on squid catches for a period from 1990 to 2008; – use the data to obtain patterns of spatial and seasonal on squid distribution and biology; – assess the role of different species in seasonal dynamics of distribution density in the epi- and mesopelagic layers in different years; – use synoptic observations to reveal relationships between squid distribution density and variability in atmospheric pressure in the study area Upper-mesopelagic Region expeditions investigations years (expeditions) northern Okhotsk Sea 20 12 1990-2008 southern 18 2 1990-2008 Okhotsk Sea off west 12 7 1998-2007 Kamchatka the entire Okhotsk Sea 25 13 1990-2008 - Investigations of epipelagic (0-200 m) - Investigations of epipelagic and upper- mesopelagic (200-500 m) northern Okhotsk Sea Kamchatka Biomass density (kg/km2) of the Gonatidae in the northern Okhotsk Sea kg/km2 0,6 2 - Berryteuthis magister 0,5 4000,4 - Gonatus madokai 0,3 2000,2 0,1 0 w w s s о w s s о w s s о w s s о w s s о о w s s о w s s s о 1991 ] [ 1993][1994 1995 ][ 1997 1998 1999 2000 1,2 - Boreoteuthis borealis
    [Show full text]