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Biology of Neustonic Larval and Juvenile Fishes and Crabs Off Oregon, 1984

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Biology of Neustonic Larval and Juvenile Fishes and Crabs Off Oregon, 1984 AN ABSTRACT OF THETHESIS OF Jonathan M, Shenker forthe degree of DoctorofPhilosophy Jib. i 2Col]ee of Oceanographypresented on April J, Ti±le:Biology of Neustonic Larva],and Juvenile Fishes and Crabs off Oreoon.1984 Redacted for privacy AStraCt A survey of theneustonic larval andjuvenile fishes and invert ebratemacroplankton was conductedbiweekl alonc a 50 kin transect offthe central Oregon coastibm io:ril throuah July,1984.A Nanta neuston net Used tO assess the abundanceof larval fishes andzooplankton, .Jjie a 1araneuston trawl with amouth ooeninc-r 3.5 m 1.0 m was used to collectthe previouslyunstiidied juvc- nile fish component of theneuston. Larval andjuvenile fishes wereabundant in}iab.itarJ:s of Li soner 1 inof the ocean duringthe nqbLime, hut .cre rarely collectedduring the day.Several spocacs 50w3- sp. , Ronuilusjordani, Hemilepidotus sos anc acorpaenichthysmarrnoratus) were stjhutea abc I transect, while othersoecies were morerestni crea in oboir distribution.Offshore species includedAccp1croma ii obi-ia, Enoraulismordax and Sebastes spp.Parophoys wai.e cbcndarAt atthe inshore s-ta tinsin earlo' d R. Tv of the dominant species,Hexararimcs op. were generallywidelydispersed, while Lho other tare were more aggrecated .Several c;.roqat ionsrere the associated withhydreg:-aphiccharac.tet: .1 aLice such us a River plume orsonvergence c'ncs boo e-cet 00 uy:.oei.i leg tnic ered a matic shift in lob Lupankiro spcC. -as rnaopoo Iion. 'The domi cant component ofall catches was the vega-' I c.aof the L;anqene se crab,Cancer va etc r. Do-a a were usually highestat night.Despite their broaddi:trii hution over the transect,the largest aggregationsof raegalopae were found inassociation with specificenviron- mental features such as convergencezones and raftsof the pleustonic hydroid Velellavelella. Live juvenile sablefish(Anoploponia iiinbria)were brought into the laboratoryfor an investigationof their feeding and growth biology.Sablefish were capableof consuming >30% wetbody weight/day, andachieved rates of growth in excess of 2mm/day.Live mysid shrimp were su- perior food to live adultbrine shrimp.CQastal and estuarine juvenile fishes haveslow growth compared to sablefish.Several other epipelacicspecies have juve- niles that grow as fast orfaster than sablefish.This eattern suggests that strongselective pressures forrapid growth exist in the open oceanwhere refugia frompreda- tion are very rare, and thatsufficient food resourcesfor such growth exists in theepipelagic realm. ©Copyright by Jonathan M. Shenker April 26, 1985 All Rights Reserved Biology of Neustonic Larval and Juvenile Fishes and Crabs off Oregon, 1984 by Jonathan M. Shenker A THESIS submitted to Oregon State University in partial fulfillment of the requirements for the degree of Doctor of Philosophy Completed April 26, 1985 Coimitencernent June 1986 APPROVED: Redacted for privacy Professor of Oceanography in harge of major Redacted for privacy Head of o1lege of Oceanography Redacted for privacy Dean of Gvuate Date thesis is presented April 26, 1985 Typed by Jonathan N. Shenker ACKNOWLEDGEMENTS Numerous people have assisted me throughout my graduate program at Oregon State University, arid it would require many, many pages to properly thank everyone for their contributions to my academic development and research projects. I am particularly grateful to my major professor, Dr. William G. Pearcy, for his support during my graduate career. Dr. Pearcy has been a continual source of inspiration and valuable advice, and has provided important critical evaluation of my research ideas, data analysis and interpretation, and manuscript writing. The financial support provided by Dr. Pearcy, and his assistance in getting National Marine Fisheries Service funding for my dissertation research, made it possible for me to initiate and complete my program at 0. S. U. Bori 0l].a deserves recognition for his enthusiastic assistance, financial support and encouragement of my research. Bori has been instrumental in broadening my interests into such diverse fields as behavioral biology, pollution ecology and the politics associated with establishment of research priorities and funding. His help in developing the feeding and growth experiments on juvenile sablefish (Chapter 6) has been extremely valuable, and his editorial advice has dramatically aided my writing. Through their courses and in individual discussions, Drs. George Boehiert and Charles Miller provided me with important insights into the biology and ecology of ichthyoplankton and zooplarikton. They made important editorial contributions to several papers in addition to this thesis, and have encouraged me throughout my graduate career. Captain Leland Oldenberg and his crew on the F/v "Cumberland Trail" deserve much of the credit for the field survey. Leland's superb seamanship, constructive ideas and unflagging enthusiasm are major reasons or the success of much of my research. It would have been impossible to conduct my research without the able assistance of many graduate students and research associates. I very much appreciate their help in collecting samples from the ocean, in conducting laboratory experiments, and in providing suggestions on data analysis and editorial comments. Ric Brodeur was involved in virtually every project of mine, and his assistance has been invaluable. The members of larval fish group, especially Bruce Mundy, Mary Yoklavich and Chris Wilson, helped in all phases of my neuston research program. Dozens of people who worked on the ocean salmon project, led by Waldo Wakefield, Joe Fisher and Alton Chung, were instrumental in collecting data on scyphomedusae for an earlier project of mine. I cannot express how grateful I am for their help in collecting and processing immense volumes of the slimy, slippery, stinging jellyfish. John Kern deserves my thanks for his assistance in various projects and his never-ending attempts to introduce me to new-wave music (although it still hasn't crept around my mental block). Gary Braun aided many of my lab projects, and was especially proficient in our joint program of running polychaete races in cadmium-laden tanks. Wayne L.aroche helped identify to species many of the juvenile rockfishes. Many other friends aided in my research or provided valuable discussions of the work. My thanks go to all of them: Richard Merrick and Linda Taylor, Eric Rexstad, Lynne Krasnow, John Hennessey, Joyce Royland, Steve Ellis, Mark Brzezinski, Jim Anderson, Ken Yates, Joe Choromanski, Liz Clarke, Dan Gant, Jill Grover, Jim Harvey, Kathy Sercu, David Stein, Marc Willis, Chip Hogue, Hal Batchelder and, of course, Simon the dog. Finally, I would like to dedicate this dissertation to my parents. They introduced me to the marine environment when I was a small child, and have continually supported my life-long interest in marine science. TABLE OF CONTENTS Chapter 1. GENERAL INTRODUCTION 1 Terminology and Objectives 1 The Neustonic Environment 4 The Neustonic Biota 9 Chapter 2. FIELD SURVEY MATERIALS AND METHODS 17 Chapter 3. HYDROGRAPHIC CHARACTERISTICS OF THE NEUSTONIC LAYER 23 Introduction 23 Hydrographic Data 25 Chapter 4. ICHTHYONEUSTON OFF THE OREGON COAST 29 Introduction 29 Results and Discussion 32 Diel Fish Distribution Patterns 32 Species Analysis 34 Hydrographic Associations 48 Summary 54 Chapter 5. UTILIZATION OF THE NEUSTONIC HABITAT BY DUtJGENESS CRAB (CANCER MAGISTER) MEGALOPAE 56 Introduction 56 Results 60 Discussion 68 Chapter 6. LABORATORY FEEDING AND GROWTH OF JUVENILE SABLEFISH, ANOPLOPOMA FIMBRIA. 79 Introduction 79 Materials and Methods 81 Collection and Experimental Procedures 81 Analytical Procedures 87 Results 88 Growth Data 90 Gross Conversion Efficiency 96 Discussion FIGURES 106 TABLES 131 LITERATURE CITED 146 LIST OF FIGURES Figure Page 1 Location of stations along the transect of f Newport, Oregon. 106 2a Front view of the neuston trawl; B = inflated 40 cm diameter spar buoys; C = cloth collar around mouth of net; R = polypropylene fib lines on the net. 107 2b Side view of the neuston trawl showing construction of the towing bridle. Spar buoy floats were removed for clarity. 107 3a Day and night salinity profiles in sur- face waters along the transect on each cruise. Daily upwelling indices are presented for 14 days prior to the first Oruise, and for the interim periods be- tween subsequent cruises. Positive index values indicate the occurrence of upwelling winds. 109 3b Day and night temperature profiles in surface waters along the transect on each cruise. 110 3c Day and night chlorophyll a concentra- tions in surface waters along the tran- sect on each cruise 111 4 Size frequency of larval and juvenile fishes collected by the Manta net and the neuston trawl throughout the survey. a) sablefish Anoplopoma fimbria; b) greenling Hexagrammos sp.; c) brown Irish lord Hemilepidotus spinsosUs; d) cabezon Scorpaenichthys marmoratus. 112 5 Comparison of Dungeness crab megalopae densities made by pairs of simultaneous nighttime Manta net and trawl net tows made at regular transect stations. 113 6 Daytime and nighttime densities of megalopae collected by the Manta net. Rough weather prevented use of the Manta det during the daytime on 19 May; data from the trawl net for this portion of the cruise are presented. Circled letters in the figure refer to events LIST OF FIGURES (CONTINUED) Figure Page discussed in the text. n = not sampled. 114 7 Relationship between density of daytime catches of megalopae and ambient light levels. Large catches of megalopae were made only under relatively dim light conditions. 116 8 Relationship between density of daytime catches of megalopae and water clarity (Secchi depth). Nega- lopae were found only in relatively turbid water close to the coast in the daytime. 117 9 Diel variation in density of lnega- lopae collected with both types of nets during a 27 hour study on 8-9 June at the 50 km station. 119 lOa Relationship of daily growth in length against size of individual fish fed on mysids (Mb) or Artemia (AlO) at a ration size of 10% bw/day. Each data point indicates mean daily growth over an approximate 7 day period. 121 lOb Relationship of daily growth in weight against length of individual fish fed on Mb or AlO diets.
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