AN ABSTRACT OF THE THESIS OF
Thom H. Gilbert for the degree of Master of Science in Fisheries Science presented on
February 23, 2006.
Title: Prey Swimming Behavior and Culture Techniques for Copper, Sebastes
caurinus, and Quillback Rockfish, S. malinger.
Abstract approved:
Chris Langdon
Rotifers and brine shrimp (Artemia) are important prey items for rearing marine
fish larvae. Their availability in the water column may be reduced when they are
transferred to larval rearing tanks at lower temperature. In this study, Brachionus
rotundiformis (SS-type) and Brachionus plicatilis (L-type) were semi-continuously
cultured and fed on live microalgae (Isochrysis galbana) at 20C. Upon hatching,
Artemia nauplii were fed I. galbana for 24 h at 20C before temperature shock and
handling experiments took place. Temperature shock and handling stress experiments
with prey were conducted to test prey availability for larval culture of Eastern Pacific
rockfish (Sebastes) species. Prey was sampled in 1 mL aliquots in the water column
from 10 L buckets at 10, 14, 18, and 20C after 0, 2, 4, 6, 12, 24, and 48 h suspension
and from four water levels (top, middle, 5 cm above bottom, and bottom). The
concentration of suspended prey (initially 10 prey per ml) was significantly reduced for
all species after temperature transfer occurred and recovery was correlated with
handling and transfer temperature. Rotifers and Artemia should be cultured at similar
or lower temperatures compared with those of larval cultures or subjected to an
acclimation period before being added to larval tanks.
Rockfish culture remains at a preliminary stage due to difficulties in obtaining
larvae and establishing optimal culture conditions. Attempts to obtain larvae from
hook-and-line captured wild rockfish have failed due to high larval mortalities;
however, maintaining mature reproducing rockfish in tanks is an alternative to
obtaining viable larvae. Visibly gravid females were collected monthly from the
Oregon Coast Aquarium in Newport and held in isolation until they naturally released
live larvae. In this study, we evaluated optimal temperature (10, 14, and 18ºC), greenwater techniques, and grow-out in static cultures with Sebastes caurinus and S.
malinger larvae. Survival of Sebastes caurinus larvae at 18 ºC was <15%, while
survival was >40% at 10 and 14 ºC. Nannochloropsis occulata (Nanno) and Isochrysis
galbana, Tahitian strain (T-Iso) were tested in a green-water and enrichment study with
S. malinger larvae. T-Iso was better than Nanno for green-water conditioner and as a
food for rotifers and either newly hatched or enriched Artemia. An average growth rate
of 0.13 mm per day was observed for all three broods from females of different sizes,
2.95, 0.86, and 0.77 kg. Survival and initial size of larvae were greater for larvae from
the largest female. Results from these experiments will be helpful in optimizing
rockfish larval culture conditions for possible restoration of threatened rockfish species
of the Eastern Pacific and for aquaculture.
©Copyright by Thom H. Gilbert
February 23, 2006
All Rights Reserved
Prey Swimming Behavior and Culture Techniques for Copper, Sebastes caurinus, and
Quillback Rockfish, S. malinger
by
Thom H. Gilbert
A THESIS
submitted to
Oregon State University
in partial fulfillment of
the requirement for the
degree of
Master of Science
Presented February 23, 2006
Commencement June 2006
Master of Science thesis of Thom H. Gilbert
presented on February 23, 2006.
APPROVED:
Major Professor, representing Fisheries Science
Head of the Department of Fisheries and Wildlife
Dean of the Graduate School
I understand that my thesis will become part of the permanent collection of Oregon
State university libraries. My signature below authorizes release of my thesis to any
reader upon request.
Thom H. Gilbert, Author
ACKNOWLEDGEMENTS
First and foremost I would like to thank Chris Langdon (Oregon State
University) and Michael Davis (Alaska NMFS) for supporting this research, providing
lab space and reviewing this manuscript as well as, Kevin Clifford (Oregon Coast
Aquarium), for his expertise in helping design and construct broodstock isolation and
larval collection systems and also for his assistance with capturing gravid females. I
would also like to thank Jim Burke, Evonne Mochon-Collura, Aaron Spotswood, and
Tad Smith for helping check for larval releases, enthusiasm, and other various
assistance along the way. I thank Ford Evans and Marileen Reavis (Oregon State
University) for statistical analysis assistance and microalgae culture respectively.
Special thanks to Paula Sylvia (Hubbs Sea World Research Institute), Mike Rust
(Northwest Marine Fisheries Science Center, NMFSC), Mark Tagal, (NMFSC) and
Neil Ashton, (NMFSC) for sharing facilities and providing helpful advice.
CONTRIBUTION OF THE AUTHORS
Special thanks to Chris Langdon for supporting this thesis and manuscripts with
lab space, funding, advice, and editing. Michael Davis for providing lab space, larval
culture advice, and editing the manuscripts. Kevin Clifford (Oregon Coast Aquarium),
for his expertise in helping design and construct broodstock isolation and larval
collection systems and also for his assistance with capturing gravid females. The
completion of this work would not have been accomplished if it had not been for the
help and assistance I received from them. Thank You!
TABLE OF CONTENTS
Page
Chapter 1: General introduction…………………………………........………………....1
Chapter 2: Effects of temperature shock on availability of rotifers Brachionus
plicitilis and Brachionus rotundiformis and Brine Shrimp Artemia metanauplii:
application to rearing larval rockfish, Sebastes species…………….…………………...5
Chapter 3: Larval culture of Quillback, Sebastes malinger and Copper Rockfish,
Sebastes caurinus………………………………………………………………………18
Chapter 4: General Conclusion………………………………………………………..37
Chapter 5: Bibliography………………………………………………………………..39
Chapter 6: Appendices………………………………………………………………...45
LIST OF FIGURES
Figure
1.1
Page
Mean percent swimming SS-rotifers, B rotundiformis after rapid transfer from
20 ºC to 10, 14, 18, or 20 ºC.…………………….………………………………….12
1.2. Mean percent swimming L-rotifers, B. plicitilis after rapid transfer from 20C
to 10, 14, 18, or 20C.……………………………………………………………….13
1.3. Mean percent swimming Artemia after rapid transfer from 20C to 10, 14, 18,
or 20C.……………………………………………………………………………...14
2.1. Diagram of gravid rockfish isolation and larval collection system located at the
Oregon Coast Aquarium……………………………………………………………….29
2.2. Mean percent survival of S. caurinus larvae cultured at different
temperatures.……………….…………………………………………………………..30
2.3. Box plot of S. caurinus larval size measurements cultured at different
temperatures……………………………………………………………………………31
2.4. Box plot of S. caurinus larval standard length cultured at different
temperatures……………………………………………………………………………32
2.5. Mean percent survival of S. malinger larvae cultured for 20 d under different
enrichment and green-water conditions.……………………………………………….33
2.6.
Mean percentages of survival of S. caurinus larvae from three different
sized females.….…………………………………………………….……………...34
2.7.
S. caurinus larvae culture for 30 d from three different size females………...….....35
LIST OF TABLES
Table
Page
1.1. Repeated ANOVA (a) and SNK (b and c) analysis of SS-rotifer densities in
the water column at 0-48 h after temperature shock from 20C to 10, 14, or
18C (n = 5 replicates per treatment). Experiment 1………………………………...15
1.2. Repeated ANOVA (a) and SNK (b and c) analysis of L-rotifers densities in
the water column at 0-48 h after temperature shock from 20C to 10, 14, or
18C (n = 5 replicates per treatment). Experiment 2……………………………….16
1.3.
Repeated ANOVA (a) and SNK (b and c) analysis of densities of Artemia
in the water column 0-48 h after temperature shock from 20ºC to 10, 14, or
18ºC (n = 5 replicates per treatment). Experiment 3………………………………..17
2.1.
Means initial size measurements and growth rates of S. caurinus larvae from
three broods………………………………………………………….……………...36
LIST OF APPENDIX FIGURES
Figure
Page
1.
Percent survival of S. malinger larvae cultured with different rotifer densities
(10 and 50 rotifers per mL) and with or without aeration…………………………45
2.
Percent mortality and percent of larvae initiating feeding on days 1-6 post
hatch………………………………………………………………………………….46
3.
Hatched and unhatched Artemia from different amounts (wet weight) of initial
cysts used during hatching process…………………………………………………..47
DEDICATION
This thesis is dedicated to many people, first, to my son, Jackson Daniel Gilbert,
whose birth into this world provided all the motivation for completing this thesis. I
would also like to dedicate it to my parents who have done so much for me that I can
never pay back and must try to pay forward. I want to dedicate this thesis to Betsy
Gilbert and Ann Mattison, my grandma’s, whose love and support is truly appreciated
and will never be forgotten. Finally to Lisa and other family and friends who believed
in my rehabilitation and my ability to walk again, for you all made it possible,
providing me with strength to push myself.