Establishing the optimal salinity for rearing salmon in recirculating aquaculture systems

108 Pages·2016·0.89 MB·English

Establishing the optimal salinity for rearing
salmon in recirculating aquaculture systems

by

Joshua David Emerman

B.S., University of New England, 2010

A THESIS SUBMITTED IN PARTIAL FULFILLMENT OF
THE REQUIREMENTS FOR THE DEGREE OF
MASTER OF SCIENCE

in

THE FACULTY OF GRADUATE AND POSTDOCTORAL STUDIES
(Zoology)

THE UNIVERSITY OF BRITISH COLUMBIA
(Vancouver)

February, 2016

© Joshua David Emerman, 2016
Abstract

Aquaculture of salmon worldwide is a 15.3 billion dollar industry and the majority of fish are
produced in net-pen systems in coastal waters. Recently producers have begun investigating the
feasibility of moving salmon production onto land and into recirculating aquaculture systems
(RAS). The major downsides to RAS are the startup and operational costs; however the ability to
optimize many environmental variables to enhance growth and feed conversion, something
impossible to do in net-pen systems, may help defray these otherwise prohibitive costs. Salinity
may be the most important of these variables due to the metabolic cost of osmoregulation, which
has been estimated to account for 5-50% of routine metabolic rate. Decreased osmoregulatory
costs could result in a greater allocation of energy toward growth, thus shortening production
times and improving feed conversion efficiency. To establish an optimal salinity for growth in
salmon, seven replicate, 15,000 liter RAS were constructed at the University of British
Columbia’s InSEAS research facility. I conducted a preliminary study to validate that each
system was able to control water quality parameters and yield similar levels of growth and feed
conversion in coho salmon (Oncorhynchus kisutch). I then conducted salinity trials with Atlantic
(Salmo salar) and coho salmon. Fish were grown in five salinities ranging from freshwater to
seawater (0, 5, 10, 20, 30 ppt) for approximately five months. Growth rates and feed conversion
ratios (FCR) were measured throughout the trial. The fastest growth rate and lowest FCR in coho
salmon was at 10 ppt, which is approximately isosmotic to the blood. Growth rate of coho at
intermediate salinities was almost double that at 0 or 30 ppt through the first growth period. This
trend was not seen during the second coho growth period, possibly due to a size-dependent or
density effect. Unexpectedly, salinity had no effect on growth rate and FCR in Atlantic salmon,
although growth rates were consistent with those seen in industry. This research will help further
ii
move salmon production out of the oceans and onto land, alleviating some of the environmental
costs associated with salmon grown in the oceans.
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Preface

I conducted all of the research under the supervision of Drs. Jeffrey G. Richards and Colin J.
Brauner. I wrote all 4 chapters of the thesis and received editorial feedback from Drs. Colin J.
Brauner, Jeffrey G. Richards, and Anthony P. Farrell. Treatment and experimental protocols
involving animals were followed according to The University of British Columbia’s Animal
Care Committee, certificate A13-0016.

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Table of Contents

Abstract .......................................................................................................................................... ii
Preface ........................................................................................................................................... iv
Table of Contents ...........................................................................................................................v
List of Tables .............................................................................................................................. viii
List of Figures ............................................................................................................................... ix
List of Abbreviations ................................................................................................................... xi
Acknowledgements ..................................................................................................................... xii
Chapter 1: General Introduction .................................................................................................1
1.1 History of Aquaculture ......................................................................................................... 1
1.2 Aquaculture of Salmon and Environmental Impacts ............................................................ 4
1.3 Recirculating Aquaculture .................................................................................................... 7
1.4 Salinity .................................................................................................................................. 9
1.5 Research Goals.................................................................................................................... 12
Chapter 2: Validation of a novel RAS research facility: InSEAS ...........................................14
2.1 Summary ............................................................................................................................. 14
2.2 Introduction ......................................................................................................................... 15
2.3 Methods............................................................................................................................... 20
2.3.1 Overview ...................................................................................................................... 20
2.3.2 Experimental Design .................................................................................................... 20
2.3.3 Water Parameter Testing & Analysis .......................................................................... 22
2.3.4 Calculations.................................................................................................................. 23
2.3.4.1 Growth Rates ........................................................................................................ 23
2.3.5 Statistical Analysis ....................................................................................................... 24
2.4 Results ................................................................................................................................. 24
2.4.1 Water Parameters ......................................................................................................... 24
2.4.2 Freshwater Growth Trial .............................................................................................. 25
2.4.3 VAKI Biomass Estimator Validation .......................................................................... 29
2.5 Discussion ........................................................................................................................... 30
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2.5.2 Fish Growth ................................................................................................................. 30
2.5.1 Environmental Parameters ........................................................................................... 31
2.5.3 Biomass Estimator ....................................................................................................... 32
2.6 Conclusion .......................................................................................................................... 33
Chapter 3: The effects of salinity on the growth and feed conversion of coho and Atlantic
salmon ...........................................................................................................................................34
3.1 Summary ............................................................................................................................. 34
3.2 Introduction ......................................................................................................................... 35
3.3 Methods............................................................................................................................... 38
3.3.1 Overview ...................................................................................................................... 38
3.3.2 Experimental Design .................................................................................................... 40
3.3.3 Water Testing & Analysis ............................................................................................ 42
3.3.4 Calculations.................................................................................................................. 43
3.3.4.1 Growth Rates ........................................................................................................ 43
3.3.4.2 Condition Factor ................................................................................................... 44
3.3.4.3 Feed Conversion ................................................................................................... 44
3.3.4.4 Muscle Water Content .......................................................................................... 45
3.3.5 Statistical Analysis ....................................................................................................... 45
3.4 Results ................................................................................................................................. 46
3.4.1 Water Parameters ......................................................................................................... 46
3.4.2 Coho Salmon ................................................................................................................ 48
3.4.3 Atlantic Salmon ........................................................................................................... 55
3.5 Discussion ........................................................................................................................... 60
3.5.1 Coho Salmon ................................................................................................................ 60
3.5.2 Atlantic Salmon ........................................................................................................... 65
3.5.3 Water Quality ............................................................................................................... 67
3.6 Conclusion .......................................................................................................................... 68
Chapter 4: General Conclusion ..................................................................................................70
4.1 Summary ............................................................................................................................. 70
4.2 Potential Economic Impact of Results ................................................................................ 71
4.3 Study Strengths and Limitations ......................................................................................... 73
vi
4.4 Future Directions ................................................................................................................ 74
4.6 Issues to Address................................................................................................................. 75
References .....................................................................................................................................77
Appendix .......................................................................................................................................86
Appendix A: Supplementary Figures and Tables ..................................................................... 86

vii
List of Tables

Table 2.1 Acceptable values of unionized ammonia (NH3), nitrite, nitrate and oxygen in
freshwater.. ............................................................................................................................ 23
Table 2.2 Water parameters for five systems throughout the duration of the freshwater validation
growth trial. ........................................................................................................................... 25
Table 3.1 Mean values for all water parameters measured within each treatment system for the
duration of the optimal salinity growth trial (May-October). ............................................... 47
Table A.1 Mean monthly values for all water parameters measured within each salinity treatment
(Chapter 3) for the duration of the experiment. .................................................................... 88

viii
List of Figures

Figure 2.1 Schematic of one InSEAS recirculation aquaculture system, consisting of two 5000 l
tanks and associated mechanical and biological components.. ............................................. 17
Figure 2.2 Overhead schematic of our large experimental room in InSEAS, which houses five of
the independent 15,000 L recirculation aquaculture systems and their respective biofilters
(BF). ...................................................................................................................................... 18
Figure 2.3 Mean body mass of all coho salmon (n = 338-404) measured during freshwater
validation growth trial over the 5-month growth trial........................................................... 26
Figure 2.4 Mean growth rates between all coho (n = 338-404) measured during freshwater
validation growth trial over the 5-month growth trial........................................................... 28
Figure 2.5 Initial and final total biomass and stocking density of each tank of coho salmon
measured during freshwater validation growth trial over the 5-month growth trial. ............ 28
Figure 2.6 Estimated (using the VAKI biomass estimator) and measured final masses of coho
salmon measured during freshwater validation growth trial over the 5-month growth trial. 29
Figure 3.1 Gantt chart outlining the growth periods within each growth trial. Dates fish were
added and removed from trials are denoted by black bars. ................................................... 42
Figure 3.2 Mean body mass of 100 coho salmon (randomly selected from a group of
approximately 400-800 fish per tank) reared at salinities of 0, 5, 10, 20 or 30 ppt and
measured at 3 time points over the 5-month growth trial. .................................................... 49
Fig 3.3 Mean growth rates between subsamples of 100 coho salmon (randomly selected from a
group of approximately 400-800 fish per tank) reared at salinities of 0, 5, 10, 20 or 30 ppt
and measured at 3 time points over the 5-month growth trial. ............................................. 51
Fig 3.4 Mean condition factor of 100 coho salmon (randomly selected from a group of
approximately 400-800 fish per tank) reared at salinities of 0, 5, 10, 20 or 30 ppt and
measured at 3 time points over the 5-month growth trial. .................................................... 52
Fig 3.5 Mean economic feed conversion ratio (eFCR) between subsamples of 100 coho salmon
(randomly selected from a group of approximately 400-800 fish per tank) reared at salinities
of 0, 5, 10, 20 or 30 ppt and measured at 3 time points over the 5-month growth trial. ....... 53
Fig 3.6 Mean muscle water content (MWC) of muscle tissue samples taken from 15 coho salmon
(randomly selected from a group of approximately 400-800 fish per tank) reared at salinities
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of 0, 5, 10, 20 or 30 ppt and measured at the second time point of the 5-month growth trial.
............................................................................................................................................... 54
Fig 3.7 Mean body mass of 100 Atlantic salmon (randomly selected from a group of
approximately 400-550 fish per tank) reared at salinities of 0, 5, 10, 20 or 30 ppt and
measured 96 days after being added to the trial (Time point 1). .......................................... 55
Fig 3.8 Mean growth rate between the average initial stocking mass and 100 Atlantic salmon
(randomly selected from a group of approximately 400-550 fish per tank) reared at salinities
of 0, 5, 10, 20 or 30 ppt and measured 96 days after being added to the trial. ..................... 57
Fig 3.9 Mean condition factor of 100 Atlantic salmon (randomly selected from a group of
approximately 400-550 fish per tank) reared at salinities of 0, 5, 10, 20 or 30 ppt and
measured 96 days after being added to the trial. ................................................................... 58
Fig 3.10 Mean economic feed conversion ratio (eFCR) between the average initial stocking mass
and subsamples of 100 Atlantic salmon (randomly selected from a group of approximately
400-550 fish per tank) reared at salinities of 0, 5, 10, 20 or 30 ppt and measured 96 days
after being added to the trial. ................................................................................................ 59
Fig A.1 Mean body mass of all Atlantic salmon (n=74-119 fish per tank) reared at salinities of 0,
5, 10, 20 or 30 ppt. ................................................................................................................ 89
Fig A.2 Mean growth rate of all Atlantic salmon (n=74-119 fish per tank) reared at salinities of
0, 5, 10, 20 or 30 ppt between time point 1 and time point 2.. ............................................. 90
Fig A.3 Mean condition factor of all Atlantic salmon (n=74-119 fish per tank) reared at salinities
of 0, 5, 10, 20 or 30 ppt. ........................................................................................................ 91
Fig A.4 Economic feed conversion ratio (eFCR) of all Atlantic salmon (n=74-119 fish per tank)
reared at salinities of 0, 5, 10, 20 or 30 ppt between time point 1 and time point 2. ............ 92
Fig A.5 Mean muscle water content (MWC) of muscle tissue samples taken from 15 Atlantic
salmon (randomly selected from a group of 74-119 fish per tank) reared at salinities of 0, 5,
10, 20 or 30 ppt and measured at the second time point of the 59 day growth trial. ............ 93

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