Success Factors for Fish Larval Production E-Book

• Herausgeber: John Wiley & Sons
• Kategorie: Fachliteratur
• Sprache: Englisch

Seitenzahl: 1265

Veröffentlichungsjahr: 2018

Beschreibung

A comprehensive and authoritative synthesis on the successful production of fish larvae 

Success Factors for Fish Larval Production is a vital resource that includes the most current understanding of larval biology, in the context of larval production. The text covers topics such as how external (environmental and nutritional) and internal (molecular/ developmental/ physiological/ behavioral/ genetic) factors interact in defining the phenotype and quality of fish larvae and juveniles. The expert contributors review broodstock genetics and husbandry, water quality, larval nutrition and feeding, growth physiology, health, metamorphosis, underlying molecular mechanisms, including epigenetics, for development, larval behavior and environmental conditions. Compiled by members of a European Union-funded consortium of top researchers, Success Factors for Fish Larval Production provides a wide-range of authoritative information for the aquaculture industry and academia.

In addition to a wealth of information, the authors review research and commercially applicable larval quality indicators and predictors. The successful production of good-quality fish larvae is of vital importance for fish farming and stock enhancement of wild fisheries: 

• Includes contributions from a consortium of noted researchers and experts in the field
• Deals with on how to improve egg quality and larval production via broodstock management and nutrition
• Suggests ways to control the phenotype of juveniles and table-size fish via manipulations of the conditions of larval rearing (e.g., epigenetics)
• Includes ideas for optimizing diet composition, formulation, and technology
• Integrates knowledge and practical experience in order to help advancing excellence in aquaculture 

Success Factors for Fish Larval Production offers fish biologists, developmental biologists, physiologists and zoologists the most current and reliable information on the topic. All those working in fish aquaculture facilities and hatcheries in particular will find great interest to their commercial operations within this book. 

Leseprobe

Table of Contents

Cover

Title Page

Copyright

List of Contributors

Acknowledgements

Chapter 1: Introduction

Reference

Chapter 2: Gamete Quality and Broodstock Management in Temperate Fish

Executive Summary

Introduction

Egg and Sperm Quality and Assessment

Germ Cell Preservation

Broodstock Nutrition

Applications of Genetics and Genomics to Broodstock Management

Broodstock Environmental and Hormonal Manipulations

Overall Conclusions

References

Chapter 3: Feeding Behaviour and Digestive Physiology in Larval Fish: Current Knowledge, and Gaps and Bottlenecks in Research

Executive Summary

Introduction

Feeding Behaviour and Appetite

Detection

Capture and Ingestion

Feeding Rhythms

Neuroendocrine Control of Appetite and Ingestion

Adaptation of Feeding Protocols to the Feeding Behaviour

Digestive Physiology

Digestion: An Overview

Digestion of Proteins and Peptides

Absorption

Lipids

Digestion of Carbohydrates

Regulatory Systems of Digestion

Future Research Strategies for Studies in Feeding Behaviour and Digestive Physiology to Advance Larval Rearing of Marine Fish

References

Chapter 4: Fish Larval Nutrition and Feed Formulation: Knowledge Gaps and Bottlenecks for Advances in Larval Rearing

Executive Summary

Introduction

Larval Nutrition

Feed Formulation

Gaps and Bottlenecks in Obtaining Knowledge on Nutritional Requirements of Marine Fish Larvae

References

Chapter 5: What Determines Growth Potential and Juvenile Quality of Farmed Fish Species?

Executive Summary

Introduction

Development of Skeletal Muscle

Control of Muscle Mass

Genetics of Muscle Growth

Environmental Factors and Growth

Available Methodology to Assess Growth and Quality

Concluding Remarks

Acknowledgements

References

Chapter 6: Skeletal Anomalies in Reared European Fish Larvae and Juveniles. Part 1: Normal and Anomalous Skeletogenic Processes

Executive Summary

Introduction

Plasticity, Ontogenesis, Remodelling and Resorption of Skeletal Elements in Teleost Fish

Teleost Skeletal Tissues

The Notochord

Regulatory Mechanisms of Skeletal Tissues in Fish

Bone Formation and the Replacement of the Cartilaginous Anlage

Modulation and Transformation

Late Events in Teleost Skeletal Tissue Modelling and Remodelling

Bone Resorption and Remodelling

Main Gaps in Scientific Knowledge and Further Research Needs

References

Chapter 7: Skeletal Anomalies in Reared European Fish Larvae and Juveniles. Part 2: Main Typologies, Occurrences and Causative Factors

Executive Summary

Introduction

Early Developmental Anomalies

Vertebral Column Anomalies

Vertebrae Anomalies

Anomalies of the Fins

Skull Anomalies

Effects of Skeletal Anomalies on Fish Biological Performance

Causative Factors of Skeletal Anomalies in Reared Fish

Sorting Methods

Elements of Solutions

Main Gaps in Scientific Knowledge and Further Research Needs

References

Chapter 8: Microbiology and Immunology of Fish Larvae

Executive Summary

Introduction

The Microbial Environment of Fish Larvae

Methodological Aspects of Microbial Community Characterization

Pathogens and Challenge Models

Immunology of Fish Larvae

Steering Larval Microbial Communities to the Benefit of the Host

References

Chapter 9: Fantastically Plastic: Fish Larvae Equipped for a New World

Executive Summary

Introduction

Mediating Environment – Structural Basis of Plasticity

Functional Plasticity – Interactions Between the Internal and External Environment Which Define the Phenotype

Consequences of External Factors

Conclusions

References

Chapter 10: Quality Descriptors and Predictors in Farmed Marine Fish Larvae and Juveniles

Executive Summary

Introduction

Morphology and Malformations

Biochemical and Molecular Biomarkers of Bone Formation and Remodelling

Nutritional Condition

Growth Potential

Immunology and Microbiology

Sperm and Oocyte Quality as Predictor of Fertilizing Capacity

Conclusions and Perspectives

References

Chapter 11: Conclusions

Broodstock and Egg Quality

Microbiology, Immunology and Larval Health

Feeding Biology and Digestive Function

Nutritional Requirements

Growth Potential and Dispersion

Skeletal Deformities and Other Abnormalities

Quality Indicators and Predictors

Index

End User License Agreement

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Guide

Cover

Table of Contents

Begin Reading

List of Illustrations

Chapter 2: Gamete Quality and Broodstock Management in Temperate Fish

Figure 2.1 Main factors that can influence gamete quality in fish and main parameters that can be recorded to fully characterize gamete quality.

Figure 2.2 Schematic representation of regulatory pathways in the BPG axis during puberty in teleosts (adapted from Migaud

et al.

2010; Taranger

et al.

2010).

Chapter 3: Feeding Behaviour and Digestive Physiology in Larval Fish: Current Knowledge, and Gaps and Bottlenecks in Research

Figure 3.1 Three-dimensional model of the digestive tract with associated organs in Atlantic cod, an altricial fish that does not possess a stomach at first feeding. 4 dph, first feeding larvae; 53 dph, later stages of metamorphosis (modified from Kamisaka & Rønnestad 2011, with permission of Springer).

Figure 3.2 Age of detection of first gastric glands in various species of interest in aquaculture. Inserts show two examples of first developing gastric glands (

arrows

). (1) Zaiss

et al.

2006; (2) Gisbert

et al.

1999; (3) Cousin & Baudin-Laurencin 1985; (4) Faulk

et al.

2007; (5) Önal

et al.

2008; (6) Chen

et al.

2006; (7) Kaji

et al.

1999; (8) Ortiz-Delgado

et al.

2003; (9) Tanaka 1971; (10) Douglas

et al.

1999; (11) Mai

et al.

2005; (12) Santamaría

et al.

2004; (13) Kato

et al.

2004; (14) Darias

et al.

2005; (15) Ribeiro

et al.

1999; (16) Micale

et al.

2006; (17) Micale

et al.

2008; (18) Bisbal & Bengtson 1995; (19) Hamlin

et al.

2000; (20) Kamisaka & Rønnestad 2011; (21) García-Hernández

et al.

2001; (22) Elbal

et al.

2004; (23) Luizi

et al.

1999.

Figure 3.3 The digestive tract is a multifunctional organ. Digestion includes a range of closely orchestrated processes that are integrated in ways that is believed to optimize efficiency and maximize absorption in feeding larvae under natural conditions. See text for more information.

Figure 3.4 Increase in tryptic activity with increasing larval size. Comparison of six species reared under laboratory conditions. The regression line was calculated within the given lifespan in days after hatching. Age-dependent variability of tryptic activity was not considered here (redrawn from Ueberschär 2006).

Figure 3.5 Significance of tryptic activity compared with total alkaline proteolytic activity in 1–52-day-old laboratory-reared herring (

Clupea harengus

) and 1–36-day-old turbot (

Psetta maxima

) larvae (F, fed larvae; S, starving larvae). Mean values with error bars (± SD) of two time intervals are shown (adapted from Ueberschär 1993). () Trypsin; () Other proteases.

Figure 3.6 Development of tryptic activity in experiments on larvae from common pandora (

Pagellus erythrinus

). Newly hatched larvae were fed rotifers from day 3. Tryptic activity was measured in individual larvae and shown with standard deviations. () Group A; () Group B; () Group C (reused from Suzer

et al.

2006, with permission of Elsevier).

Figure 3.7 Development of pepsin activity in experiments using larvae from common pandora (

Pagellus erythrinus

). Pepsin was detected on day 25 in connection with stomach formation and a sharp increase until 30 dph. () Group A; () Group B; () Group C (reused from Suzer

et al.

2006, with permission of Elsevier).

Figure 3.8 Expression pattern of PepT1 mRNA in the digestive tract of Atlantic cod larvae fed natural zooplankton at 4 dph. Arrowheads point to sphincter regions with no PepT1 expression. Oes, oesophagus; Li, liver; MG, midgut; HG, hindgut (modified from Amberg

et al.

2008, with permission of Elsevier).

Figure 3.9 Diurnal pattern of tryptic enzyme activity in relation to food and feeding time in laboratory-reared and continuously fed 12-day-old (dph) turbot larvae (

Psetta maxima

). Arrows indicate when food was supplied (

Brachionus plicatilis

, 5 ind ml

−1

). Data points with positive error bars (SD) are means of 10–15 individually measured larvae. Bars indicate mean larval length () Mean larval length; () Tryptic activity; () Food administration.

Figure 3.10 Lipid digestion in fish larvae. (1) Lipids form micelles with the emulsifying effect of bile acids and PLs. (2) BAL hydrolyses TAG and (3) hydrolysed products are absorbed in the enterocytes. (4) TAG is synthesized. (5) PLs are hydrolysed by PLA

2

and (6) products are absorbed. (7) Lyso-PL is remodelled to PL. (8) Intact PL is absorbed by enterocytes.

Figure 3.11 Effect of ingesting live prey and inert spheres on trypsinogen (inactive enzyme stored in pancreas) and trypsin (active enzyme present in midgut) in Atlantic herring. The insert shows that pancreas (Pa) can easily be separated from the midgut (MG) in herring larvae by a section just prior to the anterior part of the midgut as indicated by the line. This location is clearly visible in live specimens due to the transparency that makes this larva a good model for such studies. (•) Basal content; (○) Polystyrene; (▪)

Acartia

nauplii; (▴)

Acartia

copepodites (adapted from Hjelmeland

et al.

1988. Reproduced with permission from Springer Science and Business Media, drawing by I. Rønnestad).

Figure 3.12 Natural variability in tryptic activity and CCK level (CCK-8s) in young cod larvae. The graph depicts the antagonistic behaviour of trypsin and CCK concentration, indicating the existence of a feedback mechanism. () Tryptic activity; () CCK.

Chapter 4: Fish Larval Nutrition and Feed Formulation: Knowledge Gaps and Bottlenecks for Advances in Larval Rearing

Figure 4.1 Final weight of (a) Atlantic cod (weight range of 5.2–7.3 g) and (b) Atlantic halibut juveniles (weight range of 4.5–8.5 g) grown for 2 months, from 0.26 and 0.5 g, respectively, on diets differing in macronutrient composition. The triangle represents all possible combinations of the three nutrients, while the red dots give the composition of the different diets (reproduced from Hamre

et al

. 2013, with permission of John Wiley & Sons). (

See color plate section for color representation of this figure

).

Chapter 5: What Determines Growth Potential and Juvenile Quality of Farmed Fish Species?

Figure 5.1 A model of muscle growth in teleost fish. The model assumes a rare stem cell population that can undergo an asymmetric division to produce a daughter cell that becomes committed to the myogenic lineage under the influence of myogenic regulatory factors (myoD, Myf, MRF4). These cells then undergo several rounds of proliferation to produce much more numerous myogenic progenitor cells (MPCs). Myogenin (MyoG), MRF4 and myostatin are part of a complex genetic network regulating the exit of MPCs from the cell cycle and the initiation of terminal differentiation involving the fusion of MPCs to form myotubes, myofibrillogenesis and sarcomere assembly. Inputs to these pathways (light, temperature, nutrition) determine the balance between proliferation and terminal differentiation and hence the production of MPCs required for growth. Other growth signalling pathways, including IGF-mTor, control protein synthesis and degradation determining the rate of fibre hypertrophy and elongation. As fibres increase in diameter and length, additional MPCs are absorbed to maintain the nuclear to cytoplasmic ratio within certain limits.

Figure 5.2 Slow and fast muscles segregate from the onset of myogenesis in the zebrafish embryo. Slow muscles are derived from the adaxial cells (

in red

). In the epithelial somite, anterior cells (

green domain

) express first Pax3 then Pax7, whereas posterior cells (

blue domain

) already express MyoD and will contribute to the medial fast fibres. During development, the somite undergoes a rearrangement and at 24 hours post fertilization, the Pax3/7 positive cells are now in a dermomyotome-like position. Adaxial cells differentiate into slow pioneer fibres that form the myoseptum and slow fibres that migrate laterally across the medial fast fibres to form the most superficial layer of the myotome, the superficial slow fibres. After formation of the embryonic myotome, Pax7 positive cells colonize the myotome in order to form a second major wave of fast fibres (lateral fast fibres;

dark blue region

) and resident progenitor cells within the muscle (adapted from Buckingham & Vincent 2009, with permission of Elsevier). (

See color plate section for color representation of this figure

).

Figure 5.3 Sarcomeric proteins genes represented in the fast muscle transcriptome of the sea bream

Sparus aurata

(reproduced from Garcia de la Serrana

et al.

2012, with permission of BioMed Central).

Chapter 6: Skeletal Anomalies in Reared European Fish Larvae and Juveniles. Part 1: Normal and Anomalous Skeletogenic Processes

Figure 6.1 Diagram showing the main factors that may impact skeletal cells, cartilage or bone matrix development and bone mineralization in reared fish larvae and juveniles (modified after Waagbø 2006). Arrows do not indicate any particular body region. Bar = 1 mm.

Figure 6.2 Relationships between phylogeny, environment, the presence of osteocytes, and the predominant (predom.) type of osteoclasts (osteocl.) in teleost fish. (II–V) Basal Osteichthyans (I), which also gave rise to tetrapods, and Basal Teleosts (II) have bone that contains osteocytes. These fish have mononucleated and many multinucleated osteoclasts. Osteocytes and multinucleated osteoclasts have been preserved during ‘a first’ wave of freshwater reinvasion by teleost fish (III); ‘primary freshwater fish’: it refers to fish such as cyprinids and salmonids. During a long evolutionary period in the marine environment, osteocytes disappeared (acellular bone) in almost all advanced marine teleosts groups (IV). The predominant osteoclast type of ‘Advanced Teleosts’ is mononucleated. This character was maintained when advanced teleosts reinvaded the fresh waters (V); ‘secondary freshwater fish’: e.g. chichlids. Consequently, teleosts that live in fresh water (c.f. III and V) or in the marine environment (c.f. II and IV) can have different bone types and different predominant types of bone resorbing cells (modified after Witten & Huysseune 2009, with permission of John Wiley & Sons).

Figure 6.3 Possible fate of cartilage templates in vertebrates. For each step, some features (expressed molecules, staining) are indicated. It should be emphasized that spongiosa (spongy or trabecular bone) is rather uncommon in fish; larvae essentially do not have spongiosa and no endochondral bone formation, but perichondral bone formation. Coll, collagen; ECM, extracellular matrix; OSN, osteonectin.

Figure 6.4 Perichondral ossification in dorsal pterygiophores of Senegalese sole (

Solea senegalensis

) (

left

: Toluidine blue;

right

: von Kossa's). Photograph by P. Gavaia. (

See color plate section for color representation of this figure

).

Chapter 7: Skeletal Anomalies in Reared European Fish Larvae and Juveniles. Part 2: Main Typologies, Occurrences and Causative Factors

Figure 7.1 Some of the whole-mounting methodologies more commonly used to check for skeletal anomalies in fish larvae and juveniles. (a)

In vivo

fluorescent calcium-binding dye (calcein): fluorescence analysis of calcein bound to calcium phosphate (hydroxyapatite) allows direct quantification of extracellular matrix mineral content. Strength: yellow-green fluorescence upon binding to calcium; live staining; highly sensitive; stained live larvae can be followed for several days, until squamation occurs; <2 h for observation; total bound calcein could be quantified by direct fluorescence analysis. Weakness: it only permits the identification of calcified structures; larger fish or those with scales do not allow clear visualization of internal structures (photograph by P. Gavaia). (b) Whole-mount specific staining for bone (Alizarin red) and cartilage (Alcian blue). Strength: it dyes both bone and cartilage; it allows easy observation of each skeletal element since hatching (higher resolution than X-rays). Weakness: no information is achievable on the different bone types and it is not entirely specific: Alizarin red is not a specific dye for hydroxyapatite, the main mineral phase of bone (Zerekh 1993) and its staining of areas of calcium salt deposition (Humason 1962; Pearse 1985) may indicate the deposition of calcium salts in non-ossifying embryonic connective tissue (Faustino & Power 1998). Alcian blue dye is more aspecific: it stains acid mucopolysaccharides and glycosaminoglycans, which are also present in tissues other than cartilage. Furthermore, its entails the use of acetic acid, which can demineralize lightly ossified elements that lose Alizarin red affinity (photograph by S. Fontagné). (c) Radiographic analysis. Strength: it can be used in live fish. Weakness: low resolution for larval stages as it can only be performed at stages when enough calcified tissue is present; it permits observation only on one side of the body (no evaluation of asymmetry); low resolution of pectoral and pelvic fins and of rays (photograph by Boglione/University TV). (

See color plate section for color representation of this figure

).

Figure 7.2 Examples of some skeletal anomalies detected in reared European larvae and juveniles. (a) Atlantic bluefin tuna (

Thunnus thynnus

) juvenile (SL: 27 mm) showing a severe prehaemal kyphosis (

arrow

) (photograph by Marroncini/University TV). (b) White seabream (

Diplodus sargus

) juveniles (SL: 77 and 82 mm). The fish at the top has a normal skeleton, the other shows a severe lordosis spanning posterior prehaemal and anterior haemal vertebrae (

arrow

) (photograph by P. Gavaia). (c) White seabream (

Diplodus sargus

) juvenile (SL: 73 mm) showing a saddle-back located between the anterior and posterior portions of the dorsal fin (photograph by P. Gavaia). (d) Senegalese sole (

Solea senegalensis

) juveniles (90 dph) with ectopical formation of a fin connecting anal and dorsal fins (

arrowhead

), and neural and haemal arches anomalies (

arrows

) (photograph by P. Gavaia). (e) Senegalese sole (

Solea senegalensis

) juveniles (90 dph) with severe kypho-lordo-kyphosis in haemal and caudal vertebrae. Note rays and neural and haemal arches anomalies (photograph by P. Gavaia). (f) Meagre (

Argyrosomus regius

) larva (35 dph) with partly fused and deformed vertebral bodies and arches (

arrow

) (photograph by P. Gavaia). (g) European seabass (

Dicentrarchus labrax

) postlarva (50 dph) with a supernumerary ectopic pelvic fin (photograph by Boglione/University TV). (h) European seabass (

Dicentrarchus labrax

) juveniles showing different cephalic, caudal fin and axis anomalies. The fish on the bottom is normal (photograph by E. Gisbert). (i) Thicklip grey mullet (

Chelon labrosus

) early juvenile (SL 8.4 mm) showing different vertebrae and axis anomalies (photograph by Boglione/University TV). (j) Gilthead seabream (

Sparus aurata

) with anomalous opercular plates, at market (photograph by Boglione/University TV). (k) Dusky grouper (

Epinephelus marginatus

) larva (50 dph) with deformed body, neural and haemal arches of caudal vertebra. Note the ossification defects in the hypuralia and last haemal spine (

arrows

) (photograph by Boglione/University TV). (l) Rainbow trout (

Oncorhynchus mykiss

) fry (20 days after first feeding) with fused and deformed haemal vertebral bodies and fused spines of caudal vertebra (photograph by S. Fontagné). (m) European seabass (

Dicentrarchus labrax

) juveniles (85 dph) with haemal lordosis (

top

); with haemal lordosis and caudal kyphosis (

centre

); with fused prehaemal and haemal vertebrae (

bottom

) (photograph by G. Koumoundouros). (n) European seabass (

Dicentrarchus labrax

) juvenile (80 dph) with fusions and lordosis of anteriormost prehaemal vertebrae (

top

); without spines of the dorsal fin (

bottom

) (photograph by G. Koumoundouros). (o) Gilthead seabream (

Sparus aurata

) juvenile (75 dph) with haemal lordosis (

top

) and with prehaemal lordosis and non-inflated swim bladder (

bottom

) (photograph by G. Koumoundouros). (

See color plate section for color representation of this figure

).

Figure 7.3 Occurrences of skeletal anomalies in 28 gilthead seabream lots of juveniles reared in a commercial hatchery. All batches were reared under the same methodology and the same raw materials (G. Koumoundouros, unpubl. data).

Figure 7.4 Trend of frequencies of severe skeletal anomalies in a commercial hatchery, before (

dark bars

) and after (

grey bars

) the application of LoQ strategy. Data do not include the incidence of fish without an inflated swim bladder (the rate was improved from 12% in year 3 to 2–4% in years 4–8) (G. Koumoundouros, unpubl. data).

Chapter 8: Microbiology and Immunology of Fish Larvae

Figure 8.1 Important microbial sources interacting with mucosal surfaces of larval fish. Various external sources of microbes (

blue/grey arrows

), such as water, live feed and microalgae, enter the rearing environment and interact with the fish (

red/black arrows

). Internally, the rearing environment is enriched by microbes due to defaecation by fish or live feed, or indirectly through growth based on organic matter released by defaecation by animals or exudation by microalgae (after Vadstein

et al.

2004, reproduced with permission of John Wiley & Sons). (

See color plate section for color representation of this figure

).

Figure 8.2 Simplified scheme of fish innate immune TLRs signalling pathways. Fish detects microbial invaders through highly specific pattern recognition receptors, called TLRs. Fish TLRs according to their transmembrane or endosomal location recruit the adaptor protein MyD88 or TICAM, respectively, to activate the master regulator NF-κB leading to the transcription of several potent inflammatory mediators. TLR, Toll-like receptor; MyD88, myeloid differentiation primary response gene; TICAM, Toll-like receptor adaptor molecule.

Figure 8.3 Degranulation of mast cells in response to pathogens. Upon activation by pathogens, mast cells migrate to specific tissues to undergo degranulation of preformed or newly synthesized products showing specific time patterns and increasing target specificity, which ultimately lead to mast cell survival and proliferation.

Figure 8.4 TCRβ

in situ

hybridization of developing thymus aged 75 days post hatch. (a) TCRβ

+

cells were clearly concentrated in cortical region. Bar = 20 µm. (b) Negative control of ISH with a sense RNA probe. Bar = 20 µm. GC, gill chamber; C, cortex; M, medulla.

Chapter 9: Fantastically Plastic: Fish Larvae Equipped for a New World

Figure 9.1 Schematic showing the sources of plasticity acting on empirical results in larval teleost research. Evolution represents the effects of the third round of whole-genome duplication (fish-specific genome duplication), epigenetics represents the continual influences of environment and diet on the expression of genes including those acting on the primordial germ cells of the parent fish, life stage includes especially metamorphosis when thyroid-driven up- and down-regulation of genes allow the transition from larval to adult form and finally the experimental conditions under which the larvae have been reared.

Figure 9.2 The morphology and pituitary development of Atlantic halibut from a few days after hatching until post-settlement, in daydegrees (D° = days post hatch × average temperature in Celsius). The appearance of the pituitary as a distinct organ coincides with the first traces of cells producing GH, PRL and SL and thyroid follicles. The first detection of TSH-producing cells coincides with first feeding (Stage 5). By metamorphosis (Stage 8), there are numerous thyroid follicles and increased thyroid activity which continues to peak hormone levels leading to the juvenile phenotype. GH, growth hormone; PRL, prolactin; SL, somatolactin; NH, neurohypophysis; AH, adenohypophysis. () NH; () AH; (→) anterior; (←) posterior (redrawn from Einarsdóttir

et al.

2006, with permission from Springer Science and Business Media).

Figure 9.3 Development and functioning of the HPI axis in zebrafish (redrawn from Alsop & Vijayan 2009, with permission from Elsevier).

Figure 9.4 Proposed action of melanin-concentrating hormone (MCH) and α-melanophore-stimulating hormone (αMSH) signalling to induce colour changes in fish. The antagonistic action of the hormones moves the melanosomes, where MCH stimulates aggregation and αMSH stimulates dispersion via receptors on the cell membrane, activation of the Gi or Gs protein and their action on cAMP levels (redrawn from Kawauchi 2006, with permission from John Wiley & Sons).

Figure 9.5 Phenotypic differences in size and pigmentation in 53 dph postlarvae of Atlantic halibut between early-weaned and control fish at the end of the trial. (a) Trial group weaned at 32 days post-first feeding; (b) trial group weaned at 43 days post-first feeding; (c) control fish fed on live prey (from Murray

et al.

2010, with permission from Springer Science and Business Media).

Chapter 10: Quality Descriptors and Predictors in Farmed Marine Fish Larvae and Juveniles

Figure 10.1 Critical factors for quality descriptors and predictors for fish larvae and juveniles.

Figure 10.2 The main developmental stages and the related immune capacities (

green

,

blue

,

purple

), effective proven immune regulators to fight against different stressors (

brown

), and some simple evaluation quality indices (

black

) are shown in a typical fish lifecycle.

(See color plate section for color representation of this figure).

List of Tables

Chapter 2: Gamete Quality and Broodstock Management in Temperate Fish

Table 2.1 Application of sperm analysis in most common commercial species

Table 2.2 Fatty acid compositions (% weight) of farmed and wild Scottish salmon and farmed Chilean salmon

Table 2.3 Present status of breeding programmes in some European species. Some of this information is derived from an AQUAbreeding Survey on the breeding practices in the European aquaculture industry (up to 2009) and the various species reviews available at www.aquabreeding.eu.

Table 2.4 Spawning characteristics for a range of commercially important temperate fish species

Table 2.5 Time after ovulation when oocytes maintain the highest quality; after this point, the ageing process referred to as over-ripening will occur

Chapter 3: Feeding Behaviour and Digestive Physiology in Larval Fish: Current Knowledge, and Gaps and Bottlenecks in Research

Table 3.1 Ranking of lipase activity from the most active part of the GI tract (1) to the least active (4)

Chapter 4: Fish Larval Nutrition and Feed Formulation: Knowledge Gaps and Bottlenecks for Advances in Larval Rearing

Table 4.1 Basic levels of macronutrients, vitamins and minerals in unenriched rotifers, Artemia nauplii (EG-type, Great Salt Lake UT, USA, INVE Aquaculture), ongrown Artemia and zooplankton, mainly copepods, harvested from a fertilized seawater pond in western Norway (Svartatjønn). The ranges of requirements in juvenile and adult fish given by NRC (2011) are listed for comparison.

Table 4.2 Composition of total amino acids (% of protein) in rotifers,

Artemia

(EG-type, Great Salt Lake UT, USA, INVE Aquaculture) and copepods harvested from a fertilized seawater pond in western Norway (Svartatjønn)

Table 4.3 Composition of free amino acids and metabolits (% of total free amino acids) in rotifers,

Artemia

(EG-type, Great Salt Lake UT, USA, INVE Aquaculture) and copepods harvested from a fertilized seawater pond in western Norway (Svartatjønn)

Table 4.4 Fatty acid profiles of unenriched rotifers grown on yeast and cod liver oil (CLO) or yeast and EPAX 2010 (a synthetic oil from Pronova, Norway, with 50% DHA and 10% EPA of total fatty acids), unenriched

Artemia

(EG-type, Great Salt Lake UT, USA, INVE Aquaculture) and copepods harvested from a fertilized seawater pond in western Norway (Svartatjønn)

Chapter 5: What Determines Growth Potential and Juvenile Quality of Farmed Fish Species?

Table 5.1 Onset of hyperplasia stages in different marine species

Table 5.2 Summary of polymorphism identified in candidate growth genes of European marine fish species

Table 5.3 Examples of available microarrays for commercially important fish species

Chapter 6: Skeletal Anomalies in Reared European Fish Larvae and Juveniles. Part 1: Normal and Anomalous Skeletogenic Processes

Table 6.1 Main type of cartilage tissues in fish, reviewed by Witten et al. 2010. Data from Benjamin 1988a,b, 1990; Benjamin & Ralphs 1991; Beresford 1993; Huysseune 1990; Huysseune and Verras 1986; Huysseune & Sire 1992; Witten & Hall 2002.

Chapter 10: Quality Descriptors and Predictors in Farmed Marine Fish Larvae and Juveniles

Table 10.1 Quality descriptors and predictors for fish larvae related to morphology traits

Table 10.2 Quality descriptors and predictors for fish larvae related to bone metabolism.

Table 10.3 Quality descriptors and predictors for fish larvae related to nutritional condition and growth potential

Table 10.4 Quality descriptors and predictors for fish larvae related to immune status

Table 10.5 Quality descriptors and predictors for fish larvae related to gamete quality

This publication is based on the work of COST Action FA0801, supported by COST (European Cooperation in Science and Technology).

COST (European Cooperation in Science and Technology) is a funding agency for research and innovation networks. Our Actions help connect research initiatives across Europe and enable scientists to grow their ideas by sharing them with their peers. This boosts their research, career and innovation. www.cost.eu

Success Factors for Fish Larval Production

Edited by

Luís E. C. Conceição

SPAROS Lda, Olhão, Portugal

and

Amos Tandler

Israel Oceanographic and Limnological Research National Center for Mariculture, Eilat, Israel

This edition first published 2018

© 2018 John Wiley & Sons Ltd

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Library of Congress Cataloging-in-Publication Data

Names: Conceição, Luís E. C., editor. | Tandler, Amos, editor.

Title: Success factors for fish larval production / edited by Luis Conceição and Amos Tandler.

Description: Hoboken, NJ : John Wiley & Sons, 2017. | Includes index. |

Identifiers: LCCN 2017016675 (print) | LCCN 2017035564 (ebook) | ISBN 9781119072140 (pdf) | ISBN 9781119072133 (epub) | ISBN 9781119072164 (cloth)

Subjects: LCSH: Fishes-Larvae.

Classification: LCC QL639.25 (ebook) | LCC QL639.25 .S83 2017 (print) | DDC 333.95/6-dc23

LC record available at https://lccn.loc.gov/2017016675

Cover Design: Wiley

Cover Image: Courtesy of Nurit Gordon, Israel

List of Contributors

Gordon Bell

Institute of Aquaculture, University of Stirling, Stirling, Scotland

Øivind Bergh

Institute of Marine Research, Bergen, Norway

Julien Bobe

INRA, UR1037 Fish Physiology and Genomics, Rennes, France

Clara Boglione

Laboratory of Experimental Ecology and Aquaculture, Department of Biology, University of Rome Tor Vergata, Rome, Italy

Nico Boon

Laboratory of Microbial Ecology and Technology (LabMET), Ghent University, Ghent, Belgium

Peter Bossier

Laboratory of Aquaculture &

Artemia

Reference Center, Ghent University, Ghent, Belgium

Elsa Cabrita

CCMAR, Centre of Marine Sciences, University of the Algarve, Campus de Gambelas, Faro, Portugal

Manuel Carrillo

Institute of Aquaculture of Torre de la Sal, Castellon, Spain

Luís E. C. Conceição

SPAROS Lda, Olhão, Portugal

Andrew Davie

Institute of Aquaculture, University of Stirling, Stirling, Scotland

Tom Defoirdt

Laboratory of Aquaculture & Artemia Reference Center, Ghent University, Ghent, Belgium

and

Laboratory of Microbial Ecology and Technology (LabMET), Ghent University, Ghent, Belgium

Peter de Schryver

Laboratory of Aquaculture & Artemia Reference Center, Ghent University, Ghent, Belgium

and

Laboratory of Microbial Ecology and Technology (LabMET), Ghent University, Ghent, Belgium

Kristof Dierckens

Laboratory of Aquaculture &

Artemia

Reference Center, Ghent University, Ghent, Belgium

Sofia Engrola

CCMAR, Centre of Marine Sciences, University of the Algarve, Campus de Gambelas, Faro, Portugal

Jorge M.O. Fernandes

Faculty of Biosciences and Aquaculture, University of Nordland, Bodø, Norway

Ignacio Fernandez

CCMAR, Centre of Marine Sciences, University of the Algarve, Campus de Gambelas, Faro, Portugal

Stéphanie Fontagné

INRA, Saint Pée-sur-Nivelle, France

Jorge Galindo-Villegas

Department of Cell Biology and Histology, University of Murcia, Murcia, Spain

François-Joel Gatesoupe

INRA, UR 1067, Nutrition, Metabolism, Aquaculture, Ifremer, Centre de Brest, Brest, France

Paulo Gavaia

University of Algarve, CCMAR, Faro, Portugal

Audrey J. Geffen

Department of Biology, University of Bergen, Bergen, Norway

Enric Gisbert

IRTA-SCR, Crta, Sant Carles de la Rapita, Spain

Kristin Hamre

National Institute of Nutrition and Seafood Research (NIFES), Bergen, Norway

Maria Paz Herráez

Department of Molecular Biology, Faculty of Biology, University of Leon, Leon, Spain

Marisol Izquierdo

Grupo de Investigación en Acuicultura, ULPGC & ICCM, Telde, Canary Islands, Spain

Ian A. Johnston

Scottish Oceans Institute, University of St Andrews, St Andrews, UK

George Koumoundouros

Biology Department, University of Crete, Heraklio, Crete, Greece

William Koven

Israel Oceanographic and Limnological Research, National Center for Mariculture, Eilat, Israel

Pavlos Makridis

Institute of Aquaculture, Hellenic Center for Marine Research, Heraklio, Crete, Greece

Brendan McAndrew

Institute of Aquaculture, University of Stirling, Stirling, Scotland

Herve Migaud

Institute of Aquaculture, University of Stirling, Stirling, Scotland

Mari Moren

NIFES, Bergen, Norway

Katerina A. Moutou

Department of Biochemistry and Biotechnology, University of Thessaly, Larissa, Greece

Victoriano Mulero

Department of Cell Biology and Histology, University of Murcia, Murcia, Spain

Yngvar Olsen

Department of Biotechnology, Norwegian University of Science and Technology, Trondheim, Norway

Michail Pavlidis

Department of Biology, University of Crete, Heraklion, Greece

Simona Picchietti

Department of Science for Innovative Biology, Agroindustry, and Forestry, University of Tuscia, Viterbo, Italy

Karin Pittman

Department of Biology, University of Bergen, Bergen, Norway

Laura Ribeiro

Aquaculture Research Center of Portuguese Institute of Sea and Atmosphere, Olhão, Portugal

Ivar Rønnestad

Department of Biology, University of Bergen, Bergen, Norway

Øystein Sæle

National Institute of Nutrition and Seafood Research (NIFES), Bergen, Norway

Giuseppe Scapigliati

Department of Science for Innovative Biology, Agroindustry, and Forestry, University of Tuscia, Viterbo, Italy

Amos Tandler

Israel Oceanographic and Limnological Research, National Center for Mariculture, Eilat, Israel

Bernd Ueberschär

Helmholtz Centre for Ocean Research Kiel – GEOMAR, Kiel, Germany

Olav Vadstein

Department of Biotechnology, Norwegian University of Science and Technology, Trondheim, Norway

Luísa M.P. Valente

CIMAR/CIIMAR LA – Interdisciplinary Centre of Marine and Environmental Research and ICBAS – Institute of Biomedical Sciences Abel Salazar, University of Porto, Porto, Portugal

Paul Eckhard Witten

Department of Biology, Ghent University, Ghent, Belgium

Manuel Yúfera

Instituto de Ciencias Marinas de Andalucía (ICMAN-CSIC), Puerto Real, Cádiz, Spain

José L. Zambonino-Infante

Ifremer, Unit of Functional Physiology of Marine Organisms, Plouzané, France

Acknowledgements

This book is based upon work from COST Action FA0801 LARVANET (Critical success factors for fish larval production in European Aquaculture: a multidisciplinary network), supported by COST. www.cost.eu/COST_Actions/fa/FA0801.

Chapter 1Introduction

As fish are efficient protein producers, in fact the most efficient farmed animal, aquaculture has been recognized as a key activity in terms of food security worldwide. Europe imports a substantial fraction of its fish consumption. Currently, the European aquaculture industry produces about 2.3 million tonnes of finfish per annum (FAO 2016), equal to one-third of the EU fishery market value, while representing only 20% of its volume! The Food and Agriculture Organization (FAO 2016) estimates that in order to achieve the per capita contribution of fisheries to the 2030 per capita consumption, the yearly global aquaculture production needs to grow by 27 million tonnes.

In order to meet the challenge of a steadily growing global aquaculture sector, there is a need to assure a steady supply of high numbers of high-quality fish larvae. Furthermore, in terms of future feed conversion efficiency, reduced malformation rates and the efficient conversion of feed to high-quality fish, quality fingerlings are of paramount importance for environmentally and economically sustainable aquaculture growth. However, aquaculture currently suffers from poor-quality fingerlings in terms of their future efficiency in converting food to fish meat, which affects aquaculture economics and its impact on the environment. Despite considerable progress in European aquaculture in the past 20 years, for example with production of over 1 billion seabass and seabream fry in 2012, high mortality during larval production and variable fry quality still plague the industry. This is exacerbated by an increasing need for diversification into new species, where these problems are even more acute. Therefore, there is still a significant amount of research to do to make the industry more cost-effective and sustainable.

The lack of a predictable supply of high-quality fish juveniles is largely attributed to uncontrolled environmental and nutritional factors during the larval rearing phase as well as the lack of tools for early prediction of larval quality in terms of phenotype and performance. There is thus a clear need for improvement of the scientific knowledge base that will support sustainable development of aquaculture. In addition, the well-documented environmental impact of factors such as climate change on fish production will place even greater demands on the application of an integrated multidisciplinary approach to improve larval performance and juvenile quality in the European aquaculture industry. This refers essentially to all non-salmonid fish species, as salmon and trout do not have a true larval stage, and most of the problems described for these species throughout this book are already solved or have a lower impact.

Maximizing fish production requires in-depth knowledge of biological, ecological and abiotic mechanisms, which affect the developing organism prior to reaching the grow-out farms. This is further exacerbated by the fact that the aquaculture industry is based on a multitude of species. So for instance, first feeding diets given to larvae have been identified as a determining factor for the quality of the juvenile phenotype in a number of species. This stems from the fact that various nutrients act on gene regulation of major physiological functions and thus should be an important feature of stage- and species-specific diet formulation but this has been largely ignored so far. While waterborne components such as endocrine disruptors have been well investigated for their effects on fish reproduction, there is almost no research on their effects on the larval to juvenile transition, despite the well-documented important role of hormones, and the endocrine system in general, in this process. The integration of molecular, nutritional and morphophysiological results is of paramount importance, as the influences on juvenile fish quality are multifactorial. Epigenetic research, for example how early environmental and nutritional impact can affect the phenotype later in life and even in the next generation(s), is relatively ‘new’ within research on farmed animals, including fish, although basic research in this area has been ongoing for several decades. The new tools which become available within this field will probably revolutionize the possibilities for juvenile quality prediction. Thus, in order to achieve a quality and sustainable aquaculture in Europe, there is a clear need for investment in fish larval research, to improve its scientific knowledge basis.

In order to tackle the aforementioned challenges, LARVANET, a network of researchers and producers working with fish larvae, was started in 2008. LARVANET was supported by a COST Action (FA0801). As a forum for constructive dialogue between stakeholders and researchers, LARVANET aimed to directly co-ordinate and build the know-how necessary to promote sustainable development and competitiveness at a basic level, and contribute to the cost-effective production of quality juveniles. It intended to integrate knowledge obtained in national and European research projects, and practical experience, in order to look for knowledge gaps on the way to improve quality of fish larvae used in aquaculture. It facilitated international co-operation, exchange of scientists and students, and efficient use of resources at all levels, and intended to exercise a lobby to influence long-term policy in the area of edible species larval research as a means to dramatically influence the resulting EU aquaculture efficiency, product quality and environmental and societal impact.

Reference

FAO (2016)

The State of World Fisheries and Aquaculture 2016. Contributing to Food Security and Nutrition for All

. Food and Agriculture Organization, Rome.

Chapter 2Gamete Quality and Broodstock Management in Temperate Fish

Herve Migaud1, Gordon Bell1, Elsa Cabrita2, Brendan McAndrew1, Andrew Davie1, Julien Bobe3, Maria Paz Herráez4 and Manuel Carrillo5

1Institute of Aquaculture, University of Stirling, Stirling, Scotland

2CCMAR, Centre of Marine Sciences, University of the Algarve, Campus de Gambelas, Faro, Portugal

3INRA, UR1037 Fish Physiology and Genomics, Rennes, France

4Department of Molecular Biology, Faculty of Biology, University of Leon, Leon, Spain

5Institute of Aquaculture of Torre de la Sal, Castellon, Spain

Executive Summary

Background

The ability to fully control sexual maturation and spawning and produce large numbers of high-quality seeds ‘on demand’ (i.e. all year long) is a primary requirement for the successful development of aquaculture. This relies on optimal broodstock management practices based on extensive knowledge of the nutritional and environmental requirements of fish in captivity. However, for many established, emerging and new farmed fish species, such knowledge is limited or not available yet. The level of domestication also plays an essential role as stocks with improved traits in farming conditions are selected. Importantly, reliable indicators of egg quality are still lacking as in many farmed fish species hatcheries still rely on wild harvested broodstocks. These key challenges must be addressed urgently to ensure the sustainable development of the European fish farming sector.

Principal Findings

The growth of the aquaculture industry depends to a large extent on the ability of hatcheries to supply good-quality eggs with selected traits, as required by the grow-out farmers. However, this remains problematic in many species, especially emerging new species selected for domestication for the diversification of the aquaculture industry. These often suffer from high variability in egg quality among stocks and parents. Therefore, more basic and applied research is required on all aspects of broodstock management including, inter alia, nutrition, environmental effects, genetics, gamete quality and preservation. This includes the definition of optimal egg quality at the genomic, proteomic and physiological levels in fish and the translation of this basic knowledge into a set of robust, reliable markers/analytical tools that can provide early confirmation of quality parameters for commercial hatcheries. A better understanding of the process of postovulatory ageing in fish broodstock is also required. The nutritional requirements of fish broodstock for optimal gametogenesis and egg/larvae quality and development (such as reduced deformity, etc.) must be defined, and sustainable, species-specific feed formulations developed.

The development of domestication/selective breeding programmes for emerging and new aquaculture species is critical to select the best strains, stocks and families for a range of traits of interest. Knowledge-based breeding programmes should be developed to minimize the effects of inbreeding on fertility, fecundity and egg/larvae quality traits (survival, growth, malformation). Research should also focus on gaining a better understanding of the environmental conditions that promote spontaneous, out-of-season spawning and good egg quality in established and new candidate species. Finally, the roles of maternally transferred mRNA, proteins and any other biomolecules on egg and larvae quality/performance should be studied and how broodstock conditioning/management can influence such epigenetic processes.

Scientific Significance

This review gives an overview of methods to assess egg/sperm quality and many of the most important factors impacting on gamete production and quality, including broodstock nutrition, environmental and spawning induction protocols, and genetic factors for broodstock management, gamete preservation and new reproductive strategies. From this review, a list of key gaps in knowledge has been identified as critical for a sustainable growth of the European fish aquaculture sector.

Practical Application

Challenges associated with the supply of seeds are amongst the most important constraints on the development of aquaculture. Scientific knowledge on optimal conditions for captive fish spawning and a set of parameters/methods that define gamete quality will be essential for the scaling up of many commercially important aquaculture species. Egg quality biomarkers could serve as predictors of fish quality to avoid occupying hatchery facilities with what may turn out to be unproductive batches of eggs.

Introduction

Aquaculture production has continued to grow at an ever-increasing rate from <1 million tonnes in the 1950s to 55 million tonnes in 2009 increasing at three times the rate of world meat production (2.7% from poultry and livestock together) with an average annual growth rate of 8.3% worldwide (FAO 2010). Much of this increase has occurred since the mid 1980s with the vast majority of the production being from Asia and the Pacific rim, particularly China. Farmed and managed seafood now accounts for 50% of global consumption. It is estimated that in order to maintain the current level of per capita consumption, global aquaculture production will need to reach 80 million tonnes by 2050. The main species farmed in Europe for human consumption are salmonids (Atlantic salmon, Salmo salar and rainbow trout, Oncorhynchus mykiss), bass and bream (mainly sea bass, Dicentrarchus labrax and sea bream, Sparus auratus), flatfish (mainly turbot, Scophthalmus maximusand halibut, Hippoglossus hippoglossus), Atlantic cod (Gadus morhua), carp (common carp, Cyprinus carpio, grass carp, Ctenopharyngodon idella and silver carp, Hypophthalmichthys molitrix), and emerging species such as sole (Solea senegalensis and S. solea), meagre (Argyrosomus regius), amberjack (Seriola dumerili) and percids (mainly Eurasian perch, Perca fluviatilis and pikeperch, Sander lucioperca).

Difficulties in the supply of seed are amongst the most important constraints to the development of aquaculture. For many farmed species, production is totally dependent on the harvest of broodstocks or seeds from wild populations. Therefore, the ability fully to control sexual maturation and spawning and to produce high quality seed is a primary requirement for a successful aquaculture production. Egg quality, defined as those characteristics of the eggs that determine its capacity to survive, is a significant problem for many of the species currently being farmed and is almost certain to be a problem for the culture of any new species. In general for many marine species, e.g. bass, bream, turbot and halibut, the mortality rate for eggs is very high with survival of larvae post-weaning often being <5–10%. Only the salmonids exhibit better egg and larval quality with survival being >50%. Little is still known about the determinants of egg quality, although many factors have been implicated as possible causative agents including broodstock nutrition, genetics, environmental conditions and any stress factors such as handling and spawning induction. Crucially, there is little agreement regarding reliable methods for the assessment of quality, an essential prerequisite if any firm conclusions regarding the factors that determine egg and larval quality are to be reached.

The aim of this article is to review the state of knowledge on methods to assess egg/sperm quality and broodstock management of key commercially important temperate fish species in Europe, focusing on the nutritional, genetic and environmental factors. The subsequent goal is to identify gaps in knowledge and research needs for the sustainable development of a growing fish farming industry.

Egg and Sperm Quality and Assessment

The control of gamete quality is a major issue for the aquaculture industry. This is especially true in the context of global environmental changes and the current increase in the number of aquaculture species (Chevassus-au-Louis & Lazard 2009) for which the success of reproduction can be a major issue.

The quality of a gamete can be defined as its ability to fertilize or to be fertilized, and subsequently develop into a normal embryo (Bobe & Labbe 2010). The identification of predictive estimators or markers of gamete quality would have major applications in research and industry. However, to date, it seems clear that no effective predictive marker of gamete quality exists even though non-viable gametes can sometimes be identified in some species, through the assessment of simple parameters such as buoyancy, appearance, or motility (Bobe & Labbe 2010). Thus, apart from markers of extremely low quality, it is still very difficult accurately to assess the quality of the gametes prior to fertilization. In contrast, a thorough analysis of developmental defects/failure or success can be extremely valuable for deciphering the cause of poor gamete quality. Given the increasing number of species that will be raised for aquaculture, the current challenge is to understand how environmental factors and rearing practices can impact gamete quality. Similarly, a better understanding of the mechanisms of gamete production during gametogenesis will be of great interest so as able to control, in fine, the quality of the gametes produced. Here we summarize the parameters that can be used to estimate or describe gamete quality and gamete characteristics and review new advances made in commercially important species (Fig. 2.1).

Figure 2.1 Main factors that can influence gamete quality in fish and main parameters that can be recorded to fully characterize gamete quality.

Egg Quality

As indicated above, fish egg quality, also known as oocyte developmental competence, can be defined as the ability of the egg to be fertilized and subsequently to develop into a normal embryo.

Prior to fertilization, it is extremely difficult to predict the success of development. As documented previously, the size of the egg is not always linked to its quality and eggs of varying size can exhibit similar developmental competence, as shown in trout (Bromage et al. 1992) and sea bass (Cerda et al. 1994a,b). Similarly, it is not possible to use morphological or macroscopic parameters to predict subsequent developmental success. Some parameters, such as sinking eggs in marine fish or white eggs in salmonids, can be used to identify non-viable eggs. The use of lipid distribution, that has been proposed to eliminate non-viable eggs in salmonids, is limited under normal hatchery conditions and the lack of a consistent relationship between the distribution of lipid droplets and egg quality has been stressed by other investigators (Ciereszko et al. 2009). A correlation exists between buoyancy and development such that buoyancy of pelagic eggs is often better in egg batches that develop normally as shown in the red sea bream (Pagrus major; Sakai et al. 1985) and other species (Kjörsvik et al. 1990), even though this does not hold true for all species (Brooks et al. 1997).

In species that produce transparent eggs, the shape of the first embryonic cells (blastomeres) and the patterns of cell division can be assessed to identify abnormal development during early embryogenesis (Shields et al. 1997; Kjørsvik et al. 2003; Avery & Brown 2005). This was, however, recently challenged by a study demonstrating that an abnormal cleavage pattern does not necessarily result in embryonic failure (Avery et al. 2009). In favour of this second hypothesis would be the ‘checkpoint’ set up by the developing embryo at the time of zygotic genome activation at mid-blastula stage (Kane et al. 1992; Kane & Kimmel 1993).

Survival at a specific embryonic stage is one of the most common and relevant ways of characterizing the ability of the fertilized egg to develop successfully. Survival can thus be assessed at specific stages such as the eyed stage, hatching and yolk sac resorption stage, which can be monitored in most fish species. It is also noteworthy that monitoring survival at successive developmental stages can be extremely valuable for characterizing the timing of embryonic mortalities that can significantly differ between experimental treatments or rearing conditions (Kopeika et al. 2003; Bonnet et al. 2007a). Similarly, monitoring embryonic and/or larval malformation can be useful for characterizing the developmental competence of the egg and to decipher potential causes of developmental failure. In rainbow trout, some malformations are specifically induced by environmental factors or husbandry practices while other malformations are female dependent and can be observed regardless of the life-history of the female broodstock (Bonnet et al. 2007a,b).

In the past few years, significant research efforts have been devoted to the study of the molecular mechanisms that are responsible for good or bad egg quality. Several types of genomic approaches such as transcriptomics (Aegerter et al. 2005; Bonnet et al. 2007b) and proteomics (Crespel et al. 2008; Ziv et al.