Improving the Reproductive Performance of Domesticated Giant Tiger Shrimp, Penaeus monodon

Abstract

The Giant or Black Tiger Shrimp, Penaeus monodon, is an economically significant aquaculture species globally, producing 4.5 million tonnes of product annually at a value of US$ 23.5 billion (FAO, 2016a). Recent innovations in the domestication and selective breeding of P. monodon have resulted in significant improvements in growth rate, survival and pathogen tolerance. However, the reproductive performance of domesticated stocks is inferior compared to that of wild-caught broodstock. Significant reductions in the number of females maturing, egg and nauplii production and hatch rates are commonly reported for domesticated stocks relative to their wild-caught counterparts.The complexities surrounding reduced reproductive performance in domesticated P. monodon are underpinned by two critical issues: 1) a poor understanding of the specific nutritional requirements for reproduction in the species and; 2) a lack of clarity as to the characteristics that define a 'good spawner' -particularly on a biochemical and molecular level. The studies that make up this thesis employed a multidisciplinary approach to assess nutritional, biochemical, and molecular factors that relate to broodstock reproductive performance. Primarily this thesis sought to: (1) investigate whether the current constraints to reproductive performance in domesticated stocks could be overcome by including the microbial biomass derived bioactive Novacq™ (Patent #2008201886) within pelleted diets; (2) evaluate whether current broodstock maturation diets are limiting in relation to repeated spawning and; (3) characterise key interactions between micronutrients and regulatory gene(s) and/or pathways linked to reproduction.A series of reproductive performance trials were undertake to assess the effect of incorporating microbial biomass (Novacq™) within pelleted maturation diets. Preliminary farm-based trials observed significant increases to maturation rate, egg production and nauplii production when domesticated broodstock were fed an experimental pelleted diet containing the Novacq™ ingredient (20% Novacq™ inclusion rate, 2.4% of total diet fed). However, in a subsequent trial conducted under controlled experimental conditions, broodstock fed commercial-grade pelleted diets (30% Novacq™, 5.5% of total diet fed) exhibited a significant decrease in egg hatch rate. Reductions in reproductive performance under controlled experimental conditions were attributed to a decrease in the quality of basal pellet diets, both as a function of increased Novacq™ inclusion and their commercial-based formulation. The above studies suggest the capacity to improve reproductive performance in domesticated P. monodon, using biofloc and its substituents, is highly dependent on the quality of the basal maturation diet fed.ii In response to the aforementioned studies, a trial was undertaken to identify potential factors limiting reproductive performance within current broodstock maturation diets. The effect of repeated spawning on reproductive performance and tissue bioche...

The State of “Omics” Research for Farmed Penaeids: Advances in Research and Impediments to Industry Utilization

“…Likewise, reproductive studies comparing male and female transcriptome profiles, along with various reproductive stages within sexes, has yielded novel insight into the molecular and genetic mechanisms underpinning maturation and sex determination of L. vannamei (Peng et al, 2015 ), F. merguiensis (Powell et al, 2015 ), and P. monodon (Rotllant et al, 2015 ; Goodall, 2017 ). As these studies are able to reconstruct complete (or near complete) RNA transcripts, it has been possible to analyse comprehensive gene pathways (Peng et al, 2015 ).…”

“…In particular, through differential gene expression analysis of whole-transcriptome data, genes related to fatty acid and steroid metabolism were found to have altered expression patterns when compared between wild sourced and domesticated stock (Rotllant et al, 2015 ). Similarly, exploration of the effects variable ovarian arachidonic acid content has on a number of key ovarian development pathways, revealed distinct differences between domesticated individuals (Goodall, 2017 ). Both studies provide a strong case for continued research into the informed improvement of reproductive maturation diets and may help the industry overcome commonly poor breeding performance (Rotllant et al, 2015 ; Goodall, 2017 ).…”

“…Similarly, exploration of the effects variable ovarian arachidonic acid content has on a number of key ovarian development pathways, revealed distinct differences between domesticated individuals (Goodall, 2017 ). Both studies provide a strong case for continued research into the informed improvement of reproductive maturation diets and may help the industry overcome commonly poor breeding performance (Rotllant et al, 2015 ; Goodall, 2017 ).…”