Significant improvement of shrimp growth performance by growth hormone‐releasing peptide‐6 immersion treatments

Growth hormone‐releasing peptide‐6 (GHRP‐6) is one of the earliest developed synthetic peptidyl growth hormone secretagogue receptor agonists. These compounds mimic the effect of the endogenous ligand ghrelin. In vertebrates, ghrelin is a potent circulating orexigenic hormone with functional roles in controlling food intake, energy expenditure, adiposity, growth hormone secretion and immunity. Ghrelin has been studied mainly in vertebrates; thus, little is known about its role in invertebrates, including crustaceans. We first evaluated the effect of GHRP‐6 injection over feed intake in shrimp and its effects on shrimp growth when the peptide was administrated by successive immersion baths. GHRP‐6 increased feed intake, body weight and size, the number of rostral spines and gill branches, protein concentration and haemocyte number in treated shrimps. We also evaluated the peptide uptake and clearance in a pharmacokinetics, using [H³]GHRP‐6 administered to postlarvae. Given a limited exposure and efficient clearance of the peptide‐associated radioactivity from larvae, our findings suggested that GHRP‐6‐treated Litopenaeus vannamei can be consumed safely by humans after aquaculture applications. These results propose that GHRP‐6 could be an additional tool to study growth physiology in crustaceans and also a promising candidate for development into a new biotechnology product for improving shrimp growth and quality.     

Reproductive resilience: a paradigm shift in understanding spawner‐recruit systems in exploited marine fish

A close relationship between adult abundance and stock productivity may not exist for many marine fish stocks, resulting in concern that the management goal of maximum sustainable yield is either inefficient or risky. Although reproductive success is tightly coupled with adult abundance and fecundity in many terrestrial animals, in exploited marine fish where and when fish spawn and consequent dispersal dynamics may have a greater impact. Here, we propose an eco‐evolutionary perspective, reproductive resilience, to understand connectivity and productivity in marine fish. Reproductive resilience is the capacity of a population to maintain the reproductive success needed to result in long‐term population stability despite disturbances. A stock's reproductive resilience is driven by the underlying traits in its spawner‐recruit system, selected for over evolutionary timescales, and the ecological context within which it is operating. Spawner‐recruit systems are species specific, have both density‐dependent and fitness feedback loops and are made up of fixed, behavioural and ecologically variable traits. They operate over multiple temporal, spatial and biological scales, with trait diversity affecting reproductive resilience at both the population and individual (i.e. portfolio) scales. Models of spawner‐recruit systems fall within three categories: (i) two‐dimensional models (i.e. spawner and recruit); (ii) process‐based biophysical dispersal models which integrate physical and environmental processes into understanding recruitment; and (iii) complex spatially explicit integrated life cycle models. We review these models and their underlying assumptions about reproductive success vs. our emerging mechanistic understanding. We conclude with practical guidelines for integrating reproductive resilience into assessments of population connectivity and stock productivity.     

A sensory and nutritional validation of open ocean mussels (Mytilus galloprovincialis Lmk.) cultured in SE Bay of Biscay (Basque Country) compared to their commercial counterparts from Galician Rías (Spain)

Mussel shell biometry, nutritional quality as well as consumer sensory evaluation of experimental open ocean cultured mussel Mytilus galloprovincialis (Lamarck 1819) were analyzed and compared to that of commercial mussels from Galician Rías available in the local market. Both mussel products were of the same commercial size. In this study, open ocean mussels were significantly higher and wider than those of Galician Rías. In addition, with the exception of ash content, both mussel products showed similar biochemical composition. Regarding fatty acid profiles, however, statistical differences were detected. These differences were not fully reflected in the sensory assessment. In terms of consumer acceptability, both mussel products were considered equally satisfactory.