The genetic modification of economically valuable organisms in fisheries is contributing toward ensuring food security. Applications of molecular tools aiming to improve productivity will further improve the outlook of fisheries productivity in a rapidly changing world.
Fish Farm. Image Credit: Marius Dobilas/Shutterstock.com
The use of molecular tools within fisheries
Food security is increasingly reliant on resources derived from aquatic systems and the species they encompass to address the increasing nutritional and energetic needs of a growing world population. As such, fisheries have experienced rapid changes in recent decades.
Fisheries are enterprises focusing on the raising or harvesting of marine life including wild and farming processes in both freshwater and marine environments. Fisheries encompass species from invertebrate mollusks through to pelagic fishes and therefore rely on a multitude of biotic and abiotic factors for long-term productivity.
However, the overexploitation of fishery stocks has led to a consistent decline in productivity. Although many issues including environmental change pose a significant challenge to fisheries, overexploitation is considered the foremost challenge facing fisheries worldwide.
In response, the application of molecular techniques within the fisheries sector has aimed to mitigate the ramifications of environmental and ecological issues.
For instance, the use of microsatellite markers to distinguish different regional populations of economically valuable species can elucidate the demographics and health of exploited populations. This was studied in the grey mullet Mugil cephalus, with findings published in February 2021 revealing that despite representing a single broad population encompassing a large region of the Mediterranean, this species showed a surprisingly low genetic diversity on a regional scale.
Information on the baseline status of a population on a genetic level can then be used to identify longer-term stock health needed to assess the effects of exploitation. Moreover, another strategy used in fisheries management to directly address issues of exploitation is through the genetic modification of organisms.
Genetic modification of organisms in fisheries
The first genetically engineered fish, a species of salmon, has been available for consumption since 2015. This salmon grows twice as fast compared to wild counterparts due to the integration of genetic material from the ocean pout, a species that grows year-round, illustrating the potential use of genetic modifications in commercially significant species.
Genome editing can be used to alter the DNA in cells, tissues, or whole organisms to understand biological processes. In agriculture, genetically modified crops have been used to develop crops more resistant to disease or drought to provide a higher yield. This approach has also been used with animals to increase their resilience to environmental stress as well as obtain more resources such as milk or meat in livestock.
In fisheries, the genetic modification of organisms is a rapidly developing approach particularly due to the use of CRISPR-Cas9 toolkits. This technique can help understand a range of impacts from the immune evading strategies of harmful bacteria for key fish species, to increasing reproductive output of organisms.
Specifically, CRISPR has been used to understand processes in many species of economic interest including Atlantic salmon, zebrafish, and tilapia. Additional instances of genetic modification in fish include accelerated growth rate in snow trout as well as alterations in sex determination of tilapia, two mechanisms that may directly increase population size thus improving overall fish stocks.
Further implications of genome editing
Gene editing has also been used to understand processes indirectly affecting fish stocks. The functional characterization of genes is of particular interest for fisheries as it may refine the targeting of CRISPR modifications further.
The benefits of improving the functional roles of genes to improve fisheries-related modifications were discussed in a 2019 collaboration between Indian and American scientists. The authors reviewed the literature on genome editing in fishes and detailed how further improvements can contribute to greater food security.
This review emphasized the importance of focusing on genetically modified model organisms that may provide a wealth of biological information to use for other species. Of particular interest may be the modification of reproductive processes, such as the synthetic manufacturing of induced breeding hormones that fish use, such as ovaprim and ovatide. Synthetic hormones could then be used in fish farms to induce spawning more efficiently and predictably.
The future of genetic modification in fisheries
As of 2019 over 270 whole genomes of fish species have been assembled. Considering DNA manipulation techniques originated in the 1970s, it is predicted that the availability and quality of genomic information will accelerate further into the future.
In July 2020, researchers published a review in the journal of Aquaculture and Fisheries on the applications of harnessing fish genomes from a world fisheries perspective. The authors presented a detailed history and current assessment as to how molecular tools are used in aquaculture to combat diseases, improve growth, understand sexual determination, and bolster overall fisheries management.
The review describes the current progress and upcoming challenges of applying genetic tools for fisheries, advocating for the integration of other technological advances such as an artificial intelligence database. Indeed, databases integrating genetic, phenotypic, and environmental data are lacking within fisheries despite the technology being available.
Moreover, many other approaches besides the main pillars of molecular research in fisheries also hold valuable interest including the molecular impacts of environmental change.
Techniques of genetic modification are contributing to greater food security through the refinement of breeding programs and the development of organisms that more stress-resilient, ultimately aiming to improve overall yield. Additional approaches including the use of synthetic biology and the integration of machine learning will further refine current practices to limit the decline of fish stocks and support the growing demand for resources.
- Cossu, P., Mura, L., Scarpa, F., Lai, T., Sanna, D., Azzena, I., Fois, N., & Casu, M. (2021). Genetic patterns in Mugil cephalus and implications for fisheries and aquaculture management. Scientific Reports, 11(1), 1 doi:10.1038/s41598-021-82515-7
- Li, M., & Wang, D. (2017). Gene editing nuclease and its application in tilapia. Science Bulletin, 62(3), 165–173. doi:10.1016/j.scib.2017.01.003
- Lu, G., & Luo, M. (2020). Genomes of major fishes in world fisheries and aquaculture: Status, application, and perspective. Aquaculture and Fisheries, 5(4), 163–173. doi:10.1016/j.aaf.2020.05.004
- Pande, A., Bhat, R. A. H., Saxena, A., & Tyagi, M. (2020). Concepts and potential applications of gene editing in aquaculture. Genomics and Biotechnological Advances in Veterinary, Poultry, and Fisheries, 249–270. doi:10.1016/b978-0-12-816352-8.00011-4
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