Globally, the aquaculture industry has seen significant development through increased fish production, as a result of increased demand for fish and fish products. Ghana's aquaculture sector has seen significant growth in recent years, due to the government/World Bank-funded fisheries program through Ministry of Fisheries and Aquaculture Development (MOFAD). The national aquaculture production grew from over 32,512 MT/y in 2013 to 52,470.49 MT/y, representing 11.3% of the national harvest, in 2016. Aquaculture production is projected to hit 72,000 Tons, representing 15% of national fish production, in the next 3-5 years. Despite the significant growth, the sector is faced with several challenges related to management and production problems. For instance, limited knowledge of modern aquaculture techniques, inadequate supplies of improved seed, lack of continuing aquaculture policy direction, and inadequate funding for research. Despite the challenges, there are some fantastic opportunities in Ghana's aquaculture industry such as the production of live fish food, marine fish and shellfish culture, integrated fish farming, the culture of indigenous fish species, and investment in the fish feed industry. In this review, we explore the current state, obstacles, potentials, and future opportunities for Ghana's aquaculture sector. We propose measures that should be looked at to overcome the challenges as well as improve production in the sector.

Despite significant improvements in aquaculture to compensate wild catch, disease organisms have thrived in limiting its national and global potential. Using antibiotics, in a bid to remedy the havoc, has given rise to complications, attracting attention to disease prevention by immune enhancement against diseases. Grouper production has been inhibited for the threats of bacterial infection, particularly of Vibrio origin. Considering the rise in vibriosis cases, improved vaccines are necessary; moreover, recombinant vaccines, the choice for trial in the present experiment have been effective and more specific in improving immunity. The current work deals with grouper immune system enhancement with a recombinant vaccine developed from VirB11 gene in Vibrio harveyi. VirB11 was cloned in V. harveyi for recombinant vaccine development against vibriosis in orange‐spotted grouper (Epinephelus coioides). As indicated by the results, recombinant VirB11 protein showed effectiveness in conferring protection against vibriosis with observable specific antibody response in enzyme‐linked immunosorbent assay (ELISA) analysis; a significant increase (p < 0.05) in antibody levels was observed after a week and after 8 weeks post‐vaccination. From the weeks post‐vaccination, log2 (antibody titres) in the sera of vaccinated groups reached a peak of 14.2 at week 5 in the vaccinated group in comparison with a peak of approximately 5 and 2 in adjuvant and PBS controls. As indicated by the challenge results, 90% relative survival was observed in vaccinated group and 13% relative survival in control group I (adjuvant control). The cumulative performance of protein concludes VirB11 commendable for recombinant vaccine development.

Pathogens respond to host immunity by secreting virulence factors which facilitate their proliferation and survival in host. Most bacteria including Vibrio harveyi coordinates gene expression by cell-cell communication termed quorum sensing. Quorum sensing (QS) involves the production, detection, and response of molecules to extracellular signals to enable bacteria monitor population density and induce specific genes in response to changes in cell number. Quorum sensing systems regulate virulence, bioluminescence, biofilm formation and antibiotic production which are necessary factors to induce infection. V. harveyi interacts inter-specially and intra-specially to overcome host defences and cause detrimental infections to a wide range of aquatic host. This review reflects the mechanism aiding infection in Vibrio species, considering V. harveyi clade.

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