In 2018, Ghana recorded disease-induced mortalities in cage farmed tilapia (Oreochromis niloticus) . The disease-induced mortalities adversely affected cage farmers on lake Volta, Ghana. Lake Volta has a track record of high fishery productivity, which offset s the pressure emanating from pathogen load, aquaculturists , and other users on and around the lake. However, ecosystems have a threshold of disturbances that can bring about equilibrium state changes . Lake Volta fish mortalities of 2018 are not limited to diseases but a combination of environmental drivers that threaten the lake’s overall productivity . This desktop study synthesized stakeholder perspectives to unravel the actual causalities of fish mortalities and infectious diseases . In addition, the study examined management practices and stakeholder collaborations to secure fish health and protect the lake environment from degradation. T he effects of fish mortalities in aquaculture are explained in broadscale terms, such as threatened food security and socio-economic losses. Regarding this, we applied t he SWOT analytical framework to uncover the strengths, weaknesses , opportunities, and threats of fish mortalities in Ghana.
Upon ethical clearance, we conducted twenty-six interviews with fish farmers, sectorial authorities , including a non-governmental organisation, a nd researchers. Atlas.ti analys ed the transcripts in to themes such as mortality risk factors, management practices and stakeholder collaboration .
The results showed that f ish health in lake Volta aquaculture is conflicted by poor water quality, Infectious Spleen and Kidney Necrosis Virus (ISKNV), and group A type 1 Streptococcus agalactiae . In addition, reinforcing variables of l ive f ish & e ggs importation and human activities affect fish health . The causation web showed the reinforcing variables and other drivers causing fish mortalities (fig. 1). The management practices deployed to secure fish health included among others, immunomodulation, vaccination, biological controls, heat shock treatment and best husbandry practices . Furthermore , the Social-Ecological System (SES) analysis showed the interplay of variables in the governance system , social domain and ecosystem that challenge the lake’s productivity. From the SES model, limited stakeholder collaboration drives the flow of ecosystem disturbances leading to lake degradation and fish mortalities. Stakeholder collaboration was rather inclin ed towards licensing & training of fish farmers , in contrast to low research & data collection for policy decisions. We documented a pathway for efficient aquaculture governance using the Collaboration for R esilience (CORE) framework. In conclusion, regulatory agencies must plan a whole system approach to minimize the threats outlined in the SWOT analysis while adopting the best management practices that protect the lake environment. In addition, diversification of cultured species will reduce the breeding pressure on O. niloticus . The study will inform policies to make aquaculture sustainable .