News Update on Fisheries : Dec 2021

The Future for Fisheries

Formal analyses of long-term global marine fisheries prospects have yet to be performed, because fisheries research focuses on local, species-specific management issues. Extrapolation of present trends implies expansion of bottom fisheries into deeper waters, serious impact on biodiversity, and declining global catches, the last possibly aggravated by fuel cost increases. Examination of four scenarios, covering various societal development choices, suggests that the negative trends now besetting fisheries can be turned around, and their supporting ecosystems rebuilt, at least partly.[1]

Towards sustainability in world fisheries

Fisheries have rarely been ‘sustainable’. Rather, fishing has induced serial depletions, long masked by improved technology, geographic expansion and exploitation of previously spurned species lower in the food web. With global catches declining since the late 1980s, continuation of present trends will lead to supply shortfall, for which aquaculture cannot be expected to compensate, and may well exacerbate. Reducing fishing capacity to appropriate levels will require strong reductions of subsidies. Zoning the oceans into unfished marine reserves and areas with limited levels of fishing effort would allow sustainable fisheries, based on resources embedded in functional, diverse ecosystems.[2]

Biocomplexity and fisheries sustainability

A classic example of a sustainable fishery is that targeting sockeye salmon in Bristol Bay, Alaska, where record catches have occurred during the last 20 years. The stock complex is an amalgamation of several hundred discrete spawning populations. Structured within lake systems, individual populations display diverse life history characteristics and local adaptations to the variation in spawning and rearing habitats. This biocomplexity has enabled the aggregate of populations to sustain its productivity despite major changes in climatic conditions affecting the freshwater and marine environments during the last century. Different geographic and life history components that were minor producers during one climatic regime have dominated during others, emphasizing that the biocomplexity of fish stocks is critical for maintaining their resilience to environmental change. [3]

Quantitative Analysis of Fish Consumption in Rivers State, Nigeria

The determinants of demand for fish in Rivers State were isolated in this study. Structured questionnaire was used in eliciting information from the respondents. Cross sectional data were randomly collected from 210 respondents from the three senatorial zones. Multiple regression analysis was used in analyzing the data. Results showed that age, household size, income, price of beef and sex of the consumers were the major determinants of fish consumption in the State. The demand for fish was relatively income inelastic. Beef was a close substitute to fish therefore an increase in the price of beef leads to a corresponding increase in the quantity of fish demanded. Fish was a normal good. Policies and programmes aimed at raising the income of households such as credit liberalization should be implemented by the government. In addition the level of education of the citizens should be raised through compulsory secondary education so as to increase the level of their nutritional enlightenment which is expected to boost their levels of protein intake. [4]

Immunostimulants and Fish Culture: An Overview

Aquaculture is one of the fast growing foods producing sector worldwide. Cultured marine, freshwater fish as well as shellfish species are major contributors to fish production and also increase the annual production. Fish farming constitutes unique and significant berth in industrial scale production worldwide. Due to intensive fish farming practices, infectious disease pose a major problem in aquaculture industry globally especially causing heavy loss to farmers. Fish disease is rarely a simple association between pathogen, a host fish and environmental problems, such as poor water quality or others stressors often contribute to the outbreak of disease. Various types of antibiotics, chemotherapeutic and vaccines are in use to control or prevent viral, bacterial, parasitic and fungal diseases. Unfortunately, vaccines are usually not able to confer protection on their own; especially those vaccines based on recombinant antigens or inactivated pathogens. Therefore, an alternative inexpensive and effective substitute is needed to enhance the activity of drugs. In this vista, use of adjuvants or immunostimulants is good remedy to increase the vaccine efficacy to control fish and shrimp diseases. Immunostimulants (IS) is a naturally occurring compound that modulates the pathogens via facilitate the function of phagocytic cells and also stimulate the natural killer cells (NK), complement, lysozyme and antibody responses of fish. The activation of the immunological functions by IS is associated with increased protection against both infectious and non-infectious diseases. In this review, we summarized the therapeutics importance of immunostimulants in fish culture and control of diseases development and progression. [5]

Reference

[1] Pauly, D., Alder, J., Bennett, E., Christensen, V., Tyedmers, P. and Watson, R., 2003. The future for fisheries. Science, 302(5649), pp.1359-1361.

[2] Pauly, D., Christensen, V., Guénette, S., Pitcher, T.J., Sumaila, U.R., Walters, C.J., Watson, R. and Zeller, D., 2002. Towards sustainability in world fisheries. Nature, 418(6898), pp.689-695.

[3] Hilborn, R., Quinn, T.P., Schindler, D.E. and Rogers, D.E., 2003. Biocomplexity and fisheries sustainability. Proceedings of the National Academy of Sciences, 100(11), pp.6564-6568.

[4] Anyanwu, S.O., 2014. Quantitative analysis of fish consumption in rivers state, Nigeria. Journal of Experimental Agriculture International, pp.469-475.

[5] Mehana, E.E., Rahmani, A.H. and Aly, S.M., 2015. Immunostimulants and fish culture: an overview. Annual Research & Review in Biology, pp.477-489.