Chapter 1 Introduction
Bangladesh is blessed with vast and well diversified inland open waters, estuaries, brackish and marine waters with the potential fisheries resources. Fisheries sector has been playing increasingly an important role in our economy for few decades (DoF, 2018). Fish is the second most valuable agricultural crop in Bangladesh and its production contributes to the livelihoods and employment of millions of people (Ghose, 2014). As an agro-based country, the contribution of fisheries sector to national economy has always been important and main source of animal protein, employment opportunities, food and nutritional security, foreign earnings, aquatic biodiversity conservation and socio-economic development. Fisheries sector contributes 3.61% to GDP and 24.41% to agricultural GDP. Fish supplements to about 60% of our daily animal protein intake. About 11% of the population dependents directly and indirectly on the fisheries sector for their livelihood (DoF, 2018).
Production of commercial feeds has increased at an average rate of 32% per year over the period 2008–2012, and has reached an estimated total of almost 1.07 million tons in 2012. Sinking feeds, which accounted for 81% of total manufactured output, still dominate over extruded floating feed (19%), but growth in the production of floating fish feed has been fastest, averaging 89% over the last four years. Around 100 commercial mills produce aquaculture feeds in Bangladesh (Rashid et al., 2013).
The costs of formulated feed and labor associated with feeding are a major component of the cost of cultured shrimp production (Lawrence and Lee, 1997). It is well established that the nutrient contents of the feed influence growth, survival and the amount of metabolic and excreted waste products entering the system. However, processing also plays a critical role as it influences stability of the feed and hence availability of the feed over time (Smith, Burford, & Tabrett, 2002).
Although filter feeding animals like mollusks or herbivorous silver carp and bighead carp do not require feeding (FAO, 2012b); however, fed aquaculture represents 81 percent of global fish and crustacean aquaculture production. Fed aquaculture contributes about 60 percent of global aquatic animal production of aquaculture (Tacon et al., 2013). Although, in developing countries fewer supplementary feeds and fishmeal are used due to lower trophic level species culture, but for the higher trophic level species, like shrimp, salmon, trout are still dependent on fish from the wild for fishmeal and oil in formulated feeds (HLPE, 2014). The use of fish from the wild in fishmeal and fish oil to produce fish has been the cause of major public controversy. In 2012, about 10 percent of total catch fish (16 million tons) was reduced to fishmeal and fish oil (Tacon et al., 2011; FAO, 2014a). In addition to fishmeal and fish oil, trash fishes are also used directly.
The aquaculture research community and the aquafeeds industry have long recognized and anticipated issues impacting the sustainability of fish meal in aquafeeds (Barrows and Hardy, 2001) and have been researching and developing aquafeeds that use alternative protein ingredients, particularly plant-derived proteins (Gatlin et al., 2007). Blue economy challenge project tried to find an alternative approach of protein source in collaboration with Waginengen University and Research, WorldFish Bangladesh, Vietnam and Khulna University developed different types of feeds supplemented with concentrated microbial proteins into shrimp feed. Moreover, most of the shrimp culture farms at different coastal districts in Bangladesh have been developed at different salinities. There is a little literature has been found who worked on protein supplementation in shrimp feed with microbial proteins and its suitability in application at different salinities, and its performance in growth of P. monodon.
1.1 Objectives of the study
In this BSc thesis attempt was taken to investigate effect of different experimental diets enriched with concentrated microbial protein and salinities on the growth of P. monodon. The idea was to understand the compatibility of these experimental diets in the shrimp farms of different coastal districts of Bangladesh. The objectives of this study were to:
- Investigate the effect of different experimental diets and salinities on the growth of P.monodon.