Hybrids production as a potential method to control prolific breeding in tilapia and adaptation to aquaculture climate-induced drought

Establishing suitable salt tolerant all-male tilapia strains with fast growth rate is a crucial requirement for successful euryhaline farming required for controlling prolific breeding and as an adaptation to the effect of climateinduced drought.This study assessed the percentage of tilapia male hybrids,their growth performance and survival rate produced by crossing female Nile tilapia(Oreochromis niloticus)and male Rufiji tilapia(Oreochromis urolepis urolepis)at different salinities.The fingerlings were reared for 70 days in triplicate concrete tanks(1 m3),each stocked with 15 fish weighing 1.62±0.03 g,1.69±0.02 g and 1.41±0.06 g exposed to 2,15 and 35 ppt salinities,respectively.Acclimatization was done by adding seawater to freshwater at a rate of 2 ppt per day for 18 days.Fish sexing was done by visual assessment of the genital papilla followed by rearing the hybrids for six months to observe reproduction.Results showed that,the cross between O.niloticus(female)and O.urolepis urolepis(male)produced hybrids that were all-males without any reproduction within six months post hybridization.The hybrids reared at a salinity of 2 ppt had higher growth performance than those reared at 15 and 35 ppt.Similarly,hybrids cultured at 15 ppt had significantly higher growth performance than those reared at 35 ppt.All the hybrids produced had survival rates of 100%.This study indicated that,all-male tilapia produced by crossing between O.niloticus(female)and O.urolepis(male)can be used by fish farmers as alternative species for mariculture development to control prolific breeding and as an adaptation strategy to climate change.

Post-displacement status of climate migrants in Rajshahi City, Bangladesh

Some big cities in Bangladesh have been experiencing a massive and rapid influx of rural people due to the impacts of climate change,and therefore the urban administration encounters enormous challenges.This study aims to investigate the drivers of climate-induced migration and the post-displacement status of the migrants living in the urban slum of Rajshahi City.Using a semi-structured questionnaire survey,this study conducted interviews with 50 migrants residing in two slums in Rajshahi City.An interpretive phenomenological analysis(IPA)approach was implemented to evaluate the survey data.This study finds that food insecurity and flood are the two significant climate drivers of migration.Among the non-climate drivers,lack of alternative livelihood is the major reason.It should be noticed that the climate migrants in many cases do not get the opportunity to improve their living standards;they are usually occupied with low-pay professions like maid,van and rickshaw puller,and scrap collector.The study also reveals that migrants,especially females and children,need several basic physiological,economic,social,and health services.Most children have no chance to attend school.Compared to males,females have more opportunities for some support and allowances.Overall,an inadequate level of change has taken place in the lives of migrants,which raises the concern if migration is ever a way to resolve a problem or the beginning of many other problems.Further research may concentrate on the impact of migration on the dynamics of social capital among slum dwellers.