Methods of fish farming (aquaculture) have evolved to reduce environmental impacts and increase efficiency.
Suggest two reasons why more fish are now produced using aquaculture than being caught from traditional wild fisheries.
Land-based Recirculating Aquaculture Systems (RAS) are increasingly used instead of traditional open-net pens located in the sea.
This new type of fish farming differs from open-net pens because:
Suggest one advantage of using recirculated filtered water inside land-based tanks rather than seawater directly from coastal areas.
Suggest the advantage of using fewer antibiotics in fish farms.
Another advantage of Recirculating Aquaculture Systems (RAS) is the reduction in waste discharge.
The nutrient waste figures for a traditional open-net pen and a land-based RAS are shown in the table below.
Nutrient wasteMass of discharge in kgper tonne of fish producedDischarge from RAS asa percentage of dischargefrom open-net pen (%)open-net penRASdissolved nitrogen45.016.236.0total phosphorus6.51.3 \begin{array}{|l|c|c|c|} \hline \text{Nutrient waste} & \begin{array}{c} \text{Mass of discharge in kg} \\ \text{per tonne of fish produced} \end{array} & & \begin{array}{c} \text{Discharge from RAS as} \\ \text{a percentage of discharge} \\ \text{from open-net pen (\%)} \end{array} \\ \hline & \text{open-net pen} & \text{RAS} & \\ \hline \text{dissolved nitrogen} & 45.0 & 16.2 & 36.0 \\ \hline \text{total phosphorus} & 6.5 & 1.3 & \\ \hline \end{array} Nutrient wastedissolved nitrogentotal phosphorusMass of discharge in kgper tonne of fish producedopen-net pen45.06.5RAS16.21.3Discharge from RAS asa percentage of dischargefrom open-net pen (%)36.0Calculate the total phosphorus in the waste from the RAS as a percentage of the total phosphorus in the waste from the open-net pen. Show your working.
If nutrient waste from fish farms is released into natural waterways, it can cause pollution.
Design an investigation to compare the pollution (such as algal growth or oxygen depletion) caused by waste discharged from an open-net pen system with waste discharged from a Recirculating Aquaculture System (RAS).
Your answer should include experimental details and be written in full sentences.
74 exam-style questions on Edexcel IGCSE Biology Food production. Each one has a worked solution and a mark scheme showing where the marks go.