Candidate Species Biology, Site Selection and Ecological Criteria for Aquaculture - Aquaculture | Agrigyan

• Environmental DNA (eDNA):
• eDNA stands for Environmental DNA.
• It refers to genetic material (cellular or extracellular nuclear and mitochondrial DNA) shed by aquatic organisms into the surrounding water matrix via sloughed skin cells, mucus, scales, urine, feces, and gametes.
• High-throughput eDNA metabarcoding enables sensitive, non-invasive detection of rare, endangered, or invasive fish species without physical capture.
• Correct Option: Option 1 (Environmental DNA).

• Carbohydrate Intolerance in Carnivorous Fishes:
• Carnivorous fishes (such as trout, salmon, sea bass, groupers) exhibit poor dietary carbohydrate utilization and prolonged post-prandial hyperglycemia.
• Key Factors:

• Low synthesis and secretion of digestive $\alpha$-amylase in the pancreas and intestinal mucosa.
• Low activity of hepatic hexokinase and glucokinase, limiting glucose phosphorylation and hepatic glycolytic flux.
  • Correct Option: Option 1 (Low amylase).

Evaluating the Assertion and Reason concerning Aquaculture practices for freshwater fish (carps, catfishes, snake heads, feather backs, tilapia, murrels, mahseer, trouts, etc.):

The correct answer is Option 1: Both (A) and (R) are true and (R) is the correct explanation of (A).

• Development of GIFT Tilapia:
• GIFT stands for Genetically Improved Farmed Tilapia.
• Developed in the Philippines by the International Center for Living Aquatic Resources Management (ICLARM / WorldFish) through multigenerational selective breeding (combined family selection) using eight founding African and Asian strains of Nile tilapia (Oreochromis niloticus).
• GIFT tilapia achieves $\gt 60\%$ higher somatic growth rates and superior survival without transgenic modification.
• Correct Option: Option 2 (Selective breeding).