मत्स्यन शिल्प, गियर एवं इंजीनियरिंग

Assertion (A) is true: The marine sextant is an optical instrument used by navigators to measure celestial altitudes (vertical angle of the sun, moon, or stars above the horizon) and horizontal angles between landmarks to determine geographic position at sea. Reason (R) is true: It operates on the optical principle of double reflection between an index mirror and a horizon glass; because the angle between the mirrors is doubled by two reflections, its arc of one-sixth of a circle ($60^\circ$, hence 'sextant') measures angles up to $120^\circ$, precisely explaining how it functions as an angular measurement tool.

Option analysis:

• Both (A) and (R) are true and (R) is the correct explanation of (A): Correct, double reflection optics explains its design and measuring range.
• Both true but not explanation: Incorrect, (R) directly explains the optical working mechanism of (A).
• is true but (R) is false: Incorrect, (R) is true.
• is false: Incorrect, (A) is true.

In commercial live-bait tuna pole-and-line fishing (as practiced in Lakshadweep and the Maldives), unbarbed (barbless) feather jigs or hooks are exclusively used. When a feeding tuna bites the lure and is swung overhead onto the deck, slackening the line immediately releases the fish without manual handling, enabling rapid continuous hooking.

In large-scale industrial Purse Seining, once a massive school of pelagic fish (sardines, menhaden, anchovies, tuna) is gathered and concentrated into the purse seine bunt alongside the vessel, large centrifugal fish suction pumps are lowered directly into the net pocket to rapidly pump fish and seawater directly into chilled sea water (CSW/RSW) holds without bruising.