Maharashtra HSC Vocational Fisheries Technology flashcards

32 cards. Read the term and the definition here. The deck at the top of this page is optional.

Composite fish culture

A polyculture method stocking surface, column and bottom feeding carps together so each species uses a different pond niche, maximizing yield per hectare.

Hypophysation

Induced breeding of fish by injecting pituitary gland extract or synthetic hormone to trigger spawning in species that do not breed naturally in captivity.

Gonadosomatic index

The ratio of gonad weight to total body weight expressed as a percentage, used to assess reproductive maturity and spawning season.

Length-weight relationship

The equation W = aL^b relating fish weight to length; the exponent b near 3 indicates isometric growth, otherwise allometric growth.

Countercurrent gas exchange

Blood flows through gill lamellae opposite to water flow, maintaining a concentration gradient that maximizes oxygen uptake.

Osmotic regulation

The physiological control of water and salt balance; freshwater fish excrete dilute urine, while marine fish drink water and excrete excess salts.

Gill net

A passive vertical net that entangles fish by the gills; mesh size determines the size range of catch.

Purse seine

An encircling net with a float line and purse line that closes the bottom, used to capture pelagic schooling fish.

Water activity

The availability of water for microbial growth; salting and drying reduce water activity below 0.75, inhibiting spoilage bacteria.

HACCP

Hazard Analysis Critical Control Point: a systematic food safety system identifying hazards, setting critical limits and monitoring control points during processing.

Break-even output

Fixed costs divided by contribution per unit, where contribution equals unit price minus unit variable cost; output at which total revenue equals total cost.

Benefit-cost ratio

Total discounted benefits divided by total discounted costs; a value above one indicates the project is economically viable.

Unionized ammonia toxicity

The toxic form of ammonia, harmful above about 0.1 mg/L; its proportion rises with higher pH and temperature.

Secchi disk transparency

A measure of water clarity indicating plankton density; 30-45 cm transparency suggests adequate pond fertility.

Epizootic ulcerative syndrome

A disease causing deep skin ulcers, associated with the oomycete Aphanomyces invadans, controlled by improving water quality and removing infected fish.

Quarantine in aquaculture

Isolating new stock for two to four weeks and disinfecting equipment to prevent introduction of pathogens into a farm.

Nitrogen cycle in aquarium

Nitrifying bacteria convert toxic ammonia to nitrite and then nitrate; the process takes four to six weeks to establish in a new tank.

Guppy reproduction

Guppies are livebearers with a gestation of about 28 days; pregnant females should be separated to prevent predation on fry.

PMMSY

Pradhan Mantri Matsya Sampada Yojana, a government scheme supporting aquaculture development, post-harvest infrastructure and fisher welfare.

Diffusion of innovation

The adoption curve classifying adopters as innovators, early adopters, early majority, late majority and laggards.

Fork length

The distance from the tip of the snout to the fork of the tail; total length extends to the tip of the caudal fin.

Condition factor

A measure of fish condition calculated as K = 100 W / L cubed, where W is weight and L is length; higher values indicate better condition.

Biofloc technology

An aquaculture system maintaining carbon-to-nitrogen ratio near 15:1 to 20:1, promoting heterotrophic bacteria that recycle nitrogen into microbial protein.

Lateral line system

A sensory system of neuromast receptors detecting water movement and pressure changes, aiding schooling and predator detection in fish.

Codend mesh size

The mesh dimension at the rear of a trawl; it regulates retention of juveniles and determines gear selectivity.

Surimi

Washed, minced fish myofibrillar protein used to make value-added products such as imitation crab and fish sausage.

Payback period

The time required for cumulative net cash flows to equal the initial investment, used to assess project liquidity and risk.

Brown blood disease

A condition caused by nitrite above 0.5 mg/L, which oxidizes haemoglobin and impairs oxygen transport in fish.

Argulus infestation

Infestation by the fish louse, a crustacean parasite controlled by salt baths or approved parasiticides.

Biological filtration

Use of nitrifying bacteria in aquarium filters to convert toxic ammonia to nitrite and then to less harmful nitrate.

FFDA

Fish Farmers Development Agency, a district-level body providing training, extension and pond development support to fish farmers.

Plankton sampling

Collecting plankton with a 50-100 micrometre mesh net and counting organisms under a microscope using a Sedgwick-Rafter cell.