WBCHSE HS Fisheries flashcards

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

Capture fishery

Harvest of naturally occurring wild fish stocks from rivers, estuaries and seas without deliberate stocking or husbandry inputs, as distinct from pond or cage culture.

Spawn

The newly hatched fish larva, about 5-8 mm long, still absorbing its yolk sac and depending on live plankton before it develops into a fry.

Blue Revolution

India's programme of rapid growth in fish and shrimp output through aquaculture technology, hatchery seed, extension support and infrastructure, mirroring the earlier Green Revolution in crops.

Fin formula

A shorthand count of fin rays in which capital letters name the fin (D, P, V, A, C), Roman numerals denote hard spines and Arabic numerals denote soft rays.

Cycloid scale

Thin, smooth, overlapping scale bearing concentric growth rings, found on most freshwater cyprinids such as rohu and catla, and used for age estimation.

Lateral line

A sensory canal running along the flank with pores that detect water vibration and pressure change; its scale count is a standard taxonomic character in fish identification.

Mrigal

Cirrhinus mrigala, a bottom-feeding Indian major carp with an inferior mouth, living on detritus, decayed plant matter and bottom organisms; it fills the pond bottom niche in polyculture.

Secchi disc transparency

A white and black disc lowered into water until it just disappears from view; a reading of about 30-40 cm indicates a healthy plankton bloom in a carp pond.

Unionized ammonia

The toxic NH3 fraction of total ammonia; its proportion rises sharply with pH above 8 and temperature above 30 C and should be kept below 0.1 mg/L.

Pond liming

Application of calcium carbonate or quicklime to raise soil and water pH, increase alkalinity and settle excess organic matter, with the dose adjusted to measured soil pH.

Nursery pond

A small pond of 0.02-0.05 hectare and 1-1.5 m depth used to raise spawn to fry and fingerling stage under careful manuring, feeding and predator control.

Hypophysation

Induced breeding by injecting homogenised pituitary gland extract from a mature donor fish into brood fish to trigger ovulation and spermiation when natural spawning fails in captivity.

Ovaprim

A commercial inducing agent combining salmon gonadotropin-releasing hormone analogue with the dopamine antagonist domperidone, injected at about 0.3-0.5 ml/kg for female carp.

Latency period

The interval between the final inducing injection and ovulation or spawning, roughly 6-12 hours in Indian major carps and shorter at higher water temperature.

Circular hatchery

A breeding complex with spawning pool, incubation tanks and a spawn collection chamber, where flowing water keeps eggs in motion and hatched larvae drain out for collection.

Feed conversion ratio

Total feed supplied divided by total fish biomass gained; values of about 1.5-2.0 are typical for carp on supplementary feed, and lower values mean better efficiency.

Pearson's square

A simple graphical calculation giving the proportions of two feed ingredients needed to reach a target crude protein percentage in a formulated fish ration.

Rice bran and oil cake

The conventional on-farm carp feed mixture of rice bran with mustard or groundnut oil cake in roughly equal parts, fed at 3-5 percent of body weight daily.

Epizootic ulcerative syndrome

A seasonal disease of wild and cultured fish in West Bengal caused by the oomycete Aphanomyces invadans, producing deep necrotic skin ulcers mostly in the cooler months.

Argulus

A crustacean fish louse that attaches to skin and gills, causing irritation, haemorrhagic spots and secondary bacterial infection, controlled by salt or permanganate baths.

Columnaris disease

A bacterial infection of freshwater fish by Flavobacterium columnare, showing grey-white saddle lesions on the back and frayed gills, favoured by warm water and crowding.

Withdrawal period

The mandatory interval between the last dose of an antibiotic or other drug and harvest or sale of fish, allowing residues to fall below permitted limits.

Composite fish culture

Polyculture of three Indian major carps with three exotic carps, combined so that surface, column and bottom feeding niches are fully used with minimal competition.

Paddy-cum-fish culture

Raising rice and fish together in one field with a refuge trench, where fish eat weeds, insects and snails while their excreta fertilise the standing crop.

Stocking density

The number of fingerlings released per unit pond area, commonly 5,000-10,000 per hectare in composite carp culture and adjusted for water depth and aeration.

Gill net

A wall of netting hung between a float line and a sinker line in which fish are gilled, wedged or tangled; mesh size determines which size classes are caught.

Seine net

An encircling net with long wings and a central bag, shot around a shoal and hauled ashore or across a pond to harvest the fish.

Hanging coefficient

The ratio of stretched netting length to the length of the float or sinker line, usually about 0.5, which controls mesh opening and the catching performance of gill nets.

TVB-N

Total volatile base nitrogen, a chemical spoilage index of fish; values above about 30-35 mg per 100 g of flesh indicate decomposition and rejection.

Chilled seawater storage

Preservation of fish in seawater cooled with ice to about -1 to 0 degrees Celsius, which cools faster and extends shelf life longer than ordinary box icing.

Benefit-cost ratio

The present value of a project's benefits divided by the present value of its costs; a ratio above one indicates that the aquaculture enterprise is financially viable.

FISHCOPFED

The National Federation of Fishermen's Cooperatives Ltd, an apex body supporting primary fishery cooperative societies in credit, input supply, marketing and member welfare.