Dictionary of Ichthyology
Brian W. Coad and Don E. McAllister†
Y
Ys = maximum sustainable yield (the average or maximum catch that can be removed under existing environmental conditions over an indefinite period without causing the stock to be depleted, assuming that removals and natural mortality are balanced by stable recruitment and growth. Abbreviated also as MSY. Also called maximum equilibrium catch, maximum sustained yield, sustainable catch).
Y/R = abbreviation for yield-per-recruit (the expected lifetime yield-per-fish of a specific age, e.g. per age 2 individual. For a given exploitation pattern, fishing regime, rate of growth and natural mortality, an expected equilibrium value of Y/R can be calculated for each level of fishing mortality (F)).
Y-piece = extension piece (tapered sections of netting between the belly and the batings and the cod end of a trawl. Also called pipe, swallow piece, tail, tail piece, taper).
ya = abbreviation for years ago.
yaag = 1) to keep a hand line in constant motion to attract fish to the bait (Shetland Isles dialect).
yaag = 2) to buy up fish on the quiet which the seller is contracted to deliver to someone else (Scottish dialect). Also spelled yagg and jag.
yaager = yagger.
yaar = yair (2).
yaffle (noun) = 1) an armful of dried or nearly dried salt fish in Newfoundland, i.e. the amount that could be comfortably carried under one arm. Also a small yaffle could be as many fish as could be held in two hands together and a large yaffle what a man can gather in his two arms.
yaffle = 2) to take up an armful of fish and referring to the work of spreading, gathering and piling fish.
yaffle at hand = call used by Newfoundland fishermen loading dried cod when a yaffle is gathered together.
yaffle up = yaffle at hand.
yag = a shoal of small and worthless fry (Scottish dialect).
yagg = yaag (2).
yagger = 1) jagger (a hawker of fish (archaic). See also jouster, jager, jaager and yaager).
yagger = 2) a tender for the Dutch herring fleet off Shetland, bringing stores from Holland and carrying the fish catch home.
yair = 1) a fish lock such as a mill dam (Durham dialect).
yair = 2) a curved enclosure of stones or stakes wattled with twigs and brushwood built on the shore or a river bank, trapping salmon as the tide recedes. Some are named, e.g. Rutyare, Maleyare (British dialect). Also spelled yaire, yaar and yare.
yaire = yair (2).
yakiboshi = a fish product dried after boiling or toasting. It is usually gutted and skewered with bamboo pins or in some cases split fish or slices are used. Usually combined with the name of the fish as a suffix (Japan).
yalla cod = smoked cod (Scottish dialect).
yamabuki = ornamental carp or koi (q.v.), being a yellow metallic fish.
yard = 0.914 m. Abbreviated as yd.
yard seine = beach seine (a net used to encircle fish in shallow water; usually operated by two people wading out from shore, the net has lead weights to keep the bottom on the sea floor and floats to keep the top of the net at or near the surface; there may be a bag extending back from the centre of the nets length to increase capture efficiency. The seine may be set from a boat but hauled in from the land. Also called shore seine, drag seine, draw net, haul seine and sweep net).
yare = yair (2).
yarkin(g) = fish biting freely.
yarkin (g) = 2) a line passed through the meshes of a fish-net and fastened to the rope attached to floats which suspend the net in the water (Newfoundland).
yarkin(g) mesh = that part of a fish-net which is fastened to the head-rope (Newfoundland).
Yarmouth bloater = 1) a red herring, q.v.
Yarmouth bloater = 2) an inhabitant of Yarmouth (Peggotty in Dickens' David Copperfield).
Yarmouth capon = a red herring. See also capon.
yarn = netting in the main body of a drift net (east Scotland).
yaw = rotation of a swimmer around its vertical or dorso-ventral axis.
yawling = 1) herring nets allowed to drift with the tide (Kentish dialect).
yawling = 2) small herring (Clupea harengus).
yawning = seen in some aquarium fish and appears to be a response to poor water quality and possibly gill disease or parasitism.
ybp = years before present.
yd = abbreviation for yard (0.914 m).
YE or YE = the yield in weight taken from a fish stock when it is in equilibrium with fishing of a given intensity, and (apart from effects of environmental variation) its biomass is not changing from one year to the next (Ricker, 1975). Also called sustainable yield, equivalent sustainable yield.
year brood = year class.
year class = all the individuals of a population of fishes born or hatched in the same year, e.g. 1995. After this brood is recruited to the fishery it appears year after year until all its members die, and is referred to as the 1995 year class throughout its life. Also called brood, year brood, cohort or generation. In the northern hemisphere where spawning occurs in fall and hatching in spring, the calendar year of the hatch is commonly used to identify the year class, except usually for salmonids (Ricker, 1975). The biomass of a year class initially increases as fish grow, reaches a peak at a certain age depending on the species, food availability and mortality, and then starts to decrease as fish die off and growth slows.
year mark = marks appearing on growing structures of a fish, such as bones, scales, otoliths, etc. These marks can be used to interpret the annual or daily growth, age, spawning time, etc,
year-class effect = the common domination of a species population by individuals recruited in one reproductive season.
year-round fishery = a fishery carried out throughout the year, without cessation.
yearling = a member of age-group I, in the second calendar year (Hubbs, 1943). May also refer to a fish about one year old or to fish 1-3 years old.
yeel couple = the fish allotted to each member of a family as a Christmas treat (Scottish dialect, from yule).
yeel fish = usually a smoked haddock, a special delicacy at Christmas (Scottish dialect. from yule).
yellow cure = Portuguese salt cod with some of the salt removed by soaking in water between stages of washing and drying, yellowish in appearance. Also called amarelo cure.
yellow fish = smoked fish, especially cold smoked white fish.
yellow grub = an infestation of fish with the metacercariae of Clinostomum marginatum, a digenetic trematode.
yellow water = water in aquaria with a slight yellowish tinge usually indicative of too much organic material. Can be removed by carbon filtration.
yield = 1) catch in weight. Catch and yield are often used interchangeably. Amount of production per unit area over a given time. A measure of production. The sustainable yield is the quantity of fish which can be taken from a stock (usually on an annual basis) without severely depleting or eliminating that stock.
yield = 2) the amount of product obtained from raw fish material. The edible yield of fish from skinless fillets is about 40%, varying with species, size, season, condition, etc.
yield curve = the relationship between the expected yield and the level of fishing mortality or fishing effort.
yield-per-recruit = the expected lifetime yield-per-fish of a specific age (or the average recruit), e.g. per age 2 individual. Abbreviated as Y/R. For a given exploitation pattern, fishing regime, rate of growth and natural mortality, an expected equilibrium value of Y/R can be calculated for each level of fishing mortality (F).
yield-per-recruit analysis = analysis of how growth, natural mortality, and fishing interact to determine the best size of the fish at which to start fishing them, and the most appropriate level of fishing mortality. The yield-per-recruit models do not consider the possibility of changes in recruitment (and reproductive capacity) due to change in stock size. They also do not deal with environmental impacts.
yo-yo = 1) retrieval of a lure by a straight up-and-down movement from the bottom to the top, enticing a fish to strike.
yo-yo = 2) a very small haddock, derived from the appearance and the movements of the fish on the hook (slang at Lossiemouth, Scotland).
yo-yo winch = a type of winch used on deep-sea stern trawlers. A winch is mounted near the stern ramp on each side and they are used for shooting the net away and for emptying the cod end.
yoke = dan leno stick (a ballasted wood pole with short rigging ropes attached, functioning like the dan leno bobbin).
yoke hoop = dan leno hoop (a hoop-shaped dan leno made of bent wood with short rigging ropes wired to the outer circumference. Also called dan leno ring, geer, hoop, hoop bridle, round dan leno and yoke hoop).
yoke stick = dan leno stick (a ballasted wood pole with short rigging ropes attached, functioning like the dan leno bobbin).
yoked key = indented key (a dichotomous key in which the first part of a couplet is followed by all subsequent couplets. Each subordinate couplet is indented to the right for reasons of clarity; not much used in ichthyology).
yolk = granules of semi-crystalline phospholipoprotein used as a nutrient store during embryonic development.
yolk ball = the anterior round region of the yolk cell present after the yolk extension forms during the segmentation period.
yolk cell = a giant syncytial uncleaved cell containing the yolk. It underlies the blastodisc early in development and becomes enveloped by the blastoderm during epiboly.
yolk extension = the posterior elongated region of the yolk cell that forms during the segmentation period.
yolk granule = a membrane-bounded sac containing yolk. These 50 μm granules are densely packed in the interior of the yolk cell and make up most of the cell.
yolk plug = yolk within the blastopore.
yolk sac = a sac containing yolk used for nourishment in larval fish.
yolk stripe = a series of melanophores along the median ventral aspect of the yolk ball and particularly the yolk extension.
yolk syncytial layer = a peripheral layer of the yolk cell including nuclei and non-yolky cytoplasm.
yolk-sac larva = a fish larva which has already hatched from the egg but has not started feeding yet and still absorbs the yolk in the ventrally attached yolk sac. At the end of this stage in development, the yolk and oil globule(s) have been used up, the major organ and sensory systems required to capture and digest prey are functional, and the primordial pectoral fins are present.
yolk-sac placenta = the yolk-sac helps in formation of a placenta which allows a connection of the embryo to the mother for nourishment.
yook = hook (northeast England).
yorking = yarkin (g).
"you fish your side of the water, I fish my side of the water, nobody fishes the middle" = Chargoggagoggmanchauggagoggchaubunagungamaugg, the Algonqin name of a lake in Webster, Massachusetts, incorrectly said to have this meaning. Really means "Englishmen at Manchaug at the Fishing Place at the Boundary". Longest place name in the United States.
young = a term loosely applied, because any precise distinction involves age determination, to immature fishes.
young-of-the-year = members of age group zero, from transformation to juvenile until January 1 in the Northern Hemisphere or July 1 in the Southern Hemisphere (Hubbs, 1943).
younger synonym = junior synonym (the junior synonym is that with the later publication date of two or more different names applied to one and the same taxon).
youthful river = a river having a steep gradient, few tributaries, rapid flow and its channel eroded deeper than wider. See also mature, old and rejuvenated rivers.
YOY = abbreviation for young-of-the-year.
yr = year.
yrs = years.
© Brian W. Coad (www.briancoad.com)