1Early Life History and Growth –Chapters 9 & 10 • 2 growth traits set fish apart from other vertebrates:• Indeterminate Growth continual increase in length and volume• Larval Stage – larval stage usually bears little resemblance to juvenile or adultAdult Larval-Juvenile2Early Life History - Gametogenesis1) Gametogenesis- Spermatogenesis (sperm very variable)- Oogenesis(oocytes w/ yolk)- Vitellogenesis –yolk granulesEarly Life History - Fecundity • 2) Fecundity = number of eggs released by a female • – 1 or 2 up to millions; depends on life history v. Fertility (fish reabsorb unused eggs);3Early Life History - Fecundity • 2) Fertility v. Fecundity (based on egg counts)• Most marine fishes = pelagic and external fertilization;• Most Freshwater = parental care/bottom or vegetation or nests. Demersal – laid on bottomEarly Life History – Reproductive Effort 3) Reproductive Effort and Activity– Look at eggs – instantaneous versus cumulative measures• Instantaneous vs. Cumulative• Gonadosomatic index – GSI usually % weight – 5% (cichlids), salmonids (20%-30%) to 47% (eels) – males much lower4Early Life History – Reproductive Effort 3) GonadosomaticindexGood for total spawnersUnderestimates –repeat, batch or serial spawnersEarly Life History - Fertilization 4) Fertilization – external in most; internal in all sharks and a few bony families;Some poeciliid live bearers = gynogenetic (use other males sperm to activate);Internal requires males have intromittent organ (claspers, gonopodium)5Early Life History – Embryology5) Embryology – after fertilizationChorion hardens = water hardeningEarly Life History – Embryology5) Embryology– Oviparous – egg laying– Viviparous – develop inside mother = live bearing – about half (+500) Chondricthyes; 500 (2%) bony– Ovoviviparity – inside mother but depend on yolk– Development depends on temperature etc –causes meristic variation – usually colder means more scales, fin rays and vertebrae6Early Life History – Embryology5) Embryology– Meristic Variation - Development depends on temperature etc – causes meristicvariation – Jordan’s rule – latitude effects on meristicnumbers - usually colder means more scales, fin rays and vertebrae – opposite guppies and plaice– V relationship – fewer at intermediateEarly Life History6) Larvae– Free embryo (free swimming young with yolk sac -alevin) to Fry (planktonic food)7Early Life History 6) Larvae– Direct v. indirect development – larval stage brief or non-definable (“miniature”) versus distinct metamorphosis Early Life History6) Larvae– Larval Feeding and Survival – Food very important right after yolk stage –important for population dynamics of commercial species – most larvae die in first week from starvation/predation– Critical Period Hypothesis – Point of No Return8Early Life History6) Larvae– Larval Feeding and Survival – Match-Mismatch Hypothesis Early Life History6) Larvae Growth – More later under bioenergetics Gross Growth Efficiency - weight increase to weight foodAssimilation Efficiency – food actually used9Early Life History 6) LarvaeLarvae usually not like adult – spines, large fins etc for anti-predator protection – as fish get older (larger) usually less risk of predation. Ecological, physiological and behavioral competence all improve. Movement of larvae – interesting/debated – many marine fish spawn off shore. Larvae move inshore to weed beds/estuaries etc. – wind driven currents, tides etc.Individuals: Life Histories & Growth• Chapter 10 – Juveniles to Adults - Growth• 1) Juvenile when larval features lost vs. miniature adult• Growth = metamorphosis• Growth = change is size (body material)10Life History Characters • Age and size at maturation - Early v late = trade-off. • More eggs older but may die first; younger fewer eggs and reduced growth and weaker state if they decide to reproduce. • Fish under heavy predation reproduce sooner.Growth and Age• Growth = any change in size or amount of body material, regardless of whether that change is positive or negative or temporary or long lasting• Growth (energetically) = change in calories stored as somatic or gonad tissue (will discuss later)11Metamorphosis• Lampreys – ammocoetes to adult.• Asymmetric flatfish.• I. Depression (dorsal ventral flat) v. Compression (lateral flat).• Ii. Incomplete ossification and rotation.• Iii. Left eye flounders - sinistral.• Iv. Right eye flounders - dextral.Metamorphosis • Smoltification – salmonids (fresh to saltwater).– Redds – eggs – alevins (egg sac) – fry – parr w/ parr marks – after months/years go downstream (smolts).– Countershade silvery; Streamline – loss lipids, more buoyant (inc gas volume) – hemoglobinschange, gill structure (inc chloride cells) – reverse rheotaxis – imprint odor.– Hormonal control most changes; If don’t get to sea they revert to parr and mature quickly (1 yr).12Growth and Age - For Time T1 to T2 With Sizes Y1 and Y2• 1) Absolute Growth = Y2 – Y1• 2) Absolute Growth Rate = (Y2 – Y1) / (T2 – T1)• 3) Relative Growth = (Y2 – Y1) / Y1• 4) Relative Growth Rate = (Y2 – Y1) / [Y1 (T2 – T1)]• Linear process but if exponential use instantaneous growth rates; G = (log e Y2 – log e Y1) / (T2 – T1)13Length Versus Age = Growth Curves• Fit model to curve – von Bertalanffygrowth equation – Gompertz equation• Lt = Lmax (1 – e –gt) • T = time units (tx – t0), Lt = length at time t, Lmax = maximum length, g = growth coefficient, e = base natural logModel Equations14Quantification of Size Changes (Growth)• 1) Body length – standard length (SL), fork length (FL), total length (TL)Quantification of Size Changes (Growth)• Weight – traditional measure growth & production• Mass & Length – Easy to do –W = aLbwhere b usually 2.5 to 3.0 – W = log a + b log L• Good = more accurate as fish get larger; > or < 3 means positive or negative allometric growth • Bad = transient, water, lipids, gonads, stomach15Other Quantification size changes• K = condition factor for fish –K = W/L3 • Some use Wet v Dry weight v Ash WeightOther Quantification of size changes• Proximate Analysis – categories of compounds in a mixture • 1) Carbohydrates (low not typical)• 2) Proteins w/ M.W. over 10,00• 3) Lipids = good indicator16Scale and Allometry• Scale and