Reading Assignment:• Chapter 10--Sensory Perception

Fish earend

Growth:• Longevity

– unconfirmed reports of carp 200-400 yr.– authenticated records for carp 50 yr.– large fish-few > 12-20 yr.– some marine spp > 100 yr. thornyspines, orange

roughy– many small spp-2 yr. or less (sardines, anchovies)

Note: aging with scales, bones, otoliths

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end19 feet long; 350 pounds

Growth: Other Generalities

• females often larger than males• growth rate varies with temp.• longevity inversely proportional to temp.• stress reduces growth• dominance hierarchies - dominant get food• overcrowding can lead to stunting• indeterminate growth - grow throughout life• growth highly variable - can loose weight

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Bioenergetic Definition of Growth

• energy accumulation (calories) vs. length or weight

end

Bioenergetics continued:

• Energy Budget:

I = M + G + Ewhere: I = ingested energy

M = energy expended for metabolism

G = energy stored as growth

E = energy lost to environment

end

G

Bioenergetic Energy Budget:

I

E

M

heat

end

Bioenergetics continued:

Ex: M = energy for body repair

maintenance

activity

digestion

end

Bioenergetics continued:

Ex: E = energy in feces

ammonia, or urea

mucus

epidermal cells

end

Terms:

• Standard Metabolic Rate– maintenance met.; no growth, no activity

• Routine Metabolic Rate– typical met.; routine growth & activity

• Active Metabolic Rate– max. aerobic metabolism

end

Factors Affecting Growth: Temperature

Temperature

Met

abol

ic R

ate

standard

activeroutine

scopeactivity

growth{Where would

growth be best?end

Factors Affecting Growth: Temperature

Temperature

Met

abol

ic R

ate

normal O2

reduced O2

reduced scope

reduced growth

end

Growth will not occur at low O2

Ex: LMB cease growing below 5 mg/L

end

Factors Affecting Growth: Dissolved oxygen

Dissolved Oxygen mg/L

Rou

tine

Met

abol

ism

0 84

O2 regulator (most species)

critical O2 concentration

O2 conformer

end

end

Effect of Ammonia on Growth:• NH3 is more toxic than NH4

+

• relative Conc. Depends on pH– at 24C: 0.5% NH3 at pH = 7

34% NH3 at pH = 9

• 96 hr LC50 = 3.8 mg/L NH3

• as low as 0.6 mg/L for some spp.• slow growth & tissue damage at 0.006-0.34 mg/L

(continuous exposure)

Transport problems

Aquarium problems

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Effects of other factors on growth:

• Growth reduced at sub-optimal salinities

end

scope

Model: effect of environment on fishes

Environmental Variable

Met

abol

ism

scope

simplify

active metabolic rate - standard metabolic rate

end

lethal

high

lethal

low

Model continued:S

cope

tolerance

lethal

low

Str

ess

stressedtolerance

hypothetical physical or

psychological stress

lethal

highEnvironmental Variable

end

end

Overview of Reproduction:Varies greatly among fishes

1. behavior:– courtship behavior– nest building– parental care versus no care– mixed behaviors

• sneaker bass• sneaker and mimic bluegills

– migration• anadromy- spawn in FW, mature in SW• catadromy - spawn in SW, mature in FW

salmon; smelt

eels

end

Anadromous salmon

end

Overview of Reproduction continued

2. Anatomy:– claspers - chondrichthyes– gonopodium - Poeciliidae– sexual dimorphism

• males larger in territorial species (salmon)

• females usu. larger in others

end

catshark with claspers

claspers

end

black molly gonopodium

end

gonopodium

end

Sexual dimorphism in salmon:

male

female

end

Overview of Reproduction continued

3. Physiology– sex chromosomes:

• XY = M; XX = F (most)

• ZZ = M and ZW = F (Poeciliidae & Tilapia spp)

• some fishes have 3 or more sex chromosomes

– sex not under complete genetic control• hermaphrodites--both sexes (many in Serranidae)

– usu. one sex at a time– exception hamlet (serranid)

• sex changes--bluehead wrasse

end

bluehead wrasse (Labridae)

female & juv.

male

• harem

• dominance hierarchy

• dominant F becomes Mend

Overview of Reproduction continued

3. Physiology continued– parthenogenesis -- egg develops w/o fertilization

• Ex: Amazon molly– all female– produce genetic clones

• Ex: gynogenesis in Phoxinus (Cyprinidae)– all female– gynogenesis--sperm required, DNA from male not

incorporated in embryo

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Reproductive Modes in Fishes:• Oviparous -- egg layers; most fishes

– internal or external fertilization

• Ovoviviparous– internal fertilization– eggs hatch internally– live birth– yolk only nutrition– EX: Lake Baikal sculpins

• marine rockfishes

• some sharks

end

Lake Baikal

Approx. 400 mi. long

> 1 mi. deep

5315 ft

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Reproductive Modes in Fishes: continued

• Viviparous--live birth– nutrition provided directly by mother– EX: embryonic cannibalism -- a few sharks

• fins against uterine wall -- surf perches• placenta-like structures--pericardial tissues in

Poeciliidae

end

nurse shark embryosend

lemon shark pup

yolk sac and stalk function like placenta and umbilical cordend

Reproductive Strategies:Energy Investment

egg size: number vs. survivability

carp > 2,000,000

salmon 1500-2000

parental investment: energy vs. surviv.

nest building

parental care

mouth brooders--cichlids; ariids

end

Parental care: pouches (seahorses, pipefishes)

end

femalemale

end

Parental care: guarding

bullhead--both sexes

smallmouth bass--males

end