Reading Assignment:
• Chapter 10--Sensory Perception
Fish ear
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Growth:
• Longevity
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–
–
–
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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19 feet long; 350 pounds
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Growth: Other Generalities
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•
•
•
•
•
•
•
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
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Bioenergetics continued:
• Energy Budget:
I=M+G+E
where: I = ingested energy
M = energy expended for metabolism
G = energy stored as growth
E = energy lost to environment
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Bioenergetic Energy Budget:
I
M
heat
G
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Bioenergetics continued:
Ex: M =
energy for body repair
maintenance
activity
digestion
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Bioenergetics continued:
Ex: E =
energy in feces
ammonia, or urea
mucus
epidermal cells
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Terms:
• Standard Metabolic Rate
– maintenance met.; no growth, no activity
• Routine Metabolic Rate
– typical met.; routine growth & activity
• Active Metabolic Rate
– max. aerobic metabolism
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Factors Affecting Growth: Temperature
routine
Metabolic Rate
active
standard
scope
{
activity
growth
Where would
Temperature
growth be best?end
Factors Affecting Growth: Temperature
Metabolic Rate
normal O2
reduced O2
reduced scope
reduced growth
Temperature
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Growth will not occur at low O2
Ex: LMB cease growing below 5 mg/L
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Routine Metabolism
Factors Affecting Growth: Dissolved oxygen
O2 regulator (most species)
O2 conformer
critical O2 concentration
0
4
8
Dissolved Oxygen mg/L
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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
Aquarium problems
Transport problems
• as low as 0.6 mg/L for some spp.
• slow growth & tissue damage at 0.006-0.34
mg/L (continuous exposure)
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Effects of other factors on growth:
• Growth reduced at sub-optimal salinities
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Model: effect of environment on fishes
Metabolism
scope
simplify
scope
active metabolic rate - standard metabolic rate
Environmental Variable
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Model continued:
hypothetical physical or
lethal
lethal
lowlow
stressed
tolerance
Environmental Variable
tolerance
Stress
Scope
psychological stress
lethal
lethal
highhigh
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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
salmon; smelt
– migration
• anadromy- spawn in FW, mature in SW
• catadromy - spawn in SW, mature in FW
eels
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Anadromous salmon
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Overview of Reproduction continued
2. Anatomy:
– claspers - chondrichthyes
– gonopodium - Poeciliidae
– sexual dimorphism
• males larger in territorial species (salmon)
• females usu. larger in others
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catshark with claspers
claspers
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black molly gonopodium
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gonopodium
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Sexual dimorphism in salmon:
female
male
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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
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bluehead wrasse (Labridae)
male
• harem
• dominance hierarchy
• dominant F becomes M
female & juv.
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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
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–
–
–
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internal fertilization
eggs hatch internally
live birth
yolk only nutrition
EX: Lake Baikal sculpins
• marine rockfishes
• some sharks
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Lake Baikal
Approx. 400 mi. long
5315 ft
> 1 mi. deep
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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
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nurse shark embryos
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lemon shark pup
yolk sac and stalk function like placenta and umbilical cord
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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
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Parental care: pouches (seahorses, pipefishes)
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female
male
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Parental care: guarding
smallmouth bass--males
bullhead--both sexes
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