Fish "Stress"

These fish are more likely to get sick then fish that remain in the pond…

These fish are more likely to get sick then fish that remain in the pond…

Largemouth Bass Tournaments

Why did the bass get sick?

Why don’t the fish grow larger?

The fish are making some sacrifices to

survive sub-optimal situations

pH 7.4Temp 21 CHardness 75 ppmOxygen 8 ppmFood, abundant

GrowthReproductionHealthy

pH 7.4Temp 21 CHardness 75 ppmOxygen 8 ppmFood, abundant

GrowthReproductionHealth

18 C

pH 7.4Temp 21 CHardness 75 ppmOxygen 8 ppmFood, Scarce

Growth

Health

5 C SickOr Dead

How do the fish make these

adjustments?

Fish use their brains and endocrine systems

(hormones) to adapt to changes in their

environment

Small changes mean small adjustments and

minor sacrifices

No Sweat

Bigger changes mean bigger adjustments and

bigger sacrifices

Yikes

Extreme changes or rapid changes can

exceed the fish’s ability to adapt

#&$!!

BassTournament

• Bass had to adapt to…– muscle fatigue– skin damage– puncture wound– temperature

changes– poor water

quality– crowding

• Some things had to be let go

• One of them was immunity

TheAquarium

• The fish had to adapt to– Poor water quality– Social competition– Photoperiod

disruption– Poor food quality

• The fish spent energy to deal with all of those problems

• There wasn’t enough energy left to support growth and reproduction

Summary• Fish adjust their behavior and

biochemistry to do the best that they can under the conditions

• If conditions are good, they will grow and reproduce

• If conditions are poor, they may have to spend all of the energy just to survive

• If things are really bad, they may not be able to adapt and will die

How Do Fish Make All The Needed Adjustments To Their Systems?

Fish Hormone

sAdapting to Sudden

Emergencies

HK

Adrenalin

Head Kidney

CardinalVein Chromaffin

Cells

Brain

Nerve

Gills

Heart LiverIntestine

Spleen

SwimBladder

Brain

Muscle

Head KidneyTrunk Kidney

• Increases heart rateIncreases heart rate• Increases breathing Increases breathing

(respiration) rate(respiration) rate• Opens gill circulatory systemOpens gill circulatory system• Open muscle circulationOpen muscle circulation• Decreases blood to gutsDecreases blood to guts• Releases sugar from liverReleases sugar from liver

The Beneficial effects of epinephrine/adrenaline are…

Better “fight or flight” capabilities

Acute Emergenc

y =

Epinephrine

Fish Hormones

Adapting to “Slow” Emergencies

•Starvation•Entrapment•Injury•Social problems

HK

Lateral LineLiverNares…

Pituitary

InterrenalInterrenalcellscells

Nerves Connecting Brain to Pituitary

Hormone-Secreting Cells

Brain

HK

InterrenalCells

ACTHAdrenocorticotropic Hormone

Cortisol

Brain: Perception of a stressful situation

Pituitary: Secretion of ACTH

Head Kidney: Secretion of Cortisol

Other Organs: Respond to cortisol

Nerves carry signal to pituitary

Blood carries ACTH to kidney

Kidney secrets cortisol into blood

Effects of Cortisol

•Protein catabolism–Breaks down protein for energy

Stress ResponseAcute

Emergency• Epinephrine• Increases

oxygen and fuel to muscles

• Fight or flight

Slow emergency

• Cortisol• Releases

stored energy

There is no such thing as a free lunch !

Stress•Fish must adapt to changes•Small changes good conditions= Great•Bigger changes or poorer condition = Trouble•Too big, bad conditions = Dead

Stress•Fish must adapt to changes•Small changes good conditions= Great•Bigger changes or poorer condition = Trouble•Too big, bad conditions = Dead

Epinephrine•Fight or flight•More oxygen and energy to muscles•Nerves from brain signal chromaffin cells in HK

Epinephrine•Fight or flight•More oxygen and energy to muscles•Nerves from brain signal chromaffin cells in HKCortisol•Slower emergencies that limit food availability•Energy from protein •Brain- nerves - pituitary – ACTH – Interrenal cells in HK

Cortisol•Slower emergencies that limit food availability•Energy from protein •Brain- nerves - pituitary – ACTH – Interrenal cells in HK