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 7.4 Temp 21 C Hardness 75 ppm Oxygen 8 ppm Food, abundant Growth Reproduction Healthy

pH 7.4 Temp 21 C Hardness 75 ppm Oxygen 8 ppm Food, abundant Growth Reproduction Health 18 C

pH 7.4 Temp 21 C Hardness 75 ppm Oxygen 8 ppm Food, Scarce Growth Health 5 C Sick Or 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 #&$! !

Bass Tournament 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

The Aquarium 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 Hormones Adapting to Sudden Emergencies

HK Adrenalin

Head Kidney Cardinal Vein Chromaffin Cells Brain Nerve

Gills Heart Liver Intestine Spleen Swim Bladder Brain Muscle Head Kidney Trunk Kidney

Increases heart rateIncreases heart rate Increases breathing (respiration) rateIncreases breathing (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 Emergency = Epinephrine

Fish Hormones Adapting to “Slow” Emergencies

Starvation Entrapment Injury Social problems

HK Lateral Line Liver Nares… Pituitary Interrenalcells

Nerves Connecting Brain to Pituitary Hormone-Secreting Cells

Brain HK Interrenal Cells ACTH Adrenocorticotropic 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 Response Acute 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 HK Cortisol 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