Lecture 14 - Growth rates of specific species

Question 1

Mahi Mahi

Answer 1

Reaches sexual maturity in year 1
Reproduces multiple times per year
Reach max size (4-6ft) and dies in 3-4 yrs
Up to 12 million eggs per spawning

Question 2

Reproduction for large, predatory surface fish

Answer 2

Grow fast
Mature early
Reproduce often

Question 3

Gnathophausia ingens

Answer 3

Longer carapic = more in brood pouch
~2900 days total life (not long for large crustacean)
~500 days brooding (long)
Slowing growth than shallow species
Large size achieved late in life
-increased fecundity and protection when brooding
65% energy of instar 12 goes into eggs (15% parental care)

Question 4

Pop structure of Gnathophausia ingens

Answer 4

Low early mortality
Higher mortality before reproduction
Low mortality of mature females

Question 5

Life style of brooding females of Gnathophausia ingens

Answer 5

Live deeper
Don't feed
Not subject to predation
   -little movement
   -not attraction to food
   -no chemo attractants from feeding

Question 6

What peeks before egg release for Gnathophausia ingens

Answer 6

Carbon content
Nitrogen content
Energy content

Question 7

Gnathophausia gracilis

Answer 7

Deeper living than ingens
Ontogentic migrator - 600 m  to 1300 m
More instars than ingens (16 to 20+)
Smaller molt increments
Iteroparous 
   -lower fecundity 
Defer reproduction to end of life

Question 8

%C for Gnathophausia gracilis

Answer 8

Larve decrease with instars

Females remain constant around 10%

Question 9

Gnathophausia longispina

Answer 9

Topical regions with min O2 > 1 ml/l
Vertical migrator - 100 to 200 m at night, near bottom in day
7 instars
3.3 females to 1 male

Question 10

Reproduction in Gnathophausia longispina

Answer 10

Low fecundity  - 8 to 14/fem
Seasonal reproduction
   -eggs produced in June
   -7 month brooding
   -released April-May
Semelparous

Question 11

Gnathophausia longispina compared to Gnathophausia ingens

Answer 11

Shorter generation time

Smaller size

Question 12

Gonatus fabricii

Answer 12

Bathypelagic squid (mesopelagic until maturity)
Semelparous
Don't feed during brooding (6-9 months)
Females degenerate
about 400 eggs

Question 13

Dosidicus gigas

Answer 13

larger cephalopods
Grow fast to 6 ft long
Short lived (2-3 yrs)
Semelparous

Question 14

Chiasmodon

Answer 14

Black, shallower fish
Can eat up to 3x body mad and 6x body calories
Growth only at feeding
Linear relation b/t # meals and size
15-30 days between meals estimated from metabolism
High calorie food
Defer reproduction to end of life

Question 15

What do transparent otolith edges tell you?

Answer 15

empty stomach

Question 16

What do opaque otolith edges tell you?

Answer 16

full stomach partially digested

Question 17

Deep living visual species of pelagic fish and crustaceans : growth

Answer 17

1. grow larger than vertical migrators
2. Have relatively linear growth
3. Grow at same rate or faster than vertical migrators

Question 18

Deep living visual species of pelagic fish and crustaceans : Life span

Answer 18

Live comparable or short lives than shallower species

Question 19

Deep living visual species of pelagic fish and crustaceans : energy to reproduction

Answer 19

Devote a greater fraction of E to reproduction and growth than shallower species

Question 20

Deep living visual species of pelagic fish and crustaceans : metabolic rate

Answer 20

Have lower metabolic rates (allow for more E to repro and growth)

Question 21

Deep living visual species of pelagic fish and crustaceans : calorie content

Answer 21

Lower caloric content of deeper species allows larger sizes for a given energy cost

Question 22

Deep living visual species of pelagic fish and crustaceans : reproduction

Answer 22

Semelparous or iteroparous
Onset of reproduction late in life
r is reduced compared to shallower species

Question 23

Deep living visual species of pelagic fish and crustaceans : reproduction (if offspring develop at depth)

Answer 23

Small to moderate number of eggs
High Iy
low r
low juvenile mortality 
high stability of recruitment and survival to reproduction

Question 24

Deep living visual species of pelagic fish and crustaceans : reproduction (if offspring develop at surface)

Answer 24

Large number of eggs
low Iy
higher r