Lecture 14 - Growth rates of specific species Flashcards
Mahi Mahi
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
Reproduction for large, predatory surface fish
Grow fast
Mature early
Reproduce often
Gnathophausia ingens
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)
Pop structure of Gnathophausia ingens
Low early mortality
Higher mortality before reproduction
Low mortality of mature females
Life style of brooding females of Gnathophausia ingens
Live deeper Don't feed Not subject to predation -little movement -not attraction to food -no chemo attractants from feeding
What peeks before egg release for Gnathophausia ingens
Carbon content
Nitrogen content
Energy content
Gnathophausia gracilis
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
%C for Gnathophausia gracilis
Larve decrease with instars
Females remain constant around 10%
Gnathophausia longispina
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
Reproduction in Gnathophausia longispina
Low fecundity - 8 to 14/fem Seasonal reproduction -eggs produced in June -7 month brooding -released April-May Semelparous
Gnathophausia longispina compared to Gnathophausia ingens
Shorter generation time
Smaller size
Gonatus fabricii
Bathypelagic squid (mesopelagic until maturity) Semelparous Don't feed during brooding (6-9 months) Females degenerate about 400 eggs
Dosidicus gigas
larger cephalopods
Grow fast to 6 ft long
Short lived (2-3 yrs)
Semelparous
Chiasmodon
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
What do transparent otolith edges tell you?
empty stomach
What do opaque otolith edges tell you?
full stomach partially digested
Deep living visual species of pelagic fish and crustaceans : growth
- grow larger than vertical migrators
- Have relatively linear growth
- Grow at same rate or faster than vertical migrators
Deep living visual species of pelagic fish and crustaceans : Life span
Live comparable or short lives than shallower species
Deep living visual species of pelagic fish and crustaceans : energy to reproduction
Devote a greater fraction of E to reproduction and growth than shallower species
Deep living visual species of pelagic fish and crustaceans : metabolic rate
Have lower metabolic rates (allow for more E to repro and growth)
Deep living visual species of pelagic fish and crustaceans : calorie content
Lower caloric content of deeper species allows larger sizes for a given energy cost
Deep living visual species of pelagic fish and crustaceans : reproduction
Semelparous or iteroparous
Onset of reproduction late in life
r is reduced compared to shallower species
Deep living visual species of pelagic fish and crustaceans : reproduction (if offspring develop at depth)
Small to moderate number of eggs High Iy low r low juvenile mortality high stability of recruitment and survival to reproduction
Deep living visual species of pelagic fish and crustaceans : reproduction (if offspring develop at surface)
Large number of eggs
low Iy
higher r
