Fisheries Reproductive Ecology Flashcards
The essential concept of the Fisheries Reproductive Ecology
Different ways to get to the same goal: Maximize reproductively active offspring relative to available energy and parental life expectancy
What are the various types of reproductive strategies?
Semelparity
Iteroparity
Latitudinal variants
Semelparity
Spawn once and die
Iteroparity
Multiple spawnings over months (annual fishes) or years
Most common, found in most fishes
latitudinal Variants
Alosa sapidissimia; south (30-33°) semelparous whereas in the north (41-47°) iteroparous
Different sex characteristics
Gonochoristism
Hermaphroditism
Sequential
Gonocharistism
Fixed sex (most common)
Hermaphroditism
Simultaneous (rare) – able to release both sperm and eggs during same spawning (Serranus])
Sequential
Different sexes at different times
Protandry
Protogyny
Protandry
Males change to females
Protogyny
Females change to males
Fertilization Characteristics
External - most common
Internal
Parental Care
Nest building, egg guarding, bearing young
Parental Care - Internal bearers
Embryonic/larval stage only; usually no care following live birth
Parental Care - External Bearers
pre- or post-hatch; forehead, mouth, gill chamber,
skin, pouch
Parental Care - Trophic Provisioning
eggs or mucous
What are the various types of spawning - site and preparation characteristics
none
substrate choosers
Nest-builders
Broadcast/group spawners
Brood-hiders
Spawning rush
What are the most commercially exploited marine fish species?
Iteroparous
Gonochoristic
No sexual dimorphism
External fertilization
No (overt) parental care
What are the considerations when analyzing reproduction?
Lifespan
Onset of maturity
Early
Late
Interplay = spawning opportunities
Number and size of eggs
Number of batches/season
Relationship with size/age
Not all eggs are the same!
