Lecture 6: Fish Life History Flashcards
What is fish life history?
Fish life history describes how a fish grows, matures, and reproduces throughout its lifetime.
What is L50 in fish life history?
L50 is the length at which 50% of the fish population achieves reproductive maturity near the spawning period.
What are the trade-offs between early and late maturity in fish?
Early maturity: Increased chance of reproduction but reduced body size and fecundity.
Late maturity: Larger body size and higher fecundity but increased risk of mortality before reproduction.
What is the Gonadosomatic Index (GSI), and what does it measure?
GSI is the weight of the gonads relative to total body weight, indicating reproductive effort.
Give an example of fish variability in age at maturity.
Age at maturity can range from weeks (e.g., tropical fish) to 35 years (e.g., spiny dogfish).
How does egg size influence offspring survival and development?
Larger eggs increase offspring survival but prolong development time, increasing exposure to predators and environmental risks.
What is the trade-off between offspring size and number?
Producing many small offspring maximizes quantity, while producing fewer large offspring increases survival chances.
What are the two main spawning strategies in fish?
Iteroparity: Multiple reproductive events throughout life (e.g., cod).
Semelparity: A single, massive reproductive event before death (e.g., Pacific salmon).
What environmental factors influence fish reproductive timing?
Temperature, food availability, and habitat conditions regulate spawning times.
Why do some fish species delay reproduction?
Delayed reproduction allows fish to reach a larger size, improving survival and fecundity.
How does fishing pressure influence fish life history?
Fishing can favor earlier maturity and smaller body sizes due to selective removal of large, mature fish.
Which fish migrates to estuarine and coastal areas to spawn?
Flounder
Which fish forms large spawning aggregations during winter to early spring?
Atlantic Cod
Which fish lays adhesive eggs that stick to vegetation or substrates?
Atlantic Herring
Which fish constructs and guards nests during the spawning season?
Stickleback
