Lecture 4: Fish Growth and Recruitment Flashcards
What is fish growth, and what factors influence it?
Fish growth refers to an increase in size over time, influenced by food availability, temperature, and genetics.
What is the Von Bertalanffy Growth Function (VBGF)?
A model that describes fish growth as an asymptotic curve, using parameters:
L∞: Maximum size
k: Growth rate
t₀: Size at time zero.
What are the major fish life stages according to the saltatory model?
Embryonic
Larval
Juvenile
Adult
Senescent
How does temperature affect fish development and growth?
Higher temperatures increase metabolic rates and growth rates but can cause malformations or mortality at extremes.
What is recruitment in fish populations?
Recruitment is the process of juvenile fish surviving to join the adult or fishable stock.
What is the stock-recruitment relationship?
It describes the relationship between spawning stock size and the number of recruits produced.
Name two key stock-recruitment models.
- Ricker model: Density-dependent mortality at high stock sizes.
- Beverton-Holt model: Recruitment saturates at high stock sizes due to resource limitations.
What is compensatory growth in fish?
It is rapid growth following a period of slowed growth due to environmental constraints.
Why is the length-weight relationship important in fish?
It indicates growth patterns, condition, and environmental influences on fish.
What are the methods for determining fish age?
1.Hard parts analysis (e.g., otoliths, scales)
2.Length-frequency analysis
3.Direct observation using tagged fish.
What are the two types of compensatory growth adjustments in fish?
Thermal adaptation: Adjusting growth to temperature.
Countergradient variation: Genetic adaptation to environmental differences.
What is the critical period hypothesis in fish recruitment?
Early life stages (larval phase) are critical for survival, as mortality rates during this stage determine year-class strength.
What is the role of food consumption in fish growth?
Fish growth depends on food intake exceeding metabolic costs, which can be difficult to measure in nature.
Why is understanding age and growth important for fisheries management?
It helps predict population dynamics, manage fish stocks, and ensure sustainable exploitation.
