Marine Fish Reproductive Strategies: Types, Cycles, and Modes

What is the primary focus of fish reproduction?

The survival of young fish to reproduce.

What are the two main reproductive strategies in fish?

Semelparity (spawn once) and Iteroparity (spawn multiple times).

Give an example of a semelparous fish.

Salmon.

What is fecundity in the context of fish reproduction?

The number of eggs produced in a batch, over a year, or over a lifetime.

How does fecundity relate to egg size?

Fecundity and egg size are inversely related; larger eggs mean fewer produced.

What is the relationship between female age and fecundity?

Fecundity increases with the age and size of females.

Which type of fish typically has higher fecundity?

Pelagic-spawning marine fish.

What are the three modes of reproduction in fish?

Oviparity (egg-laying), Ovoviviparity (live-bearing without maternal provisioning), and Viviparity (live-bearing with maternal provisioning).

What is oviparity?

The most common mode of reproduction in fishes, involving external fertilization.

What is the ancestral condition of fish reproduction?

Oviparity, producing numerous small-sized eggs with little yolk provisioning.

What is the difference between internal fertilization and external fertilization?

Internal fertilization occurs inside the female, while external fertilization involves gametes shed into water.

What are the costs and benefits of broadcast spawning?

High number of eggs but low chance of survival due to predation.

What is the role of male claspers in elasmobranchs?

They are modified pelvic fins used for copulation.

What is the significance of yolk-sac placenta in viviparous fish?

It provides maternal provisioning to the developing offspring.

What is the spawning frequency of iteroparous fish?

They can spawn multiple times, which can be annual, seasonal, lunar-cyclic, or daily.

How does egg size change for batch spawners throughout the season?

Egg size typically decreases as the season progresses.

What is the typical reproductive strategy for rockfish?

Iteroparity, as they spawn multiple times.

What is the difference between demersal guarding and non-guarding modes of oviparity?

Guarding involves parental care of eggs, while non-guarding does not.

What is a brood in the context of fish reproduction?

A group of offspring that are cared for by the parents.

What is the primary energetic cost associated with viviparity?

High maternal energetic cost due to provisioning of offspring.

What is broadcast spawning?

A reproductive strategy where eggs and sperm are shed directly into the water column for external fertilization.

What are the two hypotheses for broadcast spawning?

1) Increase dispersal of offspring (spread risk) 2) Maximize transport of offspring away from adult habitat.

What is a bipartite lifecycle?

A lifecycle where habitats for larvae and juveniles are very different.

What are the survival challenges for offspring in broadcast spawning?

Low survival due to small larval size, lack of parental protection, and inability to return to juvenile habitat.

What is demersal spawning?

A reproductive strategy where eggs are placed on or attached to a substrate.

What are the two types of demersal spawning?

Hiders (e.g., grunion) and non-hiders (e.g., herring).

What is a benefit of demersal spawning?

Eggs may be better protected and there is greater control over where offspring end up.

What is the risk associated with demersal spawning?

High risk of losing an entire batch of eggs and lower dispersal.

What is parental guarding in demersal spawning?

A strategy where one parent, often male, guards the eggs, increasing their survival.

What are the energetic costs of parental guarding?

High energetic cost to the parent and increased risk of parent mortality.

What is brooding in reproductive strategies?

A method where young are cared for within the body of the parent.

Which species commonly exhibit brooding?

Male cardinalfishes, jawfishes, catfishes, female cichlids, and male seahorses.

What is gonochorism?

A sexual strategy with separate sexes and no sex change.

What is hermaphroditism?

A reproductive strategy where an individual has both reproductive organs.

What are the two types of sequential hermaphroditism?

1) Protogynous (female first, changes to male) 2) Protandrous (male first, changes to female).

What is the Size Advantage Model in sex change?

Predicts that an individual should change sex if its current reproductive value is less than what it would be if it changed sex.

What is the advantage of gonochorism?

Allows for sexual specialization.

What is a disadvantage of gonochorism?

May not maximize fitness.

What is the role of parental care in reproductive strategies?

Enhances survival through cleaning and oxygenation of eggs.

What is a common characteristic of species that employ guarding?

The guarding parent is often male.

What is the survival benefit of brooding?

Offspring are usually well developed when released, increasing their chances of survival.

What is a potential downside of brooding?

High energetic cost to the parent and low dispersal of offspring.

What is RV in the context of fish reproduction?

RV = expected fecundity at a given size × probability of surviving to that size.

What are the two key processes affecting variation in RV between sexes?

1) Relative cost of gametes (sperm = cheap, eggs = expensive). 2) Mating system (monogamy vs. polygamy).

Define polygyny.

Polygyny is a mating system where one male mates with many females.

Define polyandry.

Polyandry is a mating system where one female mates with many males.

What is protogyny?

Protogyny is a reproductive strategy where individuals start as females and can change to males.

What is protandry?

Protandry is a reproductive strategy where individuals start as males and can change to females.

How does RV change with body size for females?

RV for females increases linearly with size.

How does RV change with body size for males?

RV for males depends on the mating system, including competition for mates.

What factors influence male reproductive success in fish?

Limited access to females, competition for and defense of territories, and female selection of large males.

What is reversible sex change in fish?

Reversible sex change is a rare phenomenon where some fish can change sex back and forth, often seen in gobies.

What is simultaneous hermaphroditism?

Simultaneous hermaphroditism is when an individual has both male and female reproductive organs at the same time.

In which groups of fishes is simultaneous hermaphroditism common?

Common in deep sea fishes and small serranids.

What is the significance of egg trading in small serranids?

Egg trading allows cheaters to be detected and punished, preventing cheating in mating.

Describe the mating behavior of deep sea anglerfish.

Males bite females, fuse blood vessels, and degenerate except for testes, allowing females to reproduce whenever they want.

How many males can a female anglerfish absorb at one time?

A female anglerfish can absorb up to 6 males at one time.

What challenges do deep sea fish face in finding mates?

Finding a mate is difficult due to the vast distances and low population densities in the deep sea.

What is the role of female selection in protogyny?

Females select the largest males, influencing male competition and mating success.

What is the main advantage of protandry in fish?

It allows small males to be successful in reproduction when there are no defendable resources or direct male competition.

How does the mating system influence RV in males?

Males' RV is influenced by competition for mates and the number of females they can fertilize.