you're reading...


Are bigger moms better moms?

The Paper

Saenz-Agudelo, P., Jones, G. P., Thorrold, S. R., & Planes, S. (2015). Mothers matter : contribution to local replenishment is linked to female size , mate replacement and fecundity in a fish metapopulation. Marine Biology, 162, 3–14. doi:10.1007/s00227-014-2556-x


We all rely on generally accepted assumptions that may or may not be true (making an ass of ‘u’ and me of course). Sometimes scientists are just like normal people and do the same. For years fisheries management has used the assumption that female size is an indicator of how many eggs will be produced and so larger females will produce more young that successfully reach adulthood. This idea seems reasonable enough but surprisingly has rarely been tested scientifically due to the logistical difficulty of following eggs to adulthood. Saenz-Agudelo et al. to the rescue!

Methods and Results

The researchers chose to use the charismatic panda anemonefish (Amphiprion polymnus) as their study mothers (Fig 1). This study followed the fish through four transitions from mother to egg to larvae to juvenile to adult. DNA fingerprinting allowed them to follow individual anemone fish, and parentage analysis creates a family tree. The researchers directly observed eggs produced by each female through regular dive surveys.


Fig 1

Fig 1. Map of study area (Bootless Bay, Papua New Guinea) and study species the panda anemone fish.

Is female size linked to number of eggs?

Yes! Larger females laid more eggs, up to 15,000 in two months (Fig 2). This part of the study upholds previous research findings. The novel part of this work comes from following the eggs to the next stage.

With so many eggs the sea would be overrun with panda anemonefish if the majority of eggs did not die. Following thousands of eggs to the larval stage and up to adulthood is no small task and had never been done before. The amazing world of genetics opened up this possibility and the researchers in this paper were able to accomplish something new and exciting and determine if the extra eggs produced by large females actually makes a difference for the population.


Fig 3.

Fig 3. (A) Larger females are more likely to have at least one successful young reach adulthood. (B) When male replacement did not occur (zero) the pair is more likely to have at least one offspring survive to adulthood.

Fig 2.

Fig 2. Larger females produce more eggs.

Do larger females contribute more new young to a population?

Not quite. Larger females are more likely to contribute at least one successful offspring to adulthood but female size is not a good indicator of how many young will make it to adulthood (Fig 3). The researchers found no evidence that larger mothers contribute a higher number of offspring to the population.

Dads matter too!

The investigators also found that stable mother-father pairs were more likely to have at least one successful offspring than a female that replaced its male partner due to the male’s death.

So- partnership stability and larger females lead to a better chance of having one child that survives long enough to enter into the adult population. But, there is no reason to believe based on this study that the many more eggs produced by large females lead to many more successful adults.


Discussion and Significance 

Using empirical evidence to test assumptions is what science is all about and this paper does just that for an important fish life history assumption. Fisheries management and conservation decisions must be based on accurate science to have the best chance at success. The work in this paper helps to further this knowledge as the first study to assess the parents’ influence on marine fish offspring as they transition from larvae to adults.

An unexpected outcome of the study was learning the importance of a stable pair for the best chance at having any successful offspring. Protecting breeding pairs, males and females, could be an important consideration for fish population health.

Protecting large females is a common management strategy. If larger females are not contributing more young to the next generation than smaller females then the strategy may not be helping. Or the higher chance of at least one successful adult could be important enough to the population that large female fish should be universally protected. Though more research is needed to understand what makes the large females more likely to have at least one successful young this study does a great job of starting a discussion about this management strategy.



No comments yet.

Post a Comment


  • by oceanbites 1 day ago
    Leveling up - did you know that crabs have a larval phase? These are both porcelain crabs, but the one on the right is the earlier stage. It’s massive spine makes it both difficult to eat and quite conspicuous in
  • by oceanbites 1 week ago
    This week for  #WriterWednesday  on  #Oceanbites  we are featuring Cierra Braga. Cierra works ultraviolet c (UVC) to discover how this light can be used to combat biofouling, or the growth of living things, on the hulls of ships. Here, you
  • by oceanbites 2 weeks ago
    This week for  #WriterWednesday  at  #Oceanbites  we are featuring Elena Gadoutsis  @haysailor  These photos feature her “favorite marine research so far: From surveying tropical coral reefs, photographing dolphins and whales, and growing my own algae to expose it to different
  • by oceanbites 1 month ago
    This week for  #WriterWednesday  on Oceanbites we are featuring Eliza Oldach. According to Ellie, “I study coastal communities, and try to understand the policies and decisions and interactions and adaptations that communities use to navigate an ever-changing world. Most of
  • by oceanbites 1 month ago
    This week for  #WriterWednesday  at  #Oceanbites  we are featuring Jiwoon Park with a little photographic help from Ryan Tabata at the University of Hawaii. When asked about her research, Jiwoon wrote “Just like we need vitamins and minerals to stay
  • by oceanbites 2 months ago
    This week for  #WriterWednesday  on  #Oceanbites  we are featuring  @riley_henning  According to Riley, ”I am interested in studying small things that make a big impact in the ocean. Right now for my master's research at the University of San Diego,
  • by oceanbites 2 months ago
    This week for  #WriterWednesday  at  #Oceanbites  we are featuring Gabby Stedman. Gabby is interested in interested in understanding how many species of small-bodied animals there are in the deep-sea and where they live so we can better protect them from
  • by oceanbites 2 months ago
    This week for  #WriterWednesday  at  #Oceanbites  we are featuring Shawn Wang! Shawn is “an oceanographer that studies ocean conditions of the past. I use everything from microfossils to complex computer models to understand how climate has changed in the past
  • by oceanbites 2 months ago
    Today we are highlighting some of our awesome new authors for  #WriterWednesday  Today we have Daniel Speer! He says, “I am driven to investigate the interface of biology, chemistry, and physics, asking questions about how organisms or biological systems respond
  • by oceanbites 3 months ago
    Here at Oceanbites we love long-term datasets. So much happens in the ocean that sometimes it can be hard to tell if a trend is a part of a natural cycle or actually an anomaly, but as we gather more
  • by oceanbites 4 months ago
    Have you ever seen a lobster molt? Because lobsters have exoskeletons, every time they grow they have to climb out of their old shell, leaving them soft and vulnerable for a few days until their new shell hardens. Young, small
  • by oceanbites 4 months ago
    A lot of zooplankton are translucent, making it much easier to hide from predators. This juvenile mantis shrimp was almost impossible to spot floating in the water, but under a dissecting scope it’s features really come into view. See the
  • by oceanbites 4 months ago
    This is a clump of Dead Man’s Fingers, scientific name Codium fragile. It’s native to the Pacific Ocean and is invasive where I found it on the east coast of the US. It’s a bit velvety, and the coolest thing
  • by oceanbites 5 months ago
    You’ve probably heard of jellyfish, but have you heard of salps? These gelatinous sea creatures band together to form long chains, but they can also fall apart and will wash up onshore like tiny gemstones that squish. Have you seen
  • by oceanbites 6 months ago
    Check out what’s happening on a cool summer research cruise! On the  #neslter  summer transect cruise, we deployed a tow sled called the In Situ Icthyoplankton Imaging System. This can take pictures of gelatinous zooplankton (like jellyfish) that would be
  • by oceanbites 6 months ago
    Did you know horseshoe crabs have more than just two eyes? In these juveniles you can see another set in the middle of the shell. Check out our website to learn about some awesome horseshoe crab research.  #oceanbites   #plankton   #horseshoecrabs 
  • by oceanbites 7 months ago
    Feeling a bit flattened by the week? So are these summer flounder larvae. Fun fact: flounder larvae start out with their eyes set like normal fish, but as they grow one of their eyes migrates to meet the other and
  • by oceanbites 7 months ago
    Have you seen a remote working setup like this? This is a photo from one of our Oceanbites team members Anne Hartwell. “A view from inside the control can of an underwater robot we used to explore the deep parts
  • by oceanbites 8 months ago
    Today is the day of  #shutdownacademia  and  #shutdownstem  and many of us at the Oceanbites team are taking the day to plan solid actions for how we can make our organization and the institutions we work at a better place
  • by oceanbites 8 months ago
    Black lives matter. The recent murders of Ahmaud Arbery, Breonna Taylor, and George Floyd have once again brought to light the racism in our country. All of us at Oceanbites stand with our Black colleagues, friends, readers, and family. The
WP2Social Auto Publish Powered By : XYZScripts.com