Are fish shrinking?
Abigail Marshall, John Pinnegar (Cefas), Grant Bigg (University of Sheffield), Tom Webb (University of Sheffield) and Julia Blanchard (University of Sheffield)
It is thought that fish might be shrinking. We look at 2 perspectives: individual and community.
We can look at how individual organisms are changing - are fish actually shrinking?
We can also look at how the community is changing, this means all fish. Is it just that big fish are moving out of ecosystems causing the average community size to reduce?
There is a lot of work on different factors that might be causing reductions in size. However, there are many hypotheses for why.
Do we really care about shrinking fish?
Yes!! If body sizes tend towards smaller sizes this could lead to altered abundances, different food web interactions and changes in ecosystem resilience and function. Size is used for fishing limits so changes in size are important to know.
Possible causes to alter either individuals or communities:
Aim: To understand the relative effects of temperature, oxygen, food and fishing. Which factors are really the important ones?
We use both real data from fish surveys and models to attempt to answer this question.
We can look at how individual organisms are changing - are fish actually shrinking?
We can also look at how the community is changing, this means all fish. Is it just that big fish are moving out of ecosystems causing the average community size to reduce?
There is a lot of work on different factors that might be causing reductions in size. However, there are many hypotheses for why.
Do we really care about shrinking fish?
Yes!! If body sizes tend towards smaller sizes this could lead to altered abundances, different food web interactions and changes in ecosystem resilience and function. Size is used for fishing limits so changes in size are important to know.
Possible causes to alter either individuals or communities:
- Warming temperatures
- Reduced oxygen
- Changes in food
- Increased fishing pressure
Aim: To understand the relative effects of temperature, oxygen, food and fishing. Which factors are really the important ones?
We use both real data from fish surveys and models to attempt to answer this question.