Big female fish lay more eggs than the small ones, and it’s a fact known for over a century. A report published on 10 May in the journal Science strengthens this fact. It also contains information and results from data gathered from the oceans’ fish.
Biologists at the Smithsonian Tropical Research Institute (Panama) and Monash University (Australia) collected data from the eggs of 342 fish species from all the oceans.
The study authors Diego Barneche and Dustin Marshall (Monash University) used the vermilion snapper as an example. They said that between the smallest and the biggest mother fish, there was a 400-fold difference in eggs. A small female would lay almost 4,000 eggs, while a big one can deposit over a million.
The Bigger the Better
Researchers want to send a message to the fishing industry. Barneche and Marshall wrote:
“Most classic fisheries models don’t account for the massively disproportionate contribution that larger fish make, yet these are the first individuals to disappear under even a moderate fishing pressure. So, fisheries scientists, despite the best of intentions, have been using models that inadvertently recommend overharvesting.”
Another example of fish is the large Atlantic codfish. The researchers of this study explain that a 30 kg female Atlantic codfish is full of eggs and so are other females in her school. But unlike her, the females in that school weigh only 2 kg, meaning they deposit fewer eggs.
It’s obvious that the larger fish will deposit more than all the other smaller fish in her school. To spawn the same numbers of eggs as the 30 kg female, over 55 kg of small female cod would have to lay eggs.
Marshall explains that what wasn’t widely known is that old female fish not only lay more eggs, but their eggs are bigger and more abundant in fat. So, based on a higher quality of eggs from big female fish, Marshall argues that a 66-pound mother of cod will be equal to 37 little female cods:
“All else being equal, more and better eggs means more fish.”
Bottom line: fishing industry shouldn’t overfish large females.
Andre Blair s is the lead editor for Advocator.ca. He holds a B.A. in Psychology from the University of Toronto, and a Master of Science in Public Health (M.S.P.H.) from the School of Public Health, Department of Health Administration, at the University of North Carolina at Chapel Hill. Andre specializes in environmental health, but writes on a variety of issues.