La Cienega Project
Organ Pipe Cactus National Monument

2004 Quitobaquito Pupfish Census

So, how do we catch those fish? We use traps, of course! We set out these traps which are specially designed so the fish can swim into either end, but they cannot swim back out until we release them. After the traps are set for two hours, we go around to each trap and open them so we can count the fish.

We don't catch all of the fish in the first try, so we set the traps three times in one day. Once the fish are counted, they are put into a holding pen in the pond so that they don't swim back into the traps and get counted again. By the end of the day, we have counted enough of them to make the population estimation and let all the fish swim free.

This year we caught 3,805 fish, which means the population is estimated between 8,000 and 12,000. That might seem like a big number of fish, but remember, it is a very small fish. It might also seem like we could get a closer guess than "between 8 and 12 thousand," but there is no way to catch all the fish in the pond, so we make the best educated guesses we can. This estimate for 2004 fits right in with what we expected from all the data previously collected. Click here to see the data from previous years.

Scientists have been trying to come up with a better, more accurate, way of counting the fish. But we have been using this method for at least 12 years. Even if we don't catch and count them all, we can still tell if the population is getting bigger, getting smaller, or even staying roughly the same. Being able to compare this year's data with the years' previous data is more important than getting the absolute, perfect, count of every single fish in the pond.

Once we count them, we also want to know how big they are. So, we randomly choose a few from each trap and use a ruler to measure them. This has to be done very quickly so the fish don't get too stressed out by being out of the water for too long.

Knowing how big the fish are will help us to understand how old they are, too. Are there lots of 2 yr old fish (average around 40-50 mm), or are they mostly tiny fry (15-25 mm)? By looking at the data we can tell. We are still looking at this year's data, stay tuned to find out how old our fish are. This year the smallest fry (baby fish) we measured was only 11mm long. The biggest was a whopping, record-breaking 60mm! (Still pretty small, smaller than a tube of lip balm).