Wednesday, April 24, 2013

How Hard Can it Really be to Count Fish?

Figuring out how many fish are in the Gulf of Mexico and how many we can harvest isn’t rocket science; it’s harder.

Photo: Stubb
Harder, because fisheries are dynamic; and because there are an overwhelming number of factors like tides, temperature, salinity, composition of the ocean floor, nutrients, and biological interactions among fish that complicate the data and prevent straight forward cause and effect relationships from being identified.
Most fishermen have experienced this firsthand; one day the bite is on fire and fish are practically jumping in the boat, but when you return to the same spot a few days later there is nothing. Fish are finicky, they move, and they are hidden from plain view.

Photo: Muehlstein
Likewise, we all have some magic formula for a good fishing day, whether it be based on tides, moon phases, water temperature, or changes in air pressure. Different variations in the environment give different results even when our approach remains the same. Add salinity, ocean currents, nutrients, and water chemistry to the mix and there are almost too many variables to handle.

These challenges, and the ever present possibility for surprise or disappointment at the end of your line, are all part of the reason fishing is such a captivating activity.  It’s these same challenges that makes studying fish a very difficult endeavor.

Photo: Cone
Truthfully, we do not, and likely never will, know exactly how many fish are living in the Gulf of Mexico. Marine scientists and fisheries managers from across the country and around the globe share the challenge of getting the best fisheries data possible to make sound fisheries management decisions.

The following series of blogs titled “How hard can it really be to count fish?” will explain how fish stocks are assessed, the difficulties involved, and how scientist are continuously working to overcome the challenges of studying fish.

Photo: NOAA
The first piece of the puzzle titled “Fisheries Dependent Data Collection” explains how data is collected from fishermen to figure out what is being caught. 

The second piece titled “Fisheries Independent Data Collection” will explain the research that is done by scientist on the water. 

The final article - “South East Data Assessment and Review” - will explain how all the data is brought together and used to make conclusions about the health of a fish stock and the amount of fish that can be harvested.

So, stay tuned as the mystery of fisheries science is revealed.