Behind the Nets: How an Otter Trawl Helps Us Understand Marine Life
An otter board, part of Tampa Bay Watch’s otter trawl net.
by Connor Krusbe
My name is Connor Krusbe and I am an intern working on the Tampa Bay Watch Discovery Center’s Eco Vessel. During our voyages out on the boat, we explore the diversity of Tampa Bay’s estuary ecosystem in many different ways, striving to conserve the bay and educate the public on the importance of this environment. When we think of marine exploration, we often picture scuba divers, underwater cameras, or submersibles venturing far in to the deep; however, sometimes the simplest tools can prove to be the most effective. One such tool that we utilize on a near daily basis is the otter trawl net; a fishing net designed to glide across the seafloor, allowing us to receive a glimpse of the marine life in a given area.
The operation of an otter trawl net is a fairly straightforward endeavor. The net itself is in the shape of a funnel, tied at the small end in order to trap fish and other organisms that might enter. It has ropes on the ends which are tied to the cleats on the back of the boat, a buoy to hold the net above the seafloor, and a tickle chain to stir up any organisms that may be below the waves. I’m sure you may be wondering at this point why it is called an otter trawl net, and the explanation is rather simple. The last notable features of the net are what we call ‘otter boards’. These two wooden boards on either end of the net are designed to keep the large mouth end of the net wide open while being pulled behind the boat in order to catch as many organisms as possible. While in the water, many believe that these boards look like otters, giving it the name, otter trawl net.
As far as practical uses, the applications are near limitless. By using this otter trawl net, we here at Tampa Bay Watch are able to obtain crucial data that can be used to help conserve the health of the ecosystem in our estuary. As we pull the net behind the boat, not only are we hoping to pull up some cool sea critters, we are also making note of many different variables including pull location, air and water temperature, salinity, etc. This information helps track environmental changes, seasonal migrations, as well as overall ecosystem health, guiding conservation efforts in Tampa Bay and aligning with the mission of Tampa Bay Watch.
Although this information is critical in terms of furthering our conservation efforts, our Special Activities License (SAL) only permits certain activities and the collection of specific organisms. We are limited in collection by factors such as species, quantity, and size; however, the majority of the species that we collect during our trawls are used for data collection only, and are then released the same day. By operating our otter trawl net in this fashion, we are able to collect crucial data that could help conserve the beauty and biodiversity in Tampa Bay, without upsetting the balance of local populations.
An otter trawl net.
