Wednesday, July 25, 2012

Trawls, longlines, and fishing poles, oh my!

I am always eager to learn more about seafood and the state of our country’s fisheries.  Last week, thanks to the Mississippi-Alabama Sea Grant Consortium, I was able to attend a week-long course titled Fins, Fishes, and Fisheries at Dauphin Island Sea Laboratory.  One of the focuses of the week was different fishing methods commonly used in commercial fisheries.  Myself and 18 other educators were able to go out on a research vessel and use the three most common fishing gears used in the Gulf of Mexico (trawls, longlines, and fishing poles) and discuss the sustainability of each gear type. 

Otter trawls and longlines are the most commonly used fishing gear in commercial fisheries.  Trawls are large nets dragged behind boats.  They have large wooden doors and a “tickle chain;” the doors help keep the net weighed down while the chain skips along the ocean bottom, scaring up creatures into the net.  
Our Research vessel       

Pulling in the trawl.  Photo by Cindy Peden

In the Gulf of Mexico, otter trawls are used in the shrimp fishery.  One of the biggest issues with bottom trawls is bycatch, or anything caught other than the target species. Below is a photo of everything our trawl caught.
Photo by Cindy Peden
Out of all those fish, we only caught a pound or two of shrimp.  As you can see in the picture below, it isn’t very much compared to the hundreds of pounds of fish the trawl pulled in.

We did get to see some interesting animals pulled in by the trawl, including Bay Squid, Atlantic Croaker, Spot, Spanish Mackerel, a gravid Blue Crab, and a Butterfly Ray.

Bay Squid
Gravid Blue Crab
Butterfly Ray
We even caught a remora, or a shark sucker.  I couldn’t resist trying to get this little fish to attach to my arm. It felt a little like a rubber suction cup.
Photo by Susan Howell
Thanks to the quick sorting by the Dauphin Island research staff, some of the bycatch was able to go back into the water alive.  However, most of it died, and unfortunately that is the norm.  The Food and Agriculture Organization (FAO) estimates that approximately 19 million pounds of bycatch is discarded as dead or dying, each year worldwide.  

After trawling, we put out the longlines, a central line that has hundreds of hooks hanging in the water column.  It is very similar to the trotlining TNACI does for Lake Sturgeon monitoring.  Longlines are commonly used for large pelagic species of fish, such as tuna, mahi mahi, and swordfish.

Mackerel Heads
We baited the longlines with mackerel heads and Atlantic Croaker and put out one mile of 1,000 pound test line with hooks at 60 foot intervals.  Commercial fishermen often deploy over 60 miles of hooks.

Spool of 1,000 pound test line.
Bycatch is also a problem with longline fishing.  While fishermen may be going after tuna or swordfish, sharks are commonly caught.  On the R/V Alabama Discover, we were actually targeting sharks to assist in research.  We caught two species, a Blacknose Shark and a seven foot Hammerhead Shark.  We tagged the Blacknose Shark, but the Hammerhead got away before we could tag it.  When a seven foot long fish that has lots of teeth starts struggling, you let it go!

Blacknose Shark
Hammerhead Shark.  Photo by Connie Gusmus.
Measuring the Hammerhead.  Photo by Lauren Morin
Lastly, we got to partake in one of the oldest fishing methods, pole and line fishing. Not only is this an ancient way to fish, it is also the most sustainable.  Only one or two fish can be caught at a time, and any bycatch can  usually be returned to the water alive.  Since this was the last day of Red Snapper season, that's what we were going for.

Susan Howell, a mathematics professor from University of Southern Mississippi with a Red Snapper.
While in Alabama, it was sobering to see some of the challenges facing fisheries management.  Communities on the Gulf are very reliant on fisheries for their income.  If this resource is not managed effectively, then many people will lose their jobs and livelihoods.  Currently, fisheries are very species specific, with fishermen only going after one species of fish on their boat.  Many of the species that are caught as bycatch in the shrimp fishery are important in other commercial fisheries, including Atlantic Croaker, Sardines, and Anchovies.  While we did not catch a sea turtle, we did see a few near our fishing areas.  Sea turtles are often caught by bottom trawls as the graze for food.  In the U.S., fishermen must use Turtle Exclusion Devices (TEDs).  Some fishermen also use Bycatch Reduction Devices (BRDs) to minimize finfish bycatch.  The takeaway message is that it is essential that we support U.S. fisheries due to the management regimes in place and to support our local fishermen.  However, continued research is necessary to ensure that the stocks we exploit for food are around for our grandchildren to enjoy.