2017 Spring Bottom Trawl Survey

Leg I: Sampling Underway– One Fish at a Time

It’s been more than  a week since we sailed from Newport, RI, sampling is well underway, and we’re still heading south.  If we’re not working up fish, we’re waiting to work up fish.  A question constantly being asked is “what is the net doing” or “where are we”?  In other words, are we fishing, are we steaming (heading for the next sampling station), is a work-up currently happening, or are we sampling for water salinity, temperature and depth or for plankton.  Ultimately, the action begins when the net comes onboard!

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The checker filled with mostly dogfish. Photo by NOAA NEFSC/Christine Kircun

The net is pulled out of the water by large winches, and with help from a crane, the contents are dumped into a checker, or a big, metal holding bin.  The little door in the checker allows a scientist to push the fish onto a ladder conveyor belt that brings them onto a sorting belt inside the lab.

Conveyor belts are used at all parts of the sampling process to move catch where it needs to go.  The scientists on watch sort the fish into small, medium or large baskets.  As the baskets are filled and sent to the watch chief, they are entered into the sampling program and sent down another conveyor belt to the three sampling stations.

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Sorting squid coming into the wet lab on the conveyor belt. Photo by NOAA NEFSC/ Christine Kircun

There’s where scientists weigh the catch, record lengths and weights, and can take stomachs for food habits studies, remove hard parts like earbones and scales for aging studies, and make observations about fish condition and whether they are ready to spawn. After a basket is worked up, the remains are placed on a lower conveyor belt which leads to a shoot emptying into the ocean.

Depending on the area and time of year, we have a rough idea of what we’ll catch, but there are always surprises.  I’m on night watch (midnight to noon), and while the catch has mostly been spiny dogfish, we’ve also caught a blueline tilefish  and a mola.

Blueline tilefish, Caulolatilus microps, are found on mud and rubble bottoms, and is thought to inhabit burrows and may get up to 15 years old.  Their diet is mostly invertebrates that live on the ocean bottom, and the occasional fish.  Blueline tilefish range from around Virginia to southern Florida/Mexico and at depths of 30-130m.

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Blueline tilefish. Photo by NOAA NEFSC/Christine Kircun

The mola (sunfish) we caught was a  Mola mola, one of the world’s three species of mola. It is the heaviest known bony fish, and can weigh in at up to 5000 pounds.  They can be up to 14 feet long and 10 feet wide.  This fish swims in the uppermost waters of the ocean and is often found swimming lethargically and relaxing at the surface; sometimes laying on their side to let birds and small fish eat the many parasites off their skin.  Their diet consists mostly of jellyfish but also eat algae and zooplankton.

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Dogfish haul. Photo by NOAA NEFSC/Christine Kircun

Sometimes, it’s not just the unique fish we catch that is impressive, but the amount.  Just before breakfast, we brought up a very large deck-tow of spiny and smooth dogfish.  With the help of our survey tech and a deck-hand, it took 8 of us 5 hours to count the entire bag!  We finished just before watch change, which was perfect timing as we were definitely ready to go to bed.

Christine Kircun

NEFSC fishery biologist

Aboard the NOAA Ship Henry B. Bigelow

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