Another survey season has just wrapped up for the Gulf of Maine Bottom Longline team. While going to sea and working on these surveys can be fun and exciting, it also drastically disrupts our social and biological schedules. During survey season—April and May in the spring and October and November in the fall—I tend not to make any land-based plans, or see many people from my non-working life. Our schedules are highly dependent on weather conditions and can change at a moment's notice. At the end of every survey season, when I announce my return from sea in various text messages and emails, I invariably get asked: "So … what do you do out there?"
Sampling the Gulf of Maine’s Rocky Bottom
The Gulf of Maine Bottom Longline Survey focuses on rocky bottom areas in the Gulf of Maine that are challenging for the Bottom Trawl Survey to sample. Using longline gear, we are able to get better data on groundfish species that live around rocky crevices that trawl nets might get hung up on. Each season, we partner with two commercial fishing vessels to sample 45 locations in the Gulf of Maine. We gather data that goes into stock assessments that help us understand what our fish stocks look like today and what they might look like in the future. Data collection at each station includes:
- Counting, weighing, and measuring every single fish that we catch
- Assessing age and maturity stage of certain species
- Gathering biological samples for researchers back on land
- Tagging and releasing some larger species like sharks and skates
Fish Ear Bones and a Spikey Giant from the Deep
How do you tell how old a fish is? It's actually similar to counting the rings on a tree. Fish have tiny circular bones in their ears called “otoliths” (from Latin “ear” and “stone”) that display distinct rings created during seasonal growth cycles. By looking closely and counting the rings in an otolith, we can determine the age of the fish at the time of catch.
To understand when fish are breeding, we look at the fish’s reproductive organs to see if they are getting ready to spawn, are actively spawning, or are in a resting phase. Scientists and fisheries managers use this information to evaluate if fish are able to reach maturity and breed successfully before they are captured, ensuring the next generation of fish are on the way.
This season we were treated to a lot of cool sights in addition to our expected ones (which are, of course, also cool). We caught seven Atlantic halibut, which are a favorite aboard our survey due to the impressive sizes they can reach. We also saw some nice big cod, which are always a highlight. Atlantic cod is a groundfish species that we have closely monitored for many years, so seeing large adults is great! One of the stranger visitors we had on board was a large Northern stone crab, a spikey giant from the deep which is more closely related to hermit crabs than it is to “true” crabs. We also caught a blue shark, which we were able to tag and release as part of the Cooperative Shark Tagging Program. This program collects information based on tagged shark recapture and is the longest continuously running shark tagging program in the world!
For me, the thrill of bringing up unusual and interesting catch is one of my favorite things about working at sea. To be able to work out on the ocean is an amazing part of my job. There is so much life out there, and we only get small glimpses of its breadth in our normal land-based lives. If you want more of a glimpse of what our field work looks like, visit our Gulf of Maine Bottom Longline Survey Gallery, which highlights some of the photos from this season taken by our team. There is so much to see on the sea!
