Post and photos by Christine Kircun, NOAA/NEFSC
As we near the end of the 2017 spring bottom trawl survey, we are about 650 miles north of our southernmost station near Cape Hatteras. With that said, it wouldn’t be surprising to know that the fish are very different in the northern part of the survey.
Here we’ll find haddock, cod, pollock, and American plaice to name a few. And just like down south, while some fish look very different there are a few that are tricky to differentiate, especially for someone’s first time out. While external features are used to quickly identify a fish, there is another important structure that can also identify a fish: the otolith.
The otolith is an earbone that we primarily use to figure out the age of a fish, although it can also be used to identify fish. Otolith shapes vary widely, but the more closely species are related, the more similar they look. I’ve chosen three fish to highlight this.
Here’s a close-up of those otoliths. The offshore hake otolith (top) isn’t as long and slender as the silver hake otolith, even from fish of approximately the same size. The offshore hake otolith in general is much wider, and its tips are more rounded than the silver hake otolith.
Atlantic herring (top) vs Alewife (bottom)
Above are two fish we’re currently catching in almost every tow: Atlantic herring and alewife, a river herring. While these two fish may seem very different in this picture, it’s not uncommon to toss a couple from the sorting belt into the wrong bucket. The quickest way to tell the difference by looking at the outside is to run your finger along its top side from tail to head. It will be smooth on the herring, but not so with the alewife as you’ll get caught on its scutes — spiny, rough scales. Their otoliths are very small in comparison to their overall body size. You can barely see them in this photo. The Atlantic herring otos are placed in the vertical black band on the measuring board, just below the herring’s jaw. The alewife’s are even smaller, placed in the black tag on the measuring board, just to the right of the number “4”, above the fish’s eye.
Here’s another confusing pair. Until you get the eye for making distinctions, these two fish are very easy to confuse. A quick way to tell the difference by just looking at these two is the length of the pelvic fin, that reddish looking string you can see running from near the throat and down the belly. It extends further along the body of the red hake. If the pelvic fin — also called a filament — is broken, the silvery color or smaller scales of the white hake are other quick identifying characteristics. But let’s go to the otoliths!
These otoliths (right) came from two very different sized fish, but the size isn’t necessarily what’s going to differentiate these two fish. Look at the rostrum, the pointed top end. Red hake have a smooth rostrum (left) while white hake’s rostrum (right) is bumpy. Also, the red hake otolith tends to have a little edge right before the rostrum begins.
I find myself using this skill the most when examining stomach samples to find out what a fish has been eating. If I am trying to ID a partially digested fish, the otolith is often remains more intact than the rest of the animal. It can also be used to identify a fish down to genus or species. This is just another way we rely on this useful little bone!
Christine Kircun, biologist
Aboard the NOAA Ship Henry Bigelow
When I tell someone I work for NOAA, they ask what the weather is going to be. When I clarify I work with Fisheries, they assume I work with groundfish. But when I explain I work with sea-run fish that need both the ocean and rivers to complete their life-cycle, for example the endangered Atlantic Salmon, they are often hearing a story for the first time. This post will be one in a series this spring to help inform folks about what sea-run fish are and why NOAA fisheries studies them.
For me, spring means the melting of snow and break-up of ice in rivers allowing sea-run fish to begin their migration inland to spawn. Monitoring these migrations is a large part of the work done at NOAA’s Maine Field Station and something I have done for the past 16 seasons as a fisheries biologist in Maine. Today (April 28) was the first day of our estuary fish survey, which encompasses the sea-run fish migration period that runs from April to November. Our study goal is to measure the timing and abundance of the 12 sea-run fish species within the Penobscot River Estuary, a system with a long history of abundant runs of salmon, shad, smelt, river herring but currently struggling to maintain the small fraction that remain today. We use two types of gear, acoustics that I will talk about in later posts, and a mid-water trawl which is the feature today.
At the start of the day, we were greeted by a familiar face as we walk onto the docks. Josh, a local lobsterman from Isleboro, is contracted with NOAA Fisheries and provides use of his boat and estuary expertise to assist us in conducting our research. Also joining us was a fellow researcher, Eric Brunsdon, with the Atlantic Salmon Federation located out of Saint Andrews, Canada. He was interested in learning about our data collection methods with hopes to bring this knowledge back to Canada to conduct similar studies. To us, collecting quality data are fundamental, but the people we work with, and the ability to share our techniques with other researchers, are just as important.
Our objective as we start the day was to verify the sonar survey conducted the previous day, which revealed few fish in the estuary – typical for early spring when the water is cold and migrations are just beginning. We planned on conducting 8 tows within our study area but are always at the mercy of the tide and river conditions. Here in the Penobscot River Estuary, the combination of a 15 feet tidal range and a river draining two-thirds of the state results in water velocities that vary minute by minute and determine what sampling we can complete. Our first few tows provided little excitement with only a couple juvenile Atlantic and Blueback Herring, typical when water temperatures are around 6°C (43°F) .
The day was not without a hiccup, when a tow came up with flounder and a tear in the net. This indicates the strong currents sunk our net to the bottom. After a quick net repair and moving locations, we were able to get the remaining tows in for the day. The most exciting haul of the day was a catch of Rainbow smelt and Atlantic tomcod in the midst of their spawning run. Rainbow smelt are a sea-run species that were once a favorite for New England anglers from Connecticut to Maine but have experienced declines in abundance with the only strong runs left today in Eastern Maine including here in the Penobscot. Although today was relatively quiet capturing hundreds of fish, in a few short weeks we hope to see these numbers increase to thousands per tow as the sea-run migration unfolds.
More to come as the season progresses….
NOAA/Northeast Fisheries Science Center (NEFSC)
Maine Field Station
2017 has been a very low calving year for the North Atlantic right whale population. Only 3 calves were documented in the Southeast U.S. calving grounds – the lowest number on record since 2000, when only one calf was sighted. In the intervening years, calving numbers have fluctuated, but on the whole have been lower than right whale researchers would like to see for the recovery of such a critically endangered species.
On April 12, both the Center for Coastal Studies and NEFSC aerial surveys documented a new mom & calf pair for the season, bringing the calf total for 2017 up to 4. While a sighting of new mom & calf pairs outside of the calving grounds is not unheard of, it is not common. So we were very excited Sunday (April 30) when we realized that we had found yet another new mom & calf pair for 2017! I tentatively identified the whale as catalog #1515 while still in the air, but researchers at the New England Aquarium, which houses and manages the North Atlantic right whale catalog, confirmed my identification on Monday morning. The new mom and calf were sighted feeding in the Great South Channel.
#1515 has not been seen since 2009 (also with a calf), so she had been presumed dead by the New England Aquarium. She has been sighted infrequently since 1985 and usually only down on the Southeast U.S. calving grounds, so, much like our other recent mom/calf sighting of 1412, we do not know where she spends the majority of her time. Another mystery mom!
Images taken under MMPA research permit #17355 by Tim Cole, NOAA Fisheries/NEFSC
NEFSC Aerial Survey Team
Leg III: 2017 Spring Bottom Trawl Survey
Photo credit for all images in this post NOAA/GARFO/William Duffy
Welcome aboard Leg 3 of the NMFS NEFSC bottom trawl survey. One of the questions I get asked frequently when I get back home is: what are the coolest types of fish you see out there? My answer is always the same, the deep-water fish species. They are interesting, they look like aliens, and I am pretty sure some of the more horrific monsters that one would see on TV or in the movies was inspired by a fish caught from the deep depths of the sea. So while I am guest blogging out here, I thought it would be great to share a few pictures from a couple of our deep-water stations with the rest of you.
In our first deep station of the trip, we towed at 300 meters (900 feet). When we dumped the bag in the checker there were almost 2,000 pounds of large barndoor skates. Also brought up from 30 meters were some cutlassfish, pearlsides, shortnose green eyes, and a grenadier. One of the more interesting types of fishes that come up from the depths are the barracudinas from the family Paralepididae. The specimen in the slideshow below was about 30cm long. . The other fish pictured here: pearlside, family Sternoptychidae; short-nose green eye, family Chlorophthalmidae; and grenadier, family Macrouridae, are all commonly seen in the deeper waters of the Gulf of Maine and Georges Bank.
In another station, we towed at 275 meters and caught a few more interesting deep-water fish species that I think most people have never seen before. These are some of the more colorful, interestingly shaped, and bizarre-looking fish species that we catch on these surveys. The first is an oddly shaped fish called a spotted tinselfish from the family Zeidae, pictured at the top of this post. We also had a few “large” Myctophids, also called lanternfishes (above). Most fish from this family are relatively small, with the largest species not getting more than 30 cm in length. These fish have light producing organs called photophores and luminous scales throughout its body. However, as you will see from the picture, most of their scales come off when they are caught in the net.
While we are out here we also get some really interesting invertebrates, and two types, crabs and squid, are quite common and are represented by quite a few different species. This brightly colored crab (right) is from the family Grapsidae and this multicolored rossia squid (below) is a type of bobtail squid from the family Sepiolidae.
These were just some of the many different types of deep-water species that we see on our surveys.
Bill Duffy, NOAA Fisheries Greater Atlantic Port Agent
Aboard the NOAA Ship Henry B. Bigelow
Leg II: Safety First!
As I write this we are about to leap-frog our original cruise track and pick up stations that would have been done earlier if not for the weather.
A typical New England Nor’easter worked its way up the coast in the last few days. The Bigelow is able to fish in most weather conditions but when the winds start howling it can become dangerous for the crew operating the equipment on deck. Plus, scientific collections could be compromised due to the surging nature of the ship in those conditions. Safety is our primary concern out here. By altering our cruise track and heading inshore we were able to ride out the storm and only lose about 12 hours of operations.
Today is also drill day. Preparing for emergencies at sea is a serious business and we are a long way away from any help. The crew conducts weekly safety drills, including some sort of simulated fire drill. For the scientists, we basically stay out of the way by gathering on the bow of the ship and assist if necessary. Several of the regular sea-going scientists are trained to help fight fire if called upon. This week we conducted a medical emergency drill that included transporting a member of the scientific party via backboard and simulating calls back to land for instructions.
Each week there is also an abandon ship drill. This involves the crew reporting to assigned life rafts and donning survival suits. Actually getting into the suits ensures that we know how do it quickly and that assigned suit fits, important details if there is a real emergency. Survival suits are buoyant wet suits that keep us afloat and protect us from getting hypothermia if we have to get in the water.
All of these add up to safe voyages where the health and welfare of the people aboard are paramount.
Aboard the NOAA Ship Henry B. Bigelow
Leg II: There’s a lot more going on than just trawling
Greetings from the NOAA Ship Henry B. Bigelow! Leg II of the NEFSC Spring Bottom Trawl left Newport, RI on Tuesday, March 28th. We made our way South to pick up where Leg I left off.
While this trip is labeled as a bottom trawl survey, there is a lot more going on than just trawling. This ship conducts a lot of exciting science: collecting hydrographic data about the physical characteristics of the water using on-board sensors and special sampling devices, using fine-meshed bongo nets to collect plankton, and of course examining the fish and other marine life that comes up in the trawl. The Bottom Trawl Survey is definitely an ecosystem survey, designed to capture all aspects of the marine environment and ecology.
As an ecosystem modeler, I am very interested in how the data is collected out here and ultimately analyzed back on land. The most basic of fish data that we collect is weight per tow. Each tow is separated by species and then weighed. This information is important so we can get a relative sense of the size of the various populations. From there we take individual length data on most species. Some things are sent back to the lab and counted/measured there.
Just as important as these basic metrics is the biological sampling that we conduct. For some species a subsample of the catch is selected for further study. We determine the sex and maturity of the fish to get information on spawning in a population. We examine their stomach contents to learn more about predators and prey. We also age them using a variety of techniques.
The most common way to age a fish is to use their ear bones or otoliths. This technique works similar to aging a tree. Seasonal changes in a fish’s growth pattern create rings or annuli. Each year a new ring is created. At sea we remove the ear bones and send them back to land. Each species requires some processing of the ear bones before an age reader can count the rings.
The end result is we have an age structure of the population and can track how each year’s cohort is growing and, along with the other data we’ve collected, help forecast sustainable catch levels for the future.
Sean Lucey, ecosystem modeller
Aboard the NOAA Ship Henry B. Bigelow