Hi everyone!

My name is Nina Pruzinsky. I am a Master’s student at Nova Southeastern University, where I am working under Dr. Tracey Sutton. Also, I am a graduate research assistant in Dr. Sutton’s Oceanic Ecology Lab, where I am studying the identification and spatiotemporal distributions of tuna early life stages (larvae and juveniles) in the Gulf of Mexico. 

Tuna are ecologically, economically and recreationally important fishes. You may know them for their large size, high speeds, and highly migratory behaviors. Fishermen enjoy catching these are fish because they average 2.5 m in size and 250 kg in weight!! They are top-predators in many coastal and oceanic environments, feeding on fish, squid and crustaceans.

Check out this video of tuna from the Blue Planet II series.

Several species have been placed on the IUCN Red List of Threatened Species. For example, Northern Atlantic bluefin tuna is listed as endangered, yellowfin and albacares as near-threatened, and bigeye as vulnerable. Several tuna species spawn in the Gulf of Mexico due to its warm temperatures and unique hydrographic features improving the survival of their eggs and larvae.

So what exactly am I studying for my thesis?

First, I am identifying features that describe the early life stages of different tuna species. The morphology (“the study of form” or appearance of physical features) of tuna early life stages is poorly-described. Collecting fishes at these small size classes (3-125 mm SL) is very rare due to limited sampling across their wide-range of habitats. However, it is extremely important because if we do not know how to identify a fish when it is young, we cannot protect it and ensure it lives to its adult reproductive stage. So, my first task was to create an identification guide for these small fishes. The key features used for identification include: pigmentation patterns, body shape, ratios of different body parts, and fin ray counts.

To date, I have identified 11 different tuna species. These include: little tunny, blackfin tuna, bluefin tuna, yellowfin tuna, frigate tuna, bullet tuna, skipjack tuna, wahoo, Atlantic chub mackerel, Atlantic bonito, and king mackerel. Pictures of these fishes are included below. You can see how differently their early life stages look compared to their adult stages.

Larval and adult little tunny.

Larval and adult blackfin tuna.

Larval and adult king mackerel.

Larval and adult wahoo.

The second part of my project is to identify the spatiotemporal distributions of larval and juvenile tunas. Once we know what species we have, then we can identify where it is found, in what season it spawns, what type of environmental features it prefers, and so on. Basically, I am gaining knowledge about its habitat preferences, so we can help protect future populations and increase recruitment levels.

There are some small tuna species such as little tuna and blackfin tuna that do not have stock assessments nor management plans currently developed. Thus, learning about the environmental conditions that affect their distributions is essential in assessing their populations. It is evident that we still have a lot of knowledge to gain about these size classes.

This summer, I participated in an ichthyoplankton cruise in the Gulf of Mexico. Left: Jason and I are collecting organisms from the bongo net. Middle: I am holding a juvenile frigate tuna collected with a dipnet. Right: I am identifying a larval tuna under the microscope in the lab onboard.

Left to right: back: Jessica, Alex, Michelle, Cori, Travis, Jillian, and Nina; front: Jason and Rich

HAPPY 4th of JULY!

Scientists still get to celebrate while we’re out at sea! Check out our tattoos! :)

Hi all,

Today is our last day of sampling. We started bright and early again at 6am. It rained a bit, but it was accompanied by a full rainbow arching over the boat. Nice way to start off the morning!

You guys are probably wondering how we collect all of the larval fish I showed you on the last blog post. Well, we deploy a bongo net off the back of the boat and a neuston net off the side. Both nets are brought on board and the samples are washed down into the codends. The contents of the codends are rinsed/poured and put into our sample jars. The samples are brought into the wet lab for a closer look and a potential photo. Some of the larger specimens (e.g., tunas, swordfish) are frozen for genetic analyses.

I set up a GoPro around the boat to show you guys how we sample at each station. Let’s take a look of some of our scientists at work:

Bongo nets and the sunset last night.                        Neuston net.

Rich is collecting water for the YSI and for the food web study.                 Nina is reading the water's temperature, salinity, and dissolved oxygen.

Rich, Nina, Jillian, and Jason are retrieving the bongo nets.                       Everyone's rinsing down the nets, while Michelle is recording the
                                                                                                          flowmeter data.

Jillian is pouring her plankton sample out of the codend.                           Jason and Nina are rinsing the bongo nets.

Nina and Jessica are putting the sample into the jar.                                Jessica is looking at a larval tuna under the microscope/taking a picture.

Alex and Cori just retrieved the neuston net.                                           Jillian, Alex, Cori, and Travis are sorting the neuston net sample.

Jason and Travis sorting through Sargassum.                                          Jason and Alex looking at our catch!

Dr. Michelle Sluis is the PI on the cruise. She is recording the data for each tow (e.g., start time, location, etc.) in the pictures above.

Hope you enjoyed the pictures!
-Nina

Hi guys!

Last night we cruised towards our southern transect. We arrived at our first station and began sampling at sunrise (6am). We've hit 10 stations so far today! We collected many of our targeted species and more!

On the boat, we use a camera attached to our microscope to help us take pictures of the tiny fish. Here's some of our catch:

Dolphinfish larva.

Swordfish larva.

Billfish larva.

Tuna larva.

Frogfish larva.

Alex found a siphonophore.

Cori, Travis and Jillian on deck and ready for the next tow! 

All smiles here!

-Nina

Hello everyone,

My name is Nina Pruzinsky. I’m out in the northern Gulf of Mexico with Texas A&M sampling for fish larvae on the R/V Pelican. We’ll be out here from July 1-5th. The scientists onboard include: Dr. Michelle Sluis (TAMUG), Jessica Lee (TAMUG), Travis Richards (TAMUG), Cori Meinert (TAMUG), Jillian Gilmartin (TAMUG), Alex Southernland (TAMUG), Jason Mostowy (TAMUG), Richard Jones (FAU) and Nina Pruzinsky (NSU).

We left the port at LUMCON at midnight on June 30th and traveled to the first station (Station 48) during the night. We started our sampling around 10am yesterday. We finished nine stations during the day and did two night tows. During the day we are using a neuston net and bongo nets to sample for larval fish. The neuston net tows for 10 minutes at the surface and the bongo nets sample to about 100 m depth. At night, we only tow the neuston net. This way, we can compare the differences between day and night tows at the same station. Additionally, Alex is sampling for gelatinous zooplankton (jellyfish) for genetic analyses, Jillian is Gtowing another plankton net to look at the community structure of zooplankton, and Travis is collecting water samples in order to characterize the food web in the Gulf.

Yesterday we caught tunas, billfish, dolphinfish, flyingfish, eel larvae, remora, frogfish, triggerfish, pufferfish, rough scad, lanternfish (at night) and more! Check out the pictures below! As you can see, all of our fish are extremely small!

Today we started sampling at sunrise around 6am and have completed three stations. We already caught some tuna and dolphinfish larvae!

Stay tuned for more pictures and updates on the cruise!

R/V Pelican before depature. 

Larval dolphinfish (mahi-mahi).

Tuna larvae.

Triggerfish larvae.

Michelle and Cori preparing the neuston net.

Jillian setting up the plankton net along with the bongo nets.

We also were able to dip net a juvenile tuna last night for my thesis!

Cheers!
Nina

Due to mechanical problems with the ship, the cruise unfortunately had to end early. We docked at Port Fourchon around 2:30am today.

However, the good news is that the next ichthyoplankton cruise will be at the end of July!

All nine of us have a specific task once the boat stops at a station. Travis and Jeff collect water samples to bring back to TAMUG; the water samples are filtered in order to characterize the food web in the Gulf. We also gather environmental data, such as salinity and temperature at each station.

Travis and Jeff collecting water samples

The bongo net and neuston net sampling methods are very similar. They only differ in mesh sizes—this allows us to catch different species along with fish of different sizes. Once the nets are brought on board, we thoroughly rinse all the fish to the bottom of the codends. Then the codends are emptied into a bucket, filtered through a net, placed in their station’s designated jar and preserved. The fish are identified back in Dr. Rooker’s lab at TAMUG.

Retrieving the bongo nets	Rinsing the net

Emptying the codend	Jarring the sample

If the fish is in good condition, it is brought to the dry lab and Kim takes a picture of it. Like this ribbonfish...

We were up early today so we could get our nets in at sunrise! It was 5:54am when we deployed the bongo nets. So far this morning, we completed 3 stations! We’ve been catching a variety of fish in our samples! Here’s a few pictures to show you guys what we are seeing:

barracuda	damselfish	swallower

Antenna codlet	lanternfish

Hello from the R/V Blazing Seven!

We are a group of eight student/scientists headed by Dr. Jay Rooker from TAMU - Galveston. We will be conducting ichthyoplankton (e.g., larval fish) tows for the next five days!

Due to some last minute repairs, we had a delayed start yesterday. However, this allowed us to set up and secure all of our nets while we were still docked at Port Fourchon. We left the dock at 1pm yesterday and arrived at our first station at 7:50am today. In order to sample a station, we deploy the bongo nets to 100 m followed by the neuston net at the surface. The bongo nets are towed for 4-8 minutes, and the neuston net is towed for 10 minutes. Once the nets are retrieved, our job is to sort through and jar the samples.

Bongo nets	neuston net

We’ve collected several larval fishes in the nets so far. At the first station, we collected a larval mahi-mahi and a larval sargassumfish. We also caught several larval tuna, to my excitement (since I am studying them for my thesis), and we are hoping to catch more! Unfortunately at Station 3, we had to replace our nets since it ripped while it was being towed, but the new net is functioning perfectly! At Station 8, we collected a swordfish! In all, we completed 11 stations today. It was a very successful first day and we’re looking forward to sampling tomorrow! Check back tomorrow for more pictures!

Mahi-mahi

Tuna larvae

Sargassumfish

Check back tomorrow for more pictures!

Best,
Nina