Our research efforts
Atlantic bluefin tuna Biological Sampling Program
Globally, commercial tuna fisheries account for more than $33 billion and conservative estimates including their recreational component exceed $45 billion. While their value is high, our understanding of their life history is not. We conduct research on a variety of tunas, but our primary focus is on Atlantic bluefin tuna in the Gulf of Maine.
Every season, the Pelagic Fisheries Lab collects over 1500 Atlantic bluefin tuna samples including heads, stomachs, and livers. These samples come from various sources including commercial dealers, local Atlantic bluefin tuna tournaments, commercial fishermen, recreational fishermen, and more.
Once we collect Atlantic bluefin tuna heads, we make sure they are iced down to preserve freshness. We remove muscle tissue samples for genetic testing as well as an archive sample to save for later projects. We also extract otoliths, small calcified structures located in the brain cavity of Atlantic bluefin tuna, which are used to estimate the age of the fish when it was caught and where the fish was spawned (stock of origin).
We would like to acknowledge that the research we conduct in the Pelagic Fisheries Lab would not be possible if it were not for industry involvement and collaboration. We thank every individual who helps us obtain these samples every field season.
Otolith aging and microchemistry
After extracting otoliths from the Atlantic bluefin tuna head, there are several different processes needed to prepare otoliths for aging and micro-milling.
For aging, tuna otoliths form annuli, which resemble “tree rings”. These rings represent fast & slow growth zones that are identifiable by dark and light shades when observed with transmitted light. By counting the fast growth bands, we can get an estimate for the number of annual feeding seasons the fish has lived through which represents the age of the fish, similar to aging a tree by counting the rings presented by growing seasons.
For determining stock of origin, the otoliths are milled using a machine called a micro-mill. At the center of each otolith are chemical markers composed of material deposited while individuals are on their spawning grounds. Based on these chemical signatures, we can estimate if the Atlantic bluefin tuna was spawned in the Gulf of Mexico (Western stock) or in the Mediterranean (Eastern stock). This information is extremely important because, although the stocks are managed separately, there is evidence of some mixing between the two stocks – particularly here in the Gulf of Maine.
The micro-mill work is conducted by the Kerr Lab of the University of Maine for their project on “Evaluating Age Structure, Aging Bias and Mixed Stock Composition of Atlantic bluefin tuna in the Northwest Atlantic”.
To learn more about the project & the Kerr Lab, visit their website!
Tagging
Tagging, or the use of implanted identification (electronic or not), has been employed on a wide variety of terrestrial and aquatic species. This tool is extremely useful for researchers looking to learn more about spatial usage (local habitat, migration patterns, vertical & horizontal movements), spawning and foraging behavior, thermal preferences, and temporal patterns. Each tag has a set duration during which the tag will record environmental data while attached to the fish. There are a variety of ways for tags to “pop-off” the fish, but ideal tag release occurs when it reaches its set duration, detaches from the fish, and floats to the surface for data transmission. Transmitted and recovered data is extremely informative as it allows managers to make informed decisions and fill in gaps within life histories. Tagging is revolutionizing how we observe these highly migratory, elusive, long-lived species providing insights that promote sustainable fisheries and conservation.
Number of Satellite Tags Deployed since 2021…
Atlantic bluefin tuna
Basking sharks
Blue sharks
White marlin
Blue marlin
Pacific sailfish
Atlantic Bluefin Tuna
Our largest tagging effort to date is deploying satellite tags on Atlantic bluefin tuna in the northwest Atlantic. We have tracks of bluefin that stay relatively local to the Gulf of Maine, some that cross the Atlantic to the Mediterranean Sea, others that travel down the coastline to the Gulf of Mexico, and even evidence of some individuals habituating the Slope Sea, which is a third proposed spawning ground.
Sharks
In a collaborative effort with the Maine Department of Marine Resources, we are deploying tags on sharks in the Gulf of Maine. The tags allow us to understand baseline species abundance, distribution, and trophic interactions. The receivers allow us to reconstruct broad and fine-scale distributions and habitat use by highly migratory and benthic fishes. Data from these efforts will be used to support fisheries management and provide a baseline that can be used to determine the potential impacts before, during, and after offshore wind turbine construction.
University of Maine & Maine Department of marine resources collaboration
To learn more about our collaboration in sharking tagging in the Gulf of Maine, please check out this link below.
Blue marlin & Pacific sailfish
Although we do not have a specific project for tagging blue marlin & pacific sailfish, we hope to continue tagging these species of billfish and others to help us begin to understand their spatial usage (local habitat, migration patterns, vertical & horizontal movements), spawning and foraging behavior, thermal preferences, and temporal patterns.
THe Skillie Project
The Skillie Project is the Billfish Foundation’s largest White Marlin satellite tagging mission with the goal of better understanding their migratory patterns and supporting effective management strategies.
University of Maine Partnership!
The Billfish Foundation is a 501(c)(3) nonprofit organization that works globally to advance the conservation of billfish and associated highly migratory species through research, advocacy and education. Founded in 1986 by Winthrop P. Rockefeller, Dr. Eric Prince, and a group of fifty founding members, The Billfish Foundation fosters strong billfish conservation ethics to educate anglers of all generations and provide a voice for billfish and the global recreational sport fishing industry. The Billfish Foundation’s Tag & Release program, which began in 1990, has grown to be the largest international private billfish tagging program with over 280,000 reports, and serves as a cornerstone of its mission. With a focus on integrating science and policy, The Billfish Foundation continues to be a leader in influencing effective fishery management solutions that benefit both billfish populations and the angling community.
Foraging Ecology
We have conducted diet analysis studies on the following highly migratory species:
Current Study
University of Maine & Maine Department of marine resources collaboration
As part of an ongoing research effort, the Pelagic Fisheries Lab initiated a long-term study on Atlantic bluefin tuna foraging ecology to see what they eat in the Gulf of Maine and how that may change over time. This project has grown into a collaborative research effort with the Maine Department of Marine Resources.
Genetics for giants & Juvies
We are extremely aware of the global demand for Atlantic bluefin tuna, their highly migratory nature, and remaining uncertainties surrounding stock of origin and absolute abundance. This project is an industry-led initiative where participants are asked to take an Atlantic bluefin tuna fin clip sample for genetic analysis using a new method for assessment called Close-Kin Mark-Recapture (CKMR). CKMR uses the DNA profiles of individual fish to identify other closely related family members within the population. Starting in 2020, NOAA Fisheries implemented the use of CKMR on Western Atlantic bluefin tuna based on the success of implementation by SCIRO on Southern bluefin tuna. Utilizing the Pelagic Fisheries Lab’s existing sampling network this methodology has been applied to bluefin in i the northwest Atlantic. The groundbreaking results from this research and other scientific advancements have led to an unexpected increase in Western quota. Over the past few years, we have garnered increasing interest and kit requests, which has very exciting implications for the Pelagic Fisheries Lab and the future of Atlantic bluefin tuna management. We would like to emphasize that none of this research would be possible without the willingness and participation of the commercial and recreational fishery.
Donate to our Non-Profit
Thank you to all those who have supported us and our research efforts over the last 14 years! We truly appreciate every single one of you! If you like what you see with our research efforts, please consider making a donation to our lab’s non-profit, the “Highly Migratory Species Fund”. Every dollar has a significant impact on our research efforts!
Questions?
pelagicfisherieslab@gmail.com