Collaborative Study on Atlantic Mackerel Spawning Seasonality

Overview

In 2026, we launched the Atlantic Mackerel Cooperative Research Initiative—an industry-driven effort to address uncertainties related to mackerel population dynamics and biomass estimates. This initiative will help improve our understanding of the stock, which is managed by the Mid-Atlantic Fishery Management Council. There are five research elements supporting the initiative. Our spawning seasonality study focusing on understanding the spawning dynamics of Atlantic mackerel is one of the five research elements.

The annual egg production estimate is a major component of the Atlantic mackerel stock assessment. The estimate uses long-term mackerel egg data from samples collected during our Ecosystem Monitoring Survey. Those samples are typically collected from late May through early June on the U.S. continental shelf. Both scientists and fishermen have had concerns that the timing of the survey may not fully capture mackerel spawning in our region, particularly as ocean conditions change. Knowing when and where mackerel spawn can be challenging because their distribution changes throughout the year, and spawning occurs outside our traditional spring and fall survey seasons. That’s why we are partnering with the fishing industry for this study. We’re building a vast network of commercial and recreational fishing partners using a range of gear types to access mackerel anywhere, anytime.

Our oceans continue to change. Reevaluating and updating what we know about spawning seasonality will help improve the accuracy and confidence of mackerel egg production estimates, and—by extension—stock assessments.

Project Goals

Our goals for this study are to:

• Characterize the spawning seasonality of Atlantic mackerel in U.S. waters
• Compare mackerel spawning activity with the long-term late May to early June egg index based on samples collected by our Ecosystem Monitoring Survey
• Improve estimates of total annual egg production for the Atlantic mackerel stock assessment
• Improve our understanding of mackerel reproductive dynamics

Data from this study will also be used to inform the timing of the Mackerel Initiative’s 2027 egg survey and tagging work—two other research elements supporting the initiative.

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Study Methods

We are partnering with more than 30 commercial and recreational fishermen, as well as shoreside fish processing facilities and research vessels. Together, we will collect mackerel from the Gulf of Maine to the Mid-Atlantic. We’ll use the data we collect from those fish to characterize their spawning seasonality.

Sample Collection

Since March 2026, we have been coordinating with our industry partners to collect weekly mackerel samples from Maine to Virginia. Each sample contains roughly 50 whole fish. We have two types of sampling seasons to ensure we capture when and where spawning occurs:

• High season: March to July, targeting fish samples from eight fishing vessels each week, totaling 400–500 whole fish
• Low season: August to February, targeting fish samples from four fishing vessels each week, totaling 100–200 whole fish

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Sample Processing

For each fish, we collect data and information on:

• Fish length
• Whole fish weight
• Gonad weight
• Gonad maturity stage

We will process a subset of fish further to remove their otoliths. Otoliths are fish ear bones, which we use to determine the age of the fish. We will also use otoliths to better understand what the mixed stock composition is and if mackerel are using natal homing. Natal homing is the process where adult fish migrate back to the spawning grounds where they were hatched. This work is part of the mackerel movement and mixing study and is another research element supporting the initiative. 
 

Data Use

We will use these data, along with fishing date and location, to:

• Characterize when and where mackerel are spawning in U.S. waters
• Calculate and track the gonadosomatic index, a metric used to identify spawning activity
• Estimate what proportion of mackerel eggs our Ecosystem Monitoring Survey has been capturing
• Determine when and where our 2027 egg survey and mackerel tagging efforts should occur to align with the spawning season

The gonadosomatic index measures the ratio between gonad weight and body weight. It is an important indicator of fish reproductive maturity and spawning stage. Measuring and tracking the index throughout the year allows us to estimate specific times that are most important for mackerel spawning.  Additionally, the gonadosomatic index generated from this study will help us understand what proportion of eggs our Ecosystem Monitoring Survey has been capturing. This will inform and improve how egg data should be scaled for mackerel egg production index.

Collaborators and Partners

Industry Partners

• Andrew Dangelo, F/V Maridee
• Bilbo Callaway, F/V M.F. HY GRADER
• Birch Brennan, The Town Dock
• Robert Ruhle and Northeast Area Monitoring and Assessment Program Nearshore Trawl Survey and Regional Industry-Based Bottom Trawl Survey, F/V Darana R
• Bill Bright, F/V Retriever
• Chris Roebuck, F/V Karen Elizabeth
• Dan Dean, F/V SeaCraft
• David Axelsson, F/V Dyrsten
• David Goethel, F/V Ellen Diane Too
• Erik Hicks, F/V Rayda Cheramie
• Gabe Folan, F/V Reel Irish
• Glenn Goodwin, F/V Buckeye
• Helger Cabral
• Jack Patrican, F/V Far Floater 
• Jason Sawyer, F/V Cody
• Joe Letourneau, F/V Lady Rebecca
• Katie Almeida, The Town Dock
• Kelly Smith, F/V C-Devil II
• Lund’s Fisheries Inc.
• Malcom McClintock, F/V Bulldog
• Mark Phillips, F/V Prevail
• Matt Wright Trucking
• Seafreeze Ltd.
• Mike Pratt, F/V Perfect C's
• Nate Phillips, F/V Illusion
• Noah Roebuck
• North Atlantic Pacific Seafood
• Phil Ruhle, F/V Persistence
• Red’s Best
• Richard Chatowsky, F/V Drifter
• Rick Bellavance, F/V Priority Too
• Rob Taylor, F/V Reel Ez
• Robert Savino, F/V C J Victoria
• Ryan Raber, F/V Providian and F/V Scappa
• Shane Kissel, F/V Osprey
• Stefan Axelsson, F/V Dyrsten
• Tom DePersia, F/V BigFish
• Tom Smith, F/V Sea Wolf
• Troy Sawyer, F/V Debbie Sue

Science Team

• Kiersten Curti, Northeast Fisheries Science Center
• Dave Richardson, Northeast Fisheries Science Center
• Lisa Kerr, University of Maine
• Catherine Foley, Northeast Fisheries Science Center
• Jim Gartland, Virginia Institute of Marine Science

Funding Source

The Atlantic Mackerel Cooperative Research Initiative received $2.3 million in fiscal year 2026 to begin this work. This initiative supports the Executive Order on Restoring American Seafood Competitiveness by:

• Applying a cooperative research approach to advance Atlantic mackerel and Atlantic herring stock assessment and management
• Modernizing data collection and analytical practices to increase the responsiveness of fisheries science
• Pursuing Exempted Fishing Permits to promote scientific research and fishing opportunities

Contact

Project/Principal Investigators

• Anna Mercer, Northeast Fisheries Science Center
• Sarah Salois, Northeast Fisheries Science Center
• Katie Viducic, Northeast Fisheries Science Center

Project Team

• Amanda Jacobsen, Northeast Fisheries Science Center
• Andy Jones, Northeast Fisheries Science Center
• Ben Church, Northeast Fisheries Science Center
• Hannah Ciarametaro, Northeast Fisheries Science Center
• Heather Soulen, Northeast Fisheries Science Center
• Katie Burchard, Northeast Fisheries Science Center
• Katie Rogers, Northeast Fisheries Science Center
• Mark Wuenschel, Northeast Fisheries Science Center
• Maura Flynn, Northeast Fisheries Science Center
• Olivia Robson, Northeast Fisheries Science Center
• Sandy Sutherland, Northeast Fisheries Science Center