Oceanographic Drivers of Shortfin Squid

Overview

Project Description

The shortfin squid fishery is a highly valuable and highly variable commercial fishery. Between 2012 and 2022, its annual value ranged from $1.1 million to $27.3 million. Despite the value of this fishery and the importance of this species, little is known about this squid’s life history and the ocean conditions and processes affecting their movements and migration. This is largely because shortfin squid:

• Live less than a year
• Spend parts of their lives offshore
• Have migratory patterns that don’t overlap with our surveys

This project supports the Magnuson-Stevens Act, which fosters the long-term biological and economic sustainability of marine fisheries, including the squid fishery. Better understanding of shortfin squid life history and oceanographic drivers help meet the Act’s objectives to:

• Prevent overfishing
• Rebuild overfished stocks
• Increase long-term economic and social benefits
• Ensure a safe and sustainable supply of seafood
• Protect habitat that fishery species need to spawn, breed, feed, and grow to maturity

In 2019, we invited researchers, industry members, and fisheries managers to an industry-led summit to identify data and knowledge gaps in the biology and ecology of shortfin squid and its fishery. We hoped to:

• Address the commercial fishing industry’s ideas about the shortfin squid stock
• Better understand life history and the ocean processes affecting shortfin squid movements and migration
• Meet the Magnuson-Stevens Act mandates

After identifying data and knowledge gaps, the “Squid Squad,” an interdisciplinary team of federal and academic researchers, industry members, and managers, discussed a series of potential research projects that could help fill those gaps. One of the selected projects was to investigate the oceanic conditions and processes driving the movements and migration of shortfin squid.

Project Goals

In 2022, we began collecting baseline oceanographic data with our academic colleagues and commercial squid fishermen. We wanted to better understand the movements and migration of shortfin squid in the Mid-Atlantic Bight and to address research questions and goals:

• How are squid movement and biology related to different oceanographic conditions?
• What are the biological characteristics (size, reproductive maturity, and age) of squid moving onto the U.S. continental shelf?
• Can oceanographic instruments be deployed on commercial fishing vessels to collect quality oceanographic data?

Study Methods

Location and Timing

In our region, the commercial fishing grounds for shortfin squid are found along the edge of the U.S. continental shelf in the Northwest Atlantic Ocean. They run from the southern edge of George’s Bank to Cape Hatteras, North Carolina.

We’re targeting static and dynamic oceanographic features thought to be associated with shortfin squid. Static oceanographic features include sub-marine canyons and the continental shelf break. Dynamic oceanographic features and the interaction of moving ocean water masses with static features may also influence shortfin squid population dynamics. The dynamic features we targeted include:

• Warm core rings—counterclockwise rotating warm salt water masses
• Salinity maximum intrusions—sub-surface pockets of warm, salty water that can be associated with a warm core ring or the Gulf Stream
• Shelf-break front—the dynamic boundary between the shelf and Slope Sea which shifts seasonally and moves depending on the location of the Gulf Stream and warm core rings

These dynamic features associated with complex physical interactions of the Gulf Stream and shifting water masses on the continental shelf can be difficult to detect. They often appear, shift, and disappear in a short amount of time, sometimes within 2 weeks.

Our specific study area and sampling locations are adaptive to help us identify areas where oceanographic features and fishing grounds intersect. To do that, we are leveraging our Study Fleet Program’s high-resolution catch data and collaborating with Squid Squad fishermen to obtain on-the-water observations. We analyze these data weeks before our research cruises to identify promising locations for data collection. This adaptability helps our field team respond in near real-time to the rapidly changing oceanography and shortfin squid movements.

We conducted our first 3-day research cruise in June 2024 after consulting fishing captains and Squid Squad members on when shortfin squid were starting to appear on the shelf. We targeted 10 locations and intend to follow similar sampling procedures during the 2025 and 2026 cruises.

Data Collection

Oceanography

During cruises we collect zooplankton samples at each location using a 75-centimeter vertical-tow plankton ring net with a 202-micrometer mesh size. Plankton data help us better understand ecosystem productivity, including shortfin squid prey abundance and distribution. Larval squid found in our plankton samples help us better identify shortfin squid spawning times and locations.

Attached to the plankton net rig is a Seabird CTD to measure conductivity, temperature, and depth in the water column. We use these data to understand the ocean’s physical, biological, and chemical conditions throughout the water column.

A fluorescence sensor attached to the CTD measures chlorophyll a fluorescence. Chlorophyll a is a proxy for phytoplankton biomass, which is a major component of the marine food web and primary food source for zooplankton.

We collect additional surface water samples to measure chlorophyll a back at the laboratory. These samples are used to calibrate the fluorescence sensor and groundtruth ocean color satellite data.

Collectively, these data help us make connections between ocean conditions, ecosystem productivity, and squid movement patterns.

Squid and Biological Sampling

Image

To collect squid data and biological samples, we tow the F/V Dyrsten’s otter trawl for 1 hour at 3 knots behind the vessel at each sampling location. We also collect oceanographic data while the trawl is fishing, using a second CTD attached to the net. This helps us know what the sub-surface conditions are throughout the sampling location. An eDNA meta probe attached to the net collects environmental DNA to be analyzed by our collaborators at the University of Maine. These samples provide information about species residing in the fishing area that we may not have caught in the net.

Once the tow is completed, the gear and catch are brought aboard the vessel for processing. We sort and identify the catch for squid and other fish species. Using an electronic data collection system, we measure mantle length and weight on a subset of squid from each tow. We also measure lengths on a subset of other fish species from each catch. We freeze a separate subset of squid for further processing back at the Narragansett Laboratory. We dissect these individuals to determine sex, reproductive maturity, and age. To determine age, we examine statoliths—hard calcareous stones located in a squid’s equilibrium organ called a statocyst. We also collect tissue samples from dissected individuals for DNA analyses.

Collaborators and Partners

The Squid Squad meets regularly to talk about near-real-time oceanographic and fishing conditions in the region. The squad includes:

• Stefan and Leif Axelsson, commercial squid captains of the F/V Dyrsten out of Cape May, New Jersey
• David Axelsson and Matt Loughlin, crew of the F/V Dyrsten
• Shortfin squid fishing fleets and processors across the northeast region
• Commercial Fisheries Research Foundation
• Mid-Atlantic Fishery Management Council
• Illex Research Track Stock Assessment Working Group
• University of Massachusetts Dartmouth School for Marine Science & Technology
• University of Maine’s Grey Aquatics Lab
• Woods Hole Oceanographic Institution
• Open Ocean Research
• University of Maryland Center for Environmental Science
• Virginia Institute of Marine Science
• Rutgers Center for Ocean Observing Leadership
• University of Rhode Island Graduate School of Oceanography

Funding Sources

This work is funded from a variety of sources, including:

• Magnuson-Stevens Act implementation
• Cooperative research funding

Contact Information

Project/Principal Investigators

• Kimberly Hyde, Northeast Fisheries Science Center

Project Team

• Anna Mercer, Northeast Fisheries Science Center
• Mary Kate Munley, Northeast Fisheries Science Center
• Sarah Salois, Northeast Fisheries Science Center
• Jeff Pessutti, Northeast Fisheries Science Center
• Adrienne Silver, Atmosphere and Environmental Research
• Glen Gawarkiewicz, Woods Hole Oceanographic Institution
• Chris Melrose, Northeast Fisheries Science Center
• Audy Peoples, Northeast Fisheries Science Center
• Tamara Holzworth-Davis, Northeast Fisheries Science Center
• Erin Grey, University of Maine
• DeCorey Bolton, University of Maine