Highly Migratory Species Research

Shark
Photo courtesy of Blaise Jenner

The western North Atlantic Ocean is home to a variety of marine species. One such group of animals, referred to as Highly Migratory Species (HMS), are capable of traveling thousands of miles each year for the purposes of foraging, reproduction, and finding optimal habitat. The biological diversity seen within HMS, which includes tunas, billfishes, and sharks, is some of the greatest amongst any group of fishes. From the large filter-feeding basking shark to the fast-swimming Atlantic bluefin tuna, HMS of all shapes and sizes can be found inhabiting the waters of the Atlantic.

Management

Highly migratory species are managed in US waters by NOAA Fisheries under the Magnuson-Stevens Act and the Atlantic Tunas Conservation Act, and under international agreements like those from the International Commission for the Conservation of Atlantic Tunas. For more information regarding the management of HMS in federal waters, please visit NOAA Fisheries Atlantic Highly Migratory Species. In state waters along the US seaboard, most sharks are regulated under the Atlantic States Marine Fisheries Commission (ASMFC) Coastal Sharks. Individual states may also employ or enact their own regulations around commercial and recreational fishing for HMS. At this time the State of Maine does not have any state-specific regulations in place that primarily focus on shark or tuna fishing, but rules from NOAA Fisheries and ASMFC still apply. The state of Maine participates in the federal Large Pelagics Survey.

Fishing Guidelines

HMS-specific fishing permits are required. Commercial and recreational fishing permits can be obtained from the NOAA Fisheries HMS permit page. Note that commercial and recreational HMS fishing permits are attached to the vessel, not the permit holder, and that permits must be renewed each year. For those who are saltwater fishing in Maine state waters, you may also need to have a Maine saltwater license. Please refer to this website for more information: https://www.maine.gov/dmr/fisheries/recreational/licenses-registry/saltwater-recreational-fishing-registry-license.

Compliance guides:

Citizen Science Opportunities

If you recreationally or commercially fish for HMS in the Gulf of Maine, consider joining the Cooperative Shark Tagging Program or the Billfish, Tuna, and Swordfish Cooperative Tagging Program. Additionally, if you fish for Atlantic bluefin tuna and are interested in contributing small fin clips or other samples used to improve our understanding of this species, visit the Pelagic Fisheries Lab website to learn how you can participate.

If you see a white shark in Maine, report it by emailing Maine DMR Scientist Matt Davis at matthew.m.davis@maine.gov and/or by submitting your sighting on the Atlantic White Shark Conservancy Sharktivity App.

Species Found in Maine

Tunas

Sharks

HMS Research Projects

Atlantic Bluefin Tuna Dietary Study

Pelagic Lab Interns
Interns at UMaine's Pelagic Fisheries Lab

Atlantic bluefin tuna (Thunnus thynnus; BFT) migrate annually into the Gulf of Maine beginning between May and June and reside throughout the summer and late fall to forage on regional concentrations of prey. While in the Gulf of Maine, BFT prey upon a variety of different species, with Atlantic herring representing the dominant prey item for much of the past 30 years. However, a recent study of stomach samples collected in 2018 and 2019 found that BFT diets had shifted away from Atlantic herring and were dominated by shortfin squid, and to a lesser but significant extent, Atlantic menhaden. This apparent dietary trend to include more Atlantic menhaden coincided with broader ecosystem changes throughout the Gulf of Maine region, where a decrease in the observed Atlantic herring biomass coincided with an increase in Atlantic menhaden biomass. Given the biological, economic, and cultural relevance of BFT to Maine and beyond, it is important that fishers and managers understand this specie’s dynamic foraging behavior as food webs fluctuate.

Beginning May 2022, the Maine DMR began working with the University of Maine’s Pelagic Fisheries Lab to collect stomach samples from commercially harvested BFT along the coast of Maine. Nearly 450 stomach samples were collected between 2022 – 2024, and contents were analyzed using stomach content analysis (SCA) to identify prey items. To date, SCA determined a further shift in BFT diet has occurred, with Atlantic menhaden occurring in > 60% of all stomachs and making up nearly 60% of all prey weight. This signifies a shifting trend for BFT and is the first time Atlantic menhaden have been the dominant prey item for this species in the Gulf of Maine. Other notable prey species identified in recent SCA include Atlantic mackerel, silver hake, river herring, shortfin squid and butterfish. These data are not only important for understanding the distribution and condition of BFT but also represent valuable information for fisheries managers who regulate forage fish species quotas such as Atlantic menhaden and Atlantic herring. The Maine DMR plans to continue to monitor BFT diet in order to establish long-term diet trends and to further inform fisheries managers.

Coastal White Shark Activity

White Shark
Photo courtesy of Matt Davis

Have you seen a white shark recently? Report it on the Atlantic White Shark Conservancy’s Sharktivity phone app!

White sharks have been historically documented in New England and are most often observed along Maine’s coastline during the months of July, August and September. White sharks are considered an apex predator, meaning they exist at the top of the food web with few predators. Young white sharks predominantly prey on bony fish, squid, and smaller sharks, but as they grow and mature the primary source of food transitions to lipid-dense prey, such as marine mammals.

The International Union for the Conservation of Nature (IUCN) designates the white shark as a species vulnerable to extinction risk. There are several reasons for this classification, including a general lack of information regarding critical habitat use, slow growth rates, slow reproduction rates, and a general tendency to travel in areas inhabited by humans (i.e., nearshore). However, on a regional scale, white shark populations in the western North Atlantic appear to be in a slow state of recovery. Research suggests that white shark abundance in the western North Atlantic has increased in recent years following the implementation of shark conservation measures in the 1990's and the protection of marine mammals in the 1970's, which resulted in the recovery of New England seal populations, which are a primary food source for sub-adult and mature white sharks.

In 2020, the Maine DMR, in collaboration with the Massachusetts Division of Marine Fisheries (MADMF), the Atlantic White Shark Conservancy (AWSC), and others initiated efforts to monitor the presence of white sharks in Southern and Mid-coast Maine waters, with hopes to expand to Downeast in the future. Each spring, scientists place acoustic receivers at fixed locations along the coast of Maine, leaving the devices submerged one or two meters beneath the surface. These receivers are designed to detect nearby acoustic transmitters, also known as tags. There are approximately 300 white sharks that have been outfitted with acoustic tags by MADMF and AWSC, and when one swims within several hundred meters of an acoustic receiver, a detection is recorded. Each winter, scientists at the DMR retrieve the acoustic receivers, download the detection data, and assess shark activity from the past year. This data is then summarized in an annual report, which can be found at the bottom of this webpage.

Beach Safety

  • Be aware of your surroundings
  • Stay close to shore
  • Swim, paddle, and surf in groups
  • Avoid areas where there are seals or schooling fish
  • Avoid murky, or low visibility water
  • Avoid swimming at dawn/dusk when lighting is low
  • Adhere to all signage at beaches and follow lifeguard instructions
  • For more information, you can check out the most recent DMR white shark report or visit floridamuseum.ufl.edu/shark-attacks/reduce-risk/swimmers/

Quick Facts

  • Sharks belong to a group of animals called Elasmobranchii - fish that have bones made of cartilage. Stingrays and skates belong to this same group!
  • Sharks are old - the first is thought to have originated over 400 million years ago!
  • Not all sharks are apex predators - some smaller species, like the spiny dogfish, are prey for larger species.
  • Some sharks give live birth, while others produce eggs. In very rare instances, scientists have observed parthenogenesis; that is, a female shark reproduced without male contact!
  • Sharks are important - whether big or small, sharks help to regulate prey populations and transfer energy within their ecosystem. This is important in sustaining marine environments.
  • Shark attacks are extremely rare - more people succumb to injury from lightening strikes than they do shark attacks.
  • When a rare attack does occur and is reported, they are tracked and compiled in the International Shark Attack File.

Highly Migratory Species & Offshore Wind

Shark
Photo courtest of Kaylyn Zipp

In 2021, the Bureau of Ocean Energy Management (BOEM) received an application from the State of Maine Governor’s Energy Office for a research lease covering approximately 9,700 acres within the U.S. Outer Continental Shelf. The purpose of the offshore research site is to allow stakeholders from various industries to study the potential impacts of floating offshore wind infrastructure in the region prior to the potential development of commercial wind turbine sites. On August 19th of 2024, BOEM announced the confirmation of the research lease site, with its location approximately 28 nautical miles from Maine’s coast. The 15,000-acre lease area is expected to support up to 12 offshore wind turbines, generating as much as 144 megawatts of energy.

The Gulf of Maine supports a trophic system comprised of complex ecological dynamics which support both seasonal and resident species. Highly migratory species such as sharks and tunas rely on the inshore and offshore waters of the Gulf of Maine for essential habitat and play important roles in their respective ecosystems as apex predators. However, relative to other species of high economic and environmental value there remains a general paucity of information regarding the life history of HMS in the Gulf of Maine, and the potential effects of offshore wind development on their biology and associated fisheries. Some potential factors that may influence HMS biology could include noise stressors, locally-altered nutrient dispersal, electromagnetic frequencies (EMFs), the influence of artificial infrastructure on animal distribution and aggregation, and potential disruptions to historical foraging patterns. This general lack of data regarding regional HMS biology and behavior with respect to offshore wind infrastructure has raised concerns among several fishery and conservation stakeholder groups, particularly fishers that harvest these species, most of whom fish in the Gulf of Maine’s open ocean habitats where wind infrastructure may be constructed.

To address existing data gaps, the Maine DMR has partnered with Dr. Walt Golet and his Pelagic Fisheries Lab at the University of Maine (UMaine) to compile HMS information from the region to characterize the spatial extent of HMS fisheries throughout the Gulf of Maine. Leveraging their combined expertise, the DMR and UMaine aim to provide stakeholders with the necessary information to make informed decisions as they relate to the planning of offshore activities, including wind infrastructure, in the Gulf of Maine and beyond.

Literature

Annual Reports

Publications

For more information, please contact DMR Scientist Matt Davis at Matthew.M.Davis@Maine.gov.