Safe Harbor: The Proposed Cape Cod Seal Cull’s Illegality Under the MMPA, Ineffectiveness, and Cruelty

Safe Harbor: The Proposed Cape Cod Seal Cull’s Illegality Under the MMPA, Ineffectiveness, and Cruelty

By: Ryan Clemens | JD/MEM at Vermont Law School and Yale School of the Environment

June 13, 2021

Joe Davies, Photograph of Harbor Seal Balancing on the Peak of a Rock, in Joe’s Retirement Blog, Blogger (Jan 29, 2006),

Massachusetts fishers and residents currently feel that the state’s seal populations must be cut down. However, neither the Marine Mammal Protection Act (MMPA) nor its many exceptions would permit this overly simplistic solution, and rightfully so.

Several Massachusetts Cape and Islands fishers, business owners, and residents feel that the state’s coastline harbors too many seals.[1] Miriam Wasser reported that Cape Cod communities blame harbor seals (Phoca vitulina) and gray seals (Halichoerus grypus) for polluting water, preventing the Atlantic cod from recovering, and limiting tourism by enticing sharks to beaches.[2] In response, the communities proposed a seal cull to directly remove their perceived threat.

This proposed cull would not be the first for these seal communities. Up until the 1970s, New England systematically depleted seal populations: Massachusetts from 1888 to 1962 and Maine from 1891 to 1905 and 1937 to 1945 held bounties for seal noses, effectively crashing their populations.[3] Neither seal species is threatened or endangered any longer[4]; in fact, Wasser’s article cites a 2017 study placing Cape and Islands seal populations between 30,000 and 50,000.[5] Contextualized with recent history, an overabundance of seals is a misperception. Additionally, a restored, back-to-regular seal population is not only a good thing for the animals themselves, but also for Massachusetts’ larger ecosystem.

Top-down or predatory control is an important ecosystem balancer. Removing top-level predators through seal bounties[6] or, ironically, cod overfishing, causes “significant ecological change” as lower trophic levels grow unchecked and place disproportionate strain on the remaining ecological communities.[7] Restoring top-level predators and their facilitated “biological and functional diversity” is an important step “as a stabilizing force in ecosystems,” ultimately bolstering economically valuable fisheries like cod.[8] Beyond the scientific argument against seal culls, the MMPA flatly prohibits any such unnecessary and cruel action.

Since 1972, the MMPA is one of, if not the, most powerful legal protections for animals. The Act broadly prohibits the take and import of marine mammals.[9] Per the Act, “take” means “to harass, hunt, capture, or kill, or attempt to harass, hunt, capture, or kill,” and “marine mammal” partly means mammals that are “morphologically adapted to the marine environment (including sea otters and members of the orders Sirenia, Pinnipedia and Cetacea).”[10] As gray seals and harbor are both pinnipeds and morphologically adapted to the marine environment,[11] and culling seals plainly includes hunting, capturing, and killing them, or at least attempting to, the MMPA applies to and flatly prohibits a seal cull. None of the MMPA’s potentially relevant exceptions actually apply here, either.

First, fishers argue that seals deplete Atlantic cod stocks and inhibit their recovery.[12] The MMPA’s first exception permits takes to enhance the survival or recovery of a species or stock, after review and approval by the Marine Mammal Commission (MMC).[13] The take must be “likely to contribute significantly to maintaining or increasing distribution or numbers necessary to ensure the survival or recovery of the species or stock.”[14] This exception likely does not allow a seal cull, not only because “species or stock” likely refers to the marine mammal itself,[15] but also because a cull would not contribute significantly to increasing cod populations.

Even if the recovery of a species or stock refers to non-marine mammals, reducing Massachusetts’ seals would not restore cod. Preliminarily, a thousand or several thousand-seal cull would barely make a significant dent in their now several tens of thousands-large population.[16] Primarily, seals’ predation on and impact to cod are small: cod comprise 6% of their diet, compared to sand lance at 53%.[17] Instead, seals eat cod’s ecologically-similar groundfish and gadid competitors, flounders and hake, respectively 21% and 4%, yet do not prey upon lobster.[18] Seals’ top-down forcing[19] thus limits cod’s competitors while avoiding its crustacean prey, aiding the stock’s recovery. Cod also faces separate challenges to recovery, distinct from seal predation. Species like Atlantic herring preying on cod juveniles[20] and climate change increasing sea-surface temperatures[21] more likely cause Atlantic cod hysteresis, or the inability of a species to regain prior population levels. Again, seals consume a near-equal amount of herring to cod, limiting their predation and in small part benefitting the stock.[22] Overall, science indicates that seals do not limit cod’s chance at recovery, failing to fit within the MMPA’s first exception’s alternative interpretation.

The MMPA’s second exception permits takes during fishing activity. However, these takes during normal fishing activity must be incidental, authorized by a formal rulemaking proceeding,  “meet the requirements of the MMPA[,] and be consistent with the primary goal of protecting marine mammals.”[23] Here, a cull is both an intentional killing and plainly inconsistent with the goal of protecting marine mammals, excluding this exception. NOAA should nevertheless keep a keener eye out to avoid preexisting permit or permit application abuse, possibly for intentional “unintentional” seal kills if fishers’ resentment grows.

The third potentially applicable MMPA exception is broad but still does not allow a seal cull. The MMPA offers a general waiver “to determine when, to what extent, if at all, and by what means, it is compatible with this chapter to waive the requirements of this section so as to allow taking” consistent with “sound principles of resource protection and conservation” and based on “the best scientific evidence available and in consultation with [MMC].”[24] Again this exception does not apply to culls because wanton killing is plainly inconsistent with the seals’ protection and conservation. Moreover, even if restoring fish stocks is compatible, the best scientific evidence available does not support that reducing seal populations is actually a means to recover fisheries stocks.[25] The third exception fails too.

The final potentially applicable exception would not permit a seal cull either. The MMPA allows incidental taking by “citizens . . . other than commercial fish[ers]” if a full public comment period shows that a five or fewer year-span of takings will have a negligible impact.[26] This negligible impact exception does not extend to “incidental takings [that] are not merely a remote possibility but a certainty,” however.[27] Thus, a cull that guarantees fatal takings fails the negligible impact exception. And, as a final, minor note, the MMPA does allow a wide range of individuals to deter marine mammals, but all determent measures must not result in death or serious injury, explicitly contrary to a seal cull.[28]

In total, the MMPA most likely prohibits a seal cull or any form of harassment. Killing any seal in Massachusetts is thus illegal, ineffective, and unnecessarily cruel. Seals are innocent and environmentally important actors for their top-down ecosystem controls. The “seal-enticed,” increasing shark presence provides top-down ecological balancing too, even including naturally balancing the seal “nuisance.” Additionally, not only is there no evidence that sharks deter tourism,[29] but to editorialize, the Cape and Islands likely do not need much more traffic this year.[30]

Applying the MMPA to seals shows that the Act is one of the few yet likely most powerful de facto protection for animals, and thus an equally powerful tool in restoring the already stressed and ecologically depleted Atlantic Ocean. NOAA and the MMC however should expand stakeholder outreach efforts by engaging fishers and Cape residents in open, two-way dialogue to bolster faith in science, foster respect within and among our human community for seals, and ultimately to preempt any illegal seal culls. Before then, to aid and maintain the ocean’s health and natural resources, simply please leave the seals alone.

[1] Miriam Wasser, Seals on Cape Cod are More than Just Shark Bait, wbur (Aug. 2, 2019),

[2] Id.

[3] Id.

[4] Nat’l Oceanic and Atmospheric Admin., Species Directory, (last visited May 19, 2021).

[5] Wasser, supra note 1.

[6] See id. (reporting that between 72,000 and 135,000 seals were killed for bounty in Massachusetts and Maine for bounty by the mid-20th century).

[7] Stephanie A. Boudreau & Boris Worm, Top-Down Control of Lobster in the Gulf of Maine: Insights from Local Ecological Knowledge and Research Surveys, 403 Marine Ecology Prog. Ser. 181, 182 (2010) (citing first HK Lotze & I. Milewski, Two Centuries of Multiple Human Impacts and Successive Changes in a North Atlantic Food Web, 14 Ecology App. 1428 (2004); and then RS Steneck et al., Accelerating Trophic-Level Dysfunction in Kelp Forest Ecosystems of the Western North Atlantic, 7 Ecosystems 323 (2004)).

[8] Kenenth T. Frank et al., Trophic Cascades in a Formerly Cod-Dominated Ecosystem, 308 Sci. 1621, 1622 (2005).

[9] 16 U.S.C. § 1371(a).

[10] Id. § 1362(6), (13).

[11] Analisa Berta & Morgan Churchill, Pinniped Taxonomy: Review of Currently Recognized Species and Subspecies, and Evidence Used for their Description, 42 Mammal Rev. 207, 222–24 (2012).

[12] Wasser, supra note 1.

[13] 16 U.S.C. § 1371(a)(1).

[14] Id. § 1374(c)(4)(A).

[15] Id. § 1362(11) (“The term “population stock” or “stock” means a group of marine mammals of the same species or smaller taxa in a common spatial arrangement, that interbreed when mature.”).

[16] Wasser, supra note 1.

[17] Kristin Ampela, The Diet and Foraging of Gray Seals (Halichoerus Grypus) in United States Waters 56 (2009) (Ph.D. dissertation, New York University),

[18] Id. at 56, 166–67.

[19] See supra notes 6–8 and accompanying text.

[20] Coilin Minto & Boris Worm, Interactions Between Small Pelagic Fish and Young Cod Across the North Atlantic, 93 Ecology 2139, 2152 (2012).

[21] Camilla Sguotti et al., Catastrophic Dynamics Limit Atlantic Cod Recovery, 286 Proc. Royal Soc. B 20182877, 20182884 (2019).

[22] Ampela, supra note 17, at 56.

[23] 16 U.S.C. § 1371(a)(2); Kokechik Fishermen’s Ass’n v. Secretary of Commerce, 839 F.2d 795, 800 (D.C. App. Cir. 1988).

[24] 16 U.S.C. § 1371(a)(3)(A). The frequent references to principles of resource protection and conservation mean that the “[marine mammal] species and population stocks should not be permitted to diminish beyond the point at which they cease to be a significant functioning element in the ecosystem of which they are a part, and, consistent with this major objective, they should not be permitted to diminish below their optimum sustainable population.” Id. § 1361(2).

[25] See supra notes 16–22 and accompanying text.

[26] 16 U.S.C. § 1371(a)(5)(A).

[27] Kokechik Fishermen’s Ass’n, 839 F.2d at 802.

[28] 16 U.S.C. § 1371(a)(4)(A).

[29] Wasser, supra note 1.

[30] Katie Johnston, On Cape Cod, Business Owners are Getting Ready for a Season of Record Crowds and Worker Shortages, Boston Globe (Apr. 6, 2021),; Rick Sobey, Cape Traffic Ahead of the Summer Influx: Sagamore Bridge Lane Closures for Weeks, Boston Herald (Apr. 12, 2021),

About the Author

Ryan Clemens is a JD/MEM student at Vermont Law School and Yale School of the Environment from Massachusetts. He plans to first advocate for both conservation and stakeholder engagement and equity in the co-management of marine and coastal natural resources, and second to litigate for environmental quality, climate resiliency, and conservation within coastal development.


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