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Are whale strandings increasing along the Jersey Shore?

Recent whale strandings along New Jersey and New York continue a period of increased humpback whale mortalities along the U.S. East Coast that began in 20161,2. In April of 2017 it was declared an Unusual Mortality Event (UME) for humpback whales by the National Oceanic Atmospheric Administration (NOAA) as defined by the Marine Mammal Protection Act1.

Have there been similar strandings in the past and why?

Three other UMEs for humpback whales have occurred since 2000. In 2003, there were 16 mortalities; in 2005, 7 occurred; and in 2006, 48 mortalities were recorded. The causes of these UMEs are still undetermined3.

This most recent increase that has been occurring since 2016 is similar to that observed between 1985-19924. The similarities include a notable increase in frequency and sightings, an increase in the number of strandings (many in mid-winter when they are believed to be primarily in tropical regions), and the age of the whales at mortality (juveniles)1-11.

What are potential causes of whale strandings?

Many factors can contribute to the stranding of an individual whale. These include illness, vessel strikes, entanglement in discarded fishing gear, high-intensity, low-frequency acoustic surveys, and contributing factors such as climate variability, long-term climate change, and predator-prey interactions.6,8,10,12

The port of New York and New Jersey is now the busiest port in the U.S, with cargo handling capacity increasing by 5.7% since 2021 and surpassing the Port of Los Angeles last year.13 Vessel density and speed are highest in nearshore waters where it is believed the juvenile humpback whales are foraging at the surface.5,6,8,11,14 The majority (93%) of humpback whale mortalities in the New York Bight caused by vessel strikes were juveniles.11 Furthermore, vessel strikes have been identified as the culprit for half of the necropsied whales that have stranded since 2017 – that’s six times higher than the 16-year average of 1.5 whales3 – while necropsy (a type of autopsy) analyses for the other stranded whales are ongoing. Adult humpback whales, along with fin, minke, and north Atlantic right, forage farther offshore.

In addition to changes in human activity across our region, the habitat of the whales and their prey changes rapidly. Characteristics of the ocean off our coast undergo remarkable variability across days and weeks to seasons, years, and decades.15 This intense ocean variability drives an equally variable ecosystem – from the primary producers (planktonic algae) to highly migratory fish and marine mammals. Tight coupling between ocean conditions and the habitat preference of local and migratory species can cause their distributions to vary significantly from season to season and year to year.

Furthermore, our coastal waters are situated in one of the most rapidly warming regions in the world. Following the recent increasing trend of carbon dioxide emissions without additional policy changes and action, local ocean temperatures in the mid-Atlantic would increase by 3-4°C over the next 70 years16. Ocean warming has led to vulnerability among approximately half of the U.S. Northeast Shelf species17, and the dominant response of fish species to ocean warming has been to shift their distribution range poleward18-20.

A primary food source of humpback whales, Atlantic menhaden have been increasing in biomass in the region since the 1980s21, and anecdotal observations suggest that their distributions have been shifting closer to shore and staying later into winter. We do not know why. Coincidentally, these nearshore areas are where juvenile humpbacks have been observed feeding at the surface5,6,8,11,14, potentially increasing susceptibility to vessel strikes or entanglement.

Are the strandings related to the research and monitoring occurring because of New Jersey’s offshore wind energy development project?

Ongoing planning and surveying activities conducted by offshore wind developers for the different projects include acoustic surveys for site evaluation. There have been recent claims that these acoustic surveying efforts have caused this recent uptick in whale strandings. At this point, there are no data or evidence linking whale mortalities to any one specific factor, including offshore wind development.10,12,22

Not all acoustic surveys are the same. Unlike the large acoustic arrays for oil and gas surveys or military sonar that use high-intensive low frequency acoustics, the wind acoustic surveys are of high frequency or lower intensity low frequency which are harder for baleen whales – including humpback whales – to hear.12,23

Notably, the recent strandings of humpbacks and other marine mammals have been occurring from Florida through Maine1, covering a large region with very different stressors. To properly assign cause to any stranding, all factors must be considered.

Why is it important to determine the cause(s) of whale strandings and what research efforts are needed to address this issue?

Most reports are too quick to assign the cause of whale strandings without much concern for data and scientific input. Now more than ever it is critical that we consider the evidence and the complexity of the entire system before drawing conclusions about the causes. Many factors, natural and human-caused, impact ecosystem health.

Decisions, particularly those as paramount as calls to shut down the development of a climate-mitigating renewable energy, need to be based on scientific data and solid evidence and consider the entirety of factors contributing to observed or perceived impacts. At this point, there are no such data or evidence linking whale mortalities to any one specific factor including offshore wind development.

We encourage the decision makers to consider all the changes occurring in and factors impacting the coastal ocean habitats utilized by these whales. In addition to ongoing baseline monitoring and planned offshore wind impact studies, it is imperative to bring together the marine mammal and broader oceanographic communities now to investigate and identify all potential drivers of this ongoing UME event before any blame can be directed toward a specific entity or activity.

What must be considered when planning responsible development of offshore wind? 

The need is clear to develop sustainable solutions to combat the single biggest threat to our ocean and the planet we inhabit – human-induced climate change resulting from greenhouse gas emissions. A solution that is rapidly gaining pace in our region is the development of offshore renewable energy generation. The production of renewable energy from offshore wind offers a mitigation pathway toward immediately needed reductions in carbon dioxide emissions. With federal and state government support, there has been significant acceleration of the planning and construction of offshore wind.

Unlike onshore power generation solutions, offshore wind facilities will be constructed in a dynamic coastal ocean environment – an environment that is tightly coupled with the marine ecosystem from the plankton to the top predators. Ongoing efforts need to be centered on monitoring and understanding this dynamic ocean environment, including baseline monitoring and impact studies related to planned offshore wind development. Ocean data and expertise will provide a tremendous resource to the decision makers ensuring that offshore wind is developed in a responsible way.

What is Rutgers’ involvement in offshore wind project, here and beyond NJ?

Rutgers scientists are engaged in multiple research efforts to both monitor and understand the dynamic movements of marine mammals and their prey in the context of planned offshore wind development. Baseline monitoring studies focus on listening devices that allow us to map the distribution of marine mammals relative to ocean characteristics like temperature, salinity, and pH and features like fronts and eddies.

Together, this work will be used to advance our understanding of the habitat preference of these animals and how those habitats move over time. Impact studies use this baseline data to understand what ecological changes are specific to offshore wind activity. The funding supporting this work is provided by state and federal government agencies, research foundations, and the private sector.



1NOAA Fisheries 2016–2023 Humpback Whale Unusual Mortality Event Along the Atlantic Coast

2Brown DM et al (2022). Site fidelity, population identity and demographic characteristics of humpback whales in the New York Bight apex. Journal of the Marine Biological Association of the United Kingdom 1–9. S0025315422000388

3NOAA Fisheries Frequent Questions: 2016-2023 Humpback Whale Atlantic Coast Unusual Mortality Event

4Wiley DN, Asmutis RA, Pitchford TD and Gannon DP (1995) Stranding and mortality of humpback whales, Megaptera novaeangliae, in the mid-Atlantic and southeast United States, 1985–1992. Fishery Bulletin 93, 196-205.

5Brown DM, Robbins J, Sieswerda PL, Schoelkopf R and Parsons ECM (2018) Humpback whale (Megaptera novaeangliae) sightings in the New York-New Jersey harbor estuary. Marine Mammal Science 34, 250–257.

6Brown DM, Sieswerda PL and Parsons ECM (2019) Potential encounters between humpback whales (Megaptera novaeangliae) and vessels in the New York Bight apex, USA. Marine Policy 106, 103527.

7Chou E, Rekdahl ML, Kopelman AH, Brown DM, Sieswerda PL, DiGiovanni RA Jr., Rosenbaum HC (2022). Occurrence of baleen whales in the New York Bight, 1998–2017: insights from opportunistic data. Journal of the Marine Biological Association of the United Kingdom 102, 438–444. S0025315422000716

8King CD, Chou E, Rekdahl ML, Trabue SG and Rosenbaum HC (2021) Baleen whale distribution, behavior and overlap with anthropogenic activity in coastal regions of the New York Bight. Marine Biology Research 17, 380–400.

9Zoidis AM, Lomac-MacNair KS, Ireland DS, Rickard ME, McKown KA and Schlesinger D (2021) Distribution and density of six large whale species in the New York Bight from monthly aerial surveys 2017 to 2020. Continental Shelf Research 230, 104572.

10NOAA Fisheries Frequent Questions – Offshore Wind and Whales

11Stepanuk JEF, Heywood EI, Lopez JF, DiGiovanni Jr. RA and Thorne LH (2021) Age-specific behavior and habitat use in humpback whales: implications for vessel strike. Marine Ecology Progress Series 663, 209–222.

12YaleEnvironment360 – The East Coast Whale Dieoffs: Unraveling the Causes

13Container Xchange: Know the top 10 busiest ports in the US

14Smith SE, Brown DM, Oliveras JR, Sieswerda PL, Ahearn S and Reiss D (2022) A Preliminary Study on Humpback Whales Lunge Feeding in the New York Bight, United States. Front. Mar. Sci. 9:798250. doi: 10.3389/fmars.2022.798250

15Houghton, R. W., R. Schlitz, R. C. Beardsley, B. Butman, and J. L. Chamberlin. 1982. The Middle Atlantic Bight Cold Pool: Evolution of the Temperature Structure During Summer 1979. Journal of Physical Oceanography, 12, 1019-1029.

16Saba, V. S., Griffies, S. M., Anderson, W. G., Winton, M., Alexander, M. A., Delworth, T. L., Hare, J. A., Harrison, M. J., Rosati, A., Vecchi, G. A., & Zhang, R. (2016). Enhanced warming of the Northwest Atlantic Ocean under climate change. Journal of Geophysical Research: Oceans 121(1): 118-132,

17Hare, J. A., Morrison, W. E., Nelson, M. W., Stachura, M. M., Teeters, E. J., Griffis, R. B., Alexander, M. A., Scott, J. D., Alade, L., Bell, R. J., Chute, A. S., Curti, K. L., Curtis, T. H., Kircheis, D., Kocik, J. F., Lucey, S. M., McCandless, C. T., Milke, L. M., Richardson, D. E., Robillard, E., Walsh, H. J., Conor McManus, M., Marancik, K. E., & Griswold, C. A. (2016). A Vulnerability Assessment of Fish and Invertebrates to Climate Change on the Northeast U.S. Continental Shelf. PLoS ONE, 11(2): e0146756,

18Pinsky, M. L., Worm, B., Fogarty, M. J., Sarmiento, J. L., & Levin, S. A. (2013). Marine taxa track local climate velocities. Science 341(6151): 1239-1242,

19Kleisner, K. M., Fogarty, M. J., McGee, S., Hare, J. A., Moret, S., Perretti, C. T., & Saba, V. S. (2017). Marine species distribution shifts on the U.S. Northeast Continental Shelf under continued ocean warming. Progress in Oceanography 153: 24-36,

20Weiskopf, S. R., Rubenstein, M. A., Crozier, L. G., Gaichas, S., Griffis, R., Halofsky, J. E., Hyde, K. J. W., Morelli, T. L., Morisette, J. T., Muñoz, R. C., Pershing, A. J., Peterson, D. L., Poudel, R., Staudinger, M. D., Sutton-Grier, A. E., Thompson, L., Vose, J., Weltzin, J. F., & Whyte, K. P. (2020). Climate change effects on biodiversity, ecosystems, ecosystem services, and natural resource management in the United States. Science of The Total Environment 733: 137782,

21SEDAR. 2020. SEDAR 69 – Atlantic Menhaden Benchmark Stock Assessment Report. SEDAR, North Charleston SC. 691 pp. available online at:

22Marine Mammal Commission Update on Strandings of Large Whales along the East Coast:

23BOEM Offshore Wind Activities and Marine Mammal Protection


Other helpful resources:

Rutgers Offshore Wind research and initiatives: