2020 CEQ Annual Report

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Lobster and Fishes of Long Island Sound

Climate Change Indicator

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Long Island Sound’s species are trending towards animals that prefer warm water.

Lobster, which thrive in cold water, have become less common. Lobster landings in Connecticut have declined dramatically from a high of over 3.7 million pounds in 1998 to just over 111,000 pounds in 2019 (most recent data) – almost a 97 percent drop.37

The decline in lobsters was also confirmed by Department of Energy and Environmental Protection’s (DEEP) spring and fall trawl surveys. Researchers investigated several possible causes for the dramatic downturn in lobster populations since 1998 including disease, changes in water quality, changes in climatic conditions and other human impacts to Long Island Sound, such as the presence of pesticides. Scientists did not detect pesticides in lobsters collected in 2014,38 leaving the warming waters as the most likely cause for Connecticut's lobster decline.

DEEP surveys marine fish, squid and lobster populations, usually every spring and fall, by towing nets from a research vessel.* The chart shows the average number of fish species caught in each tow during the spring and fall surveys combined. The well-documented trend toward species that favor warm water is apparent.39

A study of 686 species, published in 2018, projects the shifts in thermal habitat for fish species all along the North American continental shelf.40  The impacts of warmer water temperatures have had mixed effects on finfish found in Connecticut waters. As discussed above, the trend indicates that the mean number of warm-adapted species increased significantly while the average number of cold-adapted species declined since 1984. Overall, finfish diversity in Long Island Sound remains high, indicating that the Sound is healthy and that a strong balance of species is able to exploit the full mix of resources available throughout this ecosystem.

Technical Note: *Data from 2010 and 2020 are missing because no fall and/or spring survey was conducted those years. Finfish species captured in the Connecticut DEEP Long Island Sound Trawl Survey were divided into adaptation groups based on their temperature tolerance and seasonal spawning habits.


37 NOAA, Commercial Fisheries Landings, www.fisheries.noaa.gov/national/sustainable-fisheries/commercial-fisheries-landings.
38 Investigating the Presence of Pesticides in American Lobster from Long Island Sound”, 2016; portal.ct.gov/-/media/DEEP/fishing/fisheries_management/CTDEEPInvestigatingthepresenceofpesticidesinAmericanlobsterfromLongIslandSoundpdf.pdf.
39 DEEP, Division of Marine Fisheries; personal communication from K. Gottschall, May 13, 2020.
40Projecting shifts in thermal habitat for 686 species on the North American continental shelf”, May 16, 2018; www.ncbi.nlm.nih.gov/pmc/articles/PMC5955691/