Answer: No. The Sound’s indigenous invertebrate species of crustaceans and mollusks are declining due to challenges like increasing water temperatures, increasing predation, and an increase in invasive species. Details about shifts in seafloor infaunal and epifaunal habitats are also emerging, which are correlated to increasing water temperatures and more frequent and intense storms, affecting the seafloor environment in different regions of the Sound.
The Invertebrate Biomass Index and lobster abundance are both measured with data from the Connecticut Department of Energy and Environmental Protection’s (CT DEEP) Long Island Sound Trawl Survey.
Because most of the Sound’s lobster population does not migrate, the standardized catch of lobster from the Trawl Survey is used to assess the relative abundance of the local stock.
The Invertebrate Biomass Index is the annual average weight in kilograms of 15 invertebrate species collected in the Trawl Survey. These species include various crab species (blue crab, flat claw hermit crab, lady crab, rock crab, and spider crab), horseshoe crab, American lobster, Lion’s Mane jellyfish, sea star, mantis shrimp, long-finned squid, gastropods (whelks and northern moon shells), and bivalves (blue mussel and common oyster).
For further information see: 2022 A Study of Marine Recreation Fisheries in Connecticut on the CT DEEP Fisheries Publications website.
The Invertebrates Abundance and Biomass indicator indicates progress on the Partnership’s efforts to protect and enhance the health of offshore habitats and their associated species for the Offshore Habitat objective. Overall, the Sound’s invertebrate populations show a long-term decline.
Carrying out the Offshore Habitat objective to protect and enhance the health of offshore habitats and their associated species, like these invertebrates, is part of the Partnership’s plan to improve the Sound’s invertebrate populations.
The invertebrate biomass index indicates the productivity of the forage base of the food chain. Many game fish species, which are both recreationally and commercial valuable, depend on the success of invertebrate crustacean and mollusk species as they are important food sources. Like the finfish biomass, a high invertebrate biomass also indicates good health conditions of the Sound.
The Invertebrate Biomass Index shows a decreasing trend over the past 27 years. Although the American lobster makes up a large component of the invertebrate index early in the time series, analysis show a pronounced decline in many other invertebrate species over the same time series as well – such as spider, rock and lady crab species.
The fall and spring indices for American lobster are on a steady decline. Both indices have remained below the time-series average since 2003, and in recent years are nearing or reaching zero. One of the factors implicated in the lobster population decline is increased summer water temperatures in Long Island Sound. American lobsters cannot maintain their metabolisms in waters above 20°C for long periods of time. The Long Island Sound Partnership water temperature indicator, for example, shows that the bottom temperatures of the Sound have frequently measured greater than this threshold in the summer. Additionally, some warm water species that prey on lobsters are becoming more abundant in the Sound, such as Black Sea Bass. Other species such as Smooth dogfish and striped bass that have high consumption rates on lobster, may be contributing to keeping lobster abundance to the current depressed level.
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