American lobster

American lobster
Name	American lobster
Taxon	Homarus americanus
Authority	H. Milne-Edwards, 1837
Range map caption	Native range in the North Atlantic

American lobster. It is a species of crustacean found in the northern Atlantic Ocean, particularly along the coast of North America. This decapod is renowned for its large size, commercially valuable meat, and complex life history. It is a keystone species in its ecosystem and supports one of the most valuable fisheries in the United States and Canada.

Description and anatomy

The American lobster possesses a hard, protective exoskeleton composed of chitin and calcium carbonate, which it must periodically shed in a process called molting to grow. Its body is divided into two main sections: the cephalothorax and the abdomen. It is equipped with five pairs of legs, the first pair bearing large, powerful claws used for defense and feeding. Sensory capabilities are provided by long antennae and compound eyes mounted on movable stalks. Coloration is typically a mottled greenish-brown, though rare genetic variations can produce blue, yellow, or even albino specimens.

Distribution and habitat

This species is native to the coastal waters of the northwestern Atlantic Ocean, from Labrador in Canada south to Cape Hatteras in North Carolina. The highest population densities occur in the colder waters of the Gulf of Maine, the Bay of Fundy, and the Gulf of Saint Lawrence. It is a benthic organism, inhabiting a range of substrates from rocky reefs and kelp forests to muddy or sandy bottoms, where it constructs burrows for shelter. Depth range extends from the intertidal zone to approximately 500 meters on the continental shelf.

Life cycle and reproduction

Females mate shortly after molting, storing sperm for months before extruding thousands to tens of thousands of eggs, which they carry attached to their pleopods for 9-12 months. After hatching, larvae enter the planktonic stage, undergoing several molts while drifting with ocean currents for weeks. This stage is highly vulnerable to predation and dispersal. After metamorphosing into a bottom-dwelling post-larva, the juvenile seeks shelter and begins a long, slow growth phase, molting frequently at first. Sexual maturity is reached after 5-8 years, though growth and age are difficult to determine precisely. They are long-lived, with some individuals exceeding 50 years of age.

Diet and behavior

It is an opportunistic omnivore and scavenger, feeding on a wide variety of organisms including fish, mollusks like mussels and clams, other crustacea, polychaete worms, and some plant material. It uses its claws to crush shelled prey and manipulate food. Primarily nocturnal, it spends daylight hours in burrows or crevices. Behavior is influenced by molting cycles, with individuals becoming reclusive and vulnerable during the soft-shell period. They exhibit complex social interactions, including agonistic encounters over shelter, and use chemical and tactile signals for communication.

Fisheries and aquaculture

The fishery for this species is one of the oldest and most economically significant in North America, central to the economies of states like Maine and provinces like Nova Scotia. The catch is primarily landed using lobster traps, which are baited and deployed on the seafloor. Key ports include Portland, Gloucester, and Halifax. Management is intensive, governed by regulations on minimum size, protection of egg-bearing females, and licensing. Aquaculture efforts, such as those by the New England Aquarium and various commercial ventures, focus on hatchery production for stock enhancement and grow-out systems, though large-scale commercial farming faces significant biological and economic challenges.

Conservation and management

Populations are managed through a cooperative international framework involving agencies like the National Marine Fisheries Service and Fisheries and Oceans Canada. Key conservation measures include V-notch programs to protect reproductive females, strict size limits, and trap limits. Major threats include climate change, which affects ocean temperatures and larval survival, ocean acidification impacting shell formation, and diseases like epizootic shell disease. Ongoing research by institutions such as the Woods Hole Oceanographic Institution and the University of Maine monitors stock health and investigates the impacts of environmental change on this ecologically and commercially vital species.

Category:Decapods Category:Commercial crustaceans Category:Fauna of the Atlantic Ocean