Spiny lobster migrations have been watched and filmed underwater, while clawed lobster migrations are deduced from tag and recapture studies. Over the past several decades, various researchers have marked adult and adolescent lobsters with individually coded visible tags, which are then picked up by fishermen. Scientists use the tag information to compare the sites of release to the subsequent capture site and estimate straight-line distance traveled. Most lobsters have been caught relatively close to the site of release. Multiple recaptures of egg-bearing female lobsters reveal a pattern of movement from shallow warm waters during the hatching, molting, and breeding season, then to deep water for the winter.
Deep waters are warmer than shoal waters in winter.
By moving into deep water, egg-bearing female lobsters are promoting the development of their eggs because maturation occurs faster in warmer water. They then move back into shoal water where eggs hatch and are released over the course of several days or weeks. Hatching occurs primarily in the springtime and early summer in shallow coastal waters and in the shoal waters of the banks. Recent tagging of Year 1-Year 4 juveniles reveals that young lobsters also undertake seasonal migrations from shallow to deeper waters. Spending their summers near shore may result in faster growth rates.