Determination of Essential Reproductive Habitat for the American Lobster: Connectivity Between Broodstock and Nursery Grounds  (Year 1 of 1) Project Number: NAGL-01-03 Principle Investigators: Steneck, R. S., L. S. Incze, C. J. Wilson, and E. R. Annis Region(s): Coastal Maine, Gulf of Maine View project media Project Summary: Are broodstock lobsters concentrated in near-shore habitats in the northeast comer of the Gulf of Maine? If they are, then ocean currents could be carrying larvae from that source, down-stream hundreds of kilometers to nursery grounds in regions southwest of Penobscot Bay where rates of settlement and landings have been consistently high and are growing over recent years. Before a larval source-sink hypothesis can be properly tested, it will be necessary to quantify patterns in the distribution and abundance of reproductive phase lobsters. Evidence from fisheries trawl surveys and past NURP research suggests that broodstock abundance may be greatest in the vicinity of the mouth of the Bay of Fundy. The proposed research will test the hypothesis by using submersibles or ROVs to quantify the distribution, abundance and body size of near-shore, lobsters below SCUBA depths at multiple dive sites in five widely spaced regions. These data will calibrate patterns derived from sea sampling studies of trap-caught lobsters. Beginning in 1999 simultaneous plankton tows revealed newly hatched stage I larvae in the vicinity of broodstock quantified in the Bay of Fundy, and postlarvae (settling stage) most abundant 100 km downstream. This is the first suggestion of a long-distance larval source sink relationship but it must be verified. This research is necessary to determine if these coastal regions are essential lobster broodstock habitats that sustain this fishery in the Gulf of Maine. Significance of Research: The lobster, Homarus americanus, is the single most important fisheries species in the western North Atlantic. In Maine, New England's largest producer of marine resources, lobsters landings in 1999 gross well over 180 million dollars and employ over 10,000 people. The lobster fishery is the only fishery in the world that has been aggressively harvested for over a century and has not only remained stable, but stocks have increased. One conclusion drawn from this is that broodstock sufficient to sustain this fishery persists in refugia where it has been relatively safe. However, the location, size and rate-change of the broodstock populations remain unknown. Thus it is important to locate and quantify the "effective" broodstock - that is those that contribute to landed lobsters - so that management steps can be taken to preserve them and their essential habitat. This research is intended to augment traditional stock assessment approaches. It considers the stock within the Gulf of Maine at discrete regional scales and adds an ecological approach to fisheries management. From a basic perspective, understanding the structure and function of significant reproductive sources and juvenile lobster sinks (i.e., nursery grounds) is scientifically fascinating. The segregation of life history phases of lobsters and how their behavior and the physical oceanography of the Gulf of Maine interact presents a unique interdisciplinary study for marine science and the management of our marine resources. The specific objectives are: Objective 1) To test the hypothesis that reproductive-phase lobsters concentrate primarily in regions in the mouth of the Bay of Fundy and secondarily in the mouth of Penobscot Bay. Objective 2): To determine if spatial patterns of abundance and body-size derived from sea-sampling of trap-caught lobsters correspond with ROV-derived data. Objective 3: To determine if submersible data obtained in 1999 corresponds with data gathered using identical methods in 2001 (testing efficacy of approach). Objective 4) To conduct nightly neuston plankton tows to quantify the distribution and abundance of Stage I larvae and Stage IV post-larvae. Objective 5) To tie in results of this long-distance larval source sink study with on-going larval studies by Incze in Penobscot Bay and Annis/Steneck on the coast surrounding Penobscot Bay.   Reproductive phase lobsters were quantified from 49 ROV transects that surveyed over 45 km of the sea floor along a 200 km path from Boothbay Harbor in midcoast Maine to the mouth of the Bay of Fundy (including Grand Manan Island). Two concentrations of reproductive lobsters were found. The highest densities of very large reproductive phase lobsters live in shallow sediment-dominated bays on the north shore of Grand Manan Island. No similar concentrations were found at sites south on Grand Manan or along the adjacent mainland coast to just northeast of Mt. Desert Island. From Mt. Desert Island to the mouth of Penobscot Bay a second more diffuse but wider spread concentration of reproductive lobsters were found. Larval tows found stage I larvae in the vicinities of the concentrations of reproductive lobsters (see larval lobster distribution data). Later-stage postlarvae were most abundant down-stream near the regions known for annually high rates of lobster settlement (the western mouth of Penobscot Bay (see figure in hard copy report). The arrival of postlarvae in western Maine corresponded with the timing of settlement in that region. 2001 had many more larval lobsters than we had seen in 1999 and settlement data also corresponded with this temporal pattern. Leg 1    Begin Date: 7/25/2001   End Date: 8/5/2001   Support Vessel/Platform: R/V Connecticut System Ops Days Dives Dive Time (hrs) Depth (m) Phantom III S2 10 49 56.19 138.12 Keymap: Location of Project Dives: Legend: Phantom III S2

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