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MAPS OF THE LIFE HISTORY STAGES

Larval-(egg) STAGE I Distribution

As stated previously, eggs hatch immediately upon release so only the Stage I larvae would be expected to reach the surface. Unfortunately, no comprehensive maps of Stage I larvae distributions have been published. It is therefore necessary to infer Stage I larval distribution from local studies and to show where similar oceanographic conditions are present. For inshore sampling of Stage I larvae, we rely largely on the work of Fogarty and others (1983). For the offshore area, we only have published larval maps near the canyons (Katz et al. 1994).

In the offshore region, the Stage I map (see attached folder) highlights the outer shelf and upper slope which contains the canyons and the areas between them. We have no data for the area south of Block Canyon, but it is assumed that the offshore populations contribute some larvae in this area as well. In addition, it is generally believed that Georges Bank, Browns Bank, and the Bay of Fundy contribute significantly to the inshore population (Cobb and Wahle 1994)

Inshore, Fogarty and others (1983) have shown significant Stage I larvae at Block Island Sound, Buzzards Bay, Cape Cod Bay, Penobscot Bay and at least one sample at Hampton-Seabrook. Some of these maps are detailed enough to show rapid decreases away from the estuaries. Other large estuary systems are believed to contain Stage I larvae, but the work has not yet been published.

Post-larval-(larval) STAGE 1V Distribution

For the map of the larval- postlarval distribution (see attached folder) we are left with a dilemma. We can either designate the entire Gulf of Maine as EFH based on the planktonic distribution of Stage I, II, III and part of Stage IV or attempt to map only postlarval distribution. We have chosen to map Stage IV settlement because it corresponds directly to the habitats which need to be protected for the continued growth and recruitment of the species.

The postlarval map once again highlights the areas inshore where Stage IV larvae have been sampled directly by Fogarty and others (1983) and Katz (1984). Here we have combined the postlarval distribution at the surface with gravel and gravely sand substrates which are preferred for settlement. In Maine, we have included rocky shores where algae may have been established. We have also utilized the recent work in Penobscot Bay (Steneck and Wilson 1998). Finally, we have suggested that some postlarvae may settle on Stellwagen Bank, but we know of no studies to support this possibility, although current studies by Wahle (personal communication) may soon answer this question.

Juveniles

The map of juvenile distribution (see attached folder) encompasses shelter-restricted, emergent, and vagile juvenile phases. Because it is a composite of three different phases it naturally includes many habitats. These occur primarily among cobbles, rocks on sand, and peat reefs.

Work done at Great Bay Estuary (Brown et al. unpub.) provides a model for juvenile distribution in the mouths of estuaries. Long Island Sound is assumed to be a major area for juveniles, but we do not have access to detailed data for this region. Also, while the precise location of peat reefs is unknown, the distribution of salt marshes (which may contain peat reefs) have been mapped for Cape Cod and 17 estuarine systems. Gravel, gravely sand and rocky substrates have also been included in this distribution.

Finally, the outer shelf-upper slope has been highlighted including those areas which may contain a clay base in this setting. These clay areas may contain important clay depressions or mud anemone habitats (Lawton and Lavalli 1995). Clay pipe areas should also be added to this distribution as they are revealed.

Adults

The map showing the distribution of adults is perhaps the most uncertain. This map shows the most important habitats for both adolescent and adult lobsters (Lawton and Lavalli 1995). While many have argued that adult lobsters are ubiquitous, there is little published evidence to support their widespread occurrence on unfettered, sandy bottom on the shelf, except during times of migration.

Offshore, this map highlights lobster occurrence on the outer shelf-upper slope regardless of substrate. It also focuses on the gravely sand areas on the banks and the clay regions in the basin interiors.

Inshore, adult lobsters are likely to utilize all substrates, at least temporarily. Until information is forthcoming on where adult lobsters are not found inshore, it is prudent to show all habitats. This includes interior estuaries and salt marshes. Based on the limited data we have, island margins appear to be particularly important.