Methods

Volunteers were recruited and trained through a series of presentations by TLC scientists Diane F. Cowan and Sara Ellis (Appendix). All volunteers were listed on TLC's special permit to handle sub-legally sized lobsters (Appendix) from the Maine Department of Marine Resources.

Volunteers for the Intertidal Lobster Monitoring Program monitor specific sites once per month during the spring low tides from May through October. In the case of the Pen Bay Lobster Collaborative, intertidal monitoring began at 5 sites in September/October 1998, then at an additional 13 sites in May/June 1999 (Table 1).

Choice of study sites was determined by two main factors: geographic location and habitat availability. Sites were spread around Penobscot Bay to cover a wide geographical range, to allow comparison of lobster abundance in outer regions versus inner regions of the bay, as well as eastern versus western regions (Figure 1). Selected sites had to have rocks that were large enough to provide shelter for lobsters, but small enough to be overturned by volunteers. One additional site without any rocks was surveyed in 1999, because volunteers on Vinalhaven found lobsters burrowing in eel grass beds.

Volunteers used a standard ecological method of data collection called quadrat sampling (Cowan 1999a; Cowan et al. 1999). This involved setting up a 20-meter long transect line along the water's edge, then sampling along the transect line in steps, one meter at a time. Each step was defined by placing a square-meter quadrat alongside the transect. Lobster monitors returned to the same transect line each month.

A qualitative description of each quadrat was made by estimating the substrate type and percentage rock cover, and recording the presence of marine organisms and macroalgae. Movable rocks in the quadrats were overturned one at a time, and organisms found beneath the rocks were recorded.

When juvenile lobsters were found, the following information was recorded: carapace length (from the rear of the eye socket to the posterior margin of the carapace), total length (from the tip of the rostrum to the tip of the telson), handedness (right or left crusher), sex (for lobsters measuring >15 mm carapace length), condition of appendages (i.e., missing, regenerating, damaged), shell condition (hard, brittle, or soft), rock dimensions (length by width by height), and depth of water under the rock. Carapace length was measured to the nearest 0.5 mm using calipers and total length using a ruler. Each lobster was returned to its shelter.

Data were entered into an Excel spreadsheet and analyzed using Excel and SPSS. Means are presented plus or minus 1 standard deviation. Lobsters with carapace lengths of less than 16 mm were defined as settlers, or young-of-the year lobsters (Cowan 1999a).