FINAL REPORT, PROJECT # 00-072:

Summary of Project Objectives and Accomplishments:

The Lobster Conservancy has been working with community volunteers to monitor intertidal lobster nursery grounds in selected sites along the Maine shoreline since 1995. To better understand habitat needs of juvenile lobsters and to assess the population trends of this important commercial resource, we proposed to expand this long-term monitoring program throughout the Gulf of Maine region.

Year 2000 project objectives:

• Continue long-term volunteer-based lobster monitoring
• Add 12 new monitoring sites from Maine to Massachusetts
• Create a map of intertidal nursery grounds throughout coastal New England
• Communicate results to date

Year 2000 project accomplishments:

• Volunteers continued to quantify the abundance of juvenile lobster at pre-existing long-term monitoring sites.
• Ten additional lobster nursery habitats were identified and monitored: five new sites in Maine, two in New Hampshire, and three in Massachusetts
• A map was produced to illustrate the location of lobster nursery habitats being monitored by The Lobster Conservancy’s team of community volunteers (Figure 1).
• Results of the project were communicated through press coverage, public presentations and scientific publications (Appendices 1, 2, and 3).

This report summarizes our achievements between November 1999 and November 2000.

Introduction

The American lobster, Homarus americanus, is the single most important species to the fisheries of New England (NEFSC 1996). Recruitment to the fishery is likely to be influenced by the abundance of recently-settled lobsters entering the population each year. Yet efforts to quantify the abundance of the earliest juvenile stages of H. americanus only began less than 15 years ago (Hudon 1987; Able et al. 1988; Heck et al. 1989; Wahle and Steneck 1991).

To identify factors that may limit lobster abundance and restrict recruitment to the fishery, it is necessary to maintain long-term studies (~10 years or more) that can provide the basis for time-series analyses. Other than landings records and trawl surveys conducted by the National Marine Fisheries Service, there exists a general lack of long-term studies that attempt to assess the fluctuations in abundance of the American lobster population (NEFSC 1996). In addition, there is a lack of coordinated effort in the collection, analysis and interpretation of data gathered through recently-begun short- and medium-term studies (Estrella unpubl.; Hudon 1987; Wahle and Steneck, 1991; Watson and Howell 1991; NEFSC 1996; Wahle and Incze 1997). Long-term studies are of particular importance to the study of the American lobster due to the prolonged development time of an estimated seven years from benthic recruitment to sexual maturity. In addition, long-term baseline information on benthic communities can be used to understand the impact of unusual events (Dye 1988).

Various methods have been used to document abundance and distribution of early juvenile stages, including SCUBA-based visual surveys and suction sampling (reviewed in Lawton and Lavalli 1995). The 1992 observation that young lobsters inhabit the intertidal/subtidal interface (Cowan 1999a) has led to the design of a low-cost, long-term sampling program to study the settlement, abundance, distribution, growth, and small scale movements of newly-settled and early juvenile lobsters (Cowan 1999a, b; Cowan et al. 2000; Ellis and Cowan 2000). The Intertidal Lobster Monitoring Program (ILMP) addresses four major questions: (1) When and where do lobsters settle and grow? (2) What are their habitat requirements? (3) How can we identify and protect lobster nursery grounds? and (4) Can we predict future lobster landings based on annual abundance in nursery areas?

Due to the ease of sampling out of the water, the ILMP method for measuring lobster abundance allows for monthly resampling at the same location resulting in an accurate time series that may be used to develop and test predictive models for annual yields and recruitment. An accurate time series can result because the sampling method is nondestructive — it does not disturb the sediments or remove organisms from the study site. Multiple resamples can also be made via suction sampling, but it takes a long time for the area sampled to recover because the air lift removes the infaunal organisms as well as lobster and a good part of the substrate. With repeated samples, the suction-sampled environment could become so degraded that it resembles a desert patch where it is unlikely that postlarval lobster will successfully settle. Therefore, in terms of developing a time series, subtidal suction sampling only yields a "scan" sample at a particular time and then it is necessary to either wait a long time, or sample elsewhere. Sampling by overturning rocks in the lower intertidal zone gives on-going samples, month after month, year after year in the same location.

Volunteers began participating in the ILMP in Casco Bay, Maine in 1995. As of November 2000, more than 60 volunteers were monitoring 24 lobster nursery sites seasonally along the Gulf of Maine coastline, under the supervision of scientists at The Lobster Conservancy. The workforce provided by citizen volunteers allows cost-effective coverage of a wide geographical area in a way that builds a community stewardship ethic (Youth 2000).

Methods

Our primary research goal in 2000 was to expand our volunteer-based juvenile lobster monitoring program to provide more complete geographical coverage of the Gulf of Maine. New areas were targeted to fill in existing gaps in coverage. Choice of new study sites was determined by two main factors: habitat availability and geographic location. Selected sites had rocks large enough to provide shelter for lobsters, but small enough to be overturned by hand. During spring low tides in April, May, June and July 2000, TLC scientists and volunteers identified new survey sites as intertidal lobster nursery grounds in southern Maine, New Hampshire, and Massachusetts. Sites in Massachusetts and New Hampshire were chosen to coordinate our sampling with subtidal sampling by state and university scientists (Bruce Estrella and Bob Glenn of the Massachusetts Division of Marine Fisheries; Win Watson, University of New Hampshire). New sites in Casco Bay, Maine were selected with the help of Friends of Casco Bay (Joseph Payne, Mike Doan and Mary Cerullo) to begin a collaborative relationship that provides their volunteers with a new project choice and offers logistical support for TLC.

Between May and November 2000, more than 60 volunteers sampled for lobsters at 24 intertidal sites along the shoreline of the Gulf of Maine (Maine, n = 18; New Hampshire, n = 3; Massachusetts, n = 3). Additional volunteers helped TLC scientists monitor two sites in Maine, thus a total of 26 sites were monitored in 2000. Here we report on data collected at the 24 sites monitored exclusively by TLC volunteers.

Volunteers for the ILMP were recruited through a series of regional presentations by TLC scientists. Before taking on responsibility for a monitoring site, each volunteer was given hands-on training in the field, and provided with a training handbook as a permanent reference (Cowan et al. 1999). All volunteers in Maine and New Hampshire were listed on special research permits issued by the Maine Department of Marine Resources and New Hampshire Department of Fish and Game, which allow individuals to handle sub-legally sized lobsters. (The state of Massachusetts did not require a special research permit.)

Volunteers conducted monthly quadrat sampling along fixed transects at specific sites once per month during spring low tides, usually from May through October. This sampling season was chosen with the goal of sampling during months of highest lobster abundance, based on observed seasonality (Cowan 1999a; Cowan et al. 2000). Ideally sampling occurred when the predicted low tide was more than 1 ft. below mean low water. Sampling was limited to a 2-hour period centred around the low tide. Each site was monitored by the same volunteers who most often worked in teams of 2-3. Environmental data including temperature, salinity, and weather conditions were recorded at the beginning and end of each monitoring session. Air, substrate, and water temperature were measured in degrees Celsius with a digital Checktemp Pocket Thermometer (Hanna Instruments), and surface salinity was measured in parts per thousand with a temperature-compensated hand-held salinity refractometer.

To sample for lobsters, 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 tape measure to delineate a transect line along the water's edge 1 hour prior to predicted low tide, then sampling along the transect line in steps, one meter at a time. Each step was defined by a square-meter quadrat placed alongside the tape measure. A qualitative description of each quadrat was made by estimating the percentage rock cover and substrate type to the nearest 25%, 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 lobsters were found, the following data were 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 (e.g., 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 mm using sliding stainless steel Apprentice Pocket Calipers (Ben Meadows Company), and total length using a ruler. Each lobster was measured in situ and immediately returned to its shelter.

Data collection was standardized by the use of two types of data sheets: general data sheets for environmental information and quadrat sheets for lobsters and other marine organisms (Cowan et al. 1999). Data sheets were designed to be as simple as possible (Ellis and Cowan 2000).

Data were entered into an Excel spreadsheet and analysed using SPSS (Version 10.0). As a data-quality control, data on lobster size were used only if the ratio of total length to carapace length was approximately 3:1, based on the expected morphometric relationship. Lobsters were categorized by carapace length (CL); yearling, i.e. less than 365 days old (< 17 mm CL; as per Hudon 1997 and Cowan et al. 2000) and early benthic phase lobsters (<40 mm CL; Wahle and Steneck 1991).

To look for patterns on a regional scale, the 24 monitoring sites were categorized into 6 regions from northwest to southeast: Penobscot Bay, Maine (PBME, n = 6); Muscongus Bay, Maine (MBME, n = 1); Casco Bay, Maine (CBME, n = 9); Southern Maine (SME, n = 2); New Hampshire (n = 2); and Massachusetts (n = 3) (Figure 1). Means are presented ± one standard error (S.E.). While data on lobster size were collected at a new site in Rye, NH, data on density were not collected since volunteers are still scouting for an appropriate monitoring site.

Results

Between April and July 2000, TLC scientists trained 32 volunteers to monitor lobsters at 10 new sites (Table 1; Figure 1). Our stated goal was to add 12 new monitoring sites in 2000. We achieved 83% of this goal, and we plan to add 3-4 more sites in the 2001. At that point we will have achieved our goal of having good geographical coverage of the U.S. portion of the Gulf of Maine.

Size distribution

Lobsters ranged in size from 4-86 mm in carapace length (CL), with a mean of 37.1 ± 0.34 mm CL (n = 1,240; Figure 2). All lobsters but one were below minimum legal size (83 mm CL). The exception (86 mm CL) was burrowed in eel grass, a habitat that has been shown to have a larger size distribution of lobsters than rocky habitat (Wahle and Steneck 1991). Five percent of lobsters were yearlings, i.e. < 17 mm CL (n = 64).

Mean lobster size in each region varied from 33.5 ± 0.55 mm CL in Casco Bay to 42.3 ± 0.93 mm CL in Penobscot Bay (Table 2, Figure 3a). The size-frequency distribution of lobsters differed significantly between regions (Kruskal-Wallis test, p < 0.001). Casco Bay ranked lowest, indicating that more small lobsters were located in this regions than elsewhere (Figure 3b). Support for this statement lies in the fact that percentage of yearling lobsters in each regions ranged from 0.1 in New Hampshire to 9.3% in Casco Bay (Table 2, Figure 3b).

Carapace length was negatively correlated with month, even after controlling for region (partial r = -0.10, p = 0.001; n = 1,240). This trend of decreasing carapace length over the season was seen in each region (Figure 4).

Abundance of Early Benthic Phase lobsters

Recent research has shown a strong positive relationship between the abundance of newly-settled lobsters and early benthic phase lobsters (Steneck and Wilson 2000), thus we used EBP density as an index of settlement.

To determine which sites were nursery "hotspots" we compared the highest monthly density for each site. The 6 top-ranked sites, i.e., those with the highest monthly densities, were Marblehead and Lanesville in Massachusetts, Broad Cove and Jaquish Island in Casco Bay, Wells Beach in southern Maine, and Allen Island, Muscongus Bay. The highest monthly EBP densities ranged from 1.45 down to 0.70 lobsters per m² at these 6 sites (Table 3, Figure 5)

In 2000, monthly density of EBP lobsters at individual monitoring sites ranged from 0.0 to 1.45 lobsters per m². To look for within-season trends, we plotted monthly densities of EBP lobsters by region (Figure 6). By region, monthly densities ranged from 0.00 to 0.95 (Figure 6). Over the season there was a tendency for EBP density to increase until July or August, then decrease (Figure 6). It must be noted that monitoring was hampered in September and October by spring tides that did not fall as low as predicted, which prevented complete sampling in the lower intertidal zone at most sites. This seasonal trend in lobster abundance has been noted at some sites in other years (Ellis and Cowan 1999), however peak densities have also been seen later, e.g. October and November (Cowan 1999a; Cowan et al. 2000).

Discussion

Patterns of distribution and abundance

The Gulf of Maine coastline of Massachusetts and Casco Bay, Maine yielded the highest densities of juvenile lobsters in the year 2000 (Figure 5). Four out of the top six ranking monitoring sites were added to the program this year (Table 3). These results indicate that expansion of the program was highly successful. This year marked our first sampling for lobster abundance in Massachusetts. The high densities recorded in Massachusetts indicate that monitoring should be continued and expanded in the region.

In general, the lowest densities were recorded in Penobscot Bay, Maine (Figures 5 and 6) where a great deal of effort has been applied to a collaborative research effort aimed at understanding the relationships between oceanography, larval supply and postlarval recruitment (Annis and Steneck 2000; Steneck and Wilson 2000). Abundance estimates based on our surveys indicate that there are other, more suitable sites for similar modelling and hypothesis testing. Sites in Casco Bay, Maine had some of the highest densities of early benthic phase lobsters (Figure 5), and Casco Bay was the region with by far the highest proportion of yearling lobsters (Table 2; Figure 3b). These data support our hypothesis (Ellis and Cowan 2000) that Casco Bay is a particularly important nursery ground for lobsters. This is the location of Lowell’s Cove, our sentinel monitoring site, where a time series of information on settlement and juvenile abundance has been collected since 1993 (Cowan et al. 2000; Cowan 1999a, b: Solow et al. 2000).

Addition of sites in Southern Maine and New Hampshire have also been important for broader coverage. Although densities here were not as high in New Hampshire and it could be argued that these sites are less significant than sites in Casco Bay, Maine and Massachusetts — we have only seen the results of sampling in a single year. It is possible that relative densities in different sampling locations vary from year to year such that the highest density nurseries in one year may not predict the highest abundance in successive years. Our long-term studies will be able to address such questions.

There appears to be a seasonal pattern of abundance at lobster nursery sites, with abundance increasing in summer and decreasing in fall (Figure 6). The timing of the decrease may vary from year to year, therefore it is important to monitor throughout the season so as not to miss peak densities.

Size Distribution

Postlarval settlement occurs when lobsters reach a size of between 4 and 6 mm CL. Due to the brief intermolt interval (hours to days) between settlement and metamorphosis to the first juvenile stage, it is extremely rare to detect postlarval settlement directly. Therefore, juveniles measuring up to 11 mm CL are considered recently settled (Wahle and Steneck 1991; Cowan 1999a). These small individuals are within a few molts of settlement and have therefore settled recently. Tagging studies in Casco Bay, Maine indicate that lobsters measuring <17 mm CL are usually less than one year old (Cowan et al. 2000). Although yearling lobsters were found in all regions, both the smallest individuals detected and the highest proportion of yearlings were reported for Casco Bay, Maine (Table 2).

The negative correlation between month and lobster size in all regions (Figure 4) shows that, as the season progressed, smaller lobsters were captured. This is likely due to newly-settled lobsters entering the nursery grounds, as would be expected in a good settlement year.

Keys to Successful Expansion

Collaboration with organizations in Massachusetts, New Hampshire and Maine contributed to the success of the Intertidal Lobster Monitoring Program expansion.

Massachusetts Division of Marine Fisheries scientists Bruce Estrella, Bob Glenn and Brad Chase assisted in locating possible survey sites. Bob Glenn joined us in scouting expeditions during our search for new monitoring locations. Salem Sound 2000 became a new partner when Executive Director Cindy Dunn was trained as a intertidal lobster monitor in Gloucester. National Marine Fisheries Service personnel Chad Keith and Heather Sagar were also recruited as volunteers.

In New Hampshire, we coordinated sampling with Professor Win Watson at the University of New Hampshire, and we received scouting assistance from Watson's graduate student Daniel O'Grady. UNH Sea Grant helped us recruit new volunteers through their Marine Docents program and Great Bay Coast Watch.

In Maine, Friends of Casco Bay joined us to offer their volunteers a new opportunity and to help us with logistics. In York, Maine volunteers included Patrice Farrey, Associate Director of the Maine Lobstermen’s Association, and Enid White who is also affiliated with that organization.

The ultimate key to the continued success of The Lobster Conservancy’s Intertidal Lobster Monitoring Program is the superb quality, enthusiasm and dedication of volunteers from a wide spectrum of backgrounds.

Directions for Future Research

Monitoring

The primary objective of the Intertidal Lobster Monitoring Program is to develop an ongoing time series of abundance of recently-settled and early juvenile lobsters across a broad spatial scale. To accomplish this goal it is necessary to maintain a long-term monitoring program at sites throughout the Gulf of Maine. The ultimate goal is to establish temporal and spatial patterns of abundance to develop an index that may serve as an early warning system to forestall stock collapse.

Although we currently have reasonably good coverage of the Gulf of Maine region, there are a few sites missing. Based on the high density nursery sites uncovered in Massachusetts this year, it would be beneficial to do further exploration in Massachusetts. In particular, we propose to target Scituate and Boston Harbor. In New Hampshire, we aim to find a richer site near Rye and a new monitoring site in the Hampton/Seabrook area.

We also hope to establish long-term monitoring at one of two sites where settlement has been detected in Winter Harbor. During a 1993 survey of the coastline from Connecticut to Eastern Maine no juvenile lobsters were found east of Winter Harbor, Maine (Cowan 1999a). Currently, our easternmost site is Isle au Haut which is west of Winter Harbor.

Eventually, it will also be important to cross the border into the Canadian Maritimes as some of the earliest reports of intertidal lobster nursery grounds stem from there (MacKay 1926). We are exploring ways to collaborate with Canadian researchers and organizations.

Data Analysis

It is imperative that the data gathered by TLC scientists and volunteers are fully analyzed to establish temporal and spatial patterns of abundance. We intend to develop a relational database and work with statisticians to facilitate intensive data analyses.

Proposed analyses include within site and between site comparisons; monthly, seasonal and interannual patterns of abundance; as well as comparison with state and university subtidal monitoring programs in Massachusetts, Maine and New Hampshire.

Mapping

We hope to produce detailed maps of specific locations of transect lines surveyed by volunteers and TLC scientists. These maps will specify where the data were obtained and aid in locating the sites should the persons with local knowledge leave the program.

We also plan to create a map of known intertidal lobster nursery grounds throughout coastal New England, indicating relative densities of lobsters. Such maps will be valuable to state agencies involved in permitting of dredging, filling, and dumping in coastal areas and wetlands (e.g., Dept. of Environmental Protection).

Acknowledgements:

Special thanks are extended to the many volunteers who have participated in the Intertidal Lobster Monitoring Program, without whom this research would not be feasible. We gratefully acknowledge financial support from the Community Fisheries Project of the Collaboration of Community Foundations for the Gulf of Maine, Darden Environmental Trust, Davis Conservation Foundation, Greater Piscataqua Community Foundation, Island Institute, Maine Community Foundation, Lobster Advisory Council of the Maine Department of Marine Resources, Maine/New Hampshire Sea Grant, National Fish and Wildlife Foundation, New England Grassroots Environment Fund, and individual donors

References:

APPENDIX

In addition to the scientific research presented above, an important objective was to disseminate information about our research project. This was accomplished by means of presentations, monthly newsletters, our website (www.lobsters.org), media coverage, and scientific publications.

Volunteer recruitment was accomplished by giving public presentations about the program, then training interested volunteers in the field the following morning at low tide. Presentations also served to inform the public and interested groups about our research. During this reporting period, TLC scientists and volunteers gave 12 presentations about the Gulf of Maine Lobster Monitoring Project (Appendix 1).

Volunteers were kept up-to-date by means of monthly newsletters from April to September (samples enclosed). These newsletters informed volunteers about trends we were seeing in their data, such as when and where newly-settled lobsters were being detected. Newsletters were archived with color photographs on our web site (www.lobsters.org).

Over the past 12 months, The Lobster Conservancy and its lobster monitoring program have received a great deal of positive media coverage, including newspapers and radio (Appendix 2).

Two publication on TLC’s intertidal lobster monitoring program were published in peer-reviewed scientific journals, and two others were submitted (attached). In addition, we updated and reprinted TLC’s volunteer training handbook. These 5 publications are listed below (Appendix 3).

Attachments

Press Packet

Sample Newsletter

Scientific Publications

Budget Report & Final Bill

 

Appendix 1:

Presentations by TLC scientists and volunteers, November 1999-November 2000.

Appendix 2:

Media coverage of The Lobster Conservancy, November 1999-December 2000.

Appendix 3:

Scientific publications on The Lobster Conservancy's Gulf of Maine Intertidal Lobster Monitoring Program, November 1999-December 2000.