Lobster is possibly the icon Maritimers and tourists alike associate most with the East Coast. Once the sandwich meat poor children were ashamed to bring to school, lobster is now highlighted at finer restaurants and reserved by most Maritimers for special occasions.
Although the small French and English communities that pepper the shores on both sides of the Northumberland Strait have traditionally relied on a variety of fisheries, after the collapse of the ground fish stocks, the lobster fishery came increasingly to define the survival of coastal communities throughout Atlantic Canada. Out of good fortune, ecological compensation, economic imperative, or some combination thereof, the amount of lobster caught throughout the Atlantic region increased during the 1970s and 1980s. This sustained increase in lobster catch is remarkable, however in the Northumberland Strait there has been a decline in catch since the early 1990s.
I started my research on lobster movement in the Northumberland Strait with Dr. Jeff Hutchings of Dalhousie University in the fall of 2000. This project arose out of the concerns of both the fish harvesters and the fish processing
industry about the lobster population in the area. In a unique partnership, the Maritime Fishermen's Union (MFU), Orion Seafood Canada, Dalhousie University and the Department of Fisheries and Oceans Canada (DFO) are supporting my project. Such a collaborative research initiative demonstrates the commitment of all partners to the future of the fishery, provides an opportunity for the partners to work together towards a common goal, helps to develop a common understanding of the lobster resource and focuses both financial resources and expertise.
Catch data, interpreted by both the fish harvesters and DFO scientists suggest that lobster move into the Northumberland Strait from either end. In order to investigate the movement behaviour and dispersal of lobster, I embarked on a two part project that would look at the small scale movements of several individual lobster and a large scale "mark and recapture" tagging study of the movement of lobster over years.
American lobster (Homarus americanus) have he capacity to move great distances and have even demonstrated homing capabilities in shallow waters in New England A seasonal inshore-offshore migration ha been documented and capitalized on by fish harvesters f r some time. lathe Bay of Fundy and on the Atlantic coast o Nova Scotia, lobster movements of hundreds of kilometres have been recorded by tagging studies. In the Southern Gulf of St. Lawrence 1obster movement is limited by the unique temperature pr file of the Gulf. The Labrador Current ensures a deep water layer of cold water that appears to create a barrier of lobster movement.
The Northumberland Strait, which is spanned b Confederation Bridge joining Prince Edward Island an New Brunswick, is a unique marine habitat. It is part of the southern Gulf of St. Lawrence. In 1999 20 percent of the fisheries catches in Atlantic Canada occurred in the southern Gulf of St. Lawrence, over 50 percent of which was lobster. The Northumberland Strait is about 320 km long and between 13 and 48 km wide. It fills with pack ice during the winter and the surface water is between 16 and 20 degrees Celcius in the central areas throughout the summer. On the New Brunswick shore of the Strait, Shediac boasts the warmest waters north of the Carolinas, and has claimed the title of lobster capital. Late last spring, I was lucky to find a cottage in Robichaud, New Brunswick in the middle of this vacation mecca. For eight weeks this cottage became a centre of activity, cluttered with electronic equipment, boots, life jackets, diving gear and a pair of lanky researchers busily meeting the demands of getting the first field season off the ground.
The first part of my research project used radio acoustic telemetry to complete the first continuous monitoring of lobster movement in the Northumberland Strait. Eight market size lobster were fitted with telemetry tags in order to observe the local smallscale movements of lobster. These tags emitted sound at unique frequencies making it possible to determine the location of individual lobster. Using triangulation from receivers or hydrophones attached to 3 communication buoys, the location of individual lobster was transmitted by radio to the base station - our lovely red cottage nestled in a spruce grove.
All eight tagged lobster were released inside a triangle formed by buoys 300 meters apart. Three lobster (two female and one male) remained inside the triangle for the three-week period in July. Five lobster left the triangle within the first five hours. Two of these animals settled just outside of the triangle, but provided location data intermittently throughout the study. One lobster moved about a quarter of a kilometer away and could be picked up by hand held receiver at the same place throughout the three-week period. One of the males disappeared for a week and then returned to wander through the triangle for three days and then disappear again. And one lobster disappeared the first day, not to be heard from again.
This data will be used to determine home range size, activity patterns, interactions between individuals, variability between individuals, and to compare the behavior in the Northumberland Strait with similar studies on the Atlantic coast of Nova Scotia. My preliminary inspection shows no strong day/night patterns, does suggest an effect of tide on lobster movement, and shows no clear trends based on sex.
Field work is full of unexpected challenges. The establishment and maintenance of the communication buoys for the radio-acoustic telemetry would not have been possible without the help of Donald LeBlanc, a fisherman in Robichaud, New Brunswick. He provided a wealth of knowledge, skills and an abundance of common sense accumulated, no doubt, in his 50-plus years of fishing. I was also lucky to have a field technician, Ken Bryenton, who literally rose to the challenges; climbing spruce trees to fix the antenna for the base station. I don't think the residents of Robichaud knew what to make of the biologists up in the trees looking for lobster.
The second part of this study included tagging lobster with streamer tags and releasing them to be recaptured by fish harvesters during the August-September lobster fishing season. Streamer tags are plastic tags about the size of twist ties with unique numbers that are attached to the meat of the lobster between the carapace of the body and the tail.
In May, June and July, 249 lobster were tagged with the help of three commercial fishermen. Many fish harvesters warned that it would be hard to catch lobster in the spring and early summer, arguing either that the lobster simply weren't there or would not be susceptible to trapping because they weren't feeding. Even with these warnings, the observed catches were surprisingly low. In one bay no lobster were caught in four days of fishing, yet traps set for just a few hours on the first day of the fishing season in August will catch lobster. At another port catches were so low that the fisherman I was out with called his father in a seniors' home to ask him where he would have set traps in the spring, before the August-September fishing seasons was established. The dramatically lower catch rate in the spring demonstrates the importance of understanding the movement and behavior of lobster.
As part of the DFO commitment to this project I was also provided the opportunity to participate in the DFO lobster trawl survey on the Coast Guard Boat the Opilio before and after the lobster fishing season. This annual survey provides fishery independent data on the distribution and size of lobster. In total, I tagged and released 1,841 lobster in the western part of Northumberland Strait with the help of three fishermen and the DFO. Although some tags will be lost during molting or by the death of animals, recaptured tagged lobster caught during the 2001 and 2002 lobster fishing seasons will give information on the movement of lobster over a two year period. I will be able to look at the movement of lobster and compare based on size, proximity to a moult determined by protein analysis of haemolymph (lobster blood) samples, sex and length of time at large.
Fish harvesters play a crucial role in this research. To report a tagged animal, harvesters are asked to record the date, depth and location where the lobster was caught and the tag number and colour. This may take only a few minutes per tagged lobster, but as there is hardly a wasted movement on a commercial fishing boat this represents a significant commitment of time. There have been over 50 release sites throughout the Strait and reporting from all areas is critical to determine movement. The participation of fish harvesters in collecting this data makes possible research that otherwise would be prohibitively expensive.
In addition to the support of the fishing community, the other partners also provided valuable in-kind donations including Orion Seafood providing half a crate of lobster to practice tagging lobster in May, a considerable investment of time and resources by the DFO staff, organizational assistance of the MFU and the lending of the communication buoy system from Dr. Ron O'Dor at Dalhousie University. Both the MFU and the Prince Edward Island Fishermen's Association have provided contact information for fish harvesters at wharves on both sides of the Strait. They have also arranged for press releases in their newsletters and discussions of the project at union meetings.
My project benefits from the partnership of fish harvesters, the government, academic researchers and the fish processing industry. All partners bring to the table financial resources, expertise and a commitment to a better understanding of this economically and socially important species. Collaborative projects can contribute to better management and conservation by enhancing and creating a common understanding of resources.
Nell den Heyer completed her M.Sc. studying freshwater ecology at McGill University She then worked for the New Brunswick Department of the Environment, returned to Nova Scotia to work with the Interdisciplinary Studies in Aquatic Resources Program at St. Francis Xavier University and is now working on her Ph.D. at Dalhousie University.
A bit about the lobster.... American lobster have a complex life cycle that involves a 3-10 week free-swimming larval stage in surface water, after which individuals settle to a non-mobile shelter-restricted juvenile benthic (bottom dwelling) stage, and then a mobile benthic stage during juvenile, adolescent and adult phase. Some adult lobster establish home dens under rocks or in crevices and territories in which they range about, while others are nomadic and appear to have no fixed home. Lobster can live as long as 70 years, but the lobster caught by the inshore fishery are generally 5 to 20 years old. Lobster have an external skeleton and grow by shedding the old skeleton and excreting a new one. Smaller lobster will molt several time in a year, while larger lobster will molt once every couple years.
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