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The number of traps set in Maine waters has greatly increased
over the past forty years. However, lobster harvests have remained relatively
stable during this time. Although the reasons for this stability are unknown,
researchers have come up with some possible explanations.
Lobster larvae go through three planktonic or swimming stages before they
reach the post-larval stage. In this stage, they can swim but are ready to
settle out on the bottom. After they settle, they become early benthic (bottom)
phase or EBP lobsters. Sea Grant-sponsored research conducted by Robert Steneck
and Richard Wahle of the University of Maine has shown that very specific bottom
characteristics seem to be necessary for EBP lobsters to survive. Steneck also
found that suitable bottom habitat is limited and patchily distributed along the
shoreline. If larvae are very abundant and there is not enough appropriate
habitat available for settlement, this could produce a "bottleneck" in the
recruitment process.
Lewis Incze of the Bigelow Laboratory for Ocean Sciences in West Boothbay Harbor
is studying how planktonic larval lobsters are delivered to desireable bottom
habitats, what factors contribute to their survival, and how larval behavior
and physiology help them settle out in appropriate areas. Incze's study, funded
by the Sea Grant College Program, will investigate patterns of distribution and
abundance of lobster larvae relative to suitable bottom habitat. According to
Incze, "Because of the background provided by Steneck and Wahle's work, I feel
there is a unique opportunity to evaluate how planktonic distributions affect
the number of post-larval lobsters that can successfully settle on the bottom."
Incze will examine how larval lobster abundance and distribution are influenced
by surface water "convergences," winds, and tides in the Johns Bay-Linekin Neck
area of central coastal Maine. Convergences result from tidal circulations as
well as flow around headlands and islands, and can be identified by surface
slicks, and foam and debris lines. Aerial surveys of the sea surface will help
determine the best locations for oceanographic sampling.
Incze's study could help explain another of the possible key processes which
lead to the present stability of the lobster fishery.
Trap Worms: Small but Co$tly
Lobstermen who fish offshore are very familiar with Xylophaga atlantica, a small
wood-boring bivalve which can cause considerable damage to untreated lobster
traps. Even though the the trap worm is very small, with a shell height of about
one centimeter, it can infest and destroy an unprotected wood trap in less than
a year. A noninfested trap, on the other hand, will last longer than five years.
Considering that each trap costs between $50 and $100, the trap worm is a very
costly pest to the industry.
The lobster industry has used a variety of wood preservatives to protect traps
against fouling organisms, particularly the trap worm. The most effective trap
preservative in use today contains tributyltin (TBT). However, this chemical
pesticide was recently banned by the Environmental Protection Agency as there
is increasing evidence that high concentrations have toxic effects on marine
organisms. The lobster industry is concerned not only about the effects on the
environment but on lobstermen who handle the traps.
In 1986, the industry brought the problem to the attention of the Rhode Island
Sea Grant Marine Advisory Service. A partnership was formed between industry,
the advisory service, University of Rhode Island (URI) researchers, and Dr.
Ruth Turner of Harvard University to investigate the biology of the trap worm
and to develop a treatment system to prevent the destruction of wood lobster
traps by the worm. The treatment had to be safe, simple, and effect a 100%
mortality on recently settled juvenile trap worms.
Joseph De Alteris, Fisheries Specialist for the Sea Grant Marine Advisory
Service, along with Robert Bullock and William Romey of URI's Department of
Zoology, tested the effectiveness of three alternative treatments that would
kill recently settled trap worms. Treatments included heated sea water, a
chlorine bleach solution, and a sodium chloride (salt) brine solution.
Researchers discovered that while most treatments caused significant mortality,
a saturated brine solution of 265% proved to be the most effective and practical
treatment. When panels were dipped in this salt solution for 30 seconds and
exposed at sea for 30 to 45 days, there was a 99% mortality rate for trap worms;
dipped for 60 seconds and exposed at sea for 60 to 75 days, virtually all trap
worms were killed on the panels.
The next step in the project is to field test the technique at sea.
Participating lobstermen have been given 2 experimental traps-one dipped at 30
day intervals in the saturated brine solution and one untreated. After a period
of six months, URI researchers and lobstermen will be able to critically
evaluate this potential solution to the trap worm problem.
Your Opinion Wanted
All licensed lobstermen, pound owners, and dealers in the state of Maine now
have a chance to express their opinions on major issues affecting their industry
on the Lobster Industry Opinion Survey.
Compiled by the Maine Lobster Institute, the survey was designed to get a sense
of who agrees on what. Bill Anderson, lobsterman and member of the Institute's
Board of Advisors, helped decide what topics should be included on the survey.
University of Maine economists Jim Wilson and Steve Riley gave advice on the
survey's format.
The idea for the survey originally came from a meeting of the state's Lobster
Advisory Council where industry members pointed out that lobstermen from the
southern end of the state do not always agree with those who fish near the
Canadian border.
David Dow, Director of the Institute, stressed that individual responses to the
survey will be confidential since the purpose of the poll is to find out where
lobstermen stand as a group, not as individuals.
As we go to press, Dow exclaims, "The surveys are rolling in and it looks like
we're getting a great response. We should have the results later this spring."
Economics Study Slated for Summer
H. Ty Cheng, Agricultural and Resource Economist at the University of Maine, has
been funded by the Lobster Institute to begin a study of the economics of the
lobster resource. Cheng will first analyze the demand for lobsters within the
U.S. and throughout the world. He will also collect data on lobster landings,
pounding, and trade between the U.S. and Canada over the past decade.
Another timely issue that Cheng will address is the impact of the gauge increase
on national and international markets. As the average size of the lobster
increases, making it potentially more expensive, will it meet with consumer
resistance?
Cheng comes to the University of Maine from Virginia where he earned his
doctorate in Agricultural Economics at Virginia Polytechnic Institute and State
University. According to Cheng, "My research efforts here have been directed to
developing marketing strategies to increase economic efficiency, productivity,
and demand for shellfish species native to Maine. In my analysis of the demand
and consumption of lobster, I'm attempting to provide more realistic and
detailed models that describe what variables most affect consumption, how
consumer patterns are changing over time, and the dynamics of the marketing
system."
Bands Don't Taste Bad
After researchers at the University of Maine discovered there was a taste
difference between meat from pegged and banded lobsters, the next step was to
determine whether there is a difference between claw meat from lobsters cooked
with bands on and those from which bands were removed before cooking.
Twenty panelists were first asked to taste lobster meat which served as the
standard. Next, they tasted three meat samples from lobsters cooked with rubber
bands, synthetic bands, and no bands. They then compared the flavor of each
sample to the standard and described it according to a five-point scale.
Categories were: better than standard, equal to it, and slight, moderate, or
large degree of off flavor. Results showed that panelists detected no
significant difference in the taste of the three samples.
Test Results are in:
Results showed that there was a wide variation in elasticity initially, and a
change in elasticity over time. Since the Maine Agricultural Experiment Station
cannot endorse or comment on commercial products, the bands are referred to only
by their color.
Statistically, the gray bands (advertised as "cold water bands") were far
superior. Blue, white, and green showed only marginal differences, and yellow,
brown, and red were significantly different and showed progressively poorer
elasticity.
There seems to be a difference in band quality, not only between different
manufacturers' products, but between different colored bands produced by the
same company. The majority of bands used in Maine come from Thailand or the
Philippines. U.S. manufacturers have difficulty competing with the cost of these
foreign imports. Although researchers are convinced that a better band could be
made, no manufacturer has been interested in helping so far.
Another piece of useful information was obtained during the project. Some of the
bands were left out on a shelf in a brightly lit room over the summer.
The bands, especially the lighter colored ones, showed significant deterioration
and obvious reduced elasticity. This seems to indicate that bands should not be
left exposed to sunlight or heat as this may adversely affect their restraining
properties. It may be a good idea for dealers to maintain fresh stocks of bands,
store them out of sunlight, and avoid using bands left over from last season.
Research Update
V-Notch Data Is In
The MLA has been conducting this survey since 1982 and the results have been
remarkably consistent from year to year. From the 161 responses that were
received from this year's survey, 68,357 traps were hauled yielding 52,033
pounds of lobster. In addition, 6,784 V-notched lobsters and 2,839 berried
females were reported. Results showed that over 70% of the berried females had a
V-notch.
Fishermen were also asked how many traps they had lost during the year. Those
who responded had lost 2,824 traps which gives some indication of the potential
number of "ghost" traps.
Several fishermen from the Mt. Desert area suggested that the survey should be
conducted a few weeks later when there are more lobsters in their region.
However, there is now six years of data based around the same dates in October
with very consistent results. Also, if the lobsters pick up in the Mt. Desert
area at a later date, they would probably not be as abundant in other regions
to the west.
Pound Aeration Systems Tested
Do Offshore Lobsters Breed With Inshore Lobsters?
For this study, funded primarily through the Sea Grant College Program,
Kornfield will use a new class of genetic markers to quantify the variation
within and among lobster populations. These markers could also be used for
tagging juvenile lobsters raised in hatcheries - to find out how many of them
survive after they are released into the ocean. This could help hatcheries
evaluate more accurately the success of their programs.
The Impact of Dragging on Lobsters
Steneck and Wahle will begin their project next summer in the Damariscotta
River "Thread of Life" area, where lobsters and shelter spaces are most abundant
and the population is stable.
Ghost Trap Study Has Preliminary Findings
Preliminary findings indicate that lobsters do not appear to escape from traps
once they are inside. After entering the "kitchen" or first compartment,
lobsters are more likely to move deeper into the "parlor" than to leave the
trap. Also, and most importantly, it appears that the lobsters will enter
unbaited traps. These findings need to be evaluated more closely as the
experiment progresses through the summer of 1989.
Farming Lobsters:
Culturing lobsters for "stock enhancement" is not a new phenomenon. It has been
practiced in the United States, Canada, Norway, and France since the early
1900's. Hatcheries were built to hatch eggs and release larvae into the wild
because there was some concern that the traditional capture fishery could not
keep pace with the increasing demand for lobsters.
"Product enhancement" is another form of lobster culture being experimented
with in Canada. In this system, lobsters caught in the traditional fishery that
are smaller than the size required for export are kept in a culture facility
and fed until they molt and increase their size and value. These "canner"
lobsters are purchased inexpensively during the spring and are usually fully
grown by the time the export price reaches its peak in the winter.
The third type of culture, called "closed cycle" culture, involves hatching and
rearing lobsters from the eggs of broodstock raised in captivity. In the last
decade, research has eliminated most of the problems involved in broodstock
control, and lobster biology is fairly well understood. Seedstock can now be
produced on demand and systems have been developed for rearing larvae to the
fourth stage (the stage at which they are released from hatcheries), and also
for growing lobsters to adult size. However, to our knowledge, no commercial
facility is currently growing lobsters for sale.
The American lobster, Waddy believes, is an attractive culture prospect because of its
high value and established world-wide market demand. However, that demand is based on a
lobster that weighs 450-500 grams-the size which coincides with minimun legal size
regulations. A cultured product, on the other hand, could be any size that the consumer
would accept.
Waddy suggests that a 200-250 gram lobster would be the best one to culture because it
is more economical to grow. There is evidence that lobsters grow more rapidly up to 250
grams and that a disproportionate amount of time is required to double their weight to
500 grams.
Traditional fishermen are concerned about competition from lobster farming. However,
Waddy points out, there should be little direct competition between the capture fishery
and the culture industry. A 250 gram cultured lobster would be below the minimum size at
maturity in most populations, and would therefore be too small for harvest by the
traditional fishery. Since the cultivated and the capture products would likely be
directed toward different markets, they could be complementary instead of competitive.
New Research Publication
The Lobster Newsletter, edited by Stan Cobb at the University of Rhode Island and John
Pringle of the Department of Fisheries and Oceans in Halifax, Canada, is an international
publication which covers lobster research and fishery management issues worldwide.
Written primarily for scientists and resource managers, the Newsletter includes articles
on current research, as well as announcements of lobster-related meetings and workshops,
book reviews, and letters from its readers. In effect, the Newsletter provides a forum
for the exchange of information and ideas for the lobster research community.
We would like to congratulate the Lobster Newsletter on their second issue and wish them
continued success on this important communication tool.
For more information about the Newsletter or to receive a copy, contact J. Stanley Cobb,
Department of Zoology, University of Rhode Island, Kingston, RI, 02881.
Cold Water Bands are Best
The Lobster Institute requested the Maine Agricultural Experiment Station at the
University of Maine to conduct a study on the comparative effectiveness of
lobster bands. An experiment was designed to test the elasticity of seven colors
of bands from several manufacturers over a seven month period. Bands were
stretched to approximately claw size, and submerged in ocean water. From October
to April, samples were taken and changes in elasticity were recorded.
This fall, the Maine Lobstermen's Association (MLA) sent out a V-notch survey to
800 commercial lobstermen. Lobstermen were asked to supply the following
information about their catch over a two-day period in October: the number of
V-notched lobsters, number of V-notched lobsters that had eggs, number of egged
lobsters that were not V-notched, the number of traps hauled, and the total
pounds landed.
Three aeration systems have been tested in Tom Colwell's pound in Stonington.
Researchers found that the diffusion stone system is not as efficient as
previously thought for putting oxygen into the water. The other two types of
surface aeration systems, one which uses a 45 degree blower and the other a fountain,
appear to be effective. Further studies will be done to test the systems at a
time when the water is warmer and there are more lobsters in the pound.
It is important to understand the connections between inshore and offshore
lobster populations and to find out if offshore lobsters contribute to inshore
production and larval recruitment. Irv Kornfield of the University of Maine's
Zoology Department is conducting a study to determine how much offshore and
inshore lobster populations mix with each other and interbreed.
Bottom dragging for fish and shellfish in nearshore waters occurs in regions
where lobsters are abundant and potentially vulnerable. Through Sea
Grant-sponsored research, Bob Steneck and Rick Wahle of the University of Maine
will examine the impact of dragging on the survival of lobsters and the carrying
capacity of their habitats. They will determine the immediate impact of dragging in terms of lobster mortality and injuries, and assess any habitat disruption caused by changes in the size and number of shelter sites available.
Researchers in the University's Animal Science Department and Agricultural
Engineering Department began a "ghost trap" study last summer. They developed
and installed an underwater video surveillance system to monitor lobster
behavior in and around lobster traps on a 24-hour basis.
What is the Potential?
Susan Waddy of the Canadian Department of Fisheries and Oceans in St. Andrews, New
Brunswick, is investigating the science and technology required for commercial lobster
culture. Waddy suggests that before it's economically feasible to culture lobsters
commercially, costs of individual holding facilities and heated seawater need to be
reduced and an inexpensive and effective formulated feed must be developed. Lobsters
fed diets currently available grow about half as fast as those eating natural foods.