Subject: New England Aquarium Seabits 2.10 (fwd)

mike williamson (
Fri, 2 Oct 1998 12:21:03 -0400 (EDT)


---------- Forwarded message ----------
Date: Fri, 2 Oct 1998 11:58:44 -0400
To: Seabits <>
Subject: New England Aquarium Seabits 2.10

New England Aquarium Monthly e-mail Newsletter
Volume 2, Issue 10, October, 1998
Copyright, New England Aquarium, 1998.
October brings you bits from open ocean and a landlocked lake, from
thousand-pound fish to tiny echinoderms, all parts of the mysterious "world
of water" that continues to fascinate us Aquarium folk. We have a few new
ways for you to enjoy the New England Aquarium, and lots of events and
activities in the calendar section to amuse and scare you.

In this issue:
  Watery Words
    - Alien Species Invade Lake Victoria
    - Report from the Field: Fishy, Fishy, Where is the Fishy?
    - Red Knot Finds Food in Mysterious Ways
    - Farewell to Arms .. and Hello Again
  Out On The Net
  Birdwatching and Nature Harbor Cruise
  At the Aquarium
  For Members
  October Calendar
  Subscribe/Unsubscribe Information
  Contact Us

=-=-= WATERY WORDS =-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-
In honor of the New England Aquarium's film debut in Next Stop Wonderland,
currently playing in movie theaters in Boston and across the country:

  "A foolish consistency is the hobgoblin of little minds, adored by
   little statesmen and philosophers and divines."

            -- Self-Reliance, Ralph Waldo Emerson

And, as a farewell to summer days at the beach:

  "I wiped away the weeds and foam,
   I fetched my sea-born treasures home;
   But the poor, unsightly, noisome things
   Had left their beauty on the shore,
   With the sun and the sand and the wild uproar."

            -- Each and All, Ralph Waldo Emerson

=-=-= STORIES =-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=
This month's stories:
  1) Alien Species Invade Lake Victoria
  2) Report from the Field: Fishy, Fishy, Where is the Fishy?
  3) Red Knot Finds Food in Mysterious Ways
  4) A Farewell to Arms ... and Hello Again

----- ALIEN SPECIES INVADE LAKE VICTORIA ----------------------------------
Yes, it's true -- aliens have invaded the East African freshwater lake of
Lake Victoria. These are not little green men who want to blow up Earth
because it obstructs their view of Venus, but rather a species of
unremarkable-looking fish from the Nile. Why are local fishermen and
scientists from around the world up in arms about a fish? To understand, we
need a little perspective.

A relative newcomer on the freshwater scene, Lake Victoria, surrounded by
Kenya, Tanzania and Uganda, is only 400,000 years old. Its siblings, if you
will, Lake Tanganyika and Lake Malawi, are six to seven million and three
to four million years old, respectively. For such a young lake, Lake
Victoria houses an incredible diversity of fishes, over 500 species of
which are found nowhere else on earth. In comparison, all of Europe hosts
only 60 species of freshwater fishes. Scientists call the lake "a living
laboratory of evolution," since the majority of the species in the lake are
cichlids that appear to have evolved within a startlingly short period of

Some of the cichlid species in Lake Victoria have evolved to fill rather
unique niches, such as mouth-breeding fishes; infant-snatchers that snatch
the babies from mouth-breeder's mouths; scale-eaters; crab-eaters;
shrimp-eaters; fish with jaws that slide over each other rather than
socket-jaws, like most fish; and fish that lie on the bottom "pretending"
to be dead to attract prey. Because of the range of their behavioral and
anatomical adaptations, these cichlid species are of particular interest to
scientists as an opportunity to understand evolution.

However, that opportunity is slipping away. In the early 1970s, 80% of the
fish biomass (weight of living components of the ecosystem) consisted of
cichlids; today that figure is just 2-3%. In that same period of time, Nile
perch has gone from comprising 1% to 80% of the lake's biomass. When we
look around for a culprit on whom to blame extinction of several cichlid
species and the disappearance of other food fish, we find the
six-foot-long, 200-pound Nile perch staring us in the face.

Although there are several different stories, the Nile perch was probably
introduced in the early 1960s as an additional food fish with export value,
and it has certainly been that. Its oily flesh fetches a fair price on the
market and brings an important influx of foreign currency to the region.
The Nile perch is not for everyone, though -- it costs too much for local
people, many dislike the taste and storing it requires frying or smoking,
which uses up already depleted wood supplies.

The success of the Nile perch in Lake Victoria can be attributed to several
factors. First, its natural predators are absent from the lake. Second, it
eats higher on the food web than some of the species it has extinguished,
meaning that it eats other fish rather than plants and algae. Eating other
fish accomplishes at least two things: it reduces competition for space and
it reduces the numbers of fish that eat algae and plants. Reducing
algae-eaters allows algae to increase in the lake, which reduces the
visibility in the lake. In fact, the transparency of Lake Victoria has
decreased from about eight meters to about one and half meters. Nile perch
are dusk and dawn feeders, and see well in low light -- better, apparently,
than the species on which they prey. Cichlids, on the other hand, are
daylight feeders, and are less well-adapted for this new, darker lake.
Fewer cichlids means less fish to eat the algae and other plant life, so
the situation perpetuates itself.

However, the Nile perch cannot take all the credit for its success. Humans
have contributed greatly by pouring algae-supporting nitrogen and
phosphorus into the lake through sewage, agricultural runoff and industrial
effluent. The now commonly understood hazards of habitat destruction,
overfishing, using more efficient fishing gear, and feeding and employing
increasing human populations also have played roles in changing Lake
Victoria. The once clear, well-oxygenated lake is now a muddy, stratified
water body with no oxygen in its bottom layers. This is not very good for
any of the fish, but the plants are having a field day.

The question we are left to ponder is whether the Nile perch a blessing,
for its economic boon to the region, or a curse, for its decimation of
traditional fisheries and extinction of fish that may hold pieces of the
evolutionary puzzle in their, uh, fins. Blessing or curse, the Nile perch
is certainly teaching the world a valuable lesson about humans as agents of

* Special thanks to Mark Chandler, New England Aquarium Research Scientist.

Droplet: The Nile Perch is a huge fish that grows quickly. In just seven
years, it may be as much as seven feet long and four feet around. That's
about one third the time that it would take most comparably sized fish.

At last report, New England Aquarium researcher Dr. Molly Lutcavage was
working with New England fishermen to implant satellite pop-up tags in
giant Atlantic bluefin tuna (Thunnus thynnus) to find out more information
about their migratory paths and spawning areas. Giant Atlantic bluefin tuna
are at the center of a heated debate between regulators, who have been
recommending increasingly stricter quotas because they believe the species
to be depleted, and fishermen, who claim they see more bluefin tuna in a
week than regulators say exist in the entire North Atlantic all year.
Bluefin tuna are the largest living species of tuna, reaching up to 10 feet
in length and weighing more than 1,400 pounds. In the past, some fish have
fetched more than $50/pound, though prices have declined in recent years to
around $2-12/pound.

Last year, working with bluefin tuna fishermen, Molly and her colleagues
tagged 20 tuna of reproductive size, from 75 to 115 inches long (estimated
ages 8-18 years), off the New England coast. The tags have a five-inch long
antenna that transmits location and historical data about water temperature
during the tuna's travels at a predetermined time. Seventeen of 20 tags
were recovered after being on the tuna for as long as nine and a half
months, the longest time a pop-up satellite tag has ever been on a pelagic,
or open ocean, fish. Five of the tags released from the tuna were found on
the eastern side of the fisheries management line in the mid-Atlantic,
where they were not expected.

To understand the issues at stake, it is necessary to understand that
bluefin tuna in the Atlantic are managed as two distinct stocks, an eastern
stock and a western stock. The theory is that the two stocks either don't
mix, or mix minimally, and can be managed separately. Regulations in place
include area quotas, size limits and spawning area protection measures. New
England fishermen have been eager to take part in the scientific research
of bluefin tuna to find out whether there are two stocks or just one in the
Atlantic Ocean. If they are all fishing from the same body of fish, U.S.
fishermen will not necessarily benefit from the stringent quotas and their
own conservation measures.

Regulators need to have better information on exactly where bluefin tuna
spend their time and where they reproduce to manage the stocks effectively.
This has been hard information to come by since they are a highly migratory
and fast-swimming species, and spend much of their time, scientists
believe, foraging off the continental shelf before dispersing to spawning
areas to lay eggs. Before this study, it had been assumed that bluefin tuna
spawned primarily in the Mediterranean and in the Gulf of Mexico. This new
data raises the possibility that bluefin tuna traveling through New England
waters spawn in much broader regions of the mid-Atlantic, between Bermuda
and the Azores, than previously thought. Regulators may now want to
reconsider current assumptions about migration, spawning habitats and stock

Dr. Lutcavage's tagging work is done in conjunction with colleagues Dr.
Richard Brill from the Pelagic Fisheries Research Program at the University
of Hawaii, Greg Skomal and Brad Chase from the Massachusetts Division of
Marine Fisheries, and Dr. Paul Howey from Telemetry 2000 in Columbia,
Maryland, who developed the pop-up satellite tag. They receive funding from
the East Coast Tuna Association and donations from cooperating fishermen.
This season they are continuing their work with New England fishermen on
satellite tagging, and are testing a new archival satellite tag that will
provide even more information on the lives of bluefin tuna.

* Special thanks to Sue Knapp, reporter stationed at 177 Milk Street.

Droplet: The giant Atlantic bluefin tuna has a torpedo-shaped body and the
ability to retract its pectoral fins and eyes, which enable it to move the
water with reduced friction. Bluefin can reach up to 50 mph in short spurts.

----- THE RED KNOT FINDS FOOD IN MYSTERIOUS WAYS --------------------------
The June 1998 issue of Seabits featured the red knot, a shorebird that
travels 10,000 miles on a yearly basis, from the southern tip of South
America to the Arctic. In many ways an amazing creature, this bird has
recently shown scientists a new twist on previously-understood shorebird
food-finding techniques.

Scientists noticed that red knots find buried mollusks and hard-shelled
crustaceans in the water's edge seven to eight times more often than
predicted by models of random searching. How is it able to do this?
Scientists knew that microscopic pits on the bill of other birds contain
stacks of cells that are used to detect vibrations from wriggling prey, but
did not understand how similar features of the red knot's bill helped it
find immobile prey, like bivalves hidden in the sand.

A new study from the University of Groningen, Netherlands, reports that red
knots have a unique food finding system. The researcher discovered that the
red knot's habit of feeding in very wet sand is no accident. The birds dig
their bills into the sand, causing water movement in the sand. Their bill's
pits with stacked cells, or Herbst corpuscles, are able sense pressure
variations that occur when an immobile object, like a hidden bivalve,
obstructs the flow of the water, telling the bird where to find its prey.

In tests in captivity, birds only found hidden mollusks in sand pails when
the sand was wet. Birds were not able to distinguish between rocks and
living prey. The observation that these birds prefer to feed in sand so wet
that there are puddles "suddenly makes sense," say members of the research
team. For more information, see the August 15 issue of Science News.

You can see shorebirds at the New England Aquarium's Coastal Rhythms:
Creatures on the Edge special exhibit located in the new west wing.

Droplet: Unlike humans, red knots have no need to shuck or shell their
catch because their digestive systems are able to grind up and process
whole shellfish, shell included.

----- A FAREWELL TO ARMS ... AND HELLO AGAIN ------------------------------
How long does it take for a sea star to regenerate an arm? This is a
question that dozens of visitors to the Aquarium's Edge of the Sea
touch-tank exhibit ask each year. To answer this question, two education
volunteers, Amy Volock, a college student, and Carolyn McDonald, a high
school student, studied 17 sea stars that were already missing arms here at
the Aquarium. Over the course of 15 months, they measured the growth of the
both the missing and existing arms of Forbes common sea stars and Northern
sea stars.

The results of their work suggest that it takes from eight months to two
years for our sea stars to regenerate an arm. Interestingly, smaller sea
stars regenerated arms more slowly than large sea stars, and, in several
cases, the sea star's other arms actually shrank while the new arm was
regenerating. This shortening of other arms could be due to calcium
transference from the nonregenerating arms to the regenerating one. Factors
that may affect regeneration time include temperature of the water, amount
of food available and type of food available.

John Anderson, Aquarium Educator, trained and supervised the students in
their research, which was sponsored by the Edgerton Research Lab.

Droplet: Oysters in the halfshell: Sea stars have an interesting technique
for feeding on bivalves, like clams, mussels, and oysters. They position
themselves over the bivalve, attaching themselves with their tube feet to
both shells and pull the shell apart just enough (0.1 mm) to invert their
stomachs into the shell and consume their meals right there.

=-=-= OUT ON THE NET =-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-
For additional information, you might want to check out the following
websites. Some of these links represent partners in aquatic conservation
and animal husbandry; others are simply resources we think may help you
enrich your perspective on our watery world. By listing these websites, the
New England Aquarium is not automatically endorsing or verifying the
accuracy of their content unless explicitly stated.

Lake Victoria & Nile Perch

Tagging Tuna

Red Knots and Other Shorebirds

Sea Stars

=-=-= BIRDWATCHING AND NATURE HARBOR CRUISE =-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=
December 5, 1998
Bundle up, bird and nature lovers, and join New England Aquarium staff and
renowned ornithologists from around the world on a birdwatching and nature
harbor cruise aboard the well-heated Voyager II. As part of our Planet of
the Penguins celebration, we invite you to learn about local and exotic
seabirds from the experts: Dr. Tony Williams, Cape Nature Conservancy, Cape
Town, South Africa, Dr. Rob Crawford, Sea Fisheries Institute, Cape Town,
South Africa, Dr. Peter Dann, Phillip Island Penguin Reserve, Melbourne,
Australia, and Dr. Dee Boersma, University of Washington

Cost: Adults $22, Children (3-15) $16, Children under 3 not permitted. To
register and to find out more about this and other New England Aquarium
trips, email Jean Rankin at <> or call 617-973-6562.

=-=-= AT THE AQUARIUM =-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=
Aquarium Activity Center
The Aquarium Activity Center offers a space for children to supplement
their visits to the Aquarium with hands-on science activities, games,
stories and craft projects. Still in its beginning stages, the Activity
Center's projects focus on Georges Bank and fisheries related activities,
but will be expanding to explore a wide array of water-related issues, such
as water properties, weather, conservation, endangered species, specific
Aquarium animals, specific Aquarium galleries, microscopic life,
camouflage, recycling and the five senses. The Activity Center is included
with Aquarium Admission. Fall hours: Wednesday, Thursday 2:00 P.M. - 3:00
P.M., Friday 12:00 P.M. - 5:00 P.M., Saturday, Sunday 11:00 A.M. - 4:00
P.M., Storytelling Hour, Sunday 2:00 P.M. - 3:00 P.M.

Aquarium Library Hours
Looking for information on marine science for school reports or projects?
The New England Aquarium Library is open on Saturdays and Sundays 10 A.M.
to 3 P.M. Please call (617) 973-5237 to make an appointment before coming.
It is located in the Exploration/Education Center in the parking garage

Overnights at the Aquarium
Spend the night with the fish! Our overnight program is an exciting way for
groups to learn about strange and fascinating aquatic animals and their
underwater world. Kids will participate in a variety of hands-on science
and craft activities in our Exploration Center in the evening, and have the
option of going on our NEW early evening harbor cruise before returning to
the Exploration Center for science and craft activities. A bedtime snack
and breakfast are provided. Bring your sleeping bags and pillows! To find
out more, call (617) 973-6596.

More Whale Watches
It has been such a good season that we are expanding our fall whale watch
schedule to include 1:00 P.M. trips on Thursdays and Fridays in October, as
well as the 10 A.M. weekend trips on October 17, 18, 24, 25, 31 and
November 1. Please call (617) 973-5206 for information and reservations.

=-=-= FOR MEMBERS =-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=
By invitation only -- 10th Annual Fish, Fun & Fright Family Members'
night. Members who have received their invites should remember that the
RSVP deadline is Monday, October 19. Please send your SASE w/ticket order
right away -- space is limited.

=-=-= OCTOBER CALENDAR =-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-
Saturday, October 3, 9:15 A.M.
 *Coastal Rhythms Tour: Journey to the world's coasts. The amazing animals
you'll see in our newest exhibit demonstrate the wonder of coastal
diversity. Learn about how they live in today's changing world. For ages 6
and older. Tour fees are $4.00 per person for members; $8.00 per person
plus admission fee for nonmembers. Children must be accompanied by an
adult. Call (617) 973-5206 to register.

Saturday, October 3
 Native American Celebration: Gifts of the Sacred Water series continues
with Harvest Moon, highlighting shellfish, cranberries and coastal wetland
plants. This free family event is presented by the New England Aquarium and
members of the Native American tribes of our region. Celebrate the
environmental concern and expression that lies at the heart of Native
American cultural, social and economic life. Call (617) 973-0296 for more
   Schedule of events:
   11:00 A.M.: Opening Ceremony, Intertribal Dance Group, Aquarium Plaza
   11:30 A.M. on: Harvest from the Marshland, Top Deck of Discovery
      Shellfish from the Bays, Bounty from the Bogs, and interactive
      children's programs, crafts, storytelling and videos.
   2:45 and 2:15 P.M.: Dancing, Intertribal Dance Group, Aquarium Plaza
   1:00, 2:30, 4:00 P.M.: Storytelling
   4:20 P.M. Closing Ceremony

Saturday, October 10, 9:30 A.M.
 Crocodile Smiles Preschool Explorers Class: This program combines a story
about the sea and the creatures living there with an art project, a related
activity or a close look at a live animal. Recommended for ages 3-5.
Children must be accompanied by an adult. $4.00 per child for members;
$8.00 plus admission fee per child for nonmembers. Additional admission
fees required for nonmember adults. Call (617) 973-5206 to register.

Saturday, October 10, 9:15 A.M.
 *Boston Harbor Exhibit Tour: Our "Go With The Flow" exhibit offers you a
window on the Harbor Islands National Park. Boston Harbor was once
notorious for being the dirtiest harbor in the country. Come see how it's
being cleaned up and what animals now live there. Tour fees are $4.00 per
person for members; $8.00 per person plus admission fee for nonmembers.
Children must be accompanied by an adult. Call (617) 973-5206 to register.

Saturday, October 17, 9:30 A.M.
 Sharks Explorer Class: Investigate animals and habitats with hands-on
aquatic activities and enjoy personal attention from Aquarium Educators.
For ages 6-9. Children must be accompanied by an adult. Fees are $4.00 per
person for members; $8.00 per person plus admission fee for nonmembers. No
fee for adult participant. Call (617) 973-5206 to register.

Wednesday, October 21, 6:30 P.M.
 Dive Club Meeting at New England Aquarium. Guests and new members always
welcome. Call (617) 973-0240 for details.

Saturday, October 24, 9:30 A.M.
 Creatures with Pincers, Big and Small Preschool Explorers Class: This
program combines a story about the sea and the creatures living there with
an art project, a related activity or a close look at a live animal. For
ages 3-5. Children must be accompanied by an adult. Fees are $4.00 per
child for members; $8.00 plus admission fee per child for nonmembers.
Additional admission fees required for nonmember adults. Call (617)
973-5206 to register.

Saturday, October 24, 7:00 - 11:00 P.M.
 SeaMark, Annual Benefit Party. With guest speaker Stan Waterman, renowned
underwater cinematographer/photographer, music, dancing, a silent photo
auction of underwater photos, raffles, door prizes, divers in the GOT and a
sea lion show, this is an event to remember! Tickets are $20 prior to the
event and $25 at the door. Cash bar and hors d'oeuvres. Event benefits the
Cotting School in Lexington, MA, a day school for disabled children. For
tickets or more information, call Holly Martel-Bourbon at (617) 973-5248 or
Diane Newark at (781) 862-7323, ext. 146.

Friday, October 30, 6:30 - 8:30 P.M.
 "Haunted" Halloween Harbor Cruise aboard Voyager II. Call (617) 973-5281
for prices and reservations.

Saturday, October 31, 9:00 A.M. - 6:00 P.M.
 Witches, Fishes and Fun at the Aquarium. All children (ages 11 and under)
wearing a costume will be admitted free with a paying adult. Come see a
spooky Aquarium and be a part of the costume parade. A WBOS DJ will be here
giving away great prizes.

Saturday, October 31, 9:15 A.M.
 Fierce Fishes: Piranhas and eels and sharks, oh my! There are many
ferocious fish living at New England Aquarium. Or are there? Come tour
through the galleries and get the real scoop on these and other "dangerous
animals." For ages 6 and older. Tour fees are $4.00 per person for members;
$8.00 per person plus admission fee for nonmembers. Children must be
accompanied by an adult. Call (617) 973-5206 to register.

Saturday, October 31, 9:30 A.M.
 Is the Sea Scary? Explorer Class: Investigate animals and habitats with
hands-on aquatic activities and enjoy personal attention from Aquarium
Educators. For ages 6-9. Children must be accompanied by an adult. Fees are
$4.00 per person for members; $8.00 per person plus admission for
nonmembers. No fee for adult participant. Call (617) 973-5206 to register.

=-=-= CORRECTION =-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-
The September 1998 issue of Seabits mentioned the practice of finning in
relation to hammerhead sharks. It should not have been implied that
American fishermen are allowed to engage in the practice of finning, i.e.,
simply cutting off the fin and dumping the shark, alive but with little
chance of survival, overboard. Finning is prohibited under the Shark
Fishery Management Plan, which applies to U.S. fishermen.

=-=-= SUBSCRIBE/UNSUBSCRIBE INFORMATION =-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=
To subscribe to Seabits, either visit <>
OR send e-mail to <>. In the body of your email message
write "subscribe seabits" (without the quotes).

To unsubscribe to Seabits, send email to <>. In the body
of your email message write "unsubscribe seabits" (without the quotes).

=-=-= CONTACT US =-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-
Content questions and comments? Contact Jennifer Goebel at

Technical questions and comments? Contact Bruce Wyman at <>.

=-=-= THAT'S ALL FOLKS =-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-
Thanks to everyone who emailed us about last month's issue. Next month,
we'll take a look at  California sea lions. Have a happy foliage season.