Important Advances in the
Aquaculture of Marine Angelfish
The flame angel (Centropyge
loriculus) in these pictures is maintained by the author in his reef tank. This
angelfish is very popular with marine aquarists, and it is the author's hope that they
will be successfully reared in captivity, limiting the impact of collecting wild
specimens.
This month's column will focus on two very exciting announcements in
the aquaculture of marine angelfish. These developments hold the promise of significantly
reducing the negative impact of fish collection on wild populations of these beautiful
fishes while providing a source of aquarium specimens for those who wish to keep them.
Both breeding programs were established in Hawaii, based on two groups of
Hawaiian angelfish, organisms with special appeal to aquarists. The collection of fishes
from the wild for the aquarium trade is a hot issue here in Hawaii, with much public
opposition in the face of verified declines in the abundance of collected species. The
state of Hawaii, especially the Kona coast of the Big Island (Hawaii) stands third as a
world source of aquarium fishes, exceeded only by exports of live specimens from the
Philippines and Singapore.
The impact of collection is clear. The December
2001 issue of The Smithsonian reports, in "Something's Fishy," that
Brian Tissot, a Washington State University marine ecologist, found that in Hawaiian
waters targeted by aquarium collectors, populations of eight of the most popular species
had fallen by 38 to 57 percent. More than 400,000 reef fish are collected from
Hawaii's reefs annually for the aquarium trade. (Honolulu
Advertiser, January 23, 2002)
William Walsh, marine biologist attached to Hawaii's
Division of Aquatic Resources states that, based on collectors' reports, 52% of collected
fishes here are yellow tangs, yielding an astonishing figure of 200,000 yellow tangs taken
per year. To me, this leads to the clear inference that high mortality rates must exist at
every level of the trade from collection through the end point in the tanks of consumer
aquarists. The Smithsonian article quotes Hawaiian collector David Dart as saying that in
good weather, an average diver can pull in 100 to 150 yellow tangs a day, and there are
many collectors here. It is no surprise therefore, that the success of the breeding
programs were seen as important enough to gain attention in the local press.
On January
20, 2002, West Hawaii Today in an article titled "Rare ornamental fish bred in
captivity" (p.12A) reported that the Hawaiian masked angelfish, Genicanthus
personatus, had been bred in captivity at the Waikiki Aquarium. The fish, a native of
the Northwestern Hawaiian Islands, is one of the most rare and sought after aquarium
specimens.
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The newspaper article was based on a Waikiki Aquarium News
bulletin of January 18, "Waikiki Aquarium Announces Breeding Breakthrough For One Of
World's Rarest Fishes".
Bruce Carlson, the Aquarium's director stated, "The success of this
research expands the possibilities of including one of the rarest and most sought after
species to the list of ornamental fishes commercially raised for world wide trade. We're
thrilled with this landmark achievement in the field of aquaculture." Hobbyists pay
as much as $5,000 for the angelfish. Aquaculture scientists have attempted for decades
breed and to rear specimens of the more than 70 species of angelfishes.
It is important to note that the parental fish were all juvenile
females when they were collected at Midway Island in 1993 and grew to maturity at the
aquarium. Spawning began when one of the females changed sex and became a male, which is
normal in the development of the species.
The larval masked angels were successfully brought through
the 75 or more days to develop from hatching to metamorphosis, and the juveniles were
reported to be one-half inch miniatures of their parents. The article states, "A
breakthrough came when aquarium biologist Karen Brittain discovered a new, living food
source to sustain the small larval angelfish."
On January 23, 2002 the Star-Bulletin of
Honolulu, in "Researchers hatch angelfish in captivity" and the Honolulu
Advertiser in "Biologists score breakthrough in raising reef fish,"
reported another major event in the development of the aquaculture of aquarium species.
On January 17, 2002, the Oceanic Institute of Oahu had announced
that research teams led by Dr. Charles Laidley and Dr. Robin Shields succeeded in
obtaining natural spawns of the popular and beautiful flame angelfish, Centropyge
loriculus, and in nurturing the larvae through metamorphosis at the hatchery, The
initial group of juvenile flame angelfish is almost three months of age and will be joined
by additional batches in 2002.
The Institute based its success on its research in food fish aquaculture. Dr. Anthony
Ostrowski, Finfish Program Manager for the Oceanic Institute stated, "The key to this
recent success was in culturing suitable microscopic organism (zooplankton) as prey for
the angelfish larvae. Conventional diets are too large for such tiny larvae, therefore our
researchers isolated plankton directly from the local reef environment."
The flame angel (Centropyge loriculus) in these
pictures is maintained by the author in his reef tank. This angelfish is very popular with
marine aquarists, and it is the author's hope that they will be successfully reared in
captivity, limiting the impact of collecting wild specimens.
Recently, researchers at the facility also
obtained the first recorded fertilized natural spawns of yellow tang, Zebrasoma
flavescens, under aquaculture conditions and documented the early developmental stages
of the larvae. They have not yet succeeded in rearing the larvae to the juvenile stage.
"The challenge now for our researchers is to
convert these early achievements into reliable technology that will allow commercial
cultivation of high-value species such as the flame angelfish and yellow tang," said
Ostrowski. "Such advances will bring new employment opportunities and lessen the
impact the aquarium trade has on Hawai'i's fragile coral reef ecosystem."
The Honolulu Advertiser story included reports of
successful aquaculture of another aquarium species, as reported by the Oceanic Institute.
Frank Baensch, an independent researcher working in collaboration with Dr. Malia Chow at
the Hawai'i Institute of Marine Biology, has developed techniques to culture another
Hawaiian dwarf angel, Centropyge fisheri, Fisher's angelfish, in captivity. The
work was based on collaboration with respect to techniques. Some of the Fisher's angelfish
reared by Baensch will soon be on display at the Waikiki Aquarium.
In
a related development associated with the attempt to mitigate the decline in target fish
populations associated with collection for the aquarium trade, the Hawaii state
legislature enacted bills three years ago to establish "Fish Replenishment Areas
(FRA's)" covering one third of the Kona coast of Hawaii, the state's major collection
region. The sites, which are monitored, include areas protected for a minimum of ten years
that prohibit collecting, fishing, or both. Comparing target fish populations in the
recently fully restricted areas with those closed only to aquarium collecting, and those
open to all fishing, Kona marine biologist Walsh’s numbers are beginning to detect
some positive trends. Three years into a five-year study, he has found that the yellow
tang is no longer declining in the newly protected areas, but continues to decline in open
areas.
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In his surveys, Walsh also counts the baby
recruits in protected and unprotected areas. The fact that he has yet to detect much of a
difference worries him. "Without an increase in recruitment, the reserves won’t
realize their full potential," he says. I will have a full report on the recent data
on the effectiveness of the FRA strategy in my next column.
As a final note, West Hawaii Today, on February 27, reported that
Dr. Bruce Carlson, the current director of the Waikiki Aquarium, has announced that he
will resign from the aquarium to become the Vice President for Life Sciences at the new
Georgia aquarium, scheduled to open in 2005. Carlson pioneered public aquarium displays of
living corals and the fascinating mollusc, Nautilus.
