CRD 01-17
Session
V: Aquaculture
| Stock
enhancement: moving from wishful thinking toward sound ecology |
Session
V: Aquaculture
Abstract No. V-1
ORAL PRESENTATION |
Ronald Goldberg, Jose
J. Pereira, and Paul Clark
NOAA/NMFS/NEFSC,
212 Rogers Ave., Milford, CT 06460-6490
Since the late 1870s, many
releases of hatchery-reared juvenile fishes were conducted in Europe
and the United States to attempt stock enhancement. Results of these
efforts were largely inconclusive, since the fate of the stocked fish
could not be determined adequately. Beginning in the early 1990s,
a renewed interest in stock enhancement emerged, utilizing newly developed
fish-marking techniques and a rigorous experimental approach. Presently,
microscopic coded-wire tags provide a way to follow the survival of
released fish and biochemical or morphological genetic markers can
identify their progeny. Recent ecological experiments in many different
locations and for a number of species have provided statistically valid,
quantitative examples of successful stock enhancement. Adaptive models
have been applied, which have systematically identified optimal timing,
size at release, stocking density, and release habitats, resulting
in cost-effective stock enhancement programs. Concurrently, codes
of practice for responsible enhancement have been established, where
risks and benefits are evaluated. Field studies have been conducted
at Milford Laboratory to investigate potential stock enhancement for
bay scallops, Argopecten irradians and tautog, Tautoga onitis. We
have characterized nursery habitats for these species and have begun
to explore different enhancement strategies. Our results indicate
there is good potential for using aquacultural methods for enhancement
when natural recruitment is poor and habitat and environmental conditions
are not limiting.
Keywords:
stock enhancement, experimental design, bay scallops, tautog
| Bay
scallop spawning and rearing methods |
Session
V: Aquaculture
Abstract No. V-2
ORAL PRESENTATION |
David J. Veilleux
NOAA/NMFS/NEFSC,
212 Rogers Ave., Milford, CT 06460-6490
Methods for spawning and
rearing of bivalve mollusks established at the Milford Laboratory over
the past forty years have led to the development of a commercial aquaculture
industry. Currently, the Milford Lab is focusing on aquaculture techniques
for the bay scallop, Argopecten irradians irradians. The bay
scallop has been selected because of limited wild fishery yield, high
market value, and rapid growth. The methods will be described for
the laboratory requirements, conditioning of brood stock, spawning,
sampling, larval rearing, feeding, pathogen control and handling. Our
results provide insight on how to achieve batches of post-set scallop
spat, ready for any need, such as stock enhancement, or experimental
research. These methods can be extrapolated easily to a commercial
scale.
| An
experimental system for evaluating shellfish recirculating nursery
systems |
Session
V: Aquaculture
Abstract No. V-3
ORAL PRESENTATION |
James C. Widman, Jr.
NOAA/NMFS/NEFSC,
212 Rogers Ave., Milford, CT 06460-6490
Economical biofiltration
of shellfish rearing systems presents unique challenges to the aquaculture
industry. Due to these challenges, recirculating systems are used extensively
in finfish rearing, but are not used in commercial shellfish culture. It
will be an "open" system with the addition of at least 10%
replacement seawater each day. Each recirculating system will be composed
of a biofilter, ultraviolet disinfection, solids removal unit, and
protein skimmers to maximize water quality. Determining which commercially
available biofiltration systems are compatible with shellfish culture
must be the first step. Shellfish culture relies on live algal culture
for nutritional purposes, however many commercial finfish culture systems
are incompatible with live algae. Process control technology will
be used to minimize human intervention (labor costs and biases) throughout
the grow-out period. Food consumption will be monitored in order to
track food conversion efficiency ratios. Waste production will be monitored
and modeled in order to maximize stocking densities of the system while
minimizing filtration needs. To increase stocking densities, we will
attempt to minimize periodic ammonia peaks based on the data that are
collected. Management of the system with neural networks or fuzzy
logic will be explored once enough empirical data are collected. Commercial
controllers and their conversion for use in the system will be presented. Data
gathered from these experiments will be incorporated into an economic
model to determine commercial feasibility. A brief review of the current
state of bay scallop culture in New England will be presented along
with the hurdles that need to be overcome to allow a single-season
crop.
| Rotifer
production on microalgal diets: a quantitative approach to developing
a feeding strategy |
Session
V: Aquaculture
Abstract No. V-4
ORAL PRESENTATION |
Mark S. Dixon1,
Gary H. Wikfors1, and Bethann Balazsi2
1NOAA/NMFS/NEFSC, 212 Rogers Ave., Milford, CT 06460-6490
2Long Island University, Southampton College, Natural Science
Division, Southampton, NY 11968
Live food production is a
critical component in the successful culturing of finfish. Consistent
production of microalgal biomass and the efficient conversion of that
biomass into live food lead to reliable nutrition of cultured fish.
A series of small-scale experiments designed to optimize microalgal
diets, establish a feeding protocol, and define rearing conditions
for rotifers (Brachionus plicatilis) was conducted.
The microalga strain PLY429, Tetraslemis
chui, yielded the greatest rotifer production when compared to
several commonly-used strains. A constant density of 6 million microalgal
cells per milliliter and initial low rotifer stocking densities resulted
in rapid reproduction and high overall production. Under these conditions
rotifer populations doubled in as little as 2 days, and reached a
maximum density of over 2000 per milliliter in 6 days. While higher
algal densities produced slightly greater yields, conversion efficiencies
were lower.
A spectrophotometer was used
to monitor algal densities, algal cells were added manually to maintain
the target density, and rotifers were counted manually. There is good
potential to automate the entire process using “off the shelf” technology.
This potential will be explored in upcoming experiments.
| Microalgal
production to further science and aquaculture |
Session
V: Aquaculture
Abstract No. V-5
ORAL PRESENTATION |
Barry
C. Smith and Gary H. Wikfors
NOAA/NMFS/NEFSC, 212 Rogers Ave., Milford, CT 06460-6490
To
study organisms, the need to grow them in the laboratory often occurs.
This is a type of aquaculture. In aquaculture a food chain is established
as a course of necessity. If bivalve mollusks are to be grown, all
life stages require a microalgal diet. Many species of finfish feed
on rotifers and/or brine shrimp in their early feeding stages. Rotifers
and brine shrimp feed on microalgae. So, to grow species important
to aquaculture, their food must also be grown and in adequate supply.
Further, the microalgae must also be nutritionally appropriate for
the animal to be grown. Other reasons to grow microalgae include the
presence of extractable pigments and other chemicals that are abundant
in some strains.
To optimize production, aquaculture
companies will grow their organisms with several considerations: House
the organism in the most favorable environment possible to minimize
physiological stress; Grow them as densely as possible to make best
use of space; Feed the organism as much of the proper feeds as needed
to get maximum growth. This requires large amounts of microalgal biomass
to be grown cost effectively.
The
above holds true not only for the animals to be grown but also for
the plants. Microalgae need a stable environment within thermal and
saline optima. Light of an acceptable wavelength and intensity is required
for photosynthesis as well as the proper ratios of nutrients. Contaminants
must be excluded or controlled to reduce loss. Once these basic criteria
are met, the process can be optimized. To maximize the algal biomass
produced, increased nutrients leading to increased density is often
preferable to increased volume.
Culture
strategy plays a major role in algal production. Batch culture is labor
intensive and may not support maximum yield from nutrients. Continuous
culture (chemostats and turbidostats) can be unreliable. Semi-continuous
culture, so far, is the most economical and reliable strategy, because
it combines benefits of continuous culture (opportunity for process
control and less labor) and batch culture (better control over modifications
to harvest rate in response to changes in culture performance).
Keywords: aquaculture,
algae
| An
overview of the NOAA diving program |
Session
V: Aquaculture
Abstract No. V-6
ORAL PRESENTATION |
Barry C. Smith
NOAA/NMFS/NEFSC,
212 Rogers Ave., Milford, CT 06460-6490
Many of the inquiries into
the aquatic environment require us to enter the water, not only to
observe first hand the organisms and events that occur, but also to
accomplish a variety of other tasks. Ships, docks, and other structures
need periodic inspection and repair. Monitoring and sampling equipment
need installation and regular service. When equipment is lost, it must
be recovered to avoid not only monetary loss but also to salvage the
scientific information and continue with the given research program.
These tasks and more are performed under a wide range of conditions;
from crystal clear waters to zero visibility, from tropical seas to
ice diving, year-round. Further, the level of complexity ranges from
single dives to tending the Aquarius habitat to the “Monitor Project”
recovery. The NOAA Diving Program, part of the Office of Marine and
Aviation Operations, is the authority that makes sure we enter the
water safely and efficiently.
Over 300 divers, 35 Unit
Diving Supervisors, and six people staffing the NOAA Diving Center
perform over 11,000 dives per year with a safety level of 99.98%. The
majority of the dives are less than 60 feet deep. Other dives can be
over 100 feet deep. Most diving uses open circuit SCUBA but several
other breathing systems can be employed. The range of tools used is
dictated by the task undertaken. Some jobs require sample collection
or video documentation while other endeavors may require air chisels
or jack hammers.
Keywords:
NOAA, diving
