7841

• UCREFRP Catalog Number: 7841
• Author: Nickum, J. G.
• Title: Guidelines for Use of Fishes in Field Research
• USFW Year: 1988
• USFW - Doc Type: Fisheries
• Copyright Material: YES

or delineation of variation of new species, require relatively
large samples.
Capture Techniques
Capture techniques should be as environmentally benev-
olent as possible within the constraints of the sampling
design (14,15). Whenever feasible, the potential for return
to the natural environment must be incorporated into the
sampling design. Current literature should be reviewed to
ascertain when and if capture distress has been properly
documented. Those capture techniques (seines, traps, etc.)
that have minimal impact on the target fishes are not dis-
cussed below. Many capture techniques must mimic those
of commercial and recreational fishermen in order to obtain
reliable data on population trends for the regulation of such
fisheries.
Gill netting (15,16) and other forms of entangling nets are
an accepted practice in fish collecting. Many studies contrast
recent and prior sampling and thus repetition of a prior
technique is mandated for sampling reliability. Net sets
should be examined at a regular and appropriate schedule,
particularly in warm water, to avoid excessive net mortality.
Collecting fish using ichthyocides is often the only and
by far the most efficient sampling technique (cf. 1~. Use of
ichthyocides should be accomplished with maximal consid-
eration of physical factors such as water movement and
temperature, so as to avoid extensive mortality of natural
populations and nontarget species.
Electrofishing is a suitable sampling technique in water
of appropriate conductivity inasmuch as fish mortalities will
be minimal. Proper adjustment of current will stun fishes
and complete recovery is possible. Fish can be returned with
minimal adverse impact. Care must be exercised to avoid
excessive electric currents that may injure or harm the op-
erators as well as the fish.
Capture of fishes by hooks or spears is an accepted prac-
tice of recreational fishermen. Spearfishing is appropriate
to cases in which capture in special environments is nec-
essary, e.g., deep reefs, caves, kelp beds, etc., and to pro-
vide comparable data Eor recreational fishing statistics. Sim-
ilarly, many fishes are most efficiently captured by hooks.
Museum Specimens and Other Killed Specimens
The collection of live animals and their preparation as
museum specimens is necessary for research and teaching
activities in systematic zoology and for many other types
of studies. Such collections should further our understand-
ing of these animals in their natural state. Descriptions of
ichthylogical collecting techniques and accepted practices
of collection management have been compiled (18,19),, as
have references to field techniques. Whenever fishes are
collected for museum deposition, specimens should be fixed
and preserved so as to assure the maximum utility of each
animal and to minimize the need for duplicate collecting.
In principle, each animal collected should serve as a source
of information on many levels of organization from behavior
to DNA-sequencing. Whenever practical, for example, blood
and other tissues should be collected for karyotypic and
molecular study prior to formalin fixation of the specimen
(20).
Formalin fixation of specimens is an acceptable practice;
however, fishes that do not die rapidly following immersion
in a formalin solution should be killed before preservation
by means of a chemical anesthetic such as sodium pento-
barbital, hydrous chlorobutanol, MS-222, urethane or sim-
ilarly acting substances, unless justified in writing by the
investigator. When field fixation of formalin resistant fishes
without prior introduction of anesthetics is necessary, prior
numbing of the specimen in ice water should be considered.
Several kinds of anesthetics and their efficacy have been
reviewed in the Investigations in Fish Control series (21).
Their use requires little additional time and effort and adds
little to the bulk or weight of collecting equipment. Urethane
has been shown to be carcinogenic; thus, caution should
be observed with its use and field disposal.
Live Capture
investigators should be familiar with the variety of ich-
thyologicalcapture techniques and should choose a method
suited to both the species and the study. Capture techniques
should prevent or minimize injury to the animal. Care should
be exercised to avoid accidental capture or insure field re-
lease of nontarget species. The interval between visits to
traps and net sets should be as short as possible, although
it may vary with species, weather, objectives of the study,
and the type of trap or net.
Habitat and Population Considerations
Whether collecting for future release or for museum prep-
aration, each investigator should observe and pass on to
students a strict ethic of habitat conservation. Collecting
always should be conducted so as to leave the habitat as
undisturbed as possible. The collection of large series of
animals from breeding aggregations should be avoided if
possible. Systematists should be familiar with extant col-
lections of suitable specimens before conducting field work.
If the purpose of an experiment is to alter behavior, repro-
ductive potential, or survivability, the interference should
be no more than that determined by the investigator to
accurately test the hypothesis.
2. Restraint and Handling
General Principles
Restraint of wild fishes ranges from confinement in an
aquarium through various types of physical restrictions or
drug-induced immobilization. The decision whether to use
physical or chemical restraint should be based upon the
design of the experiment, knowledge of behavior of the
animals, and the availability of facilities. Investigators must
use the least amount of restraint necessary to do the job.
When not under study, aggressive species should not be
confined with other animals (other than food) which they
may injure or may injure them. The well-being o[ the animal
under study is of paramount importance, and we empha-
size that improper restraint, especially of traumatized ani-
mals, can lead to major physiological disturbances that can
result in any of a series of deleterious or even fatal conse-
quences.
Animals should be handled quietly and with the mini-
mum personnel necessary. Darkened conditions tend to
alleviate stress and subdue certain species, and are rec-
ommended whenever possible and appropriate.
March -April 1988 19