7937

• UCREFRP Catalog Number: 7937
• Author: Chart, T. E. and E. P. Bergerson.
• Title: Methods for Long-term Identification of Salmonids
• USFW Year: 1988.
• USFW - Doc Type: A Review.
• Copyright Material: NO

geographical region by the use of morphometrics, but
that differences in meristic characteristics were not
great enough to identify stocks.
Although meristic chazacteristics are generally
believed to be genetically determined, environmental
factors such as temperature, light, and salinity have been
shown to influence meristic phenotype (Gabriel 1944;
Tarring 1952; Barlow 1961; Kwain 1975). For this reason,
meristic characters appear to be useful for stock
identification when the annual variability of these
characters is examined to determine if differences in the
meristic counts among the stocks remain consistent
from year to year (Dempson and Misra 1984; Beacham
1985).
Electrophoresis and Serological
Techniques
In the mid-1950's, George Ridgeway (NMFS)
proposed that Pacific salmon (Oncorhynchus spp.)
could be identified to their country of origin by serologi-
cal differences that presumably reflected genetic dif-
ferences. In these studies, serum protein variants were
detected in sockeye sahnoa through techniques of imm-
unodiffusion, immunoelectrophoresis, and the use of
antisera developed in rabbits. These serological techni-
quesdifferentiated populations of sockeye salmon from
Bristol Bay, AK, and the Columbia River, WA (Wydos-
ki and Emery 1983). However, difficulties in producing
adequate quantities of potent antisera, coupled with the
indication that some of the variations detected may have
been artifacts of the preservation process rather than
valid genetic difference, led to the discontinuation of
this type of study (Utter et x1.1974). Serological techni-
ques were eventually replaced by electrophoresis as a
means of identifying inter- and intea-specific vaziation
of fish species. This new type of biochemical genetic
studyhad the advantage of providingvalid genetic inter-
pretation directly from raw data. The basic genetic prin-
ciples, procedures, and interpretation of electro-
phoresis were outlined by Utter et al. (1987).
In its most basic sense, researchers identify allelic
variation at polymorphic loci by using stazch gel
electrophoresis, enabling them to differentiate discrete
fish populations or stocks by examining individual loci
of genes (Allendorf et x1.1975).
Isozyme electrophoresis was used to determine
whether landlocked striped bass in Ken Reservoir in
Virginia-North Cazolina belonged to distinct
subpopulations (Rogier et x1.1985). In this study only 3
of 56 loci that could be scored were polymorphic.
Because of low degree of genetic variability resolved by
using isozyme electrophoresis, the population could not
be subdivided into distinct stocks. Previous
electrophoretic analyses have also demonstrated a low
genetic variability in anadromous striped bass
compared with that in other fish species (Otto 1975;
Grove et x1.1976; Sidell et x1.1980).
Similaz findings were reported on electrophoretic
analysis of supposedly sepazate stocks of Atlantic cod,
Gadus morhua (Odense et x1.1969; Lush 1970; Mork et
a1. 1980; Mork and Sundaes 1983). On the other hand,
investigators studying serology (immunochemical
characteristics within blood groups) suggested discrete
subpopulations throughout the range of Atlantic cod
(Frydenberg et x1.1965; Sick 1965a,1965b; Moller 1967,
1968, 1969; Jamieson 1975; Cross and Payne 1978).
Mork et al. (1985) discovered a significant correlation
between genetic variation and geographic distance
among Atlantic cod sampled at nine locations
throughout their range. Their ultimate conclusion was
that the absolute amount of genetic variation was low,
and that this lack of differentiation could be attributed
to the interstock exchange that has been revealed by
tagging experiments (Hansen 1949; Jensen 1953;
Joensen 1953; Tiews and Lamp 1974; Templeman 1974,
1976,1979; Godo 1983).
Biochemical studies have proven useful in sepazating
and distinguishing stocks of salmonids (Hodgins et al.
1969; Utter et al. 1974; Allendorf and Utter 1979).
Beacham et al. (1985), who examined genetic variation
in even and odd year brood line stocks of pink salmon
in southern British Columbia and Puget Sound, found
them to be reasonably distinct through cluster analysis
by allelic frequency. Alaskan sockeye salmon of the
Russian River (Grant et x1.1980) and the Karluk River
systems (Wilmot and Buger 1985) showed significant
differences in allelic frequency, as did fish of their
respective early and late runs. Additional efforts in
recent years have contributed to the knowledge of the
genetic makeup and variability of Pacific salmon
(Aspinwall 1974x, 1974b; Johnson 1979; Okazaki 1981;
McGregor 1982,1983; Fournier et x1.1984).
The Atlantic salmon has been severely depleted in
both European and North American drainages. To
supplement natural runs, fish culturists have operated
hatcheries on both continents for more than a century
(MacCrimmon and Gots 1979). The need to identify the
genetic structure of Atlantic salmon populations
became apparent as these hatchery stocks increased and
as the high seas fishery intensified (Stah11987). In the
West Greenland fishery, the Atlantic salmon harvested
come from both North America and Ewope (Saunders
1966,1981). Present data suggest at least four loci that
provide the combined capability of identifying fish to
region of origin with high precision (Stah11987).
Although the European populations aze genetically
more vazied than present-day North American Atlantic
salmon (Henry Booke, personal communication),
artificial propagation imposes the risk of reducing the
total genetic diversity, as has already occurred in North
America (Ryman and Stahl 1980, 1981; Ryman 1981;
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