Íslenskar landbúnaðarrannsóknir - 01.09.1978, Page 116

ÍSL. LANDBÚN.
J. AGR. RES. ICEL. 1978 10,2: 114-124
Analysis of KollaQördur Hatchery —
management alternatives
TONYJ. RASCH
Washington Department of Fisheries,
Olympia, Washington
and
SlGURDUR THÓRDARSSON
Instilute of Freshwater Fisheries,
Reykjavík
ABSTRACT
A flowcharl was prepared of the relationship between variables that are importam to the nel economices of
the Kollafjördur Hatchery. These include: how many eggs to hatch, and at what date to hatch them; at
what density to stock the ponds; at what temperature lo maintain in the ponds; when, and how many fish to
be transferred to the second-stage rearing house, moved outdoors or sold; how many fish to become 1-year,
and how many 2-year smolts; and when, where, and at what size the fish are to be released.These factors are
not independent, but are subject to biological constraints related to proper smoltification, such as photo-
period, minimum size at critical dates, and olher criteria. Specific physical halcher) constraints are the
available space and the amount of waler.
A method of analyzing various management alternatives was devised; several options were considered in
detail and some specific recommendations were made. The system will gain in value when better survival
and growth estimates of various categories of smolts become available.
INTRODUCTION
During the spring of 1974 and 1975, ex-
periments were undertaken with Atlantic
salmon (Salmo salar) at the Kollafjördur
Hatchery (Fig. 1). The objectives were to
determine survivals from a variety of dif-
ferent fish sizes, release times, release lo-
cations, ages, and smoltification methods
(IsAKSSONand Bergman 1978; and Isaksson
et al. 1978).This paper describes a proce-
dure for utilizing the results of these ex-
periments to increase the productivity of
Kollafjördur Hatchery, and for pinpoint-
ing areas where further experimentation
would yield greatest economic gains.
THE HATCHERY OPERATION
Figure 2 shows the relationship of the
variables which are important to the net
economic impact of the hatchery’s opera-
tion. While the hatchery rears some
brown trout (Salmo trutta), and Arctic Car