7016

• UCREFRP Catalog Number: 7016
• Author: Larval Fishes Laboratory.
• Title: Development of Marking and Otolith-ageing Techniques for Colorado Squawfish
• USFW Year: 1986.
• USFW - Doc Type: Report on Study-Phase 1.
• Copyright Material: NO

14ths rr_s _- red in ? "t-ct 1'.r;T-?_ =or .5 '_':;on"h
in 95% ethyl alcohol and held in the dark
retained marks for at least 6 months, as did
sections of otoliths mounted on glass slides for
the same interval.
- Conclusions
--Flourescent marker can be placed easily on
otoliths of marine fish larvae by immersion in
TC.
--Mass-marking possible with no visible marks which
may affect survival.
Tsukamoto, K. 1985. Bull. Japn. Soc. Sci. Fish.
51:903-911.
-Fishes tested--hyu (Plecog•lossuss altivelis); a
salmoniform fish, family Plecoglossidae, closely
related to Osmeridae (true smelts); eggs small (ca
1.0-1.3 mm diameter-not sure if this size is pre- or
post-water hardening), adhesive, hatch 10-14 days
after fertilization at water temperatures of 15-20C;
;*olk-sac larvae (newly hatched) 4.10-6.0 mm TL; post
yolk-sac larvae (yolk absorbed ca 4-7 days post
hatching) ca 6.4-6.9 mm TL; adults ca 30 cm (1 foot)
long on average.
-Objective--to develop a mass-marking method for fish
egos and newly hatched larvae.
-Methods
--Used Tetracycline hydrochloride as otolith marker.
--Three experiments: (1) examined/assessed optimal
concentrations of TC and treatment time, (2)
determined retention time of otolit.h marks, and
(3) determined effects of TC on hatching,
survival, and growth of larvae.
--Experiment 1
-Divided into two tests (eggs and larvae).
-In egg test, 30 eggs at the eyed stage were used
for each lot. Forty-four lots subjected to
concentrations of TC ranging from 0-2,000 mg/1
and treatment time ranging from 1.5-48_ hr in
freshwater in 100 ml beakers.
-In larva test, 50 newly_ hatched larvae were used
for each lot. Forty lots were exposed to TC
concentrations ranging from 0-1,000 mg/l and
treatment time ranging from 1.5-24 hr in 200 ml
beakers.
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