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

H? 113 370-37° F. _ _x:34 . Tr-ns . Am. _ ?sh e =o, .
- Fishes tested--spot (Leiostomuls xanthurus) and
pinfish (Lagodor_ rhomboides) 13-16 mm SL and 12-15
mm SL, respectively; marine fish larvae.
- Objectives--to describe a technique for mass-marking
larval marine fishes by immersion in a tetracycline
bath. Mark on otolith to be used as a time mark,
not to be used for mark-recapture .studies.
- Methods
--Used oxytetracycline hydrochloride (tetracycline
is parent compound; several sister comnounds
includin,J o_-ytetraevcline) in concentrations of
1016, 250, and 500 mg/l. The pH of solutions were
adjusted with Tris buffer (pH of unbuffered TC
solutions varied with concentration from 2.5 to
3.5; T:?H adjusted to 6.0-6.2 with Tris).
--Half of the treatments contained dimethyl
sulfoxide (DMSO), a solvent that may enhance the
uptake of TC. _
--Groups of 15 larvae of each species were treated;
held in flow-through cages in a flow-through
water-table; fed Artemia nauplii and dry trout
food once daily; larvae held 8 days following
treatment.
--Exposure times were 30, 60, and 120 minutes; each
treatment was replicated.
--All larvae were preserved in 95% ethyl alcohol.
--Otoliths were ground and examined under U-V
light microscope (100X and 560X).
- Results
--In higher concentrations and at longer exposure
times, OTC was absorbed by larvae of both species
and produced flourescent bands on otoliths.
--100% marked at 250 mgll for 120 minutes and 500
mg/l for 60-120 minutes.
--Use of DMSO did not enhance uptake of OTC.
--Overall survival rate ranged from 93.5% to 96.5%.

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