Hello Fellow list members,

following my request last week for information on using chemicals to stain
larval fish otoliths, I am forwarding a summary of the responses that I
have received.  I would like to thank all those who kindly took time out
of their schedules to reply to my request.

The two most recommended stains both in responses from list members and in
the literature are tetracycline and alizarin complexone.  Both have the
potential of creating reliable, consistent (among fish) stains, and both
have minimal impact on growth and mortality.  Immersion in the chemicals
appears to be the most efficient and reliable method of staining.
However, tetracycline in full strength seawater can be problematic as the
divalent ions in the water bind to the chemical.  This problem can be
circumvented by using diluted seawater (10 ppt) or artificial seawater
(leaving out the divalent cations).

Another marker, manganese, which can be detected by cathodoluminescence
spectroscopy was also suggested, as it has been used to mark mollusc shell
increments (see Hawkes et al.  1996.  Journal of Shellfish Res. 15:
659-666).

Respondents to my request did not forsee a problem with repeatedly marking
the otoliths of my larvae, as long as sufficient time was allowed between
stainings to allow distinct bands to form.  Others recommended alternating
stains (tetracycline and alizarin) to create alternating bands of
different colors.  This has apparently been used to given hatchery larvae
unique marks before being released.

Some useful references include (in no order what so ever...oh well):

Stevenson and Campana (eds.).  1992.  Otolith microstructure examination
and analysis.  Can. Spec. Publ. Fish. Aquat. Sci. 117.

Secor et al. (eds.)  1995.  Recent developments in fish otolith research.
University of S. Carolina Press, Columbia, S. Carolina.

Secor et al. 1991.  Trans Am Fish Soc 120: 261-266.

Ahrenholz et al. 1994.  Fish Bull 93: 209-216.

Hettler  1984.  Trans. Am. Fish. Soc.  113: 370-373.

Nagiec et al.  1995.  Fisheries Management and Ecol. 2:185-195.

Brooks et al.  1994.  North Am J Fish Management 14: 143-150.

Blom et al.  1994.  Aquaculture and Fisheries Management 25
(Suppl1): 229-243

Beckman et al.  1996.  Trans Am Fish Soc 125: 146-149

Dabrowski and Tsukamoto.  1986.  J. Fish Biol 29: 691-698


Hope that this helps, and thanks again to those which responded to my
request.

Cheers,

Hugues

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Hugues Benoit

Ocean Sciences Center
Memorial University of Newfoundland
St.-John's, Newfoundland, Canada
(709) 772-6184

e-mail: [log in to unmask]
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