Bulletin of the Sea Fisheries Institute 1 (155) 2002 - CEEMaR

50
DARIUSZ P. FEY
shrinkage can be the cause of considerable growth rate over- or underestimation. Thus, length
correction is necessary and can be done, for example, by using regression that describes the
relationship between fresh length and otolith size (Leak 1986, Radtke 1989). However, it has
been shown (Fey 1999) that higher accuracy is provided when the fresh length – preserved
length relationship is used. Additionally, the otolith size – fish size relationship can be significantly
affected by growth rate or temperature experienced by a given specimen (Fey 2001).
Therefore, a linear equation describing the relationship between SL measured before and after
10 days of preservation is presented in this paper as a length correction method for early life
stages of smelt and herring. It should be noted, however, that the equation was estimated for
larvae which were alive prior to fixation. If the larvae were dead one should expect additional
shrinkage related to damage while in the net. The degree of this shrinkage would depend on the
duration and speed of the tow and the abundance of other planktonic organisms (Blaxter 1971,
Theilacker 1980, Hay 1981, Jennings 1991).
Acknowledgments. I wish to thank H. Wróblewska for her assistance in larvae measurements.
This paper is a contribution to the State Committee for Scientific Research
grant PB-34/01 and the SFI project O-132, entitled: “Ecology of early life-history
stages of selected fish species in the Vistula Lagoon – recruitment mechanism studies”.
REFERENCES
Butler, J. L. 1992. Collection and preservation of materials for otolith analysis, p. 13 -17. [In:] Otolith
structure examination and analysis. D.K. Stevenson and S.E. Campana [ed.]. Canadian Special
Publication of Fisheries and Aquatic Sciences 117.
Blaxter, A. J. 1971. Feeding and conditions of clyde herring larvae. Rapp. p.-v. Reum. Cons. Int. Explor.
Mer 160: 128-136.
Ehrlich, K. F. 1974. Chemical changes during growth and starvation of herring larvae. [In:] The early
life history of fish. J.H.S. Blaxter (ed.). Springer-Verlagsges. Berlin: 301-324.
Farris, D. A. 1963. Shrinkage of sardine (Sardinops cearulea) larvae upon preservation in buffered
formalin. Copeia, 1: 185-186.
Fey, D. P. 1999. Effects of preservation technique on the length of larval fish: methods of correcting
estimates and their implication for studying growth rates. Arch. Fish. Mar. Res. 47(1): 17-29.
Fey, D. P. 2001. Differences in temperature conditions and somatic growth rate of larval and early
juvenile spring-spawned herring from the Vistula Lagoon, Baltic Sea manifested in otolith to fish
size relationship. J. Fish Biol. 58: 1257-1273.
Fowler, G. M. and S. J. Smith 1983. Length changes in silver hake (Merluccius bilinearis) larvae: effects
of formalin, ethanol, and freezing. Can. J. Fish. Aquat. Sci. 40: 866-870.
Hay, D. E. 1981. Effects of capture and fixation on gut contents and body size of Pacific herring larvae.
Rapp. p.-v. Reum. Cons. Int. Explor. Mer. 178: 395-400.
Hay, D. E. 1982. Fixation shrinkage of herring larvae: effects of salinity, formalin concentration, and
other factors. Can. J. Fish. Aquat. Sci. 39: 1138-1143.
Hjörleifsson, E. and G. Klein-MacPhee 1992. Estimation of live standard length of winter flounder
Pleuronectes americanus larvae from formalin-preserved, ethanol-preserved and frozen specimens.
Mar. Ecol. Prog. Ser. 82: 13-19.
Jennings, S. 1991. The effects of capture, net retention and preservation upon lengths of larval and
juvenile bass, Dicentrarchus labrax (L) J. Fish Biol. 38: 349-357.