Length Relations of Some Marine Fishes From Coastal Georgia 



By 



SHERRELL C. JORGENSON AND GRANT L. MILLER, Fishery Biologists 



Bureau of Commercial Fisheries Biological Laboratory 

 Brunswick, Georgia 31520 



ABSTRACT 



Information is given for converting standard length into fork and total lengths, 

 fork length into standard and total lengths, and total length into standard and fork 

 lengths of 82 species of marine fishes collected in coastal Georgia during 1953-61. 



INTRODUCTION 



The Bureau of Connmercial Fisheries Bio- 

 logical Laboratory, Brunswick, Ga., is charged 

 with a study of the life histories of fishes of 

 the western North Atlantic Ocean with emphasis 

 on those off the southeastern coastof the United 

 States. One of the laboratory's programs, a 

 study of coastal and estuarine ecology, in- 

 cludes a major project on the occurrence, 

 abundance, seasonal distribution, apparent 

 hydrographic preferences, and early life his- 

 tory of fishes of coastal Georgia. 



During 1953-61, young of marine fishes 

 were collected by seining at selected localities 

 in three types of environment in Mcintosh 

 and Glynn counties, Georgia: the upper tide- 

 waters of the Altamaha River, the ocean 

 beach, and the saltmarshes. The collections 

 included larvae, juveniles, and adults of Sonne 

 species, but only juveniles of others. 



Published information on growth and changes 

 in body form of fishes during developnnent 

 generally records length as standard, fork, or 

 total. Comparison of these data is difficult or 

 impossible without a nneans of converting one 

 measurement to another. We wanted to be able 

 to make such comparisons in detailed studies 

 we were planning; so we determined the rela- 

 tions of standard, fork, and total length by the 

 method of least squares for those species for 

 which we had adequate data. This report pre- 

 sents the statistics describing these relations 

 for 82 nnarine species and gives factors for con- 

 verting one length measurement to another. 

 Length relations for fresh-water species 



from the Altamaha River were not deter- 

 mined. 



METHODS 



To determine the relation of various length 

 measurements, we measured representative 

 samples of all sizes of all species for standard 

 and total lengths and {for species with forked 

 caudal fins) fork length. Sample sizes ranged 

 from a few specimens for some species to 

 thousands for others. 



Standard length was measured from the tip 

 of the snout to the end of the hypural bones 

 (the caudal base), fork length fronn the tip of 

 the snout to the tip of the shortest median 

 caudal ray, and total length from the tip of 

 the snout to a vertical at the tip of the longest 

 lobe, or ray, of the caudal fin. Measurements 

 (to the nearest millimeter) were made with 

 dial calipers or a measuring board. 



We measured a size series of specimens 

 for each seine sample of each species. Sonne 

 nnillimeter size groups were represented by 

 one specinnen; others by many specimens. We 

 subsampled our data to treat the species vmi- 

 formly. For each nnillinneter size group of 

 standard length represented in our data, we 

 selected at randonn one specimen and recorded 

 its fork and total lengths; for each nnillimeter 

 size group of fork length, we selected one 

 specimen and recorded its standard and total 

 lengths; and for each nnillinneter size group 

 of total length, we selected one specinnen and 

 recorded its standard and fork lengths. We had 

 three sets of data for species with forked 

 caudal fins and two sets of data for those 



