Size, Seasonal Abudance, and Length-Weight Relation 

 of Some Scombrid Fishes from Southeast Florida 



By 

 GRANT L. BEARDSLEY, JR., Fishery Biologist 



and 



WILLIAM J. RICHARDS, Supervisory Zoologist 



Bureau of Commercial Fisheries 

 Tropical Atlantic Biological Laboratory 

 Miami, Florida 33149 



ABSTRACT 



Seven species of scombrid fishes were sampled for length and weight at a taxi- 

 dermy firm for 1 year (September 1967 -September 1968). These data yielded infor- 

 mation on size distribution and seasonal abundance of the species off south Florida. 

 In addition, length-weight relations and calculated weights at given lengths are pre- 

 sented. 



INTRODUCTION 



Because the southeast coast of Florida from 

 Palm Beach to Key West is one of the major 

 centers of salt-water sportfishing in the United 

 States, samples of a variety of fish are avail- 

 able for scientific study. In 1967 TABL (Bu- 

 reau of Commercial Fisheries Tropical At- 

 lantic Biological Laboratory) in Miami began 

 sampling several species of scombrid 

 fishes received from sport fishermen for 

 mounting by Al Pflueger, Inc., a large taxi- 

 dermy firm in Hollywood, Fla. The species 

 sampled were: wahoo, Acanthocybium 

 solanderi; little tuna, Euthynnus alletteratus; 

 skipjack tuna, Katsuwonus pelamis ; king mack- 

 erel, Scomber omorus cavalla; Spanish mack- 

 erel, S, maculatus; cero, S. regalis; and 

 blackfin tuna, Thunnus atlanticus. This sam- 

 pling was undertaken to determine the seasonal 

 presence of scombrids in the area in con- 

 junction with sampling for their larvae in the 

 Straits of Florida. Since no commercialfishery 

 for most of the species exists in this area, we 

 had to turn to the well-developed sport fishery. 



TABL personnel visited the taxidermy plant 

 each week from September 1967 through Sep- 

 tember 1968 to examine fishes received the 

 previous week from the company's various 

 collecting points along the southFlorida coast. 

 We did not sample specimens from locations 

 other than south Florida. We measured length 

 and weight only. Fork length was recorded to 

 the nearest millimeter; weight was taken to the 

 nearest 0.1 pound and was later converted into 

 kilograms. 



Certainproblems arise in evaluating samples 

 of fish from a taxidermy company. Usually 

 only the largest individuals caught are pre- 

 served and mounted; size frequencies are 

 affected accordingly. Apparent seasonal 

 changes in abundance may reflect merely a 

 difference in the number of fishermen and a 

 resulting increase or decrease in the number 

 of fish received for mounting. Despite these 

 problems we believe that these data are im- 

 portant enough to warrant presentation--for 

 the most part they give a reasonably accurate 

 picture of seasonal changes in size and abun- 

 dance of these fishes along the southeast coast 

 of Florida. 



SIZE DISTRIBUTION AND RELATIVE 

 APPARENT ABUNDANCE 



Fork lengths of wahoo, little tuna, skipjack 

 tuna, king mackerel, and blackfin tuna were 

 separated by quarters of the year and arranged 

 into appropriate centimeter groupings. The 

 length frequencies were plotted. Too few cero 

 and Spanish mackerel were collected to treat 

 in this manner. 



Wahoo 



The wahoo is a highly prized game fish, and 

 probably a higher percentage are retained for 

 mounting than any of the other species dis- 

 cussed; hence seasonal abundance and size 

 distribution as represented by our samples 

 are probably more valid for wahoo than for 

 any of the other species we studied. 



