LENGTH WEIGHT RELATIONS OF HADDOCK 

 FROM COMMERCIAL LANDINGS IN NEW ENGLAND, 1931-55 



By 



Bradford E. Brown and Richard C. Hennemuth, 



National Marine Fisheries Service Biological Laboratory, 



Woods Hole, Massachusetts 02543 



ABSTRACT 



Length-weight relations (including the conversion of dressed to live weight) are 

 needed to study the population dynamics of haddock on Georges and Browns Banks. 

 Analyses of covariance were used to compare these relations among market categories, 

 years, fishing areas, and months. There was considerable variation among samples taken 

 on different trips and among subsamples taken on a single trip. Separate regression lines 

 are recommended for market categories (large and scrod) and for Georges and Browns 

 Banks. No yearly or seasonal trends were evident. Estimating equations are presented. 



INTRODUCTION 



Samples of length and weight measure- 

 ments of haddock in commercial landings of 

 United States otter trawlers were collected in 

 several of the years from 1931 to 1955. A large 

 part of these data was examined by Clark and 

 Dietsch (1959), who reported that seasonal 

 trends were evident in the length-weight rela- 

 tionships, and presented sets of weight at 

 length tables for each month by special sam- 

 pling areas (Figure 1) which have been used to 

 convert length to weight in routine estimates of 

 haddock statistics. It was desirable, however, to 

 conduct a more critical and comprehensive 

 analysis of all available length-weight data for 

 haddock, particularly since studies of the 

 dynamics of the haddock fishery depend on 

 the use of these data to estimate from length- 

 frequency samples and weight of landings the 

 number landed. In the present study, variation 

 among size categories, years, areas, and months 



was estimated, and statistical tests were applied 

 to determine the degree of homogeneity and 

 the most appropriate length-weight equations 

 to be used in the study of population dynamics 

 of haddock. 



The estimation of factors for converting 

 dressed weights, gutted or gilled and gutted, to 

 live weight is also included. 



COLLECTION OF DATA AND METHODS OF 

 ANALYSIS 



All measurements were taken from fish 

 landed at the Port of Boston. Fork lengths 

 were recorded to the nearest centimeter and 

 weights to the nearest 0.1 pound. Haddock 

 were landed either gutted, or gutted and gilled. 

 From April to November the fish were required 

 to be gutted and gilled, and they were 

 frequently so treated in the winter months 

 also. Only the data from the gutted and gilled 



