each month to enable us to determine whether worm size is affected 

 by monthly or seasonal market demands. Monthly sampling would 

 also allow us to accumulate more length, weight, sex, and condi- 

 tion information from assorted growing areas. 



Problems inherent in the analysis of lumped commercial length 

 frequency data for age (and the mortality estimates based upon that 

 age structure) have been discussed previously under the section 

 entitled "Estimates of Age." Despite the fact that commercial- 

 length frequency data collected from specific growing areas over 

 short periods of time may be more easily analyzed for age structure 

 than similar data collected from a large geographical area and 

 lumped over a longer period of time, the authors do not recommend 

 the former approach either. Our experience has been that when the 

 former procedure is followed, considerable overlap in the older 

 year classes occurs and the validity of aging results may still be 

 questioned. It would seem more appropriate to develop a means of 

 aging marine worms other than by analyzing length frequency dis- 

 tributions. In this respect, aging by 1) the possible presence of 

 annuli on bloodworm and sandworm mouth parts, and 2) mark and 

 recapture techniques using tagged or dyed worms or worms with 

 mutilated appendages, should be attempted. Age structure deter- 

 mined by these means in three or four commercial growing areas 

 could then be used to determine the numbers of worms at each year 

 class mode required for mortality estimates. Total and natural mor- 

 tality rates could be estimated from length-frequency data collected 

 from open and closed growing areas situated side by side in each of 

 the three or four study areas. Fishing (digging) mortality (F) could 

 be determined for each study area by F=Z-M where Z = total mor- 

 tality and M = natural mortality. 



ACKNOWLEDGMENTS 



I would like to thank the marine worm diggers and dealers who 

 cooperated with us in the collection of commercial sampling infor- 

 mation. 



David A. Clifford and Michael J. Hogan of the Maine Depart- 

 ment of Marine Resources (DMR), West Boothbay Harbor, trav- 

 eled long distances, worked weedends and holidays, and were 

 instrumental in the collection and summary of sampling and inter- 

 view data in the field and laboratory. 



I wish to thank James C. Thomas, principal investigator of the 

 DMR lobster project, forhis experience and assistance in sampling 

 design, for his patience with my numerous inquiries, and for his 

 encouragement throughout. 



David B. Sampson (DMR) deserves a great deal of credit for his 

 meticulous evaluation and improvement of the statistical manipula- 

 tions employed in this work. 



James A. Rollins, Bigelow Laboratory for Ocean Sciences. West 

 Boothbay Harbor, was responsible for photographic services and 

 Phyllis A. Carnahan (DMR) typed this manuscript. 



This research was conducted by the Maine Department of Marine 

 Resources in cooperation with the U.S. Department of Commerce. 

 National Marine Fisheries Service, and financed under Public Law 

 88-309. 



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