FISHERY BULLETIN: VOL. 71, NO. 3 



Estimates of tagging mortality and tag shed- 

 ding were also obtained from the experiments. 

 Because these estimates are based on fish ac- 

 climated to holding tanks, they are probably 

 minimum estimates of losses experienced in the 

 field. The combined loss was 10 to 20% for men- 

 haden averaging 110 to 160 mm in length. The 

 combined loss for menhaden less than 100 mm 

 was approximately 50% . Most tagging mortality 

 occurred within 3 days and most tag shedding 

 within 2 wk. 



A smaller version of the tag was developed for 

 juvenile menhaden. These fish can be tagged 

 most effectively by inserting a 7.0 by 2.5 by 

 0.4 mm tag posteriorly into the body cavity 

 from the base of the pectoral fin. 



The menhaden purse seine fishery provided 

 most of the fish for our work. We also tagged 

 fish obtained from commercial pound nets and 

 our own pound net, purse seines, and haul 

 seines before the purse seine fishery began or 

 where there was no menhaden fishery. 



When working with the commercial purse 

 seine fishery, two methods of obtaining and 

 holding fish were used. We accompanied com- 

 mercial vessels in our own small boats and dip- 

 ped fish from the purse seine into our holding 

 nets, or we tagged directly from the commer- 

 cial vessel, keeping the fish alive in holding 

 boxes supplied with flowing seawater. Data 

 were recorded for each group of fish released. 

 A percentage of the fish released were measured 

 to the nearest millimeter and the age determin- 

 ed by counting scale annuli. We recorded the 

 condition of fish, size of catch and time it was 

 made, time tagged fish were released, surface- 

 water temperature, and name of tagger (Pristas 

 and Willis).2 



TAG RECOVERY 



All tags were recovered from menhaden re- 

 duction plants because there is no satisfactory 

 way of recovering them from menhaden used 

 for bait or for other reasons precluding their 

 passage through a reduction plant. About 99% 



of the tags recovered were taken from magnets 

 inside the plants. Primary magnets were placed 

 in the plant's conveyor system between the fish 

 scrap drier and the scrap storage area (Figure 

 1). About 75% of the tags pass over these mag- 

 nets the same day the tagged fish are processed. 

 The following day an additional 10% pass the 

 primary magnet. More than 95% of the tags pass 

 the primary magnet within 2 wk from the time 

 they enter the plant. Secondary magnets in- 

 stalled at other locations in the system may not 

 recover tags until months after the fish are 

 landed when the fish scrap is ground into meal 

 or is shipped out of the plant. Whole tagged fish 

 were recovered by using electronic detector- 

 recovery systems which shunted fish past a 

 section of the plant's conveyor. Tagged fish were 

 ejected, and untagged fish continued through 

 processing (Parker, 1972). 



Primary and secondary magnets were us- 

 ually cleaned daily (Parker). ^ Thus, tags re- 

 covered on primary magnets indicated the ap- 

 proximate date of capture. Precise recapture 

 locations are not obtained from magnet recover- 

 ies, but along the Atlantic coast the fishery in 

 each area was localized and area of recapture 

 could usually be determined. 



We tested the efficiency of the recovery sys- 

 tem in each plant by putting tags in whole fish 

 in the catch and noting the percentage of these 

 tags recovered. Estimates of the number of 

 tagged fish recaptured were obtained using 

 these primary recovery efficiencies. Tables 1 

 through 8 give the estimated numbers of tagged 

 fish recaptured by area and season of release 

 and by area and season of recovery. A precise 

 description of tagging and release areas is given 

 in the section on migrations. We estimate that 

 202,943 tagged fish, or 19% of those released, 

 have been recaptured. Actual recoveries by area 

 and month of release are given by Coston (1971). 



MIGRATIONS 



We tagged Atlantic menhaden in the estuar- 

 ies and major fishing areas to test the following 



2 Pristas, P. J., and T. D. Willis. Field tagging methods 

 for menhaden. Atlantic Estuarine Fisheries Center, Na- 

 tional Marine Fisheries Service, NOAA, Beaufort, NC 

 28516. Manuscript in preparation. 



3 Parker, R. O.. Jr. Magnetic recovery of internal ferro- 

 magnetic tags applied to menhaden (Brevoortia spp.) At- 

 lantic Estuarine Fisheries Center, National Marine Fish- 

 eries Service, NOAA, Beaufort, NC 28516. Manuscript 

 in preparation. 



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