In 1961 Carlson and Reintjes (1972) tested 

 four internal ferromagnetic tags on captive 

 menhaden 115-168 mm long (fork length). They 

 found that the most suitable type was a smooth- 

 edged stainless steel (Type 420) torus tag, 14.0 

 by 2.5 by 0.5 mm, similar to one that had been 

 used successfully with small Atlantic herring 

 in Norway (Dragesund and Hognestad, 1960). 

 When they tagged 75-90 mm menhaden, how- 

 ever, most of the fish, including the handled 

 controls, died. Carlson and Reintjes also tested 

 the recovery of tags by magnets in a menhaden 

 reduction plant and found that about 60% of the 

 tags entering the plant in fish were recovered. 

 They believed the tag recovery efficiency could 

 be increased by installation of additional mag- 

 nets. 



METHODS OF HANDLING 



EXPERIMENTAL FISH AND 



RECOVERING TAGS 



Menhaden were conditioned to the holding 

 facilities so the results of the experiments could 

 be attributed to the procedures tested (Bayliff 

 and Klima, 1962). Most were captured with a 

 haul seine. They were held in rectangular con- 

 crete tanks, 5 by 2 by 0.7 m, with rounded cor- 

 ners or in circular fiberglass tanks, 2 by 0.8 m, 

 continuously supplied with aerated seawater. 

 Within 2 days after being captured fish began 

 feeding on a mixture of menhaden meal and 

 homogenized clams or on commercial trout food. 



Two sizes of tags were tested — one for 

 adults and one for juveniles. Juvenile menhaden 

 are those in their first year of life and adults are 

 those in their second or later years of life. Tags 

 measuring 14.0 by 3.0 by 0.5 mm for adult men- 

 haden were ground and filed to 6.9 by 1.8 by 

 0.5 mm for juveniles. The corners were rounded 

 and the edges smoothed to remove the burrs. 

 Throughout this paper, larger tags are referred 

 to as adult tags and smaller tags as juvenile 

 tags. 



In early experiments tags were inserted into 

 the fish with a scalpel and forceps, following 

 the methods of Carlson and Reintjes (1972). 

 An incision was made about 15 mm above the 

 origin of the right pelvic fin depending on the 

 size of the fish, with a scalpel, and the tag was 

 pushed anteriorly through the incision with for- 



ceps. In later experiments the tags were inserted 

 with a Bergen-Nautik tagging gun (Fig. 1). 

 The tag protruding from the barrel of the tag- 

 ging gun punctured the body wall before being 

 pushed into the body cavity with the thumb 

 plunger. An adult tagging gun was modified to 

 facilitate injecting the juvenile tags. Unless 

 stated otherwise, these tags were also inserted 

 about 15 mm above the origin of the right pelvic 

 fin and pushed forward into the body cavity. 



Standardized procedures were followed for 

 the experiments. Fish were seined from the 

 tanks, placed in 30-liter plastic tubs of seawater, 

 tagged, and returned to a tank. In most experi- 

 ments untagged menhaden, taken from the 

 same group as the tagged fish, were used as 

 controls. The sequence of tagging the fish was 

 selected randomly. In the first three experi- 

 ments fish were anesthetized in the tubs with 

 tricaine methanesulfonate (MS-222) at a con- 

 centration of 1:26,000, but in later experiments 

 they were not. 



Tagging loss, as used in the text, represents a 

 combination of the total loss of tags from fish 

 that died or shed their tags during the experi- 



Figure 1. — Adult tag about to be inserted with the tag- 

 ging gun into the body cavity of a yearling menhaden. 



