Q ?. 3 II 



B 



Figure 1.- 



-Four ferromagnetic tags tested for marking 

 Atlantic menhaden. 



Table 1. — Four types of ferromagnetic tags tested for 

 marking Atlantic menhaden. 



menhaden. Type A tags were similar to tags 

 used for Pacific herring (Rounsefell and Dahl- 

 gren, 1933) except were twice as thick and had 

 sharp edges. Type B tags, also with sharp edges, 

 were similar to tags used for California sardine 

 (Janssen and Aplin, 1945), anchoveta (Bayliff 

 and Klima, 1962) and anchovy (Vrooman, Pa- 



loma, and Jordan, 1966; Haugen, Messersmith, 

 and Wickwire, 1969; Wood and Collins, 1969). 

 Type C tags were similar to tags used for small 

 Atlantic herring in Norway (Dragesund and 

 Hognestad, 1960) and had smooth edges. Type 

 D tags, used for Pacific herring (Wilimovsky, 

 1963), were dummy radioactive tags that con- 

 sisted of a gold-plated iron core encased in 

 plastic. 



Young menhaden, 115-168 mm fork length, 

 were caught nearby and held in concrete tanks 

 at the laboratory for several weeks prior to the 

 tagging trials. They were fed a homogenized 

 slurry of fish meal and raw hard clams through- 

 out confinement. Test lots of menhaden for each 

 tag type consisted of equal numbers of tagged, 

 incised but not tagged, and handled but not in- 

 cised or tagged. A fifth lot of fish, not handled, 

 was used as controls. 



At tagging, menhaden were transferred to a 

 tank of seawater containing 50 ppm tricaine 

 methanesulfonate (MS-222) until they lost equi- 

 librium. With a scalpel a technician made a small 

 incision on the right side below the midline of 

 the body about midway between the tip of the 

 pectoral fin and the insertion of the pelvic fins 

 to minimize disturbance of viscera. He inserted 

 metal tag Type A, B, or C, into the body with 

 forceps (Figure 2) and Type D through a hol- 

 low needle. 



The tags and instruments were dipped in a 

 mixture of penicillin G and liquid terramycin. 

 These antibiotics were also added to the anes- 

 thetizing tank. All fish were hand-held for 20 

 sec whether they were tagged, incised, or only 

 handled. 



Dead fish and shed tags were removed daily. 

 The dead were measured, weighed, and exam- 

 ined for abnormalities by X-ray and by dissec- 

 tion. The study was concluded in January 1962 

 when the temperature in the tanks dropped over- 

 night from 3.0° to 0.4 °C and most of the fish 

 died. During the preceding 10 weeks the water 

 had cooled gradually from 22 °C without killing 

 the fish. Salinity, during this period, ranged 

 from 27 to 32%,. 



The Norwegian herring tag. Type C, was the 

 most suitable of the four tested. Tag D was not 

 considered further for it cost ten times more 



515 



