CORROSION RESISTANCE OF FISH TAGGING PINS 



Wire or pins made of various metals, 

 including silver, platinum, copper, and 

 nickel, have been used extensively to fasten 

 tags to fish. For some years nickel pins 

 were used with Petersen discs to mark had- 

 dock ( Melanogrammus aeglef inus L.) in the 

 Gulf of Maine (Rounsefell 1941) and on 

 Georges Bank. When recovered many of them 

 were corroded, suggesting that many tags 

 may have been lost from the fish. To avoid 

 this loss, stainless steel pins were con- 

 sidered as a possible substitute. 



An experiment with tagged haddock was 

 conducted in the Fish and Wildlife Service 

 aquarium at Woods Hole to compare the cor- 

 rosion resistsince of Type 304 stainless 

 steel pins with that of the nickel pins used 

 in the past. The metallic composition and 

 dimensions of the two types of pins are 

 shown in taible 1. 



CONDITIONS OF THE EXPERIMENT 



Tanks 



Six indoor aquaria each holding about 

 300 gallons were used in the experiment. 



Flowing sea water at the rate of four 

 changes per day was supplied to the tanks 

 from Great Harbor, on which the laboratory 

 is located. The water temperature in the 

 tanks was recorded with a Bristol recording 

 thermometer* The average salinity of the 

 water in Great Harbor is 32 parts per thou- 

 sand, and because of the frequency of change 

 the salinity of the aqu«irium water was pre- 

 sumably the same. 



Fish 



The haddock used in the experiment 

 were captured by an otter trawl on Georges 

 Bank during Albatross III cruise 59, 

 April 6-12, 1955. A total of 168 fish were 

 transported to Woods Hole on board the ves- 

 sel in wooden tanks supplied with running 

 sea water. 



Haddock are delicate and difficult to 

 maintain in aquaria. Four weeks were there- 

 fore allowed for initial mortality and to 

 acclimate the fish before the experiment 

 began. Forty-three fish survived eind 36 of 

 the strongest, ranging in size from 30 

 centimeters to 60 centimeters, were selected 

 for use. 



Table 1. -- Composition and dimensions of tagging pins — 



1/ 



Stainless Steel 



Nickel 



Length (in. ) 

 Diameter (in. ) 



*Spectrographic analysis 

 _' Analyzed by National Bureau of Standards 



99.8 



1. 81 



. 032 



Method of Tagging 



The fish were tagged with 

 Petersen discs on May 9 using the 

 technique described by Rounsefell 

 (1941) in which the pin is threaded 

 through the center of one disc and 

 then pushed through the operculum 

 from the inside. The second disc is 

 then threaded on the projecting point 

 of the pin. The surplus part of the 

 pin is cut off and the remainder 

 twisted into a loop cind bent over 

 with long-nosed pliers. To calm the 

 fish while being tagged, they were 

 placed in a tank containing 12 gal- 

 lons of sea water to which one-half 

 pound of ethyl carbamate (Urethane) 

 had been added. After about one 

 minute in the anesthetizing bath the 

 fish began to float belly up, made 

 only feeble swimming movements and 

 were generally relaxed enough to per- 

 mit tagging. On 18 fish the tags 

 were fastened with stainless steel 

 pins and on the other 18 fish the 



