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Fishery Bulletin 97(4), 1999 



catches of skates (Raja spp.) and dogfish (Squalus 

 acanthias) were avoided because their abrasive skin 

 resuhed in damage to cod and poor quahty specimens 

 for tagging. 



Fisheries research stern trawlers, 50-70 m in 

 length, equipped with a research Western Ila otter 

 trawl and with wet laboratory facilities below the 

 trawl deck, were used for large-scale tagging opera- 

 tions. Fishing operations consisted of 5-20 min tows 

 at depths ranging from 40 to 70 fathoms. At the end 

 of each tow, cod were released into a sluice way lead- 

 ing to the below-deck wet laboratory area and trans- 

 ferred into 1500-L holding tanks with recirculating 

 ambient sea water Viability of each cod was assessed 

 prior to tagging and fish in poor condition or that 

 had apparent external injuries were discarded. Con- 

 trol experiments to assess tag or stress induced 

 mortality were not conducted, but observation 

 showed that even fish that were initially inverted or 

 dormant on the bottom of the tank returned to an 

 apparent active and normal behavior within 15-30 

 minutes. Tagged fish were released through a sluice 

 way exiting about one to two meters above the water 

 line. Approximately 100 to 250 cod could be held, 

 tagged, and released from each tow, depending on 

 average fish size in a tow. 



Fish to be tagged were removed fi-om holding tanks 

 by hand with dip nets and placed on a measuring 

 board to obtain length. A tag was inserted near the 

 leading edge of the first dorsal fin and the fish was 

 released. Total elapsed time from start to end of the 

 tagging operation was in most cases less than 30 sec- 

 onds for each fish. An ad hoc representative sample 

 was examined to verify the spawning state of repro- 

 ductive development (Hunt, 1996) but results were 

 not recorded. 



Several small-scale cooperative studies were car- 

 ried out with commercial fishing vessels. The first of 

 these opportunistic tagging operations was conducted 

 aboard the U.S. FV Mary V, a longline vessel fishing 

 out of Gloucester, MA. During routine fishing opera- 

 tions on the northern edge of Georges Bank, cod 

 caught that were less than the U.S. minimum legal 

 size (49 cm 19 inches) were tagged by the vessel's 

 crew and released. Tags were also supplied to staff 

 of the Massachusetts Division of Marine Fisheries 

 (MA-DMF) and the Maine Department of Marine 

 Resources (ME-DMR) to use during trips when 

 onboard fishery observers were present on commer- 

 cial longliners fishing in the Nantucket Shoals (MA- 

 DMF) and on commercial charter boats fishing the 

 inshore waters of the Gulf of Maine (ME-DMR). Dur- 

 ing these trips, undersize cod were also tagged and 

 released. A small number of cod, taken as bycatch in 

 lobster traps during the winter lobster fishing sea- 



son (4Xq inshore), were tagged and released by Cana- 

 dian fishermen. 



All tags were of the T-bar type (FD-67 and FD-94 

 in 1994) applied with the Mark-II tag insertion gun 

 and were supplied by Floy Tag and Manufacturing, 

 Inc (4616 Union Bay Place NE, Seattle, WA 98105). 

 Overall length of the tag was about 6.5 cm and each 

 tag had a 3.5-cm bright yellow address sleeve and a 

 1.0-cm attachment T-bar. Each tag was imprinted 

 with a unique identification number and Canadian 

 return mail address on the vinyl sleeve. Tags used 

 in the 1994 experiment included a second mailing 

 address for the National Marine Fisheries Service 

 (NMFS), Northeast Fisheries Science Center, Woods 

 Hole, MA. Tags were provided in clips of fifty with 

 consecutive numbering to facilitate record keeping. 



An extensive advertising campaign, targeting Ca- 

 nadian and U.S. fishing enterprises and communi- 

 ties, was completed prior to and after each of the 

 large-scale tagging experiments. This included no- 

 tices in local newspapers and other industry publi- 

 cations, all-weather bilingual posters located at ma- 

 jor fish landing and processing facilities, personal 

 contact with industry representatives, and follow-up 

 with individuals submitting tags. A representative 

 of the fishing sector participated in the 1994 experi- 

 ment to obtain firsthand knowledge of operations 

 and, as was hoped, to convey the importance of re- 

 turning tags to colleagues. 



In Canada, a nominal reward of seven dollars was 

 offered for each tag returned. In the United States, 

 a reward of five dollars was paid for tags returned 

 with recapture information and two dollars for tag 

 only returns. In addition to the reward, the finder 

 was provided with a summary of release and recap- 

 ture information for each tag returned. 



All release and recapture data were loaded to a 

 database to facilitate analysis. Tag-recapture infor- 

 mation was edited to eliminate obvious errors such 

 as onshore recoveries, substantial decreases in fish 

 length, unrealistic travel and elapsed time factors, 

 etc. Quality of recapture data was variable, ranging 

 from no information to a detailed record of how, when, 

 and where ( latitude and longitude ) fish were caught, 

 fish size at recapture, age determination material, 

 and other anecdotal information. About 80% of recap- 

 tures included detailed information on location and 

 about 20'7f had length-at-recapture measurements. 



Analysis of recapture data was completed first at 

 the divisional level, then at the unit area level for 

 the Gulf of Maine and finally at 10-min latitude and 

 longitude squares. Results were compiled to show 

 movement from area of release to adjacent areas and, 

 conversely, movement to an area from adjacent sites. 

 Analysis of recapture patterns at the divisional level 



