FISHERY BULLETIN: VOL. 71. NO. 3 



LEVELS OF MERCURY IN 



TUNAS AND OTHER LARGE 



PELAGIC MARINE FISHES 



Published data on levels of mercury in 

 tunas and other large pelagic fishes are scarce 

 and difficult to interpret. For example, it has 

 been shown for skipjack tuna caught off Hawaii 

 that the amount of mercury in the red muscle 

 is about 1.6 times greater than that in the 

 white muscle (Lasker and Leong, see footnote 

 3), and for swordfish caught off the Canadian 

 and U.S. Atlantic coast the amount of mercury 

 in the red muscle is about 1.4 times greater 

 than in the dorsal muscle (Beckett and Freeman, 

 in press), but the majority of published data 

 do not name the parts of the fish which were 

 analyzed. 



Table 1 summarizes information on mercury 

 levels in tunas and billfishes, obtained princi- 



pally from data published within the last 2 yr. 

 The area designations marked with a 4 or 5 

 refer to museum specimens all of which date 

 from the period 1878-1901 (except for the 

 swordfish which was captured in 1946) and 

 thus predate the period in which mercury 

 pollution became important. It is evident that 

 there is no significant difference in mercury 

 levels between the museum tuna samples cap- 

 tured 62-93 years ago and the tunas caught 

 within about the last 5 yr. The mercury level 

 from the single museum specimen of swordfish 

 falls within the range of the six "modern" 

 specimens caught off California. 



The similarity in mercury levels of tunas 

 collected prior to 1900 and those captured in 

 the last several years is substantiated by similar 

 findings in other types of marine fishes. For 

 example, in a recent study of mercury in 

 benthopelagic fishes it was found that mercury 



Yellowfin tuna, Thunnn.s ulbiicares: 



Gulf of Guinea 



Hawaii 



Pacific 



Atlantic (Africa) 

 Skipjack tuna, Katsuwonits pelumis: 



Hawaii 



Gulf of Guinea 

 Pacific 



Massachusetts^ 

 Philippines^ 

 Pacific 



San Diego, Calif.'' 

 Hawaii 

 Albacore, Thunnus alulunga: 

 California'* 



Bluefin tuna, Thunnus ihynnus: 



Gulf of Cadiz 



Western Atlantic 



Massachusetts'* 

 Bigeye tuna. Thunnus nhesus. 



Gulf of Guinea 

 Swordfish, Xiphias gludius: 



Western Atlantic 



California 



Gibraltar Strait 



Gulf of Guinea 



Boja California^ 

 Pacific blue morlin, Miikairci mcizara: 



Hawaii 

 White marlin, Tetrapluius alhidus: 



Western Atlantic 



200-271 

 172 



74-247 



187 



0.07 -1.20 



0.24 -1.32 



0.20 -0.76 



0.29 -0.77 



-0.15 -0.35 



0.27 -0.52 



0.11 -0.20 



0.27 0.64 



0.183-0.209 



0.46 -0.91 



0.23 -0.75 



0.05 -4.90 



0.23 -1.27 



0.99 -2.01 



0.95 -1.25 



0.35 -14.0 



0.42 

 0.54 



0.49 



0.38 



0.18 

 0.46 

 0.26 

 0.18 

 0.45 

 0.42 



0.27 

 0.13 



0.193 



0,68 

 0.80 

 0.38 



1.15 

 1.36 

 0.52 

 4.78 

 1.34 



Ivory Coast Fisheries Service, 1972' 

 Rivers et al., 1972 

 Unpublished data 

 Establier, 1972 



Lasker and Leong, 1972'^ 



Rivers et al, 1972 



Ivory Coast Fisheries Service, 1972' 



Miller et al., 1972 



Miller et al., 1972 



Miller et al., 1972 



Miller ef ol., 1972 



Miller et ol., 1972 



Miller et ol., 1972 



Miller et al., 1972 

 Miller et al., 1972 

 Knauer and Martin, pers. comm. 



Establier, 1972 



Beckett and Freeman, in press 



Miller et al., 1972 



Ivory Coast Fisheries Service, 1972' 



Beckett and Freeman, in press 



Miller et al., 1972 



Establier, 1972 



Ivory Coast Fisheries Service, 1972' 



Miller et al., 1972 



Rivers et al., 1972 



Beckett and Freeman, in press 



' See text footnote 4. 



- White meat only. 



^ See text footnote 3. 



■* Museum specimens collected from 1878 to 1901. 



Museum specimen captured in 1946. 



606 



