FISHERY BULLETIN: VOL. 72. NO. 2 



were comparable to larger fish, while others con- 

 tained less DDT than might be expected in larger 

 fish taken at the same time and in the same local- 

 ity. 



This variation in pesticide content appeared to 

 be related to the "fat" content (hexane extractable 

 portion of the fish) of the specimens. The fat con- 

 tent of the fishes (Figure 2) increased very rapidly 

 and with considerable variation to 30 mm length, 

 6.5% fat of the dry weight of the fish in an 18-mm 

 specimen to 42.5% in a 29-mm specimen) where it 

 began to level off. In mature fish the fat is about 

 49% of dry weight and 16% of wet weight. There is 

 no apparent seasonal fat cycle. For comparison of 

 DDT in time and space, only myctophids 30 mm or 

 longer were used. 



METHODS 



The myctophids used in this study were pre- 

 served in Formalin which had no apparent effect 

 on the pesticides to be analyzed. The specimens 

 were measured and weighed and placed in tared 

 disposable pipets that had been plugged with glass 

 wool at the small end, or for larger fish in similarly 

 prepared glass tubing of appropriate size. The fish 

 were dried in an oven at 65^0 to constant weight 

 and reweighed to obtain dry weight. Each fish was 



20 



••• ••••"^, •,• 



w * V A 



CO 



cPcP 



J^ 



"h 



J L 



20 



30 40 50 60 



STANDARD LENGTH (mm) 



Figure 2. — Increase in percent fat with increase in length for 

 Stenobrachius leucopsarus. Dark circles equal fat as a percent of 

 dry weight; open circles, as a percent of wet weight. Fat equals 

 hexane extractable substances. Pesticide values forfish less than 30 

 mm standard length (SL) were not used because of the greater 

 variation in these values than in larger fish in which fat content was 

 more stabilized. 



macerated in the tube and extracted into a 15-ml 

 graduated centrifuge tube with 10 ml of hexane. 

 The remains of the fish in the pipet were dried and 

 reweighed to obtain the weight of material ex- 

 tracted. 



The extract in the centrifuge tube was mixed to 

 uniformity, and an aliquot equal to 20 mg or less of 

 fat removed. This was reduced in volume if neces- 

 sary and passed through an activated alumina 

 column as described by McClure (1972). The 

 cleaned up sample was again reduced in volume if 

 necessary and injected into a model 402 Hewlett 

 Packard gas chromatograph (GLC) with a Ni^^ 

 electron capture detector. The 6-foot glass column 

 contained 1.5% OV-17/1.95%QF-l, on 100/120 

 mesh Supelcoport. 



DDT gets its name from its former chemical 

 designation, p,p'-dichlorodiphenyltrichloro- 

 ethane. The current chemical designations for 

 DDT and its metabolic products mentioned in this 

 paper are: 



p,p -DDT 



p,p -DDD (TDE) 



p,p -DDE 



p,p, -DDMU 



Kelthane (Dicofol) 



1 , l-dichloro-2,2-bis(p-chloro- 



phenyDethane 

 l,l-dichloro-2,2-bis(p-chloro- 



phenyDethane 

 l,l-dichloro-2,2-bis(p-chloro- 



pheny 1 )ethy lene 

 l-chloro-2,2-bis(p-chlorophe- 



nyl)ethylene 

 l,l-bis(p-chlorophenyl)-2,2, 



2-trichloroethanol 



For the ortho-para isomers of DDT, DDD, DDE, 

 and DDMU substitute 2(o-chlorophenyl)-2-('p- 

 chlorophenyl) for 2,2-bisrp-chlorophenyl). In this 

 paper total DDT includes p,p 'DDT, o,p 'DDT, 

 p,p 'DDD, o,p 'DDD, andp.p'DDE. While o,p'DDE 

 andp,p'DDMU are present, although not as major 

 constituents of the fish samples, both have the 

 same short retention times on the column used 

 and are interfered with by a number of other un- 

 knowns as tends to be true of anything having a 

 shorter retention time than p,p 'DDE in these 

 samples; therefore they were omitted because of 

 the difficulty in identification and quantification. 

 Kelthane was also omitted because it breaks down 

 on this column (Morgan, 1967) to a material that 

 has a low response and an even shorter retention 

 time than DDMU. 



For the purposes of this paper we assume that 

 DDT is metabolized (O'Brien, 1967; Morgan, 1967; 

 Menzie, 1969) as follows: 



280 



