OLLA, BEJDA, and.MARTIN: ACTIVITY OF TAUTOGA ONITIS 



100 METERS 



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Figure 2. — Areas demarcating the locations of tautog 

 during their daily movements as presented in Table 1 

 (an enlargement of area A, Figure 1). 



vations with our tracks of similar-sized fish, we 

 were led to conclude that this increase was the 

 result of the normal nightly return to the basin. 

 However the number of smaller fish (^25 cm) 

 appeared to remain the same throughout the 

 day and during evening twilight, i.e., there was 

 no discernible increase at evening twilight. To 

 affirm whether the smaller, younger fish did in 

 fact remain closer to the basin during the day 

 than the larger, older ones, we tagged two fish 

 20 and 25 cm (No. 7 and 8, Table 1), tracking 

 one for 34 and the other for 66.8 h. These fish 

 exhibited the typical habit of the larger fish of 

 being active during the day and inactive at night 

 (Table 2). However, in contrast to the larger 

 fish, these smaller fish remained within the 

 basin and never ventured farther than 2 m from 

 the walls. Examination of the digestive tract of 

 one of these smaller fish, recaptured after track- 

 ing had been terminated, showed the presence 

 of mussels throughout the tract, indicating 

 that this fish had been feeding on mussels at- 

 tached to the basin walls or other substrate 

 within the basin. 



These data indicate that tautog occur as an 

 essentially localized population at least from 

 July through mid-October. The basin acts as a 

 focal point for the population, providing a suit- 

 able night habitat for all fish and a forage area 

 for smaller fish. 



Four fish (No. 9-12, Table 1) tracked during 

 June 1972 exhibited quite different patterns of 

 daily movements. Two of these (No. 9 and 10) 

 ranged farther during the day and spent the 

 night at various locations other than the basin. 

 Tracking was discontinued on the other two 

 fish of this group (No. 11 and 12) during the 

 first day due to inclement weather. However, 

 a search the night following tracking termina- 

 tion and on three successive nights failed to 

 detect the presence of either fish in or around 

 the basin. They, too, evidently spent the night 

 at other locations. 



The major difference in fish tracked during 

 June from all other fish tracked was that all 

 June fish were in spawning condition, readily 

 extruding sperm or ova during the tagging pro- 

 cedure. Further, if this population bears any 

 similarities to the Narragansett Bay popula- 

 tion (Cooper, 1966), we surmise that during 

 June, fish are still arriving inshore from their 

 offshore wintering area and have not yet be- 

 come localized (at least fish of the size we were 

 tracking). 



On 26 September 1972, during the day, we 

 sighted just outside the basin (Area 3, Figure 2) 

 a tautog with a transmitter attached. Although 

 we could not ascertain when this fish was tagged, 

 it had been 49 days since the last tagging. The 

 fish, which appeared normally responsive, had 

 either remained localized within this area for 

 at least 49 days or possibly was one of the four 

 fish tagged during June that had not returned 

 to the basin at that time. 



Feeding 



There were varying amounts of food through- 

 out the digestive tracts of fish sampled at vari- 

 ous times of the day and just after evening twi- 

 light (Table 3). The tracts of fish sampled just 

 prior to morning twilight (23-83 min), while 

 still in an inactive night condition, were empty. 

 Thus it appears that the fish feed throughout 

 the day, beginning soon after morning twilight 

 and continuing up to evening twilight. Assum- 

 ing that the fish sampled just before morning 



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