OLLA. BEJDA, and MARTIN: ACTIVITY OF TAUTOGA ONITIS 



larger than could be crushed by the pharyngeal 

 teeth. The fish would ingest the mussel, unsuc- 

 cessfully attempt to crush it, and then egest 

 it, the process being repeated 20 to 30 times. 

 We also found in a preliminary determination 

 of the maximum crushable size that fish, 34 to 

 53 cm, could crush mussels that were only 0.47 

 times the maximum size they could ingest. 



Seasonal Movements 



Direct observations made during the day with 

 scuba from October 1971 through May 1972 

 and from October 1972 through January 1973 

 indicated that there was a difference in the 

 seasonal movement between small fish (^25 cm, 

 2-3 yr old) and large fish (>25 cm, >4 yr old). 

 The ages of fish were estimated from calculated 

 total lengths by Cooper (1967). Tautog of vary- 

 ing sizes were observed in close proximity to 

 the basin on 12 October 1971, at an average 

 water temperature of 17.0°C (range: 15.2°- 

 19.5 °C). On 1 November with the water temper- 

 ature averaging 10.0°C (range: 8.9°-10.6°C), 

 no large tautog were sighted, but about 25 

 small ones were seen swimming within 1 m of 

 the basin walls. Small fish were still active on 

 18 November (water temperature 10.0° C: 

 9.7°-10.1°C). On 9 December 1971, and 5 

 January 1972, with temperatures ranging from 

 4.0° to 5.5°C, a total of approximately 40 small 

 tautog was sighted within the basin. These fish 

 appeared lethargic and rested against the basin 

 walls. When prodded by a diver, they moved 

 only a few feet before settling to the bottom 

 once again. 



Both large and small fish were sighted on 10 

 May 1972 with an average temperature of 

 10.6°C (range: 8.5°-11.5°C) and appeared nor- 

 mally active. 



Diving observations the following fall and 

 winter substantially supported the fact that 

 small fish wintered inshore. On 2 October 1972, 

 we sighted normally active large and small 

 tautog (water temperature 16.8°C: 16.2°- 

 17.7° C). On 26 October with the temperature 

 averaging 10.0°C (range: 9.6°-10.5°C), we 

 found no large fish but sighted at least 30 small 

 fish which appeared normally active. During 

 dives on 27 November and 29 December 1972, 

 and 9 January 1973, with the temperature rang- 

 ing 2.0° to 4.8°C, we sighted approximately 35 

 small fish (^ 25 cm) lying in a torpid state on 



the bottom between pilings and the basin walls 

 or in bottom depressions within 10 cm of the 

 wall. Some of these fish were partially covered 

 with silt. Opercular movements were so shallow 

 as to be almost undiscernible. Examination of 

 the digestive tracts of five fish captured during 

 this period showed that the fish had not eaten 

 for some time as indicated by the empty and 

 flaccid condition of the tracts. 



We concluded from these observations that 

 fish at least larger than 25 cm moved offshore 

 to winter, agreeing with the conclusions of 

 Cooper (1966) for a population residing in Nar- 

 ragansett Bay, Rhode Island. However, small 

 fish (approximately ^25 cm) remained inshore 

 throughout the year in close proximity to the 

 home site. 



DISCUSSION 



The tautog's pattern of being active during 

 the day and inactive at night is a typical labrid 

 trait having been observed in a number of spe- 

 cies. For example, field observations in the Pa- 

 cific by Hobson (1965, 1968, 1972) showed this 

 pattern to be present in five species (Bodiaiius 

 diplotaeiiia, Halichoeres )iicholsi, Labroides 

 phthirophagus, Thalassoma duperrey, and T. 

 lucasanum). Th* pattern was presumed to be 

 present in Hali^oeres dispilus, Hemipteronotus 

 mundiceps, and H. pavoninus since the fish were 

 observed in the active state during the day but 

 not sighted at night, having apparently buried 

 under sand or rested in crevices. Field obser- 

 vations in the Atlantic by'^arck and Davis 

 (1966) on Bodianus rufus, Clepticus parrai, 

 Lachitolaimus ma.vimus, and Thalassoma bi- 

 fasciatum also show the typical labrid day ac- 

 tive/night inactive pattern. 



Whether a labrid species spends the night 

 buried under sand or lying in cracks or crevices, 

 all appear to be in a state of low responsiveness. 

 Tauber and Weitzman (1969) investigated the 

 level of responsiveness of the slippery dick, 

 Irideo bivittata, at night. They found the fish 

 to be in a state that resembled the mammalian 

 sleep phase characterized by decreased respon- 

 siveness to altering stimuli, diminished or ir- 

 regular respiration, and eye movement activity. 



The low level of responsiveness present at 

 night in labrids and other species with a similar 

 habit has wide ramifications with regard to 



33 



