OLLA ET AL.: FEEDING BEHAVIOR OF THE GUNNER 



tracked intermittently. When tracking was possi- 

 ble, the fish exhibited the same movement pattern 

 as the other seven fish. All observed movements 

 were restricted to the area of riprap surrounding 

 the release point and did not exceed 25 m from the 

 release point. 



While using scuba, we were able to sight three of 

 the tagged fish directly (no. 1, 2, and 4; Table 1). 

 They were feeding and appeared to be normally 

 responsive. The attached transmitter had no ap- 

 parent effect on orientation or swimming ability. 



Seasonal Activity 



In late fall, when water temperatures dropped 

 to 5° to 6°C, cunner were observed to be inactive 

 and torpid, lying in cracks and crevices both day 

 and night, similar to what Green and Farwell 

 (1971) described for cunner in Newfoundland and 

 what we described for young tautog (011a et al. 

 1974). Some of these fish were covered with a fine 

 layer of silt. Examination of digestive tracts from 

 17 torpid fish indicated that they were not feeding. 

 The fish remained torpid throughout the winter 

 with water temperatures ranging from 2.5° to 

 5.0°C until the early spring when they became 

 active as the water temperature rose above 6°C. 



Feeding 



Cunner generally occur in loosely formed 

 aggregations and feed primarily as individuals 

 rather than in any organized social grouping. One 

 exception to this is the social interaction and 

 facilitation which occur when one or more fish 

 come upon a particularly abundant concentration 

 of food. An increase in the intensity of feeding 

 above that which constitutes the normal grazing, 

 picking, and searching activity serves to attract 

 cunner from the surrounding areas. As the 

 number of fish attracted to the feeding area 

 increases, so does the intensity of feeding, serving 

 to attract more and more fish until the food has 

 been consumed. On a number of occasions (30-40), 

 after placing a clump of Mytilus edulis with 

 crushed shells at a particular place on the bottom, 

 we have observed the attraction of 50 or more 

 cunner within 1 to 2 min after the first few fish had 

 found the food and begun to feed. 



Cunner feed both in the water column and 

 benthically. When feeding in the water column 

 with a current present, the fish face into the 

 current while maintaining position and visually 



scanning for suspended food items. Water column 

 foraging is typified by high frequency of eye and 

 head movements as the fish search in all directions. 

 When a food item is sighted, the fish swims to it, 

 grasps the item, and then returns to the original 

 search posture. Fish often search the water column 

 while remaining in close proximity to objects af- 

 fording cover from the full force of the current. 

 Only after sighting a food item does the fish move 

 into the current to ingest it and then return to its 

 searching position. In this manner, the fish effec- 

 tively conserves energy otherwise required to 

 maintain its position in the current between 

 ingestions. Discontinuities of the bottom, while 

 providing cover from the current, also act to cause 

 turbulence and upwellings, aiding in separating 

 and spreading the food items. Fish may feed in 

 this manner during the day for an entire tidal 

 cycle, the duration and frequency depending both 

 on food density and level of satiation. A typical 

 food item which cunner may be ingesting during 

 this type of feeding and which occurred in sig- 

 nificant quantities in stomach samples was the 

 isopod, Idofea baltica (Table 3). This species may 

 occur free floating, attached to bits of flotsam, 

 such as algae or eel grass, or on fixed substrates. 



In situations where there is little or no current, 

 cunner search the water column by actively mov- 

 ing. There is a general dispersal and lack of any 

 particular directional orientation in the absence of 

 a current which is similar to Stevenson's (1972) 

 observations of reef inhabitants at Bimini. 



When feeding on bottom or vertical substrates, 

 the fish, exhibiting a high intensity of eye 

 movements, visually search the forage area, their 

 snouts touching or within several centimeters of 



Table 3.-Gontents of cunner and tautxjg digestive tracts. 



Percent of total contents' 



Cunner Tautog 



May- July- Sept.- May- July- Sept.- 



Item June Aug. Oct. June Aug. Oct. 



Mytilus edulis 57.1 4.3 13.0 74.3 87.9 83.1 



Idotea baltica 0.5 72.1 61.7 4.6 2.7 — 

 Microcrusta- 



ceans^ 4.4 — — 0,5 — — 



Cirripeds 0.2 1.6 1.9 15.3 2.7 7.4 



Bractiyurans 13.4 2.0 10.9 4.2 3.6 5.9 



Fish remains 11.8 18.1 10.6 _ _ _ 



Debris 7.6 1.9 1.9 1.1 3.1 3.6 



Fish eggs 0.4 — — — — — 



Gastropods 1.2 — — — — — 



Carldeans 3.2 — — — — — 



No. fish 31 21 12 14 12 13 



TL (mm) 63-215 108-240 154-223 105-254 136-260 177-235 



'Determined by volume (Windell 1968). 

 ^Amphipods, copepods, and mysids. 



897 



