Able and Grothues: Diversity of the estuarine movements of Morone saxatilis 



433 



stream followed quickly (within a few days) for most 

 fish, but the range of speeds during these movements 

 overlapped with the speed of upstream movements from 

 Lower Bank to Chestnut Neck (0.1-0.3 km/h, n=ll 

 fish) and from Chestnut Neck to Little Egg Inlet (0.1- 

 2.2 km/h, «=12). Perhaps the slower movements be- 

 tween Chestnut Neck and Lower Bank reflect the steep- 

 er gradients in salinity, temperature, and especially pH 

 in this region (Fig. 3). Although most of these move- 

 ments occurred during the spring, others of similar 

 magnitude occurred at other times of the year, as was 

 the case for one fish during the winter of 2004 (Tag no. 

 99, Fig. 4). 



Discussion 



Annual and seasonal visits to the estuary 



The seasonal visits of many tagged striped bass to this 

 estuary reflect their seasonal migrations up and down 

 the east coast of the United States. This seasonal migra- 

 tion to the south in the fall and winter and to the north 

 in the spring and summer has been observed from prior 

 tag-recapture studies (e.g., Boreman and Lewis, 1987; 

 Waldman et al., 1990). The coastal ocean migrations of 

 larger juvenile and adult striped bass must influence 

 the timing and duration of their occurrence in estuaries. 

 These patterns differ along the east coast of the United 

 States and thus have to be taken into consideration when 

 evaluating occurrences in the study area. In general, 

 populations from North Carolina and southward are 

 considered riverine and do not make coastal migrations, 

 whereas those from Chesapeake Bay to the Bay of Fundy 

 are generally considered to be anadromous and highly 

 migratory (see Rulifson and Dadswell, 1995; Haeseker 

 et al., 1996; Bjorgo et al., 2000 for reviews of the rel- 

 evant literature), with the exception of the population 

 of the St. Lawrence estuary which is believed to be 

 resident (Coutant, 1985). Thus, it is not surprising that 

 large juvenile and adult striped bass from the Mullica 

 River-Great Bay estuary frequently left the estuary 

 for extended periods. This interpretation is supported 

 by the recapture by hook and line of fish we tagged in 

 the study area at a variety of locations along the coast 

 (northern New Jersey, south shore of Long Island, New 

 Hampshire) and implies the same seasonal migration 

 pattern. Further support is based on the detection of 

 one striped bass tagged in the Mullica River-Great Bay 

 and later detected in the Saco River, Maine, in a similar 

 observation site (Carter-) and fish tagged at Saco River, 

 Maine, that have been detected in the southern New 

 Jersey study estuary (n = 3) (Able and Grothues, pers. 

 observ.). Earlier tag-recapture studies found striped bass 

 in the Mullica River-Great Bay estuarine system that 



had been tagged on the south shore of Long Island and 

 northern New Jersey (Clark, 1968). 



This study is one of the few that presents data on 

 the high (589^) and seasonal rate of return to an estu- 

 ary. Most of these returns occurred in the spring and 

 fall when water temperatures were 10-20°C. Annual 

 returns to the same estuary have also been reported in 

 Chesapeake Bay tributaries for a few individuals in =9) 

 where the returns were assumed to be related to spawn- 

 ing (Hocutt et al., 1990). Many of the instances of fidel- 

 ity of tagged striped bass to the Mullica River-Great 

 Bay system were the result of detections at the inlet 

 and not farther up the estuary. One possible interpre- 

 tation is that these fish enter numerous inlets during 

 the north and south coastal ocean migrations, thus 

 providing the relatively high frequency of detections at 

 the study site. This idea could be tested at observation 

 sites in other estuaries. 



Spatial and temporal patterns within the estuary 



Movements within the estuary were frequently dynamic 

 and were most likely to occur in the spring and fall. The 

 spring movements of several fish tagged near Little Egg 

 Inlet and near Chestnut Neck were commonly upstream 

 to the vicinity of the freshwater-saltwater interface 

 (Fig. 4). These were typically quick movements followed 

 by similarly rapid movements downstream and into the 

 ocean. The short duration in the riverine portion of the 

 study area may reflect the avoidance of the low pH that 

 typically occurs in this system (Fig. 3). These brief visits 

 in the study area were very different from those found in 

 a pilot study iii=4 males, 5 females) in upper Chesapeake 

 Bay tributaries, which indicated a long residence time in 

 the spawning areas (30 days) at least for males (Hocutt 

 et al., 1990). Similarly, in the Roanoke River in North 

 Carolina males remained on the spawning grounds for 

 21-22 days and females for 8-11 days in different years 

 (Carmichael et al., 1998). The timing and types of move- 

 ment in the study area, although consistent with an 

 upstream movement for spawning, do not appear to be 

 consistently successful. Some spawning does occur in the 

 upstream portion of the estuary (see Hoff'^ for accounts 

 of egg and larvae collections). However, numerous col- 

 lections in this estuary with a variety of gears, such as 

 otter trawls (Martino and Able, 2003), seines (Able et al., 

 1996), traps (Able et al., 2006), and weirs (Able et al., 

 1996), have yielded less than 20 young-of-the-year ( YOY) 

 (<100 mm FL) striped bass. Over the same period, we 

 have frequently collected numerous YOY striped bass in 



2 Carter, J. 2005. Unpubl. data. Department of Life Sci- 

 ences, Univ. New England, 11 Hills Beach Road, Biddeford, 

 ME 04005. 



3 Hoff, H. K. 1976. The life history of striped bass, Morone 

 saxatilis ( Walbaum). in the Great Bay-Mullica River estuary 

 and in the vicinity of Little Egg Inlet. In Ecological studies 

 in the bays and other waterways near Little Egg Inlet and in 

 the ocean in the vicinity of the proposed site for the Atlantic 

 Generating Sation, New Jersey (C. D. Milstein, and D. L. 

 Thomas, eds.), p. 43-53. Progress Report for the period 

 January-December 1975. Public Service Electric and Gas 

 Company, 80 Park Plaza T-17-A, Newark, NJ 07101. 



