Behavior of Adult American Shad (Alosa sapidissima) Homing to the Connecticut River from Long Island Sound

1973 ◽  
Vol 30 (12) ◽  
pp. 1847-1860 ◽  
Author(s):  
Julian J. Dodson ◽  
William C. Leggett
Keyword(s):  
Tidal Current ◽  
Open Water ◽  
American Shad ◽  
Behavior Patterns ◽  
Connecticut River ◽  
Directed Movement ◽  
Alosa Sapidissima ◽  
Preferred Direction ◽  
Tidal Current Velocity ◽  
Ultrasonic Tracking

The migratory behavior of American shad (Alosa sapidissima) approaching their natal river during the final saltwater stage of the spawning migration was studied using ultrasonic tracking and conventional tagging procedures. Initial displacement of most sonic-tagged shad released without displacement adjacent to and 10 km west of the Connecticut River was not in the direction of the home river. These fish, however, homed successfully to the Connecticut River as did dart-tagged shad released in the same areas.Shad exhibited two major behavior patterns; countercurrent orientation in response to the reversing tidal current and adjustment of swimming speed to changes in tidal velocity. Countercurrent orientation was equally significant during daylight and darkness, whereas the adjustment of swimming speeds to tidal current velocity was more significant during daylight than darkness.Shad tracked to the west exhibited a westerly bias inherent in the basic open water behavior patterns. Shad exhibited a greater degree of directed movement when oriented against the ebb tide and adjusted their swimming speeds to exceed the ebb tide velocity and to approximately equal the flood tide velocity. Shad tracked to the east exhibited the same major behavior patterns but with the opposite directional bias.A hypothesis is presented suggesting that the location of the home river is achieved by means of a nonrandom search. Environmental clues indicative of the Connecticut River act to establish a preferred direction of displacement while the actual unidirectional displacement is achieved by reference to the rate and direction of tidal currents.

Role of Olfaction and Vision in the Behavior of American Shad (Alosa sapidissima) Homing to the Connecticut River from Long Island Sound

1974 ◽  
Vol 31 (10) ◽  
pp. 1607-1619 ◽  
Author(s):  
Julian J. Dodson ◽  
William C. Leggett
Keyword(s):  
Tidal Current ◽  
Long Island ◽  
Long Island Sound ◽  
American Shad ◽  
Connecticut River ◽  
Alosa Sapidissima ◽  
Preferred Direction ◽  
Tidal Current Velocity ◽  
Migratory Path ◽  
Island Sound

Twenty-two adult American shad (Alosa sapidissima), captured, sensory-impaired, sonic-tagged, and released adjacent to and 10 km west of the Connecticut River, were tracked in Long Island Sound in 1972. Both anosmic and blind/anosmic shad oriented into the tidal current and altered swimming speeds in relation to changes in tidal current velocity as do unimpaired fish. They did not, however, exhibit the consistency in these behavioral responses that resulted in westerly displacement in unimpaired shad. Blind shad exhibited neither of these behavior patterns but did tend to affect a westerly displacement in Long Island Sound.Dart-tagged adult shad that were sensory-impaired and released without displacement in the same areas of Long Island Sound in 1971 and 1972 homed less successfully to the Connecticut River than did unimpaired dart-tagged shad released in the same years. Anosmic dart-tagged shad located the Connecticut River less successfully than unimpaired shad. Blind shad successfully located the river from 10 km distance but failed to do so when released adjacent to the river. Blind/anosmic shad failed to locate the river from either release site.It was concluded that an olfactory–rheotaxic mechanism forms the basis of the location of the Connecticut River by shad. The preferred direction of displacement appears to be established by olfactory clues indicative of the Connecticut River whereas the orientation along the migratory path is maintained by reference to the rate and direction of tidal currents. Vision alone cannot account for this rheotaxic response.

Net Avoidance Behavior in American Shad (Alosa sapidissima) as Observed by Ultrasonic Tracking Techniques

1971 ◽  
Vol 28 (8) ◽  
pp. 1167-1171 ◽  
Author(s):  
William C. Leggett ◽  
Robert A. Jones
Keyword(s):  
Lateral Line ◽  
Avoidance Behavior ◽  
Visual Detection ◽  
American Shad ◽  
Connecticut River ◽  
Alosa Sapidissima ◽  
Light Intensities ◽  
Ultrasonic Tracking ◽  
Ultrasonic Transmitters

During tracking of 13 adult American shad (Alosa sapidissima) with ultrasonic transmitters in 49 approaches to commercial drift gillnets in the lower Connecticut River, only one shad was captured. Typically, shad moved to within 1–2 m of the net before sensing its presence, then turned and swam along the net, close to the mesh, to its end, where they turned and continued their upriver migration. Sight appeared to play an important role in net detection. However, 14 avoidances were observed when light intensities were inadequate to allow visual detection of the mesh. It was concluded that other senses, perhaps the lateral line, also function in net avoidance, especially when sight is impaired.

The Behavior of Adult American Shad (Alosa sapidissima) During Migration from Salt to Fresh Water as Observed by Ultrasonic Tracking Techniques

1972 ◽  
Vol 29 (10) ◽  
pp. 1445-1449 ◽  
Author(s):  
Julian J. Dodson ◽  
William C. Leggett ◽  
Robert A. Jones
Keyword(s):  
Fresh Water ◽  
Behavior Pattern ◽  
Salt Water ◽  
Leading Edge ◽  
American Shad ◽  
Physiological Adaptation ◽  
Connecticut River ◽  
Alosa Sapidissima ◽  
Discharge Rates ◽  
Ultrasonic Tracking

Five of seven adult American shad (Alosa sapidissima), tracked continuously with ultrasonic transmitters in the lower estuary of the Connecticut River in 1968 during their spawning migration to fresh water, exhibited extensive meandering, ranging 24–53 hr in duration in the region of the saltwater–freshwater interface. The salinity in the Connecticut River is like a wedge; its daily position is dependent on upland discharge, and its hourly position is dependent on tidal activity. The fish were observed during all tidal conditions and at several discharge rates, and in all cases they remained near the leading edge of salt water during the meandering phase. This behavior pattern was not a result of handling nor was it a typical behavioral response to tidal cycle. It was concluded that the meandering observed in the region of the saltwater–freshwater interface was due to physiological adaptation of the fish to fresh water. Of the remaining two shad tagged, one proceeded directly upstream without meandering, and one moved downstream.

Food Availability and Consumption by Young Connecticut River Shad Alosa sapidissima

1972 ◽  
Vol 29 (10) ◽  
pp. 1495-1499 ◽  
Author(s):  
Raymond C. Levesque ◽  
Roger J. Reed
Keyword(s):  
Stomach Content ◽  
Food Habits ◽  
Negative Selection ◽  
Content Volume ◽  
American Shad ◽  
Initial Time ◽  
Connecticut River ◽  
Alosa Sapidissima ◽  
Selection For ◽  
Selection Of

Food habits of young American shad (Alosa sapidissima) were studied in the Connecticut River above Holyoke, Massachusetts, 1969. Diurnal feeding data revealed a peak in stomach content volume at 8:00 PM during midsummer. Larval shad fed mainly on aquatic crustaceans and tendipedid larvae and pupae. Juveniles ingested the most abundant organisms: crustaceans, tendipedid larvae and pupae, hydropsychid larvae and adult insects. Electivity data indicated positive selection for tendipedid pupae and crustaceans and negative selection for hydropsychid larvae and tendipedid larvae. Selection of Trichoptera larvae by young shad in significant amounts was documented for the initial time.

Comparison of Logistic Regression and Discriminant Analyses for Stock Identification of Anadromous Fish, with Application to Striped Bass (Morone saxatilis) and American Shad (Alosa sapidissima)

1990 ◽  
Vol 47 (8) ◽  
pp. 1570-1577 ◽  
Author(s):  
Michael H. Prager ◽  
Mary C. Fabrizio
Keyword(s):  
Logistic Regression ◽  
Striped Bass ◽  
Logistic Model ◽  
Morone Saxatilis ◽  
Hudson River ◽  
American Shad ◽  
Stock Identification ◽  
Connecticut River ◽  
Alosa Sapidissima ◽  
Discriminant Analyses

We examined the applicability of logistic regression to stock identification studies and compared its performance on two data sets to that of linear and quadratic discriminant functions. Logistic regression can be used to model a categorical dependent variable associated with continuous or discrete independent variables, and is preferred to discriminant analyses when the explanatory variables are not multivariate normal. Our examples were American shad (Alosa sapidissima) from the Connecticut River and Hudson River estuaries, and striped bass (Morone Saxatilis) from the Hudson River, Chesapeake Bay, and Roanoke River estuaries. In the examples we used a resampling method to assess classification and allocation errors of the two methods on new data. For the shad data, the logistic model classified significantly more fish correctly, and provided a significantly better estimate of stock composition. For the striped bass data, the two methods classified about the same proportion of fish correctly, but the logistic model gave a significantly better estimate of stock composition.

Effects of Biotic and Abiotic Factors on Growth and Relative Survival of Young American Shad, Alosa sapidissima, in the Connecticut River

1985 ◽  
Vol 42 (10) ◽  
pp. 1640-1648 ◽  
Author(s):  
Victor A. Crecco ◽  
Thomas F. Savoy
Keyword(s):  
Growth Rates ◽  
Abiotic Factors ◽  
Survival Rates ◽  
Relative Survival ◽  
American Shad ◽  
Zooplankton Abundance ◽  
Connecticut River ◽  
River Flows ◽  
Alosa Sapidissima ◽  
Specific Growth Rates

We examined the hypothesis that temporal oscillations in zooplankton abundance, river flows, and temperatures in the Connecticut River affect the survival and growth rates of larval and juvenile American shad, Alosa sapidissima, among 5-d cohorts. The relative survival rates between newly hatched shad larvae and juveniles were low among early cohorts (May 21 – June 15), but rose rapidly among later cohorts (June 21 – July 6) when river flows were low and temperatures and zooplankton densities were high. Age of larval and juvenile shad was estimated by counting daily rings on sagittal otoliths and age-specific length increments determined by backcalculation techniques. Cohort-specific growth rates of larval shad increased linearly with rising zooplankton densities, and asymptotically with rising river temperatures and declining flows. By contrast, juvenile growth rates among 5-d cohorts showed no significant linear or nonlinear relationships to water temperatures and flows.

Effects of Fluctuations in Hydrographic Conditions on Year-Class Strength of American Shad (Alosa sapidissima) in the Connecticut River

1984 ◽  
Vol 41 (8) ◽  
pp. 1216-1223 ◽  
Author(s):  
Victor A. Crecco ◽  
Thomas F. Savoy
Keyword(s):  
Environmental Variables ◽  
River Flow ◽  
Abiotic Factors ◽  
American Shad ◽  
Larval Feeding ◽  
Monthly Precipitation ◽  
Connecticut River ◽  
Alosa Sapidissima ◽  
Hydrographic Conditions ◽  
Class Strength

We evaluated a parent–progeny relationship for Connecticut River shad, Alosa sapidissima, with population data from 1966 through 1982. The hypothesis that shad year-class strength is established during larval development mainly by abiotic factors was assessed by correlation analysis between environmental variables, year-class strength, weekly zooplankton densities, hydrographic conditions, and larval feeding success among the 1979 through 1982 year-classes. No significant parent–progeny relationship was found for American shad even after recruitment variations due to river flow and water temperatures were removed. All three environmental variables (mean river discharge, water temperatures, and total monthly precipitation) were significantly correlated with shad year-class strength for the month of June, the period when most American shad larvae emerge.

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