Gulf and Caribbean Research Volume 2 Issue 2 January 1966 Habits of Juvenile Fishes in Two Rhode Island Estuaries Mohammed Saeed Mulkana Follow this and additional works at: https://aquila.usm.edu/gcr Part of the Marine Biology Commons Recommended Citation Mulkana, M. S. 1966. Habits of Juvenile Fishes in Two Rhode Island Estuaries. Gulf Research Reports 2 (2): 97-167. Retrieved from https://aquila.usm.edu/gcr/vol2/iss2/2 DOI: https://doi.org/10.18785/grr.0202.02 This Article is brought to you for free and open access by The Aquila Digital Community. It has been accepted for inclusion in Gulf and Caribbean Research by an authorized editor of The Aquila Digital Community. For more information, please contact [email protected]. The Growth And Feeding Habits of Juvenile Fishes In Two Rhode Island Estuaries bY MOHAMMED SAEED MULKANA 97 TABLE OF CONTENTS Page ABSTRACT .................................................................................................. 100 LIST OF FIGURES .................................................................................... 101 LIST OF TABLES ...................................................................................... 102 I . INTRODUCTION .......................................................................... 103 I1 . REVIEW OF THE LITERATURE ............................................ 106 I11 . METHODS AND MATERIALS ................................................ 107 IV. THE ENVIRONMENT ......................................................... 109 A . Topographic and Edaphic Features ................................. 109 1. Topography ...................................................................... 109 2 . Hydrographic zones ........................................................ 110 3 . Edaphic and biological aspects ...................................... 111 B . Hydrography ........................................................................... 113 .. 1. Salinity .............................................................................. 113 2 . Temperature .................................................................... 113 V . RESULTS .......................................................................................... 116 A . Occurrence and Abundance of Fishes ............................ 116 1. Total Abundance .............................................................. 116 2. Population Components ................................................ 116 121 3 . Relative Abundance... 4. Horizontal Distribution .................................................. 127 B . Growth ..................................................................................... 129 1. Pseudopleuronectes americanus .................................... 129 2. Brevoortia.. tyrannzis.. ......................................................... 131 3 . Menzdza memzdza ............................................................. 132 C. Food and Feeding Habits ..................................................... 136 1. Pseudopleuronectes.. .. americamus ...................................... 136 2 . Menzdza menzdza .............................................................. 146 3 . Brevoortia tyrarnnus ......................................................... 153 D . Predators and Parasites ....................................................... 156 VI . DISCUSSION .................................................................................. 157 VI1. SUMMARY ..................................................................................... 162 VI11 . ACKNOWLEDGEMENTS ............................................................ 163 IX. BIBLIOGRAPHY ............................................................................ 164 99 ABSTRACT The basic purpose of this work was to gain information on the possible role of some Rhode Island estuaries as nursery grounds for young migrant and resident species of fishes. The areas selected were, the lower Pettaquamscutt River and the lower Point Judith Pond, both in the town of Narragansett, Rhode Island. The seining operations were carried through summer and early fall of 1962 when these estuaries are heavily used as nursery grounds. Major features of the occurrence, abundance and distribution of young fishes were deduced by examining samples from seine hauls. Thirty-six species were recorded from the lower river while only twenty-four species occurred in the lower pond. The abundance of fishes rose with a rise in tempera- ture and declined with decreasing temperature, but no correlation was observed between maximum temperature and maximum number of individ- uals occurring at any time. The number of species and the abundance of indiuidual fish were highest at the seaward station (Sta. 11) in the lower river. Among the selected species, the abundance of Menidia menidia was two to three times higher at Middle Bridge (Sta. 11) than at any other station. The behavior of Pseudopleuronectes americanus, found primarily at seaward stations, and the migrant species Brevoortia tyrannus observed at landward stations, is discussed. The species P. americanus grew at the rate of 10 mm per month, but exhibited no variation in growth in the two estuarine systems. The popu- lations of B. tyrannus from the lower Pettaquamscutt River had a growth rate that was almost twice that of populations in the lower Point Judith Pond. The growth rate of these species in Rhode lsland waters compare favorably with similar data from other studies. The juvenile M. menidia demonstrated a higher rate of growth at seaward stations in both the areas, especially in the lower riuer. Forty-three types of prey organisms belonging to diverse taxonomic groups were identified from stomach contents of P. americanus and thirty- nine types were noted in the gut contents of M. menidia. Amlysis of the degree of fullness indicated markedly high percentage of full stomachs in the two study areas. However the degree of fullness was comparatively less in fish occurring in the lower pond. The scarcity of food in the lower pond, apparently forced M. menidia (51-80 mm) to feed upon phytoplank- ton as a substitute food or “forced diet”. Im P. americanus and M. menidia a change in diet was noted with change itz size. The taxon, B. tyrannus, which depended upon phytoplankton and suspended organic matter, did not show any change in food with change in body size. While no effective predation was observed, an infection by the sporo- zoan parasites, Glugea hertwigi, was marked in both Osmerus mordax and P. americanus. Low catches of P. americanus were perhaps due to higher infection. A comparison of the parameters of abundance, growth and food habits reveal that the two estuarine systems are suitable nursery grounds, and that the lower river is a more favorable taursery than the lower pond. 100 LIST OF FIGURES Figure Page 1. Map of Pettaquamscutt River estuary showing location of seining.. stations ................................................................................ 104 2. Map of Point Judith Pond estuary with locations of seining .............................................................................. stations .............................................................................. 105 3. The distribution of hydrographical zones in the Pettaquams Cutt River and the lower Point Judith Pond ............................ 112 4. Surface and bottom salinities recorded from July 11 to Octo- ber 20, 1962 in the lower Pettaquamscutt River and in the lower Point Judith Pond ................................................................ 114 5. Surface and bottom salinities recorded from the lower Point Judith Pond ...................................................................................... 115 6. Surface temperature measurements recorded from July 11 to October 20, 1962 in the lower Pettaquamscutt River and in the lower Point Judith Pond ........................................................ 117 7. Variations in the total abundance of fishes and temperature at weekly intervals in the lower Pettaquamscutt River and the lower Point Judith Pond ........................................................ 120 8. Variations in abundance of migrant and resident species of fishes at weekly intervals in the lower Pettaquamscutt River and in the lower Point Judith Pond ............................................ 122 9. Variations in the weekly catches of Alenidia menidia during the summer and early fall of 1962 at four seining stations ...... 124 10. Variations in weekly catches of Pseudopleuronectes ameri- canus and Brevoortia tyrannus in the lower Pettaquamscutt River .................................................................................................. 125 11. Variations in weekly catches of Pseudopleuronectes ameri- canus and Brevoortia tyrannus in the lower Point Judith Pond .................................................................................................. 126 12. The class size (in cms) distribution of the selected species at four seining.. stations ........................................................................ 128 13. Test of the significance of the differences of average weekly growth of Psezcdopleuronectes americanus collected from the lower river and the lower pond stations .................................... 130 14. Comparison of the average growth data of Brevoortia tyrannus Collected from the lower pond the lower river stations ........... 133 15. Comparison of the average growth data of Melzidia menidia