Date of Award

Fall 12-20-2022

Degree Type

Masters Thesis

Degree Name

Master of Science (MS)

School

Ocean Science and Engineering

Committee Chair

Eric N. Powell

Committee Chair School

Ocean Science and Engineering

Committee Member 2

Roger Mann

Committee Member 3

Chet Rakocinski

Committee Member 3 School

Ocean Science and Engineering

Abstract

The ocean quahog (Arctica islandica) support an economically important fishery in the US, though little is known about their life history traits. To determine how these traits vary geographically, the age frequencies and growth rates from two New Jersey sites (NJ1 & NJ2) as well as Georges Bank (GB) and Long Island (LI) were analyzed. Though sexual dimorphism in bivalves is rare, recent research has shown that A. islandica display distinct differences in sizes between males and females, with females reaching larger sizes than those of males. To determine when this difference in size occurs, the growth rates of males and females were analyzed using Welch’s t-test. Results indicate that females begin outgrowing males between the ages of 10-15, at an average size of 50-55 mm. Rarely do males keep pace in growth with females beyond this point. Larger sizes in females may influence their presence in age frequencies based on size selectivity (> 80 mm) by commercial dredge. This is observed in the New Jersey sex ratios, as females are more frequent at a ratio 1:~0.80 at both sites. Age frequencies of NJ1 are very similar to those of LI and GB, yet NJ2 displays recruitment events not observed in any of the other sites. When comparing growth rates, A. islandica from southern sites are reaching milestone sizes 2-3x faster than those of Georges Bank, an effect of warmer bottom water temperatures in these southern areas.

Available for download on Tuesday, December 20, 2022

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