An examination of the population characteristics, movement patterns, and recreational fishing of striped bass (Morone saxatilis) in Minas Basin, N.S. during summer 2008
Executive Summary
This striped bass study was initiated because of the known presence of both Shubenacadie River origin and migrant USA striped bass in the Minas Basin, the “threatened” species COSEWIC designation, the existence of a strong recreational fishery, and the potential for impacts on the population due to the operation of in-stream tidal energy technology in the area.
Striped bass were sampled from Minas Basin through angling creel census during summer 2008. In total, 574 striped bass were sampled for length, weight, scales, and tissue. In addition, 529 were tagged with individually numbered spaghetti tags. Striped bass ranged in length from 20.7-90.6cm FL, with a mean fork length of 40.5cm. Data from FL(cm) and Wt(Kg) measurements determined a weight-length relationship: LOG(Wt) = 3.30LOG(FL)-5.58. Age frequency showed a range from 1-11 years. The mean age was 4.3 years, with 75% of bass sampled being within the Age 2-4 year class. Total mortality (Z) was estimated to be 0.60. Angling effort totalling 1732 rod hours was recorded from June to October, 2008, with an average 7 anglers fishing per tide. Catch per unit effort (Fish/Rod Hour) was determined to be 0.35, with peak landing periods indicating a relationship with the lunar cycle. Recreational anglers were responsible for all tag returns, which resulted in a 25% recapture rate. On average, striped bass recaptures were at large 27 days post tagging. Growth rates were compared across age groups which produced the exponential equation: Growth Rate (mm/day) = 1.71e-0.35(Age). Bass movements obtained from tag returns was limited, as 92% of returns were from bass recaptured at the site of initial tagging, indicating a pattern of site fidelity throughout the summer season. Further studies on striped bass movements, using acoustic tracking technology, are planned for 2009.
Genetic analysis using mitochondrial DNA was performed on 60 striped bass tissue samples; 20 fish each from Shubenacadie River, Five Islands, and Southern Bight of the Minas Basin near Wolfville. The analysis showed that 11% of the fish sampled were significantly different from the Shubenacadie captured bass and thus considered to be from other stocks, most likely US migrants. The highest level of differentiation from NS spawned bass was observed in samples collected from Five Islands, NS.