Research Document - 2001/006

Status of striped bass (Morone saxatilis) in the Gulf of St. Lawrence in 1998.

By Bradford, Chaput, G., Douglas, S., Hayward, J.

Abstract

Spawner abundance for 1998 was estimated as a minimum at about 3,400 fish (575 females; 2,825 males) and as a maximum, about 4,150 fish (700 females; 3450 males). The latter estimate assumes that 22% of the adults had spawned before population estimates were logistically feasible on the Northwest Miramichi. The spawning population has not recovered from the precipitous decline from 1995 when spawners, dominated by the 1991 yearclass, were estimated to be 50,000 fish. The 1991 yearclass now appears to number no more than 1000 fish. Combined losses from natural factors and human activities during 1997-1998 exceeded recruitment (males at age 3, females at age 4) by at least a factor of two. The 1995 yearclass is poor (age 3⁺ males numbered ~3,000 fish), a result contrary to earlier expectations that a combination of high abundance at age 0⁺ and above average body size leading to high first winter survivorship would yield a strong yearclass in 1998. Available data indicates the 1995 yearclass experienced high mortality during their second winter (1996-1997). Female spawner abundance could increase in 1999 to 2,000-2,500 fish with full recruitment of age 4⁺ females (1995 yearclass). Although this would represent an improvement over 1998 levels, the provisional conservation requirement for this population of 5,000 females would not be met, for the third consecutive year. The juvenile abundance index obtained by sampling of the bycatch in the autumn smelt fishery corresponded to the low number of females in the spawning population in 1998. The yearclass is, however, large bodied (modal length = 13 cm FL), possibly due to a protracted growth season realized by an nusually-early-for-this-population onset of spawning (~20 May). Their prospects for winter survival are correspondingly good. Production of Miramichi striped bass through to the year 2000, will likely depend on the weak 1995 yearclass, with only marginal further contributions from the once strong 1991 yearclass. The decline in abundance of southern Gulf of St. Lawrence striped bass that was precipitated by unregulated commercial fishing from July, 1994 to March, 1996 has continued through to 1998. The likelihood that this population will meet conservation spawning requirements in either 1999 or 2000 is low. Tolerances within the current management framework for mortalities incurred through hook-and-release recreational angling and First Nation food fisheries can no longer be justified.

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