ABSTRACT
Introduction It has been demonstrated that hagsh populations cannot withstand heavy shing pressure (Martini et al., 1997a; Honma, 1998; Martini, 1998; AHWG, 2003). Subsequently, there is a clear need not only to understand how hagsh populations respond to a commercial shery, but also conservation measures that avoid overharvesting. Unfortunately, much of the scientic information required to assess the status of sh stocks is completely lacking for hagsh. Unambiguous estimates of abundance are dif-cult, if not impossible to obtain, growth rate and longevity are unknown, several aspects of the reproductive cycle are poorly understood, and it is unclear as to what extent populations can undergo a compensatory increase in production at low stock size. For example, for Atlantic hagsh, the time required for a clutch of eggs to ripen may approximate the teleost condition (i.e., 6-8 months) or be considerably longer (Patzner, 1998; Powell et al., 2004) and the latter may be expected to make it more dif-cult to compensate for heavy shing pressure. However, evidence for the lack of an obligatory spawning season in Atlantic hagsh populations (Cunningham, 1886; Nansen, 1887) and an ability to adjust the duration
Introduction ...................................................................................................... 41 Materials and methods .................................................................................... 43 Results and discussion .................................................................................... 45
Sex ratios and body length comparisons ................................................. 45 Distribution and evidence of a spawning migration ............................. 47
Length at maturity: Conservation harvesting .................................... 52 Is spawning a synchronized event in Atlantic hagsh?.................... 57
Can shing pressure on Atlantic hagsh stocks induce a compensatory increase in production? .................................................... 60
Acknowledgments ........................................................................................... 70 References ......................................................................................................... 71
of various phases of the reproductive cycle to environmental conditions may positively inuence production at reduced stock size. Ultimately, sustainable resource management seeks to match the level of removals to a level the resource can sustain. Challenges to sustainable management of hagsh sheries include high susceptibility to overexploitation due to life-history traits, catchability, and predominance of females in the catch which have been well documented for Atlantic hagsh (Scott and Scott, 1988; Honma, 1998; Martini, 1998; Patzner, 1998; AHWG, 2003; NEFSC, 2003; Grant, 2006). In addition, evidence of only short migrations (Walvig, 1963, 1967) suggests Atlantic hagsh populations are localized and recruitment-dependent.
